Notchiness and lockout in T45 after burnout

[TonyG]

Right after a burnout, my T45 is very notchy. I try to loosen things up by shifting through all the gears (with the clutch pushed in) right before staging. It helps, but I still have intermittent problems getting locked out of gear during high-rpm shifting.

The problem seems to be related to the burnout. If I do a very light burnout or no burnout at all, the tranny shifts like butter.

Any ideas?

 

[HoustonGT]

Sounds to me like more of a clutch issue instead of a transmission issue. How many miles on the clutch?

 

[TonyG]

Its a SPEC 3 clutch, with about 15 k miles and about 80 passes on the strip. I also have a UPR quadrant and Fiore adjuster.

But I don't think thats it -with the clutch pedal pushed in, I can feel the notchiness in all the gears.

Can the burnout be heating up the tranny too much and somehow cause the synchros to misalign?

 

[stang2004]

did you try changing the fluid?

 

[TonyG]

did you try changing the fluid?

Yes. I had Redline D3 ATF in there for a while. Then when the notchiness started, I changed the fluid and put in GM Sychromesh. I didn't get the notchy feeling on my next trip to the track, so I thought the problem was solved, and caused by the old redline fluid (it was in there for 15 k miles and 80 passes). Now this is my 2nd trip since the fluid change, and the notchiness returned.

 

[COramprat]

Maybe a bend shift fork? I'm just guessing. Is it notchy in all gears?

 

[TonyG]

Maybe a bend shift fork? I'm just guessing. Is it notchy in all gears?

yes, in all gears

 

[Rusty67]

Put the car on a fairly level surface and then put the e-brake on. Shut the car off. Now try shifting through the gears, if its not notchy then turn the car on. Clutch in and shift through the gears.

Let us know what happens.

 

[TonyG]

Put the car on a fairly level surface and then put the e-brake on. Shut the car off. Now try shifting through the gears, if its not notchy then turn the car on. Clutch in and shift through the gears.

Let us know what happens.

I tried this and it shifted smoothly in both cases.

 

[Mike97gt]

Sorry I know you disagree but I think this is a clutch/adjustment concern. What I think is happening is after your burnout your clutch air gap is reduced to the point that you start to have that notchy feeling and lockout. Even with your foot to the floor on the clutch pedal your still not 100 percent disengaged.

Maybe during your burnout you are getting a lot of clutch slippage and this is causing a reduction in air gap right after the burnout.

It's could also be a fluid issue or syncro issue but I doubt it, that should be worse with the engine cold, not after a burnout.

I tried this and it shifted smoothly in both cases.

This also is a sure fire indicator that it's a clutch and or adjustment issue. Thats why he had you do that test

 

[TonyG]

Sorry I know you disagree but I think this is a clutch/adjustment concern. What I think is happening is after your burnout your clutch air gap is reduced to the point that you start to have that notchy feeling and lockout. Even with your foot to the floor on the clutch pedal your still not 100 percent disengaged.

Maybe during your burnout you are getting a lot of clutch slippage and this is causing a reduction in air gap right after the burnout.

It's could also be a fluid issue or syncro issue but I doubt it, that should be worse with the engine cold, not after a burnout.

This also is a sure fire indicator that it's a clutch and or adjustment issue. Thats why he had you do that test

Thanks for your insight. Do you think that it would help if I set the firewall adjuster to increase the air gap -i.e., so that the clutch grab at a higher pedal position?

 

[stang2004]

Clutch quadrant and Firewall adjuster. Try fiddling with those and see what happens.

Correct me if I'm wrong, but i dont think your "supposed" to run GM Synchromesh in the T45 or T5.

 

[TonyG]

There are mixed opinions about synchromesh -and I'll probably switch back to Redline D3 ATF or Mobil 1 ATF. But this problem started before the synchromesh.

 

[Rusty67]

I'd say its a clutch problem as well.

 

[Mike97gt]

Thanks for your insight. Do you think that it would help if I set the firewall adjuster to increase the air gap -i.e., so that the clutch grab at a higher pedal position?

Maybe.

If your at a stop how far from the floor does the clutch start to engage if you let out really slow at idle. it should be a minimum of three inches from the floor.

If the air gap is not enough then maybe after the burnout the tiny bit of reduction in air gap as the clutch heats up could cause this problem.

OR... if the air gap is too much the clutch maybe slightly disengaged even with your foot off the pedal causing excessive heat and this can cause your concern too.