Yet another 915 rebuild thread...

cashflyer · 02-28-2007, 01:59 PM

Do we really need another 915 rebuild thread?

The way I see it, my problems may not be the same as the last guys or the next guys. If we each document what we encounter and get commentary regarding the process and the problems, then all the better for future rebuilders.

Anyway, as I mentioned in another thread, I dropped the engine and trans on 2/25/07. I split them apart on 2/26/07, and then degreased and drained the trans.

Today the nose cover is off and I have had an opportunity to find and photograph a few problems.

On the straight-cut end of the reverse idler, i have found several nicked teeth. The two circled are the worst.

The external teeth on this (slider?) that meshes with the idler are not too bad, but the wear on the internal teeth seems to me more than allowable for re-use. Or is this normal?

The shaft that the idler rides on has play in it. I know that the exposed end would be stabilized by the nose cover, but how much play should I be seeing here?? Is this the cause of the nicked teeth?

This is my stopping point for today. It makes for a short evening in the shop, but I want to get some input before proceeding.

Jim Sims · 02-28-2007, 02:54 PM

The chipped reverse idler teeth are likely from trying to shift into reverse while the gears are still moving (reverse is unsynchronized). Causes are out of adjustment clutch and/or an impatient driver.

cashflyer · 02-28-2007, 03:18 PM

Where can I obtain a replacement? Or can I?

I have not found them on PP, and I cannot even find a part number for it. I've been told that PET illustrates the part, but does not give a PN.

Grady Clay · 02-28-2007, 03:51 PM

cashflyer,

Another complete 915 rebuild thread is very worthwhile. You should link all of your research on prior 915 rebuilds. Your responsibility to the forum is to include all that research. In turn the Forum uses those links and original information to help you.

Each iteration should be a better discussion of a 915 rebuild.

Many of us are collecting info to help provide Wayne to publish a “transmission” book. I have even purchased some transmissions for that effort. Your rebuild can contribute to that effort.

Best,
Grady

Jim Sims · 02-28-2007, 04:32 PM

Transmission type (number on bottom); year and model of car?

john walker's workshop · 05:57 PM

i probably have a few good idlers. chipped teeth are from "less than gentle" engagement. the wobble in the idler shaft is a worn case. been seeing more of that problem lately, along with loose outer bearing races. you will have to decide if it warrants looking for a replacement center housing, or if you can live with it. you certainly don't want the idler to be moved sideways from it's proper position.

rusnak · 02-28-2007, 08:25 PM

Wow, sign me up for the 915 transmission rebuild book. Can you include upgrades such as oil squirters, selecting gear ratios, and the gear driven oil pump and cooler?

khamul02 · khamul02's Garage

"915 transmission rebuild book", I'll take one as soon as it hits the presses.

cashflyer · 07:11 AM

Grady - by "another" I only meant that the forum has several other threads - not that I have ever done one before. This is my first 915 rebuild, but I will document in text and pictures to the best of my ability. Additionally, some fellow Pelicans will be joining my work in progress, so they will also be getting some first hand experience.

John - since reverse is the least used gear, would it be acceptable to dress out those nicks in the reverse idler with a fine file? Or is this an idea that should never be considered? If this is unacceptable, please PM me details if you have a spare idler to sell.

Also, how much play is acceptable? For a point of measurement, so we're talking apples to apples, mm of travel measured from the tip of the idler shaft.

We will be diving back into the trans this afternoon. I should have a better idea of the wear to the center housing.

Is there enough material in this area be bored and sleeved? Or would a good used center housing be cheaper than the machine work?

Thanks!

Ken911 · 03-01-2007, 05:51 AM

I think wevo makes and upgrade for that part of the housing you send it to them and they beef it up and remachine verything

cashflyer · 03-01-2007, 06:38 AM

Their maincase mod addressed worn recesses where the bearings of the input shaft and pinion shaft pass through. I could contact them and inquire about the idler shaft socket, but I could probably have it done locally also. More will be determined as I get into the case further.

the · 03-01-2007, 06:43 AM

Can never have too many different 915 rebuild threads, everyone's problems, approaches and solutions are going to be a little different.

A very detailed 915 rebuild book is needed! Would sell a ton.

Bill in OKC · 03-01-2007, 06:46 AM

Has there been any discussion of a new pelican category for 911 transmission rebuilds? It might help until "THE BOOK" is available.

the · 03-01-2007, 06:50 AM

Couldn't it be machined out and an insert pressed in?

dfink · 03-01-2007, 07:03 AM

I am surprised no one has made the "Holy Crap" look at all the silicone sealer comment. I hope that is not there for any reason other than the previous builder owned stock in the company. The dingles would probably just get ground up in the gears but man that is alot of sealer. Use a copper spray on the paper gasket works really well.
Also on the sliders it is not only the teeth that wear but the inside diameter of the slider also gets worn which then doesn't grab the syncro ring as well. A used unit might look perfectly good until you put it next to a new unit then you can really tell a difference.

cashflyer · 03-01-2007, 05:41 PM

Well, pelicanites arrived and we completed the disassembly of the trans. Photos will post tomorrow, as I left my camera in the garage.

We discovered that the 1st & 2nd dog teeth are worn, as well as the slider.

We found a chunk of metal in the differential housing, but could find no associated damage to any gears. We suspect it was missed during the last rebuild.

Tomorrow night I will remove the gears from the shafts for more inspection.

Additionally, we found that the race is slightly loose for the bearing where the pinion shaft enters the main housing. No side/side play, but you can turn the race in it's seat.

1) Should I just stake the aluminum around the race, or should I remove it and reinstall with some bearing bond loctite?
2) How do we remove the race without damaging it?

sjf911 · sjf911's Garage

Staking the race is unlikely to do anything. The race likely would come out with a little effort if it is loose. The ideal solution is to do something similar to the WEVO final drive housing modification ()with or without the one piece bearing retainer (WEVO or the turbo OEM). Sleeve retainer glue is an option but durability is unknown. I chose to use the "glue" knowing that it is not permanent and I will have to deal with a permanent fix in the future.
http://www.wevo.com/Products/TransmissionProducts/WevoTransmissionProducts_RaceCaseFinalDrive.htm

SP2 · 03-01-2007, 07:22 PM

If that race is sloppy in there, that is not supposed to be good. Peter Z on Rennlist says you need to have it fixed with some custom pressed in thing. My race came out when I took my pinion shaft, but John Walker inspected it for me and said it was ok. I can't remember what he said the fix is for it but I think it also was a machined piece to go in there. JW warned me that mine might be loose because he has been seeing this alot lately. A new Wevo bearing retainer plate is not enough, I am told.

the · 03-01-2007, 07:27 PM

Seems like a lot of people glue it, but most don't consider that a permanent repair.

You can have it machined out to round and a steel insert pressed in. That's a permanent fix.

cashflyer · 03-02-2007, 05:05 AM

Picture time.

The mess so far:

Gearsets, still on shafts:

Closeup of open differential: