Transmission Swap Economics

[Jeff G 78]

Hmmm. I've owned 10 S30's and I've never had a trans go bad even after racing abuse. Buy a $150 JY 5-speed and install it. Worst case is that you have to return it and install another one. I can R&R a trans in a few hours without a hoist, so the risk is rather low.

[ggunder]

Yes, it was and AAMCO transmission shop. I will pick it up tomorrow and take some pictures to post.

The good news is that I have the oil pan all ready to reinstall, the pilot bushing removed and the rear main seal removed. All this went very well using tips available on this forum!

Gary

[cygnusx1]

For $1000 you can buy 6-10 used transmissions, just to put it in perspective. Good luck with yours, and I am sure it's likely fine as-is.

[ggunder]

They pointed out a few items that were damaged. The first was this shaft that has a scored, worn spot where a ball engages the shaft.

They also said this bearing was stuck and there was a shiny worn spot next to it.

Here is one more shot, I honestly could not see anything that was damaged.

[Zed Head]

Take a shot of the pointy parts of the teeth on the bronze colored thin gears (synchros), edge on. And try to keep the synchros with the gear that they were on. They should stay matched if possible. I hope the shop didn't just toss everything in a box.

Also, if you could take a shot of the conical shiny portion on the side of the gear (upper right in the bottom picture) it looks like there might be some surface rust there. I have an old transmission in my car, and it took a few hundred or more miles before the synchros worked right. I had a theory that the synchro cones had rusted, taking time to wear back in, and you might have some evidence to confirm that it happens.

I don't see any dramatic damage. The bearings can stick on the inner race (shaft) or the outer race (housing), it's not uncommon.

[cygnusx1]

You have to measure the the synchros. That's about all that wears out besides bearings. If you don't see chunks missing from any gears they are probably fine.

Edited April 3, 2012 by cygnusx1

[Zed Head]

When you said they took it apart and had the parts in a box, I was thinking of the assembled gears on the adapter plate and the front and back cases, along with a few odd parts. Didn't realize that they would tear it all the way down, taking gears and bearings off of the shafts. Most of what I've read suggests that it's a bad idea to reuse a bearing once you use a puller on it, because it puts high side loads on the ball bearings when they're not rolling, damaging the race and the ball. If that's true, then Aamco knew they had done some damage and was going to put it back together anyway.

They should have been able to give you a rough idea without removing the gears and bearings. I think that you might be stuck now, needing a rebuild of at least bearings and probably a little polishing on the gear cones if they do have rust on them (I've read that it can be done). I'm not sure that putting the old bearings and gears back on and running it would be a good idea. I could be wrong.

The $131 might still be a decent price for a teardown, if you can get a rebuilder to discount that portion of a rebuild. Now you've got a bunch of choices. Good luck.

Edit - One more thought - before you spend more money and time, you might be happier, in the long run, sourcing a late 80 - 83 5 speed, with the close ratio 1-4 gear set. The 77 has the big 2-3 jump and is not the best transmission to rebuild anyway. 80 - 83 has a better reverse lockout also.

Edited April 3, 2012 by Zed Head

[cygnusx1]

Just in case, I wanted to bring this to light. It may be helpful.

http://www.drivetrain.com/parts_catalog/manual_transmission_overhaul_kits/nissan_f5w71_overhaul_kit.html

[olzed]

I once took a RUNNING spare diesel injector pump from a Perkins, in to get a check over. I was quoted the price of a new one to repair the old one.Duh.!! Brought it home in a box and eventually threw it away. It wasn't worth spending more to have it reasembled.

[ggunder]

I carefully examined each piece of the puzzle and here are the three items that looked like they could be issues:

The above looks kind of worn.

There is some rust in between the teeth of the gear. The shaft has a scored mark that the shop said was bad.

I can measure the sychro rings, if that is what the following is:

I am looking for another transmission, maybe a close-ratio one from a later model or even a Maxima in case this is a dead end.

Wish I was a real mechanic!

Gary

[Zed Head]

I got a lot out of this book - http://www.amazon.com/Rebuild-Modify-Transmission-Motorbooks-Workshop/dp/0760320470/ref=sr_1_1?ie=UTF8&qid=1333848551&sr=8-1

How to Rebuild and Modify Your Manual Transmission (Motorbooks Workshop) by Robert Bowen

Lots of pictures, of both good and bad parts, with good descriptions.

The dog teeth (the pointy triangle shaped things sticking out from the side of the gear) on that gear in the first picture do look worn. The tops of the triangles should be sharp, not rounded. They look abused.

And the rust isn't good, that's actually a splined piece that has a matching splined collar that slides back and forth over it. The collar needs to slide easily over that area. The inside of the collar is probably rusted also. It would probably wear off over time, but might be stiff shifting for a while.

Just some thoughts. Someone who's actually rebuilt a transmission could tell you more.

Edited April 8, 2012 by Zed Head

[ggunder]

As it turns out I was prowling Craigslist for cars in my area and found a 5-speed out of the car that was for sale right down the street. Now I have 3 transmissions sitting on the floor (wife is suspicious)! The latest is a close-ratio from 81-83 as identified by the location of the retaining hole for the speedo drive at 6 o'clock and the single ear at the back. It does not have a speedo drive, so I will use my speedo drive (yellow gear) from the 4-speed coming out of the car. I guess I will need to grind a new retaining keyway to make the old speedo drive work on the new 5-speed. The new transmission had recently been drained, but the drain plug only had some relatively minor metallic fuzz on it. Now to get the fill plug out, so it is soaking and getting knocked with a hammer when I think of it.

I will still be examining the 5-speed in pieces to see what I can do with it.

Thanks for the info. I am sure there will be more questions soon, but I have a good start now.

Gary