Drivetrain T5 WC FAILED!

[PonyGTrider]

Hi all,
I rebuilt a T5 WC for a friend of mine few months ago. He just called me two days ago telling me that as he shifted from 1st to 2nd he heared a lowd bang and lots of noises there after, he gave me no more details as how he shifted, at what rpm's etc.
Yesterday I opened the transmission and 2nd gear's teeth are gone as well as the ones on the countershaft. The rest of the gears are clean and all the synchros are too. My question is if anyone could help me to determinate what caused this failure. I installed a short throw shifter and he is running a non-sprung clutch disc. Any ideas anyone? I'll try to post some pics.

Thank you all

 

[limp]

What was the song..... " Second gear, hold on tight"....

 

[PonyGTrider]

By the looks on the 2nd gear and countershaft broken pattern it seems to me as if the 2nd gear had walked away from the countershaft gear (Towards the front) but there was no contact markings on the face of 1st on the countershaft. Also there was no endplay on the input shaft/main shaft, In fact I left about 0.002" preload because of new bearings. No endplay on the countershaft either....
So what could of happen there?

Any help would be greatly appreciated because trying to get the damaged parts and put everything back together.

Thank you all

 

[Noobz347]

I would guess that it's a material failure. How much power is the engine producing? Where did the trans internals come from?

Generally, it's 3rd gear on a T5 that gives up the ghost.

 

[PonyGTrider]

Power output is low I guess, 300hp at the most.
I think unsprung clutch disc is relatively hard on the transmission depending on how hard the clutch pedal is released. Could that be the case here? According with the casting numbers on the trans. case it came out of a Camaro but my friend has it in his 94 GT

 

[AeroCoupe]

Have to ask but did the positive stops get adjusted correctly?

As fragile as the T5’s can be I would not use a springless clutch disc. Also, are you running a counter shaft stabilizing plate?

 

[PonyGTrider]

Have to ask but did the positive stops get adjusted correctly?

As fragile as the T5’s can be I would not use a springless clutch disc. Also, are you running a counter shaft stabilizing plate?

Yes I calibrated those positive stops to a 0.010" clearance. I'm a bit concern about my friend using a non-spring clutch disc but that is his choice. No billet stabilizing plate just the regular stamped one, but I'll suggest that to my friend. I have that plate on my T5 WC "Z" and I feel a bit more insurance on my tranny.

Thank you for sharing your ideas

 

[AeroCoupe]

So the shifter handle should touch the positive stop locks and there should be no gap. Video talks about this at 5:00.


View: https://www.youtube.com/watch?v=9JiJLXGn5c4

 

[85GTStangGuy]

So the shifter handle should touch the positive stop locks and there should be no gap. Video talks about this at 5:00.

Actually, the video says (incorrectly) that there should be a gap. At the 5:23 mark he says to back off the stop one-half turn after the stop touches the shifter handle. Later he says the same thing when he's setting the 3rd gear stop.

But, like you said, there shouldn't be any gap. That is made clear in Holley's instructions for their Hurst shifter. Refer to Step 5 on Page 3 of the Shifter Installation section in the following link:

https://documents.holley.com/3915033_instructions.pdf

 

[90sickfox]

I saw that before when a guy tried to do a second gear burn out but the rear brakes were adjusted properly. The power had no where to go when he let the clutch out with the rpms singin'. Second gear ended up looking just like that. Not saying your friend is lying but it would take a lot of power to do that in second. Usually the tires would break loose first during a normal hard pull. If it happened during normal driving that gear would've been humming its own tune before wearing the gear enough to shear off. The fluid would also be gray with metal flake. I would think he would've let you know that before it failed completely.

 

[PonyGTrider]

So the shifter handle should touch the positive stop locks and there should be no gap. Video talks about this at 5:00.


View: https://www.youtube.com/watch?v=9JiJLXGn5c4

Well the instructions on the shifter I installed says to move the shifter into gear and to drive the stop bolt until it touches the shifter and then to back off the bolt half of turn which equals to 0.010", and then fix it with the locking nut. That's what I did.
in my opinion 0.010" slack is not enough to over-throw the slider against the gear... but maybe it is.

Have to mention that the 2nd gear was making a slight whining sound and some time before it broke my friend said that the noise was a bit louder.

 

[PonyGTrider]

I saw that before when a guy tried to do a second gear burn out but the rear brakes were adjusted properly. The power had no where to go when he let the clutch out with the rpms singin'. Second gear ended up looking just like that. Not saying your friend is lying but it would take a lot of power to do that in second. Usually the tires would break loose first during a normal hard pull. If it happened during normal driving that gear would've been humming its own tune before wearing the gear enough to shear off. The fluid would also be gray with metal flake. I would think he would've let you know that before it failed completely.

