Topic #10 from our series.
You will get efficient and thoughtful service from Teao.
Read on for more expert advice on transforming your Mustang into a high-performance handling machine. This week's topic is all about dampers, one of the key elements to creating a good-handling Mustang. (If you missed the previous episodes, they're posted on our website in the FAQs & Tech Tips section.)
Please note that what we're talking about here are dampers&#;not dampeners. Often misspelled and mispronounced as "dampener," "damper" is the correct term for today's subject, high performance struts and shocks for your Mustang. For the record, a dampener is something that makes something else damp, i.e., moist. If your dampers turn into dampeners you need new dampers.
OK, it's a damper. Why is it called that?
"Damper" comes from the primary function of a shock or strut, which is to control spring oscillation by damping, i.e., calming it down or reducing it. After an initial compression or extension, a spring will vibrate for quite some time unless something damps the oscillation. A damped oscillation is one that fades away to zero over time. A damper, in the case of a late model Mustang in the form of a strut or shock, damps the spring's natural tendency to oscillate. When the strut or shock is well matched to the spring it controls, the spring oscillation will damp to zero very quickly, usually in only one complete oscillation cycle. If your Mustang had no dampers it would bounce uncontrollably while driving down the road, as hitting a succession of bumps would add new spring oscillations on top of the slowly fading oscillations of previous bumps. Not a sexy look, in our opinion, and downright dangerous.
What's the difference between a shock and a strut?
While a shock is primarily a damper, it may also have secondary functions. For example, a shock may also be used to limit suspension droop travel, to limit suspension jounce (bump) travel, or to mount a spring (commonly called a coil-over design).
On the other hand, a strut has an additional function over that of a shock; it's an integral structural link that helps define the suspension geometry. If you remove a strut from the car's suspension, the wheel will flop about as the geometry of the suspension is no longer completely defined. This cannot happen when you remove a shock from the suspension. Struts are made quite robustly because they are structural links and must withstand high bending loads from cornering and braking.
All to present Mustangs left Ford's assembly line with a strut front suspension and shocks in the rear suspension.
How a damper damps
The suspension springs and the car's mass form a resonant system; think of a guitar. Once activated by a bump, like plucking a string, the spring (string) and mass (car or guitar body) will continue to vibrate for a long time unless the energy is more quickly absorbed by a damper. On a guitar, you can stop the vibration by putting a finger on the string you plucked. In a Mustang, the damper works something like that finger to stop the spring from oscillating.
Give me some details on this spring oscillation thing.
Here's the big picture of how a damper does its work: it converts kinetic energy (motion) into heat. In the case of a Mustang, the hydraulic dampers have a piston inside an oil-filled tube. The piston moves up and down as the suspension moves. The piston motion forces hydraulic oil through a number of small holes. As the oil moves it heats up from friction, which dissipates the kinetic energy.
There are many different damper designs. Some of the differences are large, such as monotube vs. twin-tube, gas charged or not, high-pressure gas vs. lower pressure, adjustable damping or fixed. Other differences are small, and include a myriad of little design differences affecting a damper's performance and effectiveness.
What else does a damper do?
Dampers help keep the tires' tread in contact with the pavement. As every Mustang (and driving) enthusiast knows, that's pretty much the most important thing! They control how quickly weight transfers when braking, turning into a corner, and while accelerating (whether out of a fun curve on your commute or during a drag strip launch).
Dampers produce a force based on how fast the shaft moves, so the amount of damping produced is somewhat proportional to the shaft velocity. The damper only produces a force when it's moving. Good dampers will alter the amount of force according to the shaft velocity. The specifics of the valving design and resulting damping at different velocities affect ride quality as well as performance.
How much damping do you need?
The exact amount can be difficult to quantify&#;and more difficult to achieve&#;especially over a range of shaft velocities. Too much damping reduces tire grip and makes ride quality worse. Too little damping leads to vehicle instability because the spring oscillations are uncontrolled. Since both overdamping and underdamping reduce tire grip, getting it right is quite a trick!
If you're up for some technical stuff, in general, the suspension needs more damping forces at low shaft velocities. More damping is required during turning, braking and accelerating, when the velocity of the shafts in the dampers is low (1"-3"/sec). When the car goes over sharp bumps, the shaft velocities are going to be much higher (10"-20"/sec). To maintain decent ride quality, higher velocities require lower damping forces.
