What exactly causes 2nd gear lockout...?

[75blackray]

I've seen it posted a couple of times recently, and it brought it to my attention that I don't know the actual cause. My clutch was one of the first things I bought for the car, so I went with sb rally (450 ft/lbs, that would be plenty right...).
On 15 psi I made 380 ft/lbs at the wheels, the car is much stronger now at 18psi with a way better tune, so I would say that I am a good bit over 450 ft/lbs at the crank. The clutch has never slipped on me in high gear, but if I launch the car I have to really stuff it into second, or wait a while for it to drop in peacefully.

I have always just assumed that the clutch blocked out second, but have also read before that worn syncros can cause the same issue at redline wot.

Anyone care to take the time to explain what exactly is causing the problem?

[familyMAN]

Make sure your clutch is adjusted properly and isn't dragging slightly. Takes very little to mess up shifting. First place to start since its free.

[75blackray]

Thanks, I will double check that, but I'm pretty sure it is adjusted properly and I can shift fine into 2nd if I don't launch the car or under part throttle conditions. I was more asking what actually causes the "blocked out of 2nd" condition.

[nodoze]

Could have a problem with your shift firms I have seen broken shift forks cause that problem

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[75blackray]

I put good forks in when I rebuilt the trans. So, I'm pretty sure that is not the cause. I have seen/experienced the same issue in a stock clutch t56 trans, but it only seems to occur when the cars slip the clutch hard at the launch. I more just curious what actually causes the problem.

[Chris@Rvengeperformance]

The trans is preventing you from shifting because proper synchronization is not occurring. Either the clutch is not releasing fully or the syncro or gear is bad.

If you rebuilt the trans because of grinding before and only replaced the syncro then your gear engagement teeth are probably rounded from grinding. This will make shifts notchy and can prevent fast shifting.

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[anyonebutme]

also, if you can bang 2nd at high RPM without a launch but not with, don't forget the clutch expands when it's slipped.......so "over" adjusting it might help but if you run out of slave cylinder throw......you'll need another solution like a thinner, more aggressive clutch plate and reworked pressure plate or a smaller diameter slave if you are not topping out the pressure plate.

[75blackray]

Thanks guys. That's the info I was looking for. I was getting grinding in 3rd but not second. I rebuilt BC of faulty shift fork though, and replaced all syncros while I was in it. Also had the local trans shop check all of the gears for wear. It just seemed like the problem is influenced either directly or indirectly by increased power.

[Chris@Rvengeperformance]

I guess you have strong motor mounts?

[75blackray]

I guess you have strong motor mounts?

Good poly mounts. Why?

[Chris@Rvengeperformance]

Good poly mounts. Why?

Well it doesn't sound like it in your case, but if your motor mounts are bad enough the trans can move enough to effect the shifter cables and make you miss gears.

[nodoze]

I have seen shifter cables become unbolted from the trans and cause a gear blocking.issue due to slop

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[75blackray]

Good points to double check along with the clutch adjustment. When I finally get the time/nerve, I'm going to pull the trans again (stupid os seal!), and check the internals again as well as the clutch and pp. My only problem is at that point do I want to really spend $600+ on a clutch, when the current one is holding strong (if its not the cause of 2nd gear lockout), and has <15k miles.