Problems shifting 4th to 5th at 150mph...

[PMJ]

I had a great time at the Texas Mile last weekend, however I never got a clean run. My first non-preliminary run, I shifted through all gears clean, but made the stupid mistake of shifting to 6th with about 1/10th mile to go. I ran a 151.4 1/2 mile and 175.7 mile. Then i looked up top speed per gear, and realized i was a moron for shifting to 6th...I guess i should have done my research before the event...

Anyway i got in line again bound and determined to break 180. And on the next run, i couldn't shift to fifth gear...took like 4 tries. My 1/2 mile time dropped to 142 as i was trying to slam into gear (per my log, i dropped ~ 10mph in the shift to 5th), finally made it and finished with a 175 mile...

I was pissed, but thought surely that was driver error, so back into line. The same thing happened the next run (3 tries to get into 5th)...175 again (i certainly was consistent). I decided i had to give it one final shot. So on the 3rd try i made a point to slowly and deliberately shift to 5th gear, it still didn't go until i double clutched. That certainly slowed me down (145 1/2 mile), but was my fastest run 179.3 (maybe if i didn't have the gopro outside on the fender i would have hit 180...or if i could shift cleanly ).

So after 3 times in a row not being able to shift into 5th, i'm starting to conclude i have a technical problem (although certainly haven't ruled out operator error).

Any ideas on what could be causing problems shifting 4th to 5th, but not other gears? I'm already looking to upgrade my stock clutch, but i'd think i'd have other symptoms if it was a clutch...

BTW, didn’t miss 5th gear once on the way back to Houston…I only seem to have the problem when I’m going over 150mph…

[2010SSRSM6]

How old is your fluid? Do you have a separate clutch res? What fluid are you running? What was your trans temp?

Where it was high speed (possibly high heat) your fluid my have kept the clutch from disengaging causing the issues.


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[PMJ]

My car has 11k miles (2012) and the clutch & fluid are all original stock. I don't think I logged trans temp, but will double check. In general, ambient temp was 60, and my IATs in my whipple went from 95 up to 135 when I crossed the finish line.

I'm looking at a dragon slater twin disc clutch. Would that help if it was transition temp?

[TinyToasta]

Have had the very same issue over and over again

ZR1 Clutch - fresh brake fluid - castrol SRF, Motul or stock fluid - no change!

5th gear feels like completely blocked, mostly after crossing 6000rpm in 4th gear
I guess the synchros don't like that at all.

However, clutch will be changed shortly (Twin Slayer Carbon), braided lines, separate reservoir, the whole nine yards.... If that doesn't fix it, something's not right with the tremec!

[chopss]

i had same problem while ago. all stock set up and all fluids clean and it seemed like 5th gear was blocked damn thing wouldn't shift into gear even after a few tries.

[dekan513]

i know when i drag race , most ppl like to leave there cars off till they are rdy to make a pass. i noticed everytime i did this my car seems to miss 2nd or 4th. so now i let the car warm up fully and then cut it off open the hood and let it cool off as much as possible for about 10 min or so. then let it run for a min or 2 before prestagin. shifts are dead on when the trans temps are at running temps. might try that. its better to loose a few hp do to heat soak then it is to miss a shift.

i also suck out brake fluid i can , and put in fresh fluid before i race , its made a big diff in the pedal stickin. when i have fresh fluid it never happens .When i dont change it even after 500 or so miles it will stick on hard launches or shifts.

[Trackman]

Maybe you should have bought the 180 mph painters tape instead of the 175?

[PMJ]

Originally Posted by Trackman

Maybe you should have bought the 180 mph painters tape instead of the 175?

great recommendation. I think I'll try faster tape, replacing my stock clutch w a McLeod RXT, and add a blower cam. Between the 3, I expect to blow by 180 next time around.

[SSE 4 2SS]

Originally Posted by PMJ

great recommendation. I think I'll try faster tape, replacing my stock clutch w a McLeod RXT, and add a blower cam. Between the 3, I expect to blow by 180 next time around.

The Texas mile was an absolute blast, though it will cost me a motor and heads before I go back, hopefully in march if my schedule allows it... Good luck with the trans and blowing right through 180 on your way to 190...

[Merc]

Originally Posted by SSE 4 2SS

The Texas mile was an absolute blast, though it will cost me a motor and heads before I go back, hopefully in march if my schedule allows it... Good luck with the trans and blowing right through 180 on your way to 190...

You did more damage then first thought?

:(

[PMJ]

Originally Posted by SSE 4 2SS

The Texas mile was an absolute blast, though it will cost me a motor and heads before I go back, hopefully in march if my schedule allows it... Good luck with the trans and blowing right through 180 on your way to 190...

I didn't catch up with you on Sunday, did you break 197?

[SSE 4 2SS]

Originally Posted by Mercuryman

You did more damage then first thought?

:(

A bit, hopefully it can be fixed... Corey explained it better than I can in my thread...

Originally Posted by PMJ

I didn't catch up with you on Sunday, did you break 197?

My fast pass was 197.8. I was at approximately 208 when the head gasket let loose at the 7/8 mile... Still coasted to a 197 pass... There's always next time...

[grocerygetter]

could be scarlett johansen...send her to me...I'll check it out. LOL