Hi all,
Well I guess that Suby torque finally did in my pinion gear!
Anyone have suggested resources for a replacement gear and/or tranny?
Thanks,
Tom

Click to view attachment

had to be a f/o to have a fail like that

Maybe - whats a "f/o"?

I have a bunch of transmissions and parts. If you want to look through the stuff send me a PM.

I don't think it was f/o (f**ked off). Just lots torque. Happens to V8 guys too. Tom, did you get upgraded axles with your conversion?

I have spares as well, but to make things easiest, you should get a core transmission that you can swap all your gears onto (are they stock?). Setting the pinion depth is necessary if you swap those parts, and that's a pain.

Let me know what I can do to help. I owe you for not recognizing how ahead of the curve you were by putting a Subaru motor in your car. Looks like you've already got all the parts out, so just bring them up to me or mail them my way and we'll get it sorted out.

If this is what you've experience via a 2.0 Subi motor, I would hate to what it would look like in the future. If it were me, I would simply spend the $$$ and upgrade to a 915 and call it a day.
If you do stay with these 35+ years old trans! you have better to buy a few spare 901 trains. With that amount of material missing, you had better unbolt " everything " for a look see. But then you can simply close your eyes and think it ok and if you sell it. It'd the next persons concern.....do it right or don't do it at all.
Oh just like the old oil advertisement says...pay now or pay later.

Thanks Mark!
Yep, an axle upgrade by Renegade was included in the conversion.
For the long run, doing a total replacement makes sense for sure. I'll send you a PM for more details.
Tom

I am open to that possibility too - any idea as to the expense?

Setting the pinion depth is necessary if you swap those parts, and that's a pain.

Great advice, if you don't set the pinion correctly, you can count on seeing this in the future too...unless you drive the 914 once or twice a month..then some will say its ok to eye ball the measurements.

foreign object

one tooth and tip of another gone, and no other damage to the other gears,
I'd look for some needles that might be floating around.

torque would twist the pinion off the shaft

I noticed a cheap sideshifter on SF bay area Craigslist today in So San Jose Tom. Might be a good donor.

You don't want to upgrade to an M5 Suby TY 75?

Figured. It's the ol' somethings-gotta-give problem. Strengthen your axles and the pinion takes the load.

People have had good luck with the subaru transmissions as well.

We've seen damage like in the photos before in some high-torque applications. The problems start with galling on the friction surfaces between the ring and pinion teeth. After the galling progresses and gets deeper, one of the teeth will shear, putting more stress on the others.

I haven't actually seen the pinion gear twist off the shaft, though. That might be a problem with shock-loading?

Anecdote: My first exposure to this problem was Dave Ferguson. He kept one as a trophy, and handed it to me with that trademark big grin of his. "Guess what this is? Nope, it's a sign that I make sufficient torque!"

I think that man could rebuild a trans faster than Drevil--or at least, he could when he and Ellen owned and ran that 2.8L 914-6 racer...

--DD

I don't see any galling on the other teeth or other damage, and a suby wouldnt seem to have enough torque to fatigue the gears to fail like this.

I have seen r/p fails like this in the 4x4 world from severe high shock loads when a rig starts bouncing. or from foreign object interference with failures of other differential parts getting into the ring gear tooth and as the pinion climbs into the ring the pinion cleaves off.

I've got a whole bunch that have failed like this from high torque. They either start to break the tooth off or pit and then this happens. It doesn't take anything in there. My guess is that it is usually a temp and/or lube failure that leads to this.

I can tell you all sorts of ways to kill 901 transmissions and a couple to make them live.

Hi Mark and all,
Thanks for all the great input guys!
My guess is something got in there and it just started eating itself over a long enough time to cause the eventual failure. Funny part is, we could'nt find any residue metal in the gear train. May indeed have been a lube problem too.
I ended up going to Don Wise's shop in Campbell. After some digging, he came up with decent 901 tranny to use/cherry pick from and he's hot on the track for a relatively low mileage ring and pinion gear.
I'd love to go the 915 route but that sounds like big bucks to me!
Tom

I did the same thing to my stock Vanagon Tranny a few months after I put the 230hp subbie SVX in it but the damage was on all of the teeth. I was well aware of the damage that was going to happen, but it was so much fun..... Spending money on a new tranny....not so much

Jon H.