Different Damper Designs
Monotube dampers
This design has a single tube mostly filled with oil. A piston rides inside the tube, with the oil on each side. At one end of the tube, separated from the oil by a second piston, is a section containing a high-pressure gas.
The damping is accomplished by the piston moving up and down in the oil, driven by a rod extending outside of the exterior tube. Oil moves through the piston, allowing the piston and shaft to move inside the tube. The oil's movement is carefully controlled by various holes and valves. The piston design and its valves and orifices are what determine the damping characteristics of the strut or shock. Kind of an amazing engineering feat!
The high-pressure gas keeps the oil from cavitating (creating gas bubbles in the oil) in a not-wanted process called foaming. Foamed oil has a much lower viscosity than bubble-less oil and significantly reduces the damping action.
Twin tube dampers
This design has two tubes, one inside the other. The piston rides inside the inner tube. The space between the inner and outer tubes serves as a reservoir for the oil displaced when the shock shaft moves in and out of the damper body. This reservoir can also contain a separate low-pressure gas reservoir. A valve connects the inner cylinder to the outer (reservoir) cylinder.
Just as with a monotube damper, the piston has valves and holes to control oil flow. That determines the damper's characteristics, or how much it damps.
Click on the image for a larger version.
Which is more effective?
Ah, good question. Monotube dampers have better heat dissipation than twin tube dampers because the oil doesn't have to go through as much material and distance to radiate heat into the outside environment. As the damper does more work, the temperature of the oil increases, which lowers its viscosity, which reduces its damping ability. This gives monotube dampers an advantage in high-performance applications, where the damper is worked harder.
Monotube dampers also have larger pistons that allow more fluid to flow through the valve for a given amount of suspension travel. This allows the piston valves to create a damping curve with a better tradeoff between ride quality and handling.
Pro Tip: Dampers have a very large effect on transient handling and ride quality. In fact&#;and most people don't know this&#;they have far more effect on ride quality than springs do!
Two other factors to consider: rebound and compression
Compression
This is when the spring and damper compress, when your Mustang hits a bump, or on the outside of the car when the body rolls during cornering. The spring and corresponding damper compress, allowing the suspension to absorb the bump. As the unsprung mass (tire, wheel, and suspension) moves upward toward the chassis, the damper turns this kinetic energy into heat so the chassis doesn't oscillate in an uncontrolled way in response to the bump. Picture the old beaters you've seen in grocery store parking lots heaving and bouncing up and down as they hit speed bumps. Good dampers prevent that. The compression valving in the damper is designed to keep this oscillation under control.
Rebound
This is when the spring and damper extend in situations such as after compressing to absorb a bump, or when the tire drops into a depression, or on the side of the car toward the inside of the turn when the body rolls during cornering. The unsprung mass (suspension, tires, and wheels) is moving away from the chassis of the car. When the suspension is moving in this direction, the damper is damping the kinetic energy stored in the sprung mass, turning it into heat.
Either way, during compression and rebound, good dampers damp vertical chassis movement to keep spring oscillation to a minimum, keeping the tires on the road and you in control.
Adjustable Dampers
Adjustable dampers have a provision to allow adjusting their damping force level. A damper labeled "SA" has one adjustment (single adjustable). A damper labeled "DA" has two adjustments (double adjustable).
There are two types of SA adjustment. With some dampers the adjustment changes only the amount of rebound force (typical of Koni). With other SA dampers, the adjustment changes both rebound and compression forces at the same time (typical of Tokico). Note: these settings are paired, not independent. With DA dampers, one adjustment is typically for rebound forces and the second is for compression forces. With DA dampers the adjustments are independent of each other.
Adjustable dampers can offer an advantage by letting you tune the transient handling behavior of the car, like if you have a weekend autocross that you're driving to and from. If you know what you're doing, you'll want softer settings on your way to the event to avoid spilling your morning coffee, and more performance-oriented settings while on the course.
However, this type of tuning requires knowledge and time to learn when and how to adjust the dampers. You need to determine what handling behavior you want to change, and then know what you should adjust, at which end of the car, and in which direction. That requires a skill set that many enthusiasts don't need for how they enjoy their Mustangs. Often, fixed dampers are a better solution because they can't be misadjusted, and they just need to damp the springs you're using with them.
