so im currently enrolled at Universal Technical Institute and while i was in my Manual Drive Train class, one of the lab assistants pulled our class aside to show us this project the school is currently doing. Hot rod, UTI and Factory Five racing are having a contest between 4 different UTI campus's where they are donated a FFR roadster kit (the AC cobra clone), and have an additional $10,000 to build an auto cross car. so far they have the chassis together, and they are using parts from a 91 mustang GT. the lab assistant wanted my instructor to have some of us look at the t5 to see if it was in good working order. so my instructor pulled me and on other student aside to rip it apart and take a look at it to see what was going on inside, there was water in the fluid and alot of crap on the mainshaft under the gears, and the syncro's were shot (dog teeth were rounded) so my teacher ordered a new set of syncros for it, and im probably going to help him put it together once the parts come in.
I'm been told the T-5's from both the F body and the fox body are pretty much the same, so i figured i'd ask you guys for your input. basically i wanna know if theres any tricks to helping the t-5 handle autocrossing for a weekend behind 400hp and 450lb/ft small block ford. one of my buddies posted this on a few mustang sites and all ive gotten so far is to shim the input shaft endplay down to zero. any other suggestions?
thanks, Adam

by the way, there should be an article sometime about this contest in Hotrod mag, i just don't know when. its called the "collegiate power challenge" so look out for it probably within the next 3-4 months.

 

They are essentially identical. The only differences are external; case details, splines, things like that.

You don't shim the clutch gear end play "down to zero". It will not last if you do that. The correct setting is actually PRELOAD on the clutch gear bearing and mainshaft bearing. The way I usually do that part of them, is to assemble the whole trans as far as all the stuff that goes in the case (it doesn't need 5th gear for this); install the extension housing; set the trans up on its back end, supported by the extension housing flange, NOT THE END OF THE MAINSHAFT (you want the whole guts of the thing hanging free); stack a whole bunch of shims, like all that come in the small parts kit, behind the clutch gear bearing in the retainer; put the retainer on; tighten the retainer bolts FINGER TIGHT ONLY, and adjust them so all 4 are equally tight, i.e. the same feeler gauge just barely goes between the retainer and the case at each bolt; see what feeler that is; and subtract that much, plus about .008", from whatever happens to be in the retainer. Then when you do get around to the final assembly, use that much shim behind the clutch gear bearing outer race. The goal being, about .008" of PRELOAD on the bearing when the retainer is bolted down.

You do the same thing with the countergear, except you want about .005" - .006" of PRELOAD there. You do that with the rear countergear bearing retainer.

You might want to consider getting yourself a copy of any factory service manual for any car that came with a 2nd design T-5; or one from B-W. I have a pdf of the B-W one, besides a paper factory one from somewhere.

There's not alot you can do to "beef one up". The way T-5s fail, is by the case stretching across the front, which allows the clutch gear and countergear to misalign. I've got 3 or 4 cases like that sitting on my shelf right now. Garbage. I fail to see how hardened gears will fix that. But people hype those $$$gears$$$ all the time, so maybe it works somehow, I just can't see how. The 1st design T-5 would stretch the case so bad that the fluid would just run out around the CG bearing with the car sitting there. The 2nd design at least has an O-ring around the bearing, so the trans doesn't run itself dry. But the case is no stronger there.

One thing you definitely can do, however, is to get the improved rear countergear bearing retainer from www.5speeds.com . What that does, is to at least hold the countergear firmly in place to the extent that the flimsy case will allow, which keeps the above mentioned misalignment to a minimum. The factory one of those is a little piece of sheet metal; the Gearzone one is a much thicker piece of steel stock.

If it only has to last a weekend, put Red Line MTL or Mobil1 gear lube in it. Trans fluid is too thin for heavy-duty use. The somewhat thicker lube will help the bearings and gear teeth live longer.