intense3123

Started last night after going to the track, grinded pretty bad going into third on one run. Didn't think much of it, cuz everything was working good on the other runs after that.

Driving home on the freeway, tried downshifting from 6th to 5th and it will not go in. No grinding or anything, just fells simply locked out. Stopped the car and tried with the car off, same results

Now here's the strange part, if I downshift from 6th, put the lever in 4th (or any other gear than 6th) all while keeping the clutch engaged, then go to fifth it will slip right in. It's strictly a problem from 6th to 5th.

Any ideas on what could be wrong?

85MikeTPI

iTrader: (9)

We were just discussing this:

https://ls1tech.com/forums/manual-tr...ing-issue.html

Although it could be a blocker ring going bad in some older/high-milage units, the consensus seems to be that the Rev lockout is somehow causing the 6->5 gate to be blocked, while all the other shifts hit it such that it doesn't interfere.

Suggestions such has unscrewing the lockout solenoid from the lockout mechanisim, or shimming out the mechanisim from the housing, behind the screw, should tell you if this is the issue..

intense3123

If I wanted to pull the solenoid to see if that's the problem, is there enough room to get it out with the trans in the car? It's just held on with one bolt right?

Do you think it would be sufficient to just duct tape the hole off while I test drove it to see if it's fixed, I don't know how much fluid would be trying to come out at speed.

turboffr

iTrader: (1)

was the root of this issue ever identified? The same exact thing happened to me after a trip to the track on Wed (missed a few 2nd to 3rd shifts). On the way home I discovered I couldn't downshift from 6th to 5th, but if I go 6th to 4th first it will go into 5th gear easily. Also it downshifts fine when running at an idle.

85MikeTPI

iTrader: (9)

FWIW, all of the situations I've been involved with, turned out to be a worn 5th gear blocker ring on the synchro... YMMV.

Z20ATE

ive had the same problem for a year now. i just destroyed my 2nd gear syncro last night at the track so im just gonna replace all syncros so thats should fix the problem

calhoon

iTrader: (6)

Going back to th OP, the reported clash-shift of 3rd was most likely a missed gate....he actually shifted into 5th. The ratio step was way too severe and the 5th blocker burned up ( some).

turboffr

iTrader: (1)

is the blocker ring not used during 4th to 5th shift. seems odd that I can shift fine from 4th to 5th (engages very smoothly), but not 6th to 5th. It's like hitting a wall, no grinding, no nothing. I should add that I have a 2006 vette

85MikeTPI

iTrader: (9)

The blocker is used in upshifts and downshifts, but has more work to do on downshift as rev-matching is rarely as precise during downshift.

My other "theory" is that the factory end-play shimming of the 5/6 extension shaft, leads to more difficulty engaging the 6->5 shift as the shaft movement takes up the effort that otherwise would go into synchronizing the downshift. Using a more precise 0.000" end-play shimming helps the 6>5 downshift alot.

calhoon

iTrader: (6)

As Mike stated the downshifts require more work than an upshift.If the ring was glazed and not fully worn out, it could give those results.
Good point on the end play affects on the situation, Mike. extra end play would add timing & travel to the shift .

turboffr

iTrader: (1)

so it sounds like I need to pull it out to diagnose and fix...bummer. Any tips/threads on removing the tranny from a C6 vette?

the_merv

iTrader: (88)

I haven't had a chance to get into mine yet, but I will say mine is a little different from the OP..I can hit 5th without a problem with the car off..with it on is when it gives me ****..lol..

I'm highly doubting the Rev. Lockout..I don't see that being the culprit IMO..

I'll pull it down and check it eventually. I built my friends T56 and his is flawless..go figure I build mine and it's being a pain..