Transmision Problems

[MRC1994]

Under hard acceleration my 94 will grind gears when doing the 2 to 3 shift. I am sure that I am depressing the clutch all the way. It only grinds going into 3rd. No other gears. Under "normal" driving I don't have the problem. So what do I have going on? Bad synchronizers?

[Z51JEFF]

Originally Posted by MRC1994

Under hard acceleration my 94 will grind gears when doing the 2 to 3 shift. I am sure that I am depressing the clutch all the way. It only grinds going into 3rd. No other gears. Under "normal" driving I don't have the problem. So what do I have going on? Bad synchronizers?

My 91 will hang up if I get aggressive going onto 3rd.Car has 21,000 miles and has always been like this.

[Franke]

Originally Posted by MRC1994

Under hard acceleration my 94 will grind gears when doing the 2 to 3 shift. I am sure that I am depressing the clutch all the way. It only grinds going into 3rd. No other gears. Under "normal" driving I don't have the problem. So what do I have going on? Bad synchronizers?

I vote for a worn synchro. Years ago I had the opportunity to rebuild some Muncie 4 speeds with gear grind problems and saw how the synchronizers have fine oil grooves on the inside of the ring which rides on the gear sleeve. The oil grooves almost looks like fine screw threads. The new syncros oil grooves were much more pronounced than the worn ones. Replacing the synchros and some other minor worn parts corrected the grind issue when hard acceleration shifting. I'm not a ZF expert so maybe Mr. Boudreau could provide insight to this issue. According to all I've read here he's the go to guy for these trannys. Hope I spelled his name right.

[scottfab]

First thing to do is change the tranny oil.
If you do have a worn synchro it will help until repairs can be made. It may even mask the problem completely. It did mine until I had time to take it apart and replace 3rd synchro (and both input shaft bearings).

Note the wear

[ZZZZZR1]

Originally Posted by scottfab

First thing to do is change the tranny oil.
If you do have a worn synchro it will help until repairs can be made. It may even mask the problem completely. It did mine until I had time to take it apart and replace 3rd synchro (and both input shaft bearings).

Note the wear

Well said Scott.

Definetly change the transmission fluid before you do anything drastic...

I think the BMW castroil is the best?

What grade?



David

[Racinfan83]

Mine was a lot quieter and easier shifting after I did this:http://www.zr1.net/forum/showthread.php?t=20819

[mike100]

I will offer a different opinion. Don't waste $50 in trans oil when you know the synchro and associated gear cluster is damaged.

Maybe if it notches a little, you can get away with a different lube, but if it flat out grinds- it needs hard parts and no oil will help it now. My 2nd gear wouldn't shift well over 5500+ rpms. I think the 2nd gear cluster, a new synchronizer, and all the parts that come with that was an additional $600. I ended up over at the ZF Docs place to get it semi blueprinted and rebuilt. Expect $2000-$3000 depending on if you pull the trans and how many hard parts and custom mods you get done.

[Z51JEFF]

Originally Posted by scottfab

First thing to do is change the tranny oil.

Thats what I did,used Amsoil tranny fluid and it didnt make any difference.I just make it a point to pay attention if Im jammin through the gears going into 3rd.My car has done this with 6000 mile on the clock.

[scottfab]

Originally Posted by Z51JEFF

Thats what I did,used Amsoil tranny fluid and it didnt make any difference.I just make it a point to pay attention if Im jammin through the gears going into 3rd.My car has done this with 6000 mile on the clock.

Why not try a different oil? Castrol TWS 10W60 ????
Amsoil may not be the best for you.
The idea is to prolong the shifting until repairs.
Cheap workaround until you can crack it open.

When I have heart burn I use an antacid. Running in for
surgery right away may not be the best approach.

[LGAFF]

Might talk to Pete first, he did mine....and knows some tricks.