Salvaging (Early) Round Top Cover NV4500

[Richard2112]

Most problems with the early round top trans covers can be resolved by purchasing the new part required. There is one condition that I haven't seen a solution to yet and that is the shifter stub seat worn out. I think there may be a solution to this also. At least it has worked for me. So far.

I have read some excellent threads penned by the members here, some of which have (and yet will) spare me agony of catastrophic failure, economic attrition or at least undue agony while I plod through the restoration of a 1970 C-30 dually. My expertise at turning a wrench has been limited to knowing which way to turn the bolt depending upon whether one desires to tighten or remove it. Basically, I'm as green as they come on the subject of transmission rebuild and replacement so any advice or critique is welcome. If I can do it, then nearly any one can, provided the idea is sound. I find that I have to work on a very restricted budget and should a situation arise that I wasn't prepared for, I better be able to devise a working solution.

Well, that has happened. When I bought my NV4500 I knew it was a high mileage part. I expected to do the typical rebuild, replace synchros, bearing, seals, hubs, rings and springs and things...And there is a lot of good advice on how to do that from people more qualified than me. Some have advised me to just buy a rebuilt trans and be done with it. Good advice to be sure but my curiosity for whats inside the mechanical box over turned the vote put forth by common sense.

Nevertheless, I am arriving at a point that I understand a great deal more about trans rebuild/swap than I did before, and that was part of the goal. One of the things I learned is that the shifter stub seat on the round (early) style top covers will wear. That thought might have been obvious to more experienced people but it was a secondary notion (at best) when I considered my rebuild. The trans I eventually bought came as an assembly, though it was evident the covers had been removed some time long passed and the shifter which came with it had simply never been returned to it's moorings. I figured these things were to be expected. It wasn't until after I had performed a good cleanup on all my parts, rebuilt my main shaft assembly and began to put it all back together that I discovered the top cover was headed for the recycle bin.

A new top cover assembly can easily cost 400 dollars or more, an expense that isn't always necessary or in my case, well outside my budget.

This '93 had seen many miles which was evident on disassembly and the top cover had seen better days.The shifter stub had worn into the seat and as you will see, the bottom of the shifter was wearing into the center rail so much that it locked the shifter from moving.

While working on the top cover, I discovered one of the shifter pins that the stub pivots on, was also broken. And while I could have purchased a small parts kit to fix the broken pin, the seat was still a problem.

To my knowledge (and I searched high and low) there seems to be no method to repair the seat inside the shifter stub tower on the one-piece, round style top covers. What follows is a brief description of how I managed to solve this problem and quite possibly save a few hundred dollars (that I didn't have anyway). This worked for me and maybe it can help some others but it has yet to be time tested. I think it will last at least as long as the transmission but given that I've never run across this technique before, that's just a weighted guess. I'll try to be as clear as possible and answer any questions as well as I can.


The beginning

This is the top cover I'll be working with throughout this write-up. It will go through some changes

[IMG][/IMG]