<VV> LM 4 speed reverse problem solution
kovacsmj at sbcglobal.net
Mon Jul 3 18:06:14 EDT 2006
After all the work under the car and replacing all the bushings etc. in the throttle linkage and shift linkage, it would NOT shift into reverse.
Working with a spare 4 speed and comparing it with mine, I determined it was not the transmission, but the linkage. With my wife trying to shift the trans into reverse, I was under the car (properly supported and no engine running) observing the linkage action.
I discovered that the last piece (with the rubber bushing) that connects to the shift rod in the trans was not rotating enough to twist the trans shift rod into the required reverse position. Well I had three NOS rods in my stash, so one should do the trick, right?? NO!
None would do the job. I noticed all three allowed the solid rod inside the rubber bushing to move and not to be able to turn the outside part enough to cause proper rotation to turn the shift rod. There is a pin that is in a small slot on the the outside and tight on the inside solid rod that prevents total slippage. It is this slot that allows the inside rod to rotate a little on the outside part attached to the trans. I assume this was for dampening purposes and to take up some stresses.
The solution was to take an appropriate washer and cut it in half. The halves were then brazed to the outside of the rod to prevent the pin from rotating in the slot resulting in a maximum rotated angle.
Yes, the rubber tries to burn, but quick brazing minimizes the problem. The rod could be returned to the original condition by grinding off the two half washer, as the pin going through is not brazed to the outside, just the washers to hold it fully rotated.
Shifting is now no problem and with the engine off there is a satisfying "click" when reverse is selected.
If I had time, I might have built a collar that would restrict the amount of slippage the pin allows.
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