more trans questions
 

As I have previously posted I'm rebuilding my 915 trans. The trans has 150,000 miles. It shifted ok, shifting from 3rd to 4th was harder as it took much more effort to up shift than shifting into any other gear. I want to do a thorough rebuild and replace the nessary parts but I do have a budget. I have questions for the experts out there. I'm confused as to what should be replaced. The syncros, brake bands and 1st and 2nd syncro teeth will definatly be replaced. The operating sleeves look pretty worn in the center from the syncros and I think they need replaced. If the operating sleeves are replaced do the guide sleeves need replaced as well? Should the syncro teeth be changed with a new operating sleeve? And when replacing the brake bands should the enegizers and stops be changed?
Are the one piece bearing retainers a desired improvement. Would they help with trans life? I'm talking about the retainers made by WEVO and Power Haus II. Are they an improvement for a stock engine/trans combo?

thanks

I've read and been told advice all the way from replace all dogteeth, operating sleeves, synchro rings, brake bands, energizer blocks, anchor blocks, and bearings(!) to just replacing the synchro rings and worn dog teeth. I replaced one set of dogteeth (2nd), 1/2 and 3/4 operating sleeves, all the synchro rings (5), all the brake bands(9 - early 1st gear syncho with only one brake band), one flanged lock nut, all the detents and the lock washers clamping the bearing retainers plus one of the reverse/5th idler needle bearings and several of the thrust washers because they had edge cracks. The synchro rings, operating sleeves and brake bands experience most of the wear in a properly shifted 915. Note the areas where the friction coating has worn off the synchro rings and brake bands. However if the drivers have shifted faster than the synchros can operate, the dogteeth will take a beating and need replacement. In my case the, the energizer blocks, anchor blocks and guide sleeves didn't appear very worn so I reused them. The only dogteeth worn were those on 2nd gear; the rest were still sharp and without the wear indicating "hook shape." I wouldn't bother replacing the bearing retainers unless they're worn or you're planning for a future engine power and torque upgrade. In your case I would suggest, at minimum replace all the synchro rings, brake bands, 1st and 2nd dogteeth and both 1/2 and 3/4 operating sleeves. Check other parts for wear (especially the 4th gear synchro assembly given your upshift problem - look at the 4th gear dogteeth) and replace as needed; the factory shop manual has some wear measurements listed. Good luck, Jim

I know some Porsche mechanics just flip the brake bands on 4th an 5th over and just reuse them. Also I think you want to deburr the sharp edges at the ends of new bands a little.

I will add this: Look closely at your 5th gear operating sleeve and what it rides on. Feel for burrs and remove them with a stone.
-Chris

Tops 911,

The bearing retainer made by Windrush (WEVO XT_032) is not individually intended to improve transmission life. It is part of an entire system that will improve the durability of the 915, specifically with higher output engines.
It will not improve the shifting, or extend the life of your existing bearings. At best it will offer longer bearing life if you install all new bearings in the pinion bearing bulkhead (all 4 bearings) and your pinion roller bearing outer race is still an OE fit in the final drive housing.
Unless you are heading for a major transmission upgrade, save your money and spend it on something you can really enjoy the improvement from.

Regards

Hayden Burvill

Windrush Evolutions Inc.

wevoid,
thanks for your honesty, i really appreciate it. I do have many parts to buy and I'd like to make sure every purchase is a wise and useful one. Again thanks, and thanks to everyone else.
(My daughter is eating my lunch on my spelling and typing abilitys,heck I'm an artillerymen not a english major)