How much can an honest T5 take?

Jul 15, 2018
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#1
Everyone calls the T5 good enough but where is its limit, will 430ft/lbs. of torque abuse it if you don't drag race on it? Same question for the "World Class" 7.5" rear.
 
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Boostedpimp

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#2
There is too many factors to say for sure... I personally have gone through four before making the leap to a 3550 and t56. Some of those were stock cars lol but personally believe the clutch type, wheel type and driver skill has allot to do with it.
 
Jul 15, 2018
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#3
Nice to make your acquaintance @Boostedpimp :)
I have to ask, four T5's or four 7.5 rears?
What kind of habits on a road track will send either to an early grave?
 
Jul 15, 2018
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#5
@General karthief
Thanks, it confirms what I thought. If you're not aggressive with it on a roadtrack and you're on nothing wider than 245s, you should be good to go. I think 430ft/lbs. is about the limit though, I wouldn't put 450 through it. You could choose the weak link to be the U-Joints as a safety measure.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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#7
Here's the thing with the lowly t5, you can trash it just being aggressive on a stock engine, it don't like high rpms or fast shifts, I will say most of the problems with mild builds were clutch miss adjustments and that damn rubber block on the firewall that moved around too much.
2nd gear gets ground into submission and 3rd just can't be found.
 
Feb 18, 2001
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#8
3rd gear is the weak link when spun fast. It's the furthest load from any sort of bearing support so the gears just naturally spread until the point they shear. At what point that happens? Hard to say because it depends on the t5, gear material quality and even how "tight" the trans was set up.

I've seen them blow inputs on stock 5.0s, and then live for years behind s healthy 351. Just so hard to say what will be "ok"
 

jrichker

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#9
It's a poker game and the players are sticky tires, grabby clutches, speedy shifts and high HP.

You never know which player will trash the T5 and you almost never have a winning hand when playing against these 4 guys...
 
Jul 15, 2018
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#10
@jrichker
We seem to have a consensus on the four horsemen of this drivetrain apocolypse but I was hoping for a more specific set of guidelines. For example:
T5 risk analysis

item..........parameter........failure probability
VR tires......225/50-16........1
VR tires......345/45-17........5
shifting......quick............2
shifting......power............4 (but not as bad on 1st gear change)
clutch........stock............2
clutch........plate............3
torque........450ft/lbs........5
torque........430ft/lbs........4
torque........400ft/lbs........3


How would adding the four numbers together and making anything <10 usable and anything >10 asking for trouble, useful guideline?
 
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Noobz347

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#11
The WC T5 was designed for a car making 300 FWTQ. Anything over that and you're adding additional stresses over what it's rated for.

Having said that, I still have a WC T5 installed and fully operational in a vehicle producing over 600 ft/lbs at the fly wheel on Cooper Cobra tires that don't stick to much that's not a corner.

Prior to that and before replacing the OEM T5 in my 86, I twisted it into a pretzel with the stock 190HP/300ish ft/lb engine on a set of summer tires.

The bottom line is that there's no chart on this planet that can predict road and driver and setup conditions. That table is completely useless. Perhaps a 20 year study on all the possible stress factors of a Fox body drive train to include a list of all possible power and mod scenarios in all environments. We could wrap this up quickly if Google or the NSA allows us time on one of their quantum computer cores. :O_o:
 
Oct 6, 2011
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#12
The width of tires wont effect it too much. The same tire in 295 will provide little more traction than say a 245. It's the sum of all parts that will effect the life of the T5. If the T5 is the weakest link in the equation then you cant expect bad things. For instance, mild engine + drag radials + stage 2 clutch + T5 = bad things. Or mild engine + drag radials + stock type clutch + T5 = you could be ok. Adding abuse into any of the equations = bad things.
 
Oct 24, 2017
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#14
Someone please let me know when they find the answer!

I think I make close to 400 and do 1.7 60ft on dr's, and just got my first 1.5 on full slick normally1.6. I also shift it like it's a glass box full of pot metal.

I bought the car with a bad second gear making 215 at the crank...
 

CarMichael Angelo

I don't like your attitude, let me fix that.
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#15
@General karthief
Thanks, it confirms what I thought. If you're not aggressive with it on a roadtrack and you're on nothing wider than 245s, you should be good to go. I think 430ft/lbs. is about the limit though, I wouldn't put 450 through it. You could choose the weak link to be the U-Joints as a safety measure.
Yeah,....Because there is nothing safer than a broken u joint that allows the drive shaft to drop, dig-in, and pole vault the car end over end, as opposed to a broken t5 as a "safety measure" :rolleyes:
 
Jul 15, 2018
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#16
@CarMichael Angelo
I think we can prevent the cataclysm you describe by periodically checking the u-joints for bending, stretching, etc. and by using some brackets/wire under it to catch the pole and eliminate that possibility while we're in test mode. U-joints are far cheaper to replace than any part of the T5 drive train and they're not likely to fail without some warning signs. Is using them as I suggest to gauge how much stress you're putting on the T5 faulty logic?