Why MM carries only certain dampers
There are many dampers available for late model Mustangs in a wide range of prices, quality, and features. Here at MM we're interested in improved performance, so we ignore the stock-replacement dampers, like those you'll find at your local auto parts store. Among performance-oriented dampers the old saying "you get what you pay for" holds true, but with some surprising exceptions: some manufacturers offer "high-performance" dampers that don't provide anywhere near the performance level advertised. Have no fear: you won't find those on the MM website.
That leads us to why we carry the dampers we do. Our primary requirement is excellent quality, of course, but we also look for whether there are versions suitable for street use and versions for track performance aimed at the amateur racing-on-a-budget enthusiast.
Two favorites, Koni and Bilstein, are excellent for street-driven Mustangs and those taken to open-track events. But many years ago we discovered their limitations for top-level amateur road racing. That moved us to develop our own line of MM Dampers based on Bilstein internal components. With our own dampers, we can offer several versions, each tailored to different uses and their own appropriate spring rates, plus additional features the big manufacturers don't offer.
Are you interested in learning more about Gear damper for automotive Interior? Contact us today to secure an expert consultation!
Note: We also like Tokico. Their D-spec and Illumina series are excellent for street & strip Mustangs. However, they left the U.S. market and the remaining selection of new Tokico dampers is sadly scanty.
And now, back to why MM Dampers are awesome. Seriously.
Damper design isn't easy; if it was, then all manufacturers would be making great products. In reality, there are more sub-par dampers on the market than good ones.
We put a lot of development time into our dampers. Designing and building a good damper requires a ton of work, and they're by far the most difficult part of the suspension system to get right. If your dampers are bad, they can make an otherwise great suspension design handle and ride like an ox cart.
For a damper intended for street use, there's always a tradeoff between good ride quality and good handling. Small differences in the damper design can skew the results too far in one direction, or even ruin both ride quality and handling.
When developing damper valving, the MM engineering team tests prototypes on a damper dynamometer, commonly called a "shock dyno." This machine extends and compresses the damper at varying velocities, while measuring and recording the forces created by the damper. Once we're happy with the dyno behavior, the damper goes onto a Mustang for real-world ride and handling testing.
Here's a generalized example of how the results of a shock dyno test look:
Click on the image for a larger version.
For on-car testing, we use a sophisticated Motec data logging system. This system has suspension travel sensors on all four corners, accelerometers for all three axes', a yaw sensor, and sensors for all the other basics such as throttle position, wheel speed, etc. We analyze the logged data to help design the next iteration of damper valving. Then it's back to the shock dyno. We repeat this process until the results meet our design goals for the ride and handling characteristics we're looking for.
Most MM dampers have fixed valving (check out the dampers listed for your Mustang to see our current offerings). This best suits the needs of most of our customers. Even for many in competitive road racing, the fixed valving provides the best results. Other than matching the MM series to your chosen spring rates, there's no need for any fiddling with damper tuning at the track (or on the street). That lets you concentrate on driving and improving your skills, rather than being a test driver.
You need a unique skill set to be a good test driver, including being able to evaluate the car's handling behavior to decide what changes to make to the dampers, if any. With adjustable dampers, decisions need to be made:You need a unique skill set to be a good test driver, including being able to evaluate the car's handling behavior to decide what changes to make to the dampers, if any.
That's a lot of decisions for an amateur racer. If you're up for it, MM does have very sophisticated high-end DA dampers for some applications, with more to come. At a more modest price level, we recommend Koni SA or DA dampers.
Matching dampers to springs
We've only been talking about dampers, but they're really just half of the important "springs and dampers" component of making a Mustang handle really well. Back in Episode 5 of this series we talked about springs in depth. We always recommend you choose the springs for your Mustang first&#;then get dampers to match. To help you make decisions we have a popular and handy Guide to Choosing Spring Rates and Dampers. The next step is contacting our Tech Associates for advice. For more advanced help, we have a Technical Services option to evaluate your situation and recommend springs and dampers just for your Mustang; choose the "Spring Rate" option.
Thanks for reading! Over the last 10 weeks we've presented the essentials of setting up a Mustang suspension that works really, really well. We hope you know now that elevating your Mustang's handling to being tremendous fun to drive in the twisties is a goal you can achieve.
If you've missed any of our popular Make Driving Fun! articles or want to forward them to a friend, you can read them all on our FAQs & Tech Tips page. Meanwhile, MM Tech Associates are standing by to help you get going on your project list to achieve maximum fun in your Mustang! More to come soon from your favorite car nerds at MM.
Super Dampers
Torque Converters
Transmissions
General Racing Tips
Q: Should I use the damper retaining bolt to
hold additional pulleys and accessory drives to the
damper?
A: No! Never use your damper retaining bolt to hold
any pulleys or accessory drive equipment. The damper
retaining bolt should be used only for bolting the damper
to the crankshaft. The damper must be banked on the
crank gear and must remain tightly secured in order
to function properly. When you use a long bolt or stud
in an attempt to hold accessory drive components and
your damper, the damper will usually come loose and
walk around on the front of the crank. This will quickly
result in damage to the keyway in the crank hub, the
key in the crankshaft, and possibly the crankshaft.
Accessory drive components should be registered on the
damper face to prevent run-out and they should be retained
using the pulley mounting bolts.
Q: Can I use my externally balanced damper on my internally
balanced engine?
A: No! Many people think you can simply remove
the weight and the damper would be okay for an internally
balanced engine. This is an incorrect assumption, however.
Due to the design of the damper, when the weight is
removed the damper will not function properly and could
potentially damage your engine. Send your damper to
ATI and we can convert your damper from externally balanced
to internally balanced.
Q: Where is the part number on my damper?
A: The part number is not stamped anywhere on the damper
itself. All of the part numbers you see stamped on the
damper are for the individual parts that comprise the
damper as a whole.
Q: What you need to know about damper bolts
A: The flat head countersunk bolts used in ATI&#;s Super Dampers require a T40 Plus Torx Bit.
If you are trying to source one yourself, this bit is also referred to as an IP40 Torx Plus
Insert Bit. Do not use a standard T40 Torx bit as it will not work and ultimately strip the
head. Remember! You must install, torque and Loctite® all bolts supplied with your Super
Damper regardless of whether or not you are bolting a pulley to the face of the damper.
Q: How do I send in my converter for a freshen-up?
A: Send your converter to: Whitestone
Road, Baltimore, MD . When sending converters to
us for a freshen-up or stall change, please make sure
that it is completely drained so transmission fluid
does not soak the box resulting in a torn box, or worse
&#; no box at all for the converter to be delivered
in. Also, be sure to provide us with a good daytime
number where you can be reached. This will
help to ensure that your converter does not sit on the
shelf waiting to be repaired and keeping you from racing
next weekend.
Click
here to download the Converter Overhaul Form
Q: Will my stall speed change after an overhaul?
A: No! Utilizing a detailed database of converter combinations
and specifications, ATI keeps detailed records of your
converter&#;s internal dimensions, build heights
and other necessary information. The converter is then
rebuilt to the exact specifications as before, unless
you request a dimension change.
Q: What happens to the converter if I change
anything in my combination?
A: It is best to check with an ATI representative before
making the change. Something as simple as tire size
can affect torque converter performance. Gear ratio,
stroke and cam timing are the three major changes that
will alter flash characteristics. If you purchase another
car, engine or transmission, your torque converter can
be sent back to ATI to update it to the new specifications.
If you switch from a Powerglide to a Turbo or Turbo
to Glide, the splines can be changed inside the converter.
You will need all the specifications on the new combination
before ATI works on your converter.
Click
here to download the Converter Spec Sheet
Q: Where is the serial number on my torque converter?
A: ATI torque converters have serial numbers
stamped across the snout of the converter (the part
that goes up against the back of the crank). Note: In January 1, ATI started stamping the number on the side of one of the mounting pads so the customer can see the number when it's installed in the car.
Any other
numbers stamped on the converter are foreign numbers
and usually mean that another manufacturer has worked
on the converter.
Q: What is the deal with big block converters?
A: With the advent of affordable 4-1/4&#;, 4-3/8&#;
and 4-1/2&#; stroke big block Chevy cranks, and
the resulting increases in torque and horsepower, has
come the increasing need for more efficient converter
designs. If your current or future engine combination
is based on a long stroke crank, don&#;t forget
that the torque converter may need to be modified or
changed to harness the additional power.
Q: How do I determine my stall speed - is it different
than flash?
A: In order to check your torque converter&#;s stall
speed, put your vehicle in high gear and drive the car
at 1 to 2 miles per hour. Push the gas pedal to the
floor and note your flash on the torque. This is the
same as your stall speed. DO NOT DO STALL TESTS
ON CARS EQUIPPED WITH TRANSBRAKES. When speaking
with your ATI sales rep or distributor, be as succinct
as possible regarding stall speed and your converter.
