I am new to this. I have a 1974 L82 with a muncie. This was rebuilt 6 years ago ago and came back slipping out on deceleration in 2 and 3 gears. I let it go at the time. My mechanic set it up with a Hurst shifter and it still slides out of 2ed when you decelerate from 2000 RPM and out of 3rd on any downhill over 1/2 mile. He claims to have sent it to a new shop last week and it is still still the same. What's going on? Is it an adjustment or are the gears shot?

 

Copied from a web site:

The most likely causes of the transmission slipping out of gear are worn detent ***** or springs in the shifter shaft cover. These spring-loaded ***** hold the shifter shaft in position. If the spring does not have enough tension or if the ***** are worn, the transmission will almost certainly slip or jump out of gear. Synchronizer damage will also cause the transmission to jump out of gear.

Slipping out of any gear is most likely to occur when the driver suddenly takes his or her foot off the accelerator pedal, especially when descending a steep hill. The thrust produced by the helical gears will tend to move all rotating gears and shafts to the rear of the transmission, as long as the torque provided by the engine is being delivered to the rear wheels by the transmission. However, when the driver takes his or her foot off of the accelerator pedal, the situation is changed. The rear wheels now try to drive the engine through the transmission. This reverses the direction of the torque being delivered through the transmission gears, and the thrust is now toward the front of the transmission. If this thrust is not controlled by the thrust washers and bearing retainers, it is likely to force the shifter shaft to move in spite of the spring-loaded ball that holds it. When this happens, the transmission slips out of gear.

 

I repectfully DISAGREE! first a 74 should have a BW Super T-10 but, if it is indeed a Muncie, the synchro sliders and hubs are old and worn and should be thrown away! The synchro assemblies are very simular between a Muncie and a T-10 Borg Warner 4 speed so again I would start checking there. There is a sychro slider hub known as a "torque lock" slider and they are sold by Auto Gear transmission parts comapny. These are the only type I use in a rebuild of any Muncie or T-10 transmission, the tooth cut on a "torque lock" style slider is undercut to grab onto the gear teeth to prevent kick-out under de-acceleration like conventional sliders can do on occasion. Your main problem seems to be using a mechanic who shouldn't be allowed to work on your Vette as they seem to be lacking in basic diagnosis/technical skills. Corvette Repair in Mtn View California (corvetterepiar.org) could do the job, S&K Speed shop on the east coast can be trusted, there are others out there, get away from the guy that is working on your Vette right now.

 

Also... there are no "*****" involved in the side-cover & forks. The only ball in a Muncie is for the reverse shifter fork. There are, however, springs and detents. The shifter forks have an extension on the rotating shaft that interfaces with steelplate detents which are spring loaded.

Either the linkage is not adjusted properly, or the synchros/sliders have issues.

 

What website was that copied from ?

 

I had a muncie in a 74 back in the early 80's and I'm pretty sure thats how it came

 

I believe 74 was the last year for the Muncies. I know the 75's used ST-10. As stated the cause is probably internal and the slider would be where I looked. The master kits do not come with sliders, they cost extra, so depending on what you paid you may have just got a master kit or part of one but certainly if the problem was there when you got the tranny back it was not done correctly.