915 Failure - ID Teeth on Drain Plug?!?!

[MK153]

I've been cosmetically restoring my '81 SC (that has a gray market '79 drivetrain) for the last 18 months or so and this past weekend while pulling it into the garage, there was a loud thunk that could be felt, then the low voltage light came on and it ran roughly for a second before evening out. I figured the belt had snapped, but it was fine, so didn't think much of it.

Later that day I reversed the car out to get the lawnmower out and when I went to pull it back in, I couldn't shift into first gear. Second felt sloppy, but I was able to put it back in using 2nd gear.

I put the car up on jack stands, then drained the transmission fluid. To my horror, the drain plug looked like it had teeth all over it, 6 or 7 of them.

What should I do next?

Options I've considered:

1. Buy a used transmission on eBay and put it in myself
2. Look for a local shop to pull and diagnose it
3. Pull the transmission and send off to be repaired (shop suggestions?)

CogsCogs on eBay has rebuilt 915s for $3650 - but it seems they are not reputable. There are used units for around $3K - but they'll have unknowns too.

The local shop I called (Reid Vann in STL) seemed like they wouldn't want to touch it if I pulled it out/apart first.

I called CMS in NV and he was super helpful over the phone, but pulling it, crating it up, and then sending it to them sounds like a pretty big ordeal.

[MK153]

Oops photo didn’t work on first post - here it is

[stownsen914]

Ugh, not a great set of symptoms. Share a pic of the bits that came out. Might even be able to tell which part of the trans they came from.

[MK153]

Originally Posted by stownsen914

Share a pic of the bits that came out.

Pic I provided good? Or should I clean em all up and take a better one off the plug?

[stownsen914]

Looks like we were posting at the same time. Looks like dog teeth, which could match the observation of not being able to find first.

In case it's not obvious, don't start the car again, so you don't run the teeth through the gears any more that whatever already happened.

I'm more of a DIY rebuild kinda person. If you take a 915 to most shops, you can expect a pretty fat bill, since they're going to want to go through the whole thing, replace all the bearings, etc. And that's if most of it is salvageable.

[RetroSC]

Yes, those are dog teeth. I rebuilt my 901 years ago, not too hard if you're somewhat handy. Too bad I'm not a little closer, I'm in KC, or I'd offer to help.

I'd guess a place like Rennsport KC here would do a synchro and dog teeth rebuild for maybe $2K.
Might be worth the 4 hour drive.

[faapgar]

From 77 up 1st gear has assymetrical coupling teeth.Well you have a sandwich on the drain plug.Not that bad a fix.Figure with the age coupling teeth for 1st and 2nd.Operating sleeve for 1 & 2,Then go from there.Ciao Fred

[faapgar]

If you were closer I would estimate labor to be $600 - 750 max plus parts.12,000 MILES or 1 year 100% Good to go.Ciao Fred

[MK153]

Thank you all so much for chiming in!

I’ll reach out to Rennsport in KC - thanks for that suggestion! I’d love to do it myself but with two kids under 5 I just don’t think I have it in me right now.

Maybe I should change my plate to CRRNCH.

[kevingross]

Probably dog teeth, a little hard to be completely certain from the angle of the bits in the photo. One definitely looks like a dog tooth.

Let me offer you, at no cost!, some advice. First, given that you have debris inside the transmission, it needs to be thoroughly disassembled, cleaned, and inspected. Debris gets into everything and everywhere, and a quick fix is not in your long term best interests. If you're lucky enough to have an LSD, they are fantastic at somehow ingesting debris and galling their clutch discs, for example.

Second bit of advice is that until the transmission is opened and inspected, you really have no idea what it's going to cost to rebuild. Two reasons for this: you cannot know what has been damaged by the debris, and unless someone has rebuilt your transmission in known history, you have no idea of what else needs attention. That broken dog ring is unlikely to be the only old, tired part needing attention.

Third is that the hassle of crating and shipping your transmission is very small compared to the migraine of dealing with a repair done improperly. I don't know Rennsport KC but if they've done a bunch of 915 gearboxes, have the special tools and know-how, it's worth the drive. If not, CMS does great work -- so do I (shameless plug, sue me!). What I do for my customers is arrange pick-up with an LTL freight carrier; all you have to do is get the transmission safely crated or lashed to a generic pallet.

Good luck with the project!

[MK153]

Originally Posted by kevingross

. If you're lucky enough to have an LSD, they are fantastic at somehow ingesting debris and galling their clutch discs, for example.!

No LSD - I guess thankfully.

Now that it’s drained - do I need to fill it back up before I even roll it out of the garage (in neutral) or onto a flatbed?

[gomezoneill]

Originally Posted by MK153

No LSD - I guess thankfully.

Now that it’s drained - do I need to fill it back up before I even roll it out of the garage (in neutral) or onto a flatbed?

No, keep it empty.

[david482]

I’m also in KC and have had work done by Karl at Rennsport, they do great work


Sent from my iPad using Tapatalk

[MK153]

Just talked to Rennsport - wow what a great and clearly honest guy! He said they don’t rebuild in house anymore - that they pull it and send to GBox in Colorado. To expect like $3-4K from them (obviously with a big spread of things go poorly).

Maybe I’ll just see if that’s something I do - or CMS. Seems like the right path to go.

Thank you again everyone for your help!