Assess used transmission?

jsilva

jsilva

Greenie N00B Member
My MS6 was popping out of gear and I assumed it was a transmission issue, so back in March I bought a used transmission (the person said it worked fine...). My goal was to learn to rebuild the old transmission and install the one I bought.

But I was thinking it’d be nice if there was some way to verify that the transmission I bought is usable before going to the effort to install it.

Any tips?
 
Check the magnets and the fluid (if still filled) for large chunks of metal. you can manually shift the transmission into each gear to make sure it moves smoothly. If you're planning on a rebuild just tear it down and check everything out. I would rebuild the one you bought first before swapping it in otherwise you're doing twice the work. Torque everything to spec, make sure to check preloads and use marking paint to check gear contact etc. Manual transmissions aren't that complicated to service but they have a lot of different parts so lay everything out as if it were an exploded view.

Last thing is to buy a TON of sandwich bags. Use a permanent marker to label every bag so all components are sorted properly.
 
L337TurboZ said:
Check the magnets and the fluid (if still filled) for large chunks of metal. you can manually shift the transmission into each gear to make sure it moves smoothly. If you're planning on a rebuild just tear it down and check everything out. I would rebuild the one you bought first before swapping it in otherwise you're doing twice the work. Torque everything to spec, make sure to check preloads and use marking paint to check gear contact etc. Manual transmissions aren't that complicated to service but they have a lot of different parts so lay everything out as if it were an exploded view.

Last thing is to buy a TON of sandwich bags. Use a permanent marker to label every bag so all components are sorted properly.
Click to expand...

Great, thanks! That’s helpful.

I agree that rebuilding the one that’s already out is a far better thing to do. However, I need to get this car running asap and I’m currently rebuilding the engine. I’d like to have it running early Jan and I am pretty busy. So my thought was to put in the transmission which supposedly works and gain a year or two to rebuild the one that doesn’t work quite right. Just so you know what I was thinking...
 
Yes my first :) I bought the book ‘How to Modify and Rebuild High Performance Manual Transmissions’ which was going to be my guide. I’ve skimmed through it and have watched some videos on YouTube, but I wouldn’t consider myself anything but a novice at the very best. Rebuilding it will be a learning experience and so I wanted to take my time with it.
 
I also suggest lots of Ziploc bags but I put a piece of paper inside with the description. I find sharpie on the outside to be too unreliable
 
Take up stock in brake cleaner, too. You'll go through a lot. When you clean something, bag it. Then when you need it, take it out of the bag and clean it again. You would be amazed how much damage even a tiny little piece of debris can do inside a transmission.
 
I forgot to mention you will need a press and a bearing puller kit. It will also help that before reassembly of the transmission or pressing components, put any component that another part will be pressed onto into a freezer overnight or for a few hours. The metal will shrink and allow an easier time when pressing it all together.

I have left pinion gears in the work fridge overnight and been able to drop a bearing right onto it without using a press or only having to use a piece of exhaust pipe and a hammer to tap the bearing down.
 
I really do appreciate everyone’s input on this!

Though I probably won’t have the time to rebuild the transmission before I need to have this car running. So I need to make a decision about whether to keep in the existing one—which pops out of 2nd and 3rd when decelerating unless I hold the gear stick in place (maybe it’s not the transmission...?)—or use the one I bought which the seller said worked fine.

The only thing I observed about the replacement transmission is that when it’s in gear I can’t turn the input shaft by hand. Not sure if I should be able to. At some point I’ll examine for any metal pieces but I haven’t yet.
 
I think at the very least you would want to crack the case open on the extra transmission and look inside.
 
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