Premature Transmission Failure

[NoDOHC]

Originally Posted by RETed

The consensus seems to be that non-turbo 13B putting down close to 200hp at the wheels will shorten the life of the (FC) non-turbo transmissions.
200 at the wheels is typically 150 lb-ft at the wheels...
You're at this level right now...and then some.
So, with the non-turbo transmissions, it's no surprise you're killing them.

With the 4-port, I agree, but I killed two transmissions with a 6-port, barely clearing 100 WLb-Ft.

Originally Posted by RETed

As for the turbo transmissions...
Hard to say...
Used units are not a very good baseline - same goes with the non-turbo transmissions.
To have good data, the transmissions need to be inspected and rebuilt.
Even a turbo trans with a problem area internally will let go quickly.
Did you tear down the turbo transmissions to verify it was the bearings / synchros that were damaged?

No, I should do that. I have some experience with ruining transmissions, the symptoms all pointed to bearings. I intend to rebuild this US spec transmission, as they are hard to come by these days.

Originally Posted by RETed

I don't think you mention what kind of clutches you're using?
Unsprung, puck clutch disc can cause damage unless you're very good as synchronizing your shifting.

I have a sprung Spec Stage 3+ Clutch (major overkill - rated at 505 Lb-Ft). I have soaked it with ATF to get a reasonable launch, as the stock condition was way too grabby. However, it is relatively mild now.

Originally Posted by RETed

Speaking of shifting...bad, slopping shifting can also damage transmission quickly.
Do you rev match often?
How about on the downshift?

I typically shift about 2,000 rpm and do so very gently. I will occasionally rev to 10,000 rpm in 1st gear and then go straight to 5th, but I let the clutch up in neutral as the engine is spinning down and then disengage it just to go for 5th when the tach drops below 2200 rpm. This is a daily driver and I don't want trouble with the police.
Bear in mind that the only synchro trouble that I have ever had was on the transmission that I drag raced with and the one that abruptly lost 5th gear synchros and reverse.

Originally Posted by RETed

What kind of fluid are you running in them?

Mobile 1 75W90 Synthetic

Originally Posted by RETed

-Ted

[RETed]

Originally Posted by NoDOHC

I have a sprung Spec Stage 3+ Clutch (major overkill - rated at 505 Lb-Ft). I have soaked it with ATF to get a reasonable launch, as the stock condition was way too grabby. However, it is relatively mild now.

I gotta ask why the overkill on the clutch?
You have other plans later down the line that will significantly raise power levels?

I would try and stick with an organic face clutch disc is possible.
This will soften the drivetrain shock.
No need to go metallic puck clutch disc unless you're making over 300 lb-ft.

Mobile 1 75W90 Synthetic

Would it be possible to go thicker on the trans oil?


I think what's killing your transmissions is the brief episodes of 10k RPM's.
No OEM trans is rated to handle revs that high...
This explains all the bad bearings.


-Ted