Yeah I know what you're saying, I don't think he is telling me the whole story, on the other hand he is not blaming me for the failure. I tried to pull more information or details but I'm sure he won't admit any wrongdoings .
Thanks for sharing

 

[PonyGTrider]

Actually, the video says (incorrectly) that there should be a gap. At the 5:23 mark he says to back off the stop one-half turn after the stop touches the shifter handle. Later he says the same thing when he's setting the 3rd gear stop.

But, like you said, there shouldn't be any gap. That is made clear in Holley's instructions for their Hurst shifter. Refer to Step 5 on Page 3 of the Shifter Installation section in the following link:

https://documents.holley.com/3915033_instructions.pdf

I was just responding about the way I set the shifter. I agree with you too there shouldn't be any gap in between the stop and the shaft but again 0.010" is just not that much to over-throw the shifter/fork/ or slider.

Thanks for your opinion

 

[85GTStangGuy]

Yes I calibrated those positive stops to a 0.010" clearance.

Calibrated how? Feeler gauges? or 1/2 turn of stop? or ?

The reason I ask is because in post # 11, you say

Well the instructions on the shifter I installed says to move the shifter into gear and drive the stop bolt until it touches the shifter and then to back off the bolt half of turn which equals to 0.010", and then fix it with the locking nut. That's what I did.
in my opinion 0.010" slack is not enough to over-throw the slider against the gear... but maybe it is.

If you just backed off the stop bolt one-half turn, I'm questioning whether the gap was actually 0.010". The stop bolt looks like a 3/8" UNC socket head set screw to me. If that's correct, then, at 16 tpi, one-half of a turn equates to 0.031" worth of gap. Could that be enough to "over-throw the slider against the gear" and cause an issue?

 

[Mustang5L5]

Is that 2nd gear a Tremec part or an aftermarket?

Really no way to determine the cause. The weakeness in the T5 is the support for the mainshaft. It's just not adequate. So as you put load on the gears furthest from support (2nd and 3rd), they spread. As they spread, they transfer the load to thinner areas of the gear teeth which increases stress, and BOOM. While 3rd and and 2nd are both in the middle of the shaft, 3rd tends to blow more often due to the gear ratio. and loading.

Do you remember how tight you shimmed the input shaft? Being a bit on the looser side may cause a bit more deflection in the mainshaft.

Honestly, factory T5's would blow up this way even when new, so I wouldn't beat yourself up too badly over this.

 

[AeroCoupe]

I completely missed him saying back it off. Think I was more focused on the video than what he was saying. Both my Pro5.0's touch on every shift. I beat the snot out of my T5 and knock on wood have never lost a gear. I will say if the transmission was whining in 2nd gear and was getting louder before it broke someone should have been smart enough to know to quit driving it.

 

[PonyGTrider]

Calibrated how? Feeler gauges? or 1/2 turn of stop? or ?

The reason I ask is because in post # 11, you say

If you just backed off the stop bolt one-half turn, I'm questioning whether the gap was actually 0.010". The stop bolt looks like a 3/8" UNC socket head set screw to me. If that's correct, then, at 16 tpi, one-half of a turn equates to 0.031" worth of gap. Could that be enough to "over-throw the slider against the gear" and cause an issue?

You could be right. I'll consider that possibility of what happened. to start the second gear was making noise after the rebuild because the transmission was in really bad shape, the idle gear was broken and some more parts were terrible and my friend acknowledge that there were chances of future problems. He also mentioned that some time before braking the gears that noise was louder.

Thank you for your ideas and suggestions.

 

[PonyGTrider]

Is that 2nd gear a Tremec part or an aftermarket?

Really no way to determine the cause. The weakeness in the T5 is the support for the mainshaft. It's just not adequate. So as you put load on the gears furthest from support (2nd and 3rd), they spread. As they spread, they transfer the load to thinner areas of the gear teeth which increases stress, and BOOM. While 3rd and and 2nd are both in the middle of the shaft, 3rd tends to blow more often due to the gear ratio. and loading.

Do you remember how tight you shimmed the input shaft? Being a bit on the looser side may cause a bit more deflection in the mainshaft.

Honestly, factory T5's would blow up this way even when new, so I wouldn't beat yourself up too badly over this.

I believe the gear is a cheap aftermarket part. And yes it make sense what you say about the weak stamped countershaft bearing/race support. I already mentioned this fact to my friend and he is looking into getting the billet plate.

I'm sure I used between 2 and 3 thousands of pre-load after zero. the same on the countershaft.

Thank you for your help

 

[manicmechanic007]

ZZ top lyrics
"She stripped the gears on me late last night"
"I don't think they were oiled right"

 

[manicmechanic007]

Simply too much power IMO
I did just about the same thing to my toploader in my Boss 302 in '88
Playing Parnelli Jones