How to Keep Your T5 Alive

[jkopp]

HOW TO KEEP YOU T5 ALIVE

by Bob Hahn

My biggest problem was wheel hop, not the little "skipping" type, but the kind that feels like the rear wheels bounce about a foot <exaggeration> off the ground! This would only happen under HARD braking, downshifting, AND letting out the clutch, with the rpms too low. In other words, whenever I'd over run a turn, or in a passing situation! We tried every band aid there was ...different brake pads, dual prop valves, cutting pads, raising and lowering the car, all the different trans fluids,...didn't matter if the transmission was brand new, or well worn...no difference!

I talked to a Ford Mustang suspension engineer who also, coincidently, used to do the Camaro stuff at GM. We moved the angle on my 3rd link about 8 ...no more wheel hop, no more transmission problems. Most of the Mustang people run torque arms. The inherent problem is that the torque arm is Non-adjustable consequently works great for anti-squat, but terrible for "antilift", which is what causes wheel hop. The Camaros have the same problem but not as bad due to the LENGTH of the arm.

If the Camaro could lower the front of the arm about 4", no wheel hop. The Mustangs need longer arms, which would help, but not eliminate the problem. I've talked to many people who strip 2nd or 3rd, and claim not to have wheel hop. Wheel hop causes the driveshaft to hit hard on the transmission gears, when the wheel bites, then when the wheels unload, the tension is lost, frees up the transmission. When the wheels hit again, the drive train literally HAMMERS at the gears. In my case, I'd get severe wheel hop about 3-4 different times during a race, or the day for that matter...then WHAM, letting out on the clutch, in middle of a straight,...we're history! ....For less severe wheel hop, as in the "skipping" type, this does the same thing, but takes a many more "hits" (because it's not hammering as hard) and EVENTUALLY you strip a gear. The "wheel hop" can be so "unnoticed", that driver's swear they don't have a problem. I have followed a couple of these drivers, on the track...yes they have a problem.

Notice I haven't gone into detail about how to make the T-5 live! The most I do is, after about every 4th weekend, I reset the endplay, at the input shaft...and change oil, using 1 qt MTL, and Mobile 1 , 5w30 for the rest. That's all!! No problems with the trans., 12 weekends, (I race the Regionals also and except when I got overconfident and screwed with my brake set up...wheel hop due to MAJOR difference in bias, first session out, transmission was history. Went back to the original set up...no problems!)

In other words...the transmission had nothing to do with the failures! The problem was, a combination of driver error and suspension set up. Unfortunately there is not a lot most people can do about their suspension...except dial out their rear brakes...but improved driving technique will help.

The T-5 does fine...for me, and wouldn't spend the money for anything else that "might" be allowed. My engine turns out as much torque as anyone's...I don't think that's the problem with the T-5s.

Now let's talk 5th gear failures. I was surprised to learn, at the Runoffs, that out of the top 4 "legal" cars, 2 used 5th, 2 did not! For those who don't realize this, the difference between using 2nd-4th, and 3rd-5th, is negligible. Most people use the longest straight, in reference to RPMs, to determine rear end ratios. In fact, the best rpms for coming out of the turns is much better...usually many more turns than straights! Also, the amount of time shifting, and the amount of shifts, have a bigger bearing than the time you "might" lose in the straight.

I never realized this, until I purchased software from Bill Mitchell,...the guy that downloads the info from Tommy Kendall's car.

Combine this info, with the fact that 5th gear is the weakest part of a T-5...why use 5th? I've put in requests to eliminate the large 5th gear, from their transmission, to Denver...no results. Take out the gear...everyone HAS to run a 4 speed, and to check for legality...put the car in 5th, let out on the clutch! This is much better than competing against the drivers using the .80-.83 5th gears! I feel it would go a long way to narrowing down some problems.

As for the case breakers..usually Camaros...my advice is use the softest bushing you can find, for the front of the torque arm. Not only does this slightly help anti-squat and anti-lift, but keeps from transferring rear wheel hop through the transmission case. Also, incorrect pinion to driveshaft angle, will cause harmonic driveline vibrations, which in turn, acts like a hammer, hitting the already stressed areas of the transmission case. Best pinion to driveshaft angle = transmission to drive shaft angle..in a "Z" pattern. Important is the total amount of angle change, under hard acceleration. If the trans/ds/pin becomes "u" shaped, big problems! We have to maintain a minimum of 2.8 trans/ds, ds/pin angle.

In the Mustangs, another driveshaft/transmission related problem is the fact that the driveshafts are too long and are made of steel. This is that vibration you feel, usually with lower rear gears(more torque per driveshaft rpm), at about 5800 rpm(Mustang). Even computer balancing doesn't help. A simple remedy is an aluminum driveshaft...but not legal. I don't know if the Camaros have aluminum driveshaft or not.

This is about everything I know. I hope it helps! Thanks Bob.

Bob,

My last outing at Summit Point resulted in massive wheel hop. In fact so much that I popped the rear shocks off the axle. At Summit I only experience the hop when braking hard going down hill into 5, the rest of the braking zones are fine. I have installed an adjustable torque arm and set the angle at 0 deg static. In your article you mention moving the third link angle 8deg. Question, what was your original angle? I am fairly new at sedan racing as for the past 15 years I have been in Formula Fords. I need to improve my braking as sometimes I think I am still in an 1100-pound car.

AL Cantrell
Washington DC Region
AS Camaro #17

[jkopp]

Originally Posted by CANTRELL17

Bob,

I have installed an adjustable torque arm and set the angle at 0 deg static.

Al,
Just curious, where did you get the adjustable torque arm? Never seen one and was wondering how it was setup.

I too experienced wheel hop problems this year. I had to dial out all the rear brake I could just to keep it manageable. My goal for the off-season is to make the mods necessary to eliminate the problem and get my rear brakes back. Jim Wheeler gave me a 3rd link setup to try. I have a D44 and have been researching the best way to install it. I hope to find a use for the pinion angle tools I just had to have 10 years ago and have never used . Hopefully someone will drop in with more tips for us.

Good luck!
-Jeff

Bob, I ran this weekend hoped the wheels bad enough to miss the corner. ran the rest of the race but would you advise going through the trans at this point?

Thanks
Morey

Per the GCR, with the Torque arm no longer specified on line 5 as a control arm, it's legal to mount the torque arm elsewhere in order to get the 4 inches and eliminate wheel hop.

This is my thought.

Anyone have any input on my interpretation? I'd like to know if I'm completely off base and not reading correctly.

Best Regards,
Justin