The problem happened the last few times I tracked my car last summer. The situation is this: I go lapping every other week and run at least one 20 minute session at race speeds.

The car is nearly stock with only the following track-mods: Toyo RA-1, Carbotech pads, bigger front swaybar, Koni sport shocks, anti-bumpsteer kit, ect.

Specifically, when driving home from the track after the last few track days, I just couldn

 

It is the synchro problem. You are lucky many people, me included, can't get it back into 6th for days and even then have to hold it in 5th for a while.

I would swear that early on there was a known issue with 5th and 6th synchros but I have been unable to find it again.

I am surmising it is from lack of use of the upper gears since that is the only thing that seems to cause this problem.

 

5th-6th synchro sleeve. See "what grinding gears can do" thread in UTH->Technical.

 

What I was thinking of is not the grinding issue. That is a completely different problem.

This just locks you out of the gear. It can be either 5th or 6th and only comes after tracking or other hard use where you don't use those gears, then when you hit the streets and start to cruise you can't go there.

 

Have you read those threads? It IS grinding that causes it. NYS2K went for 3rd a few times and hit 5th, grinding the synchros and causing a burr over which the synchro sleeve cannot pass. This locks him out of 6th.

It's a very well-known phenomenon, and the photos in the referenced thread show exactly what's happening.

 

Actually it's NOT the grinding synchro issue. I've had it and I know exactly what is happening.

It has nothing to do with previous skipping gears or anything of that nature. It only happens when you drive spritedly for a period of time (several 20 minute sessions) without using the upper gears.

If it was then my car had skipped gears and multiple grinds before I got it at 3 miles.

When you try to access the upper gears nothing happens on one or both of them. You are locked out and it is like you are hitting a wall. Once you get the juices flowing on that set of gears/synchros you can begin to access the top gears again.

I found the easiest solution was to simply use top gears on cool down laps and in track area any place you can. If you use them periodically the problem doesn't happen.

 

Que? You said it's not what's happening and you know exactly why it's happening but you fail to share the benefit of your wisdom. So tell us the basis of your great knowledge.

Every engineer I've talked to say it's what twohoos says it is and I'm inclinded to believe them since they are the ones tearing down the transmissions and dianosing the problem. They even take pictures (see above).

 

happened to me too... Ill go for third and hit 5th, grind the gears and be unable to get it into 6th. Also, the first time it happened to me was after I put the car in first without using the clutch. The engine wasnt running, and I put the car in gear to keep it from rolling. I couldnt shift into 6th after this... forcing into sixth works after a while..

 

Once you experience it you realize it is totally different cause and effect.

If you'll read their posts, and I have multiple times plus contributed, they have a different end result.

This is more the synchros stick which won't let you access that shaft of gears.

 

And what, exactly, is the cause? Why do the synchros stick?