To converter builders, stall speed and flash mean the
same thing. If you ask for stall, this means if
you flash your converter from idle, it should go to
approximately rpm. For example, a torque converter
in your car will probably only footbrake to rpm
before moving your car depending on the quality of your
brakes. Furnishing as much information as possible to
your sales rep ensures that you get the correct product
you are looking for.
Q: Should I do a stall test?
A: No!! ATI strongly recommends that you do not conduct
stall tests. Stall tests break parts, and not just converter
and transmission parts. Remember, you are at Wide-Open
Throttle (full power) and maximum load. The pistons,
pins, rods, and crank will really take a beating.
Many racers ask why it is okay to leave the line at
Wide-Open throttle, but not okay to do stall tests.
The difference is this &#; when at the starting
line at wide-open throttle, you release the brake and
the RPMs accelerate from that point. In the converter,
the stator is locked via the clutch assembly (sprag)
and goes from maximum load in a controlled constant
reduction in force to zero load (free wheel) as the
car accelerates. The hydraulic forces in the converter
are directed in a smooth and efficient manner for maximum
torque multiplication and flow for adequate cooling.
When performing a stall test at wide-open throttle (or
even with a rev limiter such as the MSD Two-Step), you
lift off the throttle and the RPMs, now at 5,000 or
6,000, get jerked down to idle. The stator and clutch
assembly goes from maximum load and torque multiplication
to zero load in an instant. The clutch is unloaded rapidly
and the hydraulic forces are instantly disrupted into
unknown flow paths due to the rapid reduction in torque.
We have seen many converters damaged by this rapid unloading
when a ring and pinion, planetary gear set, or input
shaft fail. The rampant hydraulic pressure actually
breaks the pump blades (fins) completely off the converter
pump.
It is for this reason that converter manufacturers have
for years warned against &#;snagging the slicks&#;
coming out of the water as RPMs can go from 5,000 or
6,000 to an idle as the tires catch. Once again, damage
can be done to the sprag assembly. Also remember that
the converter builds up a tremendous amount of heat
in a short period of time. By not running an engine
after a stall test, all that heated fluid lays in the
converter without having a chance to go through the
cooler. Excessive heat eventually &#;fatigues&#;
the metals in the converter.
So, just say no to stall tests. They damage parts. Use
the transbrake ON THE STARTING LINE ONLY &#; not
in the pits, not in the driveway, not for your burnouts
&#; AT THE STARTING LINE ONLY! Your cost per run
will diminish significantly.
Q: What type of fluid should I use in my transmission?
A: ATI recommends Type F in all Powerglides
and Manual Operation TH350, TH400, TF904, TF727, C4
and C6 units. If you are a Street Rodder with under
450 HP then fresh Dexron Mercon 3 is a fine choice as
well. ATI only recommends Super
F if you want to run a Full Synthetic transmission
fluid. If you are running a turbocharged or high horsepower engine, consider using ATI&#;s new 30 weight Max Duty Super F ATF. It&#;s a 100% mPAO based synthetic and provides better lubrication than straight hydraulic oil. Great for Hyrdamatics, Powerglides, C-4s, C-6&#;s and Torqueflites.
Q: What affects my stall speed?
A: Stall speed is affected by engine size,
stroke and even camshaft duration. Small changes in
engine combination can change the stall speed. At ATI,
we custom design each converter to your needs. With
the exception of our 10, 11, and 12-inch street converters,
each race converter is hand built one at a time for
individual applications.
Q: Should I install a transmission temperature
gauge and a transmission pressure gauge?
A: Yes. The information your racecar
shares with you is highly dependent upon the gauges
you install. Two commonly overlooked, but very informative
gauges, are transmission temperature and transmission
pressure.
Transmission temperature is important in determining
that sufficient heat has been built to send the car
to the starting line. Over time, a range of average
operating temperatures can be established for &#;before
run&#; and &#;after run&#; readings. Transmission
temperature can be an important factor in your search
for ultimate performance and/or consistency. Any excessive
high or low temperature condition should be noted, and
might help to indicate a present or future problem.
The addition of a transmission pressure gauge can not
only reinforce what the temperature gauge is telling
you, but also provides information about instant damage,
and normal operating wear occurring in the transmission.
For a transmission temperature gauge, look for one offering
a high range of about 225-250 degrees. Ideally, the
sending unit should be located in the pan to provide
the most stable source of temperature. If a dedicated
transmission pressure gauge is not available, an engine
oil pressure gauge offering about 200PSI will work well.
