I have an 89 Formula with the 305 TPI stock T-5 transmission. I might be upgrading to a 350 motor with 360 HP and 400 lbs of torque. Will this trans hold up to that kind of power? I don't plan on racing or abusing it, but would prob get on it on occasion. Can a stock T-5 be built up to hold this kind of power, or would I have to find another tranny? Thanks!

 

Power alone won't break it. Traction and driveline shock will. It is not notorious for being very strong but if you avoid the afore mentioned items, you can make it survive.

 

I had that much power going to mine for many years. As said, traction will play a big part here. It can live w cautious abuse. Will it, only one way to find out!

 

Just as long as you don’t drive it like a teenager, it’ll be fine. I’ve got a stock T5 in mine and routinely roll into it hard enough to light the tires. But I do make it a point not to power shift it or sidestep the clutch. It’s held together for many years now.

 

I did a driveline swap from 305/auto to 350/T5 last year. Engine is around 400hp/400tq. Been fine so far but I don't hammer on it but I'm not granny shifting either. 3rd gear is the weak spot on a T5 so keep that in mind.

 

A T5 isn't the best choice for what you are looking to do, but it's what you already got, so run it. It will live for quite a while if you are nice to it. As has already been said, traction and abuse is what will kill it fast. Lot's of torque and being nice to it will just kill it slow. Once it dies, then a T56 swap would be the way to go.

There used to be some T-5 upgrade parts out there (GForce was one company), but not sure if there is much of that available these days. Still, even with all of the upgrades available, it was still a bit weak. It's not worth spending any real money on a T5 for a high horsepower/torque application.

We used to blow up T5's, go to the junkyard and grab another one cheap and swap it out. They were plentiful way back when. Not so much anymore and the ones you do find usually need work.

 

I've had a junkyard T-5 of unknown origins behind my motor for years now, 405 hp/405 torque and it does just fine. Like has been said, as long as there is "give" somewhere (i.e. the tires spin!) you're good.
Heck, for that matter I know that my T-5 was actually in another car BEFORE it got to the junkyard car because the junkyard car had been manual swapped, so, you don't have to be too scared of it.

 

What's the point of a manual trans if you can't do 4,000 RPM clutch dumps and WOT power shifts?

 

I agree w/others that as long as you're not a "ham-fisted" retard, it'll last fine. I had one behind a 400 for years, drag tracked it a lot but w/real STREET tires, it did good. Good enough.

 

Thanks everyone for all the info, it was def helpful!

 

Edited content below from one of my webpages, just wanted to point out that clutch selection is going to be a big factor in the OP's T5 life expectancy...

Engine torque is something most car guys think they understand, so giving them torque ratings to compare while clutch shopping preemptively answers a lot of questions. A clutch manufacturers torque rating is just a quick/dirty way for the typical aftermarket clutch buying customer to feel assured that the clutch they buy isn't going to slip against the torque their engine is capable of. From the perspective of the aftermarket clutch manufacturer, if the clutch breaks something else downstream it's not their problem, at least the customer won't come back to them complaining about a weak clutch. In reality, choosing a clutch is more complicated than just engine torque. To keep your stick shift drivetrain alive, it's important to pay attention to what happens inside the bellhousing.

The T5 5spd serves as a good real-world example. It was an OE transmission for both GM and Ford, and the 2.95 gearsets for both versions are nearly identical as far as case/gear strength. But the GM version of the 2.95 V8 T5 has a reputation as being weak, while it's pretty common to see Ford version of the 2.95 V8 T5 running 10's on the dragstrip with slicks. The difference is the clutches that are commonly used with each version. The GM T5 guys almost always go to the aftermarket and end up with around 2800-2900lbs of clutch clamp from a 10.5" diaphragm, while the go-to clutch for the Ford T5 guys is the Ford Motorsport "King Cobra" 10.5" diaphragm which has 2124lbs of clamp.

The lesson to be learned is that installing more clutch clamp pressure than you need is a step in the wrong direction. Too much clutch will pull inertia out of the engine's rotating assy at an excessive rate, which in-turn leads to either bog/spin problems or broken parts. Excessive clamp pressure also narrows the sweet spot for clutch modulation, leading the clutch to act more like an on/off switch during casual driving.

The purpose of optimizing clutch clamp pressure in a street/strip application is not so much to protect the rest of the drivetrain from impacts, that happy side effect is just a BONUS! The real purpose is to make the car quicker by improving traction and optimizing your engine's power production. While it may be counter-intuitive, a softer hit on the drivetrain CAN make your car quicker!

How Much Clutch Clamp Pressure Do You Actually Need?
The typical aftermarket GM/Mopar pattern 10.5" diaphragm PP installed out of the box has about 2800lbs of clamp. It's hard to find anything less in the aftermarket, so let's see what 2800lbs of clamp gets you with different types of clutch discs....
...With an organic disc, 2800lbs is ballpark for an engine with around 500ftlbs of torque.
...With a typical dual friction disc, 2800lbs is ballpark for an engine with around 655ftlbs of torque.
...With a typical iron puck disc, 2800lbs is ballpark for an engine with around 810ftlbs of torque.
...With a cerametallic puck disc, 2800lbs is ballpark for an engine with around 820ftlbs of torque.

Let's say your engine puts out 400ftlbs, how much clamp would you then need for a typical organic disc? For that you can calculate a percentage of the above ratings. The above says 2800lbs of clamp on an organic disc is ballpark for 500ftlbs. If you divide 400 by 500, you get .80 which means you would need 80% of 2800lbs or 2800 x .80 = 2240. In other words, a 400ftlb engine needs about 2240lbs of ballpark clamp on a 10.5" organic disc. Good luck finding that in the aftermarket.

If you do find yourself in a situation with excessive clutch clamp pressure for the application, devices like my ClutchTamer and Hitmaster products can soften the hit of an overkill clutch to suit the application, without giving up any of that overkill clutch's overall torque holding capacity. You end up with similar overall performance to a "slipper clutch" from an off the shelf diaphragm, without all the inside-the-can clutch tuning hassles. Kind of like "getting your cake and eating it too" for a street/strip guy.

The key takeaway from this is that clutches typically kill T5s, not traction. With 400hp and a proper hitting clutch, a T5 can live even when dead hooking on slicks.

Grant

 

Thanks Grant! That's some good info, appreciate it!