Transmission gurus, please comment, Wear on bearing retainer plate Options

[MrKona]

I'm nearing the final stages of a "partial" transmission rebuild. To make a long story short. I started off with my original and a donor tranny. Turns out the donor had a broken shift fork, but no other problems that I can see, all synchros and gears look alright, case bearing races fine. No reason to take the shafts apart, so I'm reinstalling the drive and pinion shafts into a freshly cleaned case with all new gaskets and seals, and a brand new pinion shaft intermediate plate bearing (The old one fell apart in my hand, sound familiar?). I'll use the shift fork from the original transmission.

My concern is wear that I spotted on the bearing retainer plate that mounts on the intermediate plate. First gear had worn a groove in the plate, just less than a mm at its deepest. There was no more metal-on-metal contact, as first gear appears to have completed it's job of clearing away metal. I couldn't see any wear on first gear, tells you how tough these gears are. (As I can tell from the blue goo gasket sealer, this transmission looks to have been part at least once before).

Anyone have any ideas what could have caused this... where the tolerances could be off? It's going to nag at me as I'm putting this thing back together. Thanks.

By the way, I had the outer case plastic bead blasted and it looks absolutely beautiful. When it's done, I've got to post some before and after pics. I can't believe the difference!

[bondo]

QUOTE (MrKona @ Nov 5 2005, 11:54 AM)

Interesting... it took me awhile to digest that. I guess the takeaway is to tighten the stretch bold to the right torque. I guess it's time for Saturday morning transmission class... Two questions: 1. What part are you referring to as the "ring". 2. What is "r&p backlash". Thanks in advance. - Bryan

Ring = the big gear around the differential that the pinion gear meshes with.

R&P = ring gear and pinion gear (matched set)

backlash = how much you can turn one gear without turning the other.. a measyre of "slop". In an ideal world you would have zero, but things expand when they get hot, and machining tolerances aren't perfect, so you need some backlash to keep the gears from eating each other.

BTW, backlash isn't the only thing that's critical when adjusting the R&P. The ring gear can move side to side (based on shims under the differential bearings) and the pinion can move forward and back (based on shims on the pinion shaft, fine tuned by paper gaskets under the intermediate plate). All this adjustment allows the force of the engine to be transmitted to the middle of the teeth of the gears, instead of closer to any edge. Get it wrong and it can be loud, wear funny, or both.

Things are further complicated because the total of shims on both sides of the differential also sets the differential bearing preload.