Most popular transmission used in drag racing, both
late and early, have pressure sources that are ideally
suited for this purpose. While originally provided for
temporary dealer diagnostics, it can also be plumbed
to provide a permanent information source. Your ATI
technician can supply you with further details.
Q: What are the benefits of low gear sets for 3-speed
automatics?
A: One of the most effective improvements
that a performance street vehicle can utilize is a lower
first gear set for the transmission. When such a 2.75
gear set is installed in a T400, T350, C-4, C-6 TF-727
or TF-904, it allows a conservatively geared 3.50 ratio
car to launch with the potential of a 3.90 rear gear.
Likewise, when a 4.10 rear ratio is present, the 2.75
low gear allows the car to accelerate with much more
aggressive potential of a 4.56. Highway RPM in third
gear is unchanged from stock. These gear sets have shown
as much as a 3 tenths improvement in overall ET &#;
often half of which occurring in the first 60 feet.
Q: What is the proper transmission / flexplate
clearance?
A: The clearance between the transmission
and the flexplate should be checked on every torque
converter when it's installed. Clearance should be a
minimum of .100" but no more than .175" throughout.
Q: Should I soak my friction materials
before I install them?
A: Never install dry friction materials!
Always soak clutches and bands for at least 30 minutes
prior to installation. Soaking allows the friction materials
to be fully impregnated with oil preventing glazing
while adding to the life of the friction material.
Q: How important is it to center my transmission
and converter behind my engine?
A: It is critical to maintain a straight centerline
from your engine crankshaft through to your converter
and transmission. If your transmission and converter
are NOT centered, internal parts may experience costly
premature wear. Factors that cause misalignment include
engines that have been line-bored with the crankshaft
sunk in the block, flexplates and converters that are
out of round or unbalanced or even a flexplate that
does not &#;flex&#;. Internal converter and
transmission components must be bored to center themselves
in line with the engine crankshaft.
Q: How hot is too hot for automatic transmission
fluid?
A: In stock applications, a transmission operating at
150° to 175°, offering a service life of
miles, has its range cut in half when the temperature
increases to 195° to 200° At 295° service
life falls to only miles! In specific terms, varnishes
form at 240°, seals and sealing rings begin to harden
at 260° and friction plate slippage is unavoidable
by 295° At 350°all seals and clutches totally
burn out and conventional fluid solidifies to form carbon.
Synthetic fluids offer higher heat resistance to thermal
breakdown, but no better protection against failure
of the internal components at the stated temperature
levels.
Q: What is the proper way to warm my Powerglide?
A: Warming up a &#;bodied car&#; can hurt the
tailshaft bushing in a Powerglide. This bushing is only
splash lubed and will quickly run dry with the back
end of the car up in the air. If you need to warm up
the car, take it for a drive through the pits &#;
your tailshaft bushing will thank you for it.
Q: When is the best time to check my transmission
fluid?
A: Always check your transmission fluid level after
thoroughly warming up the vehicle. Levels will read
much higher when warmed than when cold. With your car on jack stands, run
it through each gear and reverse. Then put in neutral and
check at idle. Right in the middle of L and F is perfect.
Q: How can I troubleshoot my transmission?
A: There are five things that could keep your
transmission from moving in any direction
Q: Why should I check my shifter cables?
A: Check your shifter cable in each gear! Not all &#;shifter to bracket to transmission&#; installs will line up perfectly in EVERY gear. This will cause burnt clutch packs in the gear that is not fully seated!
Q: How can I prolond the life of my aluminum drum?
A: When using an aluminum drum in your Powerglide transmission, it is important to change the fluid and filter regularly as well as check your band adjustment. Aluminum is lighter in weight but it also wears very quickly. A regular fluid flush and filter replacement can extend your aluminum drum life significantly. Also, always use a red-lined band with an aluminum drum. Kevlar will tear the drum up in short order.
Q: Should I monitor my line pressure
A: The line pressure of a transmission is the &#;life blood&#; of the transmission and is just as important as oil pressure for a motor. You should monitor the line pressure on every tranny you use.
Q: Storing a transmission
A: Rust can be a real killer when storing transmissions and converters for long periods of time. Be sure to store your units in a dry, well ventilated place with all holes capped and plugged!
Q: What is the purpose of the input shaft?
