Embarking on home 915 rebuild. Advice needed...

[JP911]

Another Pelican (vash) and I have decided to embark on the 915 rebuild journey. Our only guide, at this point, is what we can find in workshop manuals and this forum (we've tracked down some older posts as well). We plan to document the process as best we can to help others who choose to head down the same path.

Since we both enjoy driving our 911s on a regular basis, we decided to go with a core 915 for the project. The core is an aluminum cased 915 and looks like it came out of either a late SC or a Carrera.

Day 1: We drained the gear oil and started taking things apart to see what we were working with. After removing the nose cover we discovered the first of the carnage (see pics below). It looks like teeth are stripped off of 5th and reverse, although we're not 100% sure exactly what we're looking at. Can forum members wiser than us shed some light?

Pic 1:


Pic 2:


Pic 3:

[dentist90]

Your reverse and reverse idler look pretty ugly. A gear tooth or some other frag got in there. If you are planning on using these gearshafts the question would be: has this damage bent the shafts?

I'm dyin' to see whats inside!

[boyt911sc]

Jon,

One of the most practical advice I got when I did the transmission rebuilt was; Use wooden dowels and string the gears as they come off the shaft/trans. It was a very primitive technique but saved me a lot of time during the assembly process.

And lastly, take digital pictures and make personal notes as reminder. The project was very intimidating for first timer but it was not difficult at all.

Tony

[dentist90]

Like Tony said, rebuilding the 915 isn't that tricky (it was my first tranny overhaul project) UNLESS you have an output (pinion) shaft and diff gearset that didn't come from the final drive case you are planning to use. I had to swap my diff (final drive) housing and the measurements to try to make sure the ring and pinion were aligned properly were very involved.

[vash]

Originally Posted by boyt911sc

Jon,

One of the most practical advice I got when I did the transmission rebuilt was; Use wooden dowels and string the gears as they come off the shaft/trans. It was a very primitive technique but saved me a lot of time during the assembly process.

And lastly, take digital pictures and make personal notes as reminder. The project was very intimidating for first timer but it was not difficult at all.

Tony

brilliant!

for me, i think the hardest part will be what the parts are called. all you BTDT guys will be, "take the number 3 shaft chrome moly bearing off the crush sleeve, next to the jam block...." and i will have a big Question mark floating over my head, and a big DUH! look on my face.

this is going to be a fun challenge.

[poorsha]

I am definately subscribing to this one.
This should be fun and educational too.
Thanks JP911 and vash.
Keep the info flowing.
Sorry, I can't be of any help at all.
Never been there.
Never done that.

[Fishcop]

Will also be following this thread closely!

[Matt Monson]

Hello,
As others have indicated, your reverse assembly is toast. You will need to get a replacement reverse gearset. You will also need a new 5th/R operating sleeve. Vash, that's the biggest one of the ones pictured that has the brass fork attached to it. Unfortunately it's the single most expensive part in the whole transmission. Retail on them is up over $600 these days, but if you shop around, you can find them for a bit less than that.

But before you go shopping get the thing all the way apart. It's hit or miss whether or not the damage to that reverse gear has done any damage elsewhere in the box. If those gear chunks rolled between any other ratios, you might be looking for more than just a reverse set. Hopefully because the tailcone is kind of isolated you won't be looking for another complete core tranny. It's hard to see, but I think I might see damage to your 5th. Keep posting pictures as it comes apart and we'll help you assess the condition of your core.

[mgbruno]

Hi JP911 and Vash,
I am in the middle of a tranny rebuild right now and have a thread going. Mine is from an 84 911 cab - so its a 915 too. There's lots of good threads out there. I found some bad bearings in mine - well they were going bad - and this upped the cost of course. I also regeared my car. I sold my 5th gear unfortunately already. I did replace 2nd through 5th - so depending on what you find - when you get in there, maybe you will need my other old gears. Oh, when I started this beast - I only knew how to change the oil. Up until now, it hasn't been too bad. Right now, I'm still waiting on those bearings. Once I have them (this week), I will be back in business - rebuilding the two shafts - and then I'll be back to posting pictures, etc. Good luck - and feel free to shoot me a mail if you have questions. Chances are - I've been there recently

[Otto]

First go out and buy the special Porsche tools you will need. Should only be about $600.00.