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Muncie problems Muncie guru needed

5K views 8 replies 6 participants last post by  BogiesAnnex1 
#1 ·
I have a 69 camaro SS with a Muncie 4 speed and its been re-built. Immediately after the re-build everything was great. About 500-1000 miles after the re-build I experienced some grinding going into 2nd gear at high RPM (if I go into 2nd hard it happens if i go easy it doesn't). I sent it back and the re-builder said it was the front bearing retainer wearing uneven. He said it looked like it had 100k miles on it. He replaced the front bearing retainer and 2nd gear and It was great again for the first 500 miles. Now I am experiencing the same problem in 2nd & 4th ( same as before going in easy no prob. slam it in going down the strip it grinds). His thoughts on why the bearing retainer was so worn was that the throwout bearing was not applying even pressure on the clutch therefore not fully disengaging the clutch at higher rps.
He asked if the throwout bearing was installed correctly and it was so he did not know what caused the worn front bearing retainer. Now that I am having the problem again I am wondering if it could be the clutch linkage. I am wondering if anyone has heard of the linkage being worn bad enough to affect the pushing of the clutch fork. The linkage is all mechanical Z-bar on a ball pivot connected to a rod by a through hole with a cotter pin. The holes in the Z-bar are worn but is that enough to cause what is happening to me. I need help bad, this will be the 3rd time the trans is coming out and don't want there to be a 4th. Any ideas please help. I need a Muncie guru
 
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#3 ·
trans

A few things come to mind.

Try not to insult the builder, but have him show you how he installed the input nut... About 65% of rebuilders install the nut backwards... If he can't show you the special wrench needed to install the nut he has it on wrong.


Second. I have seen a few bearing retainers ( the NOS Gm part numbers )that have a missing chamfer on the inside bore where the above mentioned nut fits. I set them up on my lathe and re-machine the missing chamfer. With out this chamfer the nut with rub against it causing problems...


Also i have seen transmissions with missing snap ring cause all kind of like issues...Mybe he missed one???

Keith
 
#4 ·
On to of K-Star' comments of possible internal incorrect assembly and going back to your questions; yes the clutch can be hanging up for a bunch of reasons. Some include:

- the levers are not applying equal force around the pressure plate resulting in the plate opening unevenly and perhaps not far enough to stop the friction disk from continuing to transfer engine power. About all you can do is inspect them for standing height before assembly. The throw-out can get sideways if there is too loose of a fit between it and its carrier bearing (the nose that projects around the input shaft).

- yes the linkage can be worn enough to prevent the clutch from opening all the way
- related to this problem is engine mounts, if these are worn or broken they can allow the engine to move around such that the clutch linkage falls from alignment and cannot fully disengage the pressure plate.

- Another though is what are you running for gear box lube? Some guys are using ATF, this doesn't provide enough cushion in a Muncie for the thrust bearings and the synchros.

Bogie
 
#7 ·
trans

After re-reading your post i am thinking i took your question wrong....

Are you saying that the outside diameter of the bearing retainer where the throwout bearing rides is whats going bad????

Keith
 
#8 ·
oldbogie said:
- Another though is what are you running for gear box lube? Some guys are using ATF, this doesn't provide enough cushion in a Muncie for the thrust bearings and the synchros.

Bogie
Yikes, ATF in a Muncie :pain:? I never heard of such lunacy.

Vince
 
#9 · (Edited)
K-Star, yes it's something to look for. Excessive wear, gouges, burrs can hang the throwout bearing and kock it so it doesn't put even pressure on the clutch arms.

Another potential I forgot to mention is the pilot bearing, if this is missing or worn it will allow the input gear to kock in its bearing and side load the forward mainshaft bearing that's riding inside it. This puts the mainshaft at an angle compared to the shift forks and kock the gear mesh between the mainshaft gears and the cluster gear. This is hard on the synchros, gear teeth, bearings including if not especially the thrust bearings as they end up carrying all the load on a small contact spot instead of the entire surface, and of course the forward mainshaft bearing takes a heck of a beating.

Bogie
 
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