Which companies in the industry are capable of making input shafts properly? Who has the hobs, shapers and cutters to cut splines? Do they have the machines and the expertise that is required to manufacture this critical part? Can they properly heat treat it, straighten and finish grind it? Or, do they just buy it from someone and resell it? One thing is for sure: at ATI, if we have a problem, we have a REASON, not an EXCUSE, because we make it in-house from start to finish. We find the problems, not you. The bottom line is simple: Manufacturing technique for this product is critical. Material is critical. Heat-treat is critical.
Q: How much fluid do I need to add to my converter and transmission after I install it?
A: Always look for a converter to be full (generally about a quart +/-) before installing on the trans. Likewise, always fill the transmission with approximately 4 quarts of fluid +/-. And don&#;t forget the engine, rear, etc. It&#;s easy to do after a new build or rebuild when everything is reinstalled and ready to go.
Q: How do I calculate converter slip in low or second gear?
A: Drive shaft rpm x gear set ratio = total rpm / engine rpm=percentage of slip. If you have a converter that is &#;too locked up&#; it stops pulling on the engine and the car suffers from spinning on the gear change. This is because the converter needs to pull on the engine thereby producing horsepower. When a converter is &#;too locked up&#;, the horsepower falls off so when you shift, the full load goes onto the converter and spikes the driveshaft causing the car to spin. This is VERY dangerous for small tire cars that have a front suspension limited to no travel. Without travel to help hook the tire, the car will lose control. You can help this by shifting out of low gear sooner, but the converter will ultimately have to be changed.
Q: Why do some racers pack their carburetors
with ice?
A: Heads Up or Class racers can gain a slight elapsed
time advantage during the hot summer months by using
the age proven method of packing the intake and carburetor
in ice prior to an important run. Dual or high capacity
&#;cool cans&#; filled with dry ice will add
a similar, temporary gain. More recently, racers have
found that by keeping a very minimum amount of fuel
in the car, and adding cool or chilled fuel stored in
the trailer or tow vehicle immediately prior to the
run will add to the total elapsed time save. Replace
and re-circulate the engine cooling system with ambient
temperature water and you are ready for the next round,
a few hundredths of a second quicker. Some racers have
even drained the third member lube for and an extreme
situation final round only advantage, but be warned
&#; component damage or other consequences might
result.
Q: Should I adjust my brake bias for foot-brake racing?
A: Yes. In order to get proper performance
and winning results, do not forget your car&#;s
braking system. OEM (Original equipment manufacturer)
vehicle braking systems typically put up to 80% of the
braking bias on the front wheels. This may need to be
modified to provide more pressure to the rear tires.
Not only does this provide for better holding power
at the starting line for maximum performance and reaction
time for &#;No-E&#; racers, but is also provides
safer &#;brake light racing&#; in all forms
of ET (elapsed time) racing. When rear tire width is
often three to five times that of the front tires, front
to rear braking bias must be adjusted to ensure safe,
predictable high-speed braking.
Q: Can I damage my car doing a burnout?
A: When doing a burnout, try to avoid dry hops, tire
hop and wheel shake &#; a major factor in broken
driveline components. Although it is not always possible,
avoiding this behavior will extend the life of many
parts in your vehicle.
Q: Should I heat up my brakes during my burnout?
A: When doing your burnout, slightly apply the break
pedal to build some heat in the rear brakes. This allows
the &#;foot-brake&#; racer maximum holding potential
at the starting line, and warms the brakes to boost
stopping power in all types of cars.
Q: What is the best way to heat up my tires?
A: First, spin tires slowly in water in order to get
them wet while avoiding soaking the wheel wells. Second,
pull to the front edge of the water using Low to High
for Powerglide, Low to 2nd to high for Turbo 400, Ford
C-4 and C-6, and 2nd to High only for Torqueflite and
Turbo 350. Thirdly, when the tires are hot enough, release
the line lock and power the car out of the water 5 to
10 feet and lift. Avoid hook up that will scuff tires.
Finally &#; Stage immediately! Dry burnouts reduce
traction and consistency. If you do not believe this,
pay attention to your first dry leave behind the line.
It will hook solid every time. Small amounts of water
left on the tires will dry completely from the tire
heat long before the green comes on.
Q: Can I improve my ET by short shifting?
A: Three speed automatic transmission cars can sometimes
realize an ET gain by short-shifting the first to second
gear change. This is because there is significant rotational
resistance involved in turning the reduction planetaries.