@Stevenmverrill
You're wasting your time here, @Noobz347 already proclaimed my efforts as useless so there's no point of discussing it any further, right? ;)
 
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Oct 24, 2017
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#17
He has a bit of a point but, what could help is know who has broke what with what doing what?

Like my friend broke his fith gear, my brother broke 5th twice on a non world class, the one I had in my rx7 was losing 3rd gear syncro, the one I got my current car with obviously lost second gear syncro and he continued bang shifting, until second gear was too chewed up.

We know 5th is weak hanging out the back..

But every other failure I know of is a combination of lack of maintenance, and shifting way too fast/hard. How often are people really breaking teeth or shafts? And when they do I bet it happens at the time of shifts.

I figure take care of it, use a low level clutch at best, and when a gear becomes difficult, open it up, and put some new clutches in before you grenade a gear or the whole case.

If money is not a huge object, then get a TKO or whatever. We know the t5 is a glass box. Then move on to that 28 spline carrier.

I am interested in anyone who has popped a T5 mid gear? how many pounds were you accelerating how rapidly?

the points made about not knowing traction are extremely valid. I grenaded an eight eight carrier in an old ranger just power sliding in the snow. Hit a 2 ft long dry patch, and that diff is history, if there was a t 5 in front of it maybe that diff would still be alive.
 

CarMichael Angelo

I don't like your attitude, let me fix that.
SN Certified Technician
Nov 29, 1999
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#18
@CarMichael Angelo
I think we can prevent the cataclysm you describe by periodically checking the u-joints for bending, stretching, etc. and by using some brackets/wire under it to catch the pole and eliminate that possibility while we're in test mode. U-joints are far cheaper to replace than any part of the T5 drive train and they're not likely to fail without some warning signs. Is using them as I suggest to gauge how much stress you're putting on the T5 faulty logic?

@Stevenmverrill
You're wasting your time here, @Noobz347 already proclaimed my efforts as useless so there's no point of discussing it any further, right? ;)
Hell yes it's faulty logic.You sir have the dubious honor of being the very first person in the last 40 years of my racing history to suggest using a u joint as a fail safe against eventual internal/external transmission failure.

If I had to gauge which was the stronger of the two parts of the drive train, I'd take a u joint over a t-5 every time the scenario came up.
There are guys here making twice the power you guesstimated that a t5 would be able to withstand using standard issue ujoints......
for the sake of argument, let's just say 800 WHP.

And.....routinely enough, stay in place. They are far from the "weak link" when compared to a t5. Any t5..behind any engine.

And, they do make safety loops as a safety counter measure to ward off the danger of driveshaft/u-joint failure...its a mandated addition on any drag car with slicks, or drag radials...and just goodcommon sense on any street car that gets routinely beat on at a drag strip as well..

But relying on the u joint as a break point "safety measure" is preposterous advice.

T5s are weak. There is case after case listed of them failing behind stock engines rated at half the power you listed as your limit ( I believe that was......430 but not 450ft/lbs...wherever in the bloody hell you pulled that number from)

Please offer tech advice based on actual experience spent on this planet.
 

96pushrod

Active Member
May 15, 2018
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#19
@CarMichael Angelo
I think we can prevent the cataclysm you describe by periodically checking the u-joints for bending, stretching, etc. and by using some brackets/wire under it to catch the pole and eliminate that possibility while we're in test mode. U-joints are far cheaper to replace than any part of the T5 drive train and they're not likely to fail without some warning signs. Is using them as I suggest to gauge how much stress you're putting on the T5 faulty logic?
I’ve had u joints break without any sign of wear, and I definitely wouldn’t recommend having that be your indicator of the upper echelon of a t5’s strength. I’d take a trashed t5 on the highway or strip over a driveshaft attempting to be a pole vault.

I’ve had t5s behind 5.0s and a 383 and they all lived getting beat on fairly regularly. Mind you, these weren’t drag cars, just endured lots of clutch dumps on the street. The only one that actually gave me problems was the one in my old Chevy luv with the 383.

If :poo: break, it breaks :shrug: