Need help on why my transmission jumps gear on a 92 firebird 5.0 tbi

 

Order a rebuild kit, get it installed.

 

What does this mean... you're driving along in say 4th, and all the sudden it jumps into 5th all by itself?

 

It's shifts fine but when I'm on 5th gear it jumps into neutral with an awful clunk sound. I also noticed that when the car is turned off it shifts without engaging the clutch.... need advice ... thank you.

 

OK, so it jumps out of 5th... any other gears?

Of course; that's what it should do. Good thing it does that.

 

No. It only does it on 5th gear at any speed. I hold the shifter and I can feel vibration...

 

I've already replaced the trans mount and have inspected motor mounts. I'm going to inspect u joints next .

 

Mounts and U-joints aren't a factor.

Sounds like either the 5th gear shift fork is bent, and not shifting it into 5th all the way; or, the sleeve is farkled.

The "sleeve" is the part that the fork actually slides. It has splines on the inside that engage the dog teeth on the gear. The splines aren't cut straight; they're actually cut with a slight taper in the direction that tends to pull it onto the gear. Over a long period of use they wear out and maybe even get taper in the opposite direction. Rare, but possible.

I'd take a look at the shift fork first. Make sure the little green plastic tabs are still in it, make sure it's not bent, etc.

Some degree of vibration when abusing it by holding the shifter that way is to be expected.

When you put it into reverse, do you prevent it from grinding EVERY TIME?

 

Good news is if it just 5th gear that is very easy to work on. Just pull the trans and the tail shaft and all set.

 

I have to pump the clutch or move the shifter when reverse grinds but I do try to prevent grinding by all means. I went under a took a look at the slave cylinder and its wet of brake fluid and it has a lot of play and it moves back and forth freely with my hand. Could that possibly be the problem. Thank you for responding to my tread.

 

If you let reverse grind, it sheds metal chips into the fluid, and then 100% of the time, the trans gets busy eating itself. (Remember Pizza the Hut in "Spaceballs"?)

All you have to do to keep it from doing that, is put it into a forward gear before putting it into reverse. Any forward gear will do. What you're looking to do is STOP the clutch disc and guts from spinning before trying to jam the reverse teeth (which are not synchronized) together.

Clutch problem is probably separate from the 5th gear one, but who knows. It's ALOT LOT eeeeeezier to change that out than to fool with the trans though... so since you already know it's fornicated, go ahead and fix it, and see if that also fixes 5th not going all the way into gear.

 

Thank you so much for your input and time . I will swap out the slave cylinder and hope it's the solution to the problem.