By shifting sooner, the time period that this parasitic
horsepower loss is imposed on the engine is minimized,
freeing horsepower to the rear wheels. A similar, but
less dramatic effect may also occur on the second to
third up shift. When optimal gearing is present, the
highest RPM level reached during the run will occur
in high gear at the finish line where the least internal
transmission drag is present.
Q: Are short tires quicker?
A: The arrival of late generation performance cars brought
attention to the idea that huge, massive rear slicks
were many times not only unnecessary but also undesirable.
Twelve, eleven and ten second (and quicker) ETs have
become almost common place on modified, later model
Mustangs, Camaros and Firebirds while using only 26&#;
&#; 28&#; tall tires that are 9&#; &#;
11&#; wide. The restriction of smaller wheel wells
combined with highly improved suspensions in these cars
has brought about the &#;small tire revolution&#;.
Remember, any car has a much stiffer effective gear
ratio with a 26&#; tall tire than with a 32&#;
or 33&#; tall tire. Of course, using too small of
a tire will only result in wheel spin, thus a slower
60 foot and ET clocking in relation to the MPH achieved.
Q: Are tall tires faster?
A: In Bracket Racing, it is usually true that the car
should have rear tires that are large or wide enough
to prevent any wheel spin at all for absolute round
to round consistency. However, it is possible to have
tires so huge that the ability of the car to &#;plant&#;
the tires effectively in every launch is hindered. Likewise,
too tall of a tire is often responsible for unnecessarily
slow 60 ft and ET clockings. While taller tires can
generally produce a higher MPH reading, dragging a too
wide, too heavy slick through the finish line lights
can easily nullify a potential MPH advantage.
Q: Will my body style affect my MPH?
A: Yes. In cases where the MPH results are &#;slow&#;
in relation to ET and 60 foot, often there are several
possible causes. A pick up or shoebox body obviously
pushes more air than an early Corvette. However, other
bodies, such as full fendered street roadsters, are
also notorious wind catchers (3 to 5 MPH slower). Look
for a wing on a dragster to produce a similar predictable
result. Even slight changes, such as adding air to under
inflated front tires have been proven to produce a 1
to 3 MPH increase in extreme cases.
Q: What type of things can I do to gain additional
performance?
A: Experimenting with cam degree location, total distributor
advance, RPM at which the total advance occurs, carb
jetting, plug heat range, etc. may result in a two tenths
or more difference in otherwise &#;componently identical&#;
engines. In addition, a superior piston-ring-cylinder
wall sealing combination may provide &#;hidden power&#;
that provides a clear performance advantage over other
similar engines.
Q: What type of things can keep my car from
running properly?
A: A misadjusted cable shifter, a throttle which doesn't
fully open, a bad ignition wire, a foam hood seal pulled
into a carb, a crimped or clogged fuel line. We all
have personal lists of glitches that have hurt or stopped
vehicle performance over the years. Be sure to check
first the same sorts of things that you would in a street
vehicle when vehicle operation is impaired. The &#;trickest&#;
engine, transmission, chassis, etc. combo can be slowed
or stopped in its tracks by a broken wire connection
or less.
Q: How can I become more consistent?
A: Racers, by nature, are always looking to go quicker
and faster &#; usually a good thing. However, if
bracket racing is your game, a week in &#; week
out thrash to uncover the next two hundredths of a second
may be clouding other issues involving driver/vehicle
reaction and predictable, repeated performance. A successful
and well-known bracket racer once said, &#;fix your
car and leave it alone.&#; The major part of &#;fix&#;
he refers to is the installation of absolutely reliable
products such as ATI converters, transmissions and components.
Eliminate the &#;gypsy&#; components and let
the driver concentrate on his part of consistent performance.
Q: How can I make the most of a Test & Tune
session?
A: You can learn a lot about optimizing your race car&#;s
performance and consistency at a test and tune session.
Choose a track that you are familiar with that offers
decent track conditions. If you are a dedicated bracket
racer, resist the temptation to &#;thrash&#;
your racer in an attempt to find .04 of a second. Instead,
use this opportunity to carefully monitor and record
engine and vehicle conditions prior to staging and immediately
after each run. By eliminating the pressures of actual
competition and minimizing between round maintenance/tune
up changes, you can focus on the time intervals and
procedures required to produce absolute consistency.
By integrating cooling, starting, burnout and staging
activities into a series of events, you can find the
desired gauge readings for each. Plus, it allows the
driver to prepare for the next round with confidence
under actual race conditions at readings that will most
likely produce equal results.
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