SeattlePorsche

Well having a bit of fun this week. Here are some photos of my engine job. Clutch is in. Made a new alt ground wire. Redid my fuel injectors. John Walker tested them all for me and the spray pattern is fine for all. Used new sleeves, sleeve o-rings and fuel inj o-rings. Put the alt back together and installed the fan. Decided to backdate heat. Bought the parts last year and had them powder coated with all the other stuff. Bellcrank starting to go in.

SeattlePorsche

Sorry this is a long update guys. But I thought you would enjoy the photos. Here is CIS installed, sort of. Still need to bolt it down with 12mm copper nuts.

I took the tranny to the car wash last week and degreased it. Put it horizontal on a dolly with a pan underneath and took the backup switch out. Then the nose cap off. Pretty much following Bentley. The backup pin drops out when the nose comes off. I locked the tran by engaging 2nd and pushing down on 5th. Then punched out the pin on the main shaft nut. Removed the main shaft nut and large pinion nut with 27mm and 1-7/16th sockets and my impact wrench. Then pulled reverse slider and fork up with quite a bit of force. Then pulled off reverse idler and all the bearings and washers with it. Pulled the guide sleeve for 5th gear off. Had to wiggle it. Then I pulled off reverse gear. This was the hardest thing tonight. Just had to grip it with my fingertips and pull up. It eventually gives very quickly and comes flying off. Used a gear puller to pull off 5th and the idler shaft comes off with it (next to it.) The nose is now empty. Diagnosis is next page...

SeattlePorsche

With the nose empty now, I removed the side cover from the intermediate housing. The latter houses all the gears 1-4. Removed the int. housing. Now I can see all the gears. Cool. The tranny is on the ground now, so it is not so easy to crawl down and inspect things. But I took a bunch of photos of the gears to look at the dog teeth. Preliminarily they all look good except for 1st gear. The photos show some worn and even broken off teeth.

I took the nose cap off last weekend, then just stared at the tranny for a week. Read up on it. Tonight I did the rest in 90 minutes. I was only going to go at it for an hour, but really wanted to see what was under the int. housing. I used Bentley and two threads from Pelican:

http://www.pelicanparts.com/MotorCit...nnyRebuild.htm

http://forums.pelicanparts.com/showt...t&pagenumber=5

If you have done this before and you have advice for me, please let me know. I haven't ever done this before, but I find the disassembly much easier than the work I did on the engine. Maybe putting it back together will be the Waterloo. If I get in over my head my backup plan is to drive the tranny to John Walker nearby. Bye!

Peter Zimmermann

James: You will probably find trouble just behind fourth gear on the pinion shaft. After you remove the pinion shaft from the diff housing you will find (very likely) that the outer bearing race in the diff housing is loose. Don't think that you can knurl the case to "fix" this, the loads are too great and as soon as you drive down the street that race will be loose again. The machine shop that I use makes a steel insert for the hole and then presses the bearing race into the insert. This is a permanent fix that I've done to a large number of 915s. John W. is probably also able to do the modification, but if you need to know which machine shop does the job for me let me know. By the way, the symptom for this problem is a very subtle scraping sound noticed mostly in mid-range revs in third and fourth gear. Most owners accept this noise as "normal."
Pete

SeattlePorsche

Wow, ok I will look for this. I'm gonna read up a little on further disassembly. I haven't heard a noise in 3rd/4th midrange, but I will see if the outer bearing race is loose. Isn't there some kind of Wevo plate that is supposed to help? If so, what do you think of it Pete.

Thanks for the advice!

theiceman

Wow James things look fantastic ... looks like you have made tonnes of progress since your last post. When you did the injector inserts how did you deal with the tamping down of the runner to keep the insert in place ? did you grind it ? I ended up using a dremmel , and then using a punch in a new spot.
The transmission work looks great . You are fortunate having JW within drivig distance for sure in case you get into trouble but looking at the other stuff you have done I think you will be fine. There is another thread here about a guy who did his first and second gear, looks doable ... sign up for a copy when you right your memoirs ...

SeattlePorsche

I would be interested in that thread. I will search for it later, but let me know if you know it. I didn't undo the tamp downs, John Walker did. Story is I couldn't get the injectors out, so I asked JW if he would do it because I wanted to get my injectors tested. He just held the intake runner and banged the injector out with a big rubber hammer. He also used a dremel type tool to shave off the tamp downs. My o-rings were terrible. Must have been original 1981 stuff. JW said that was probably alot of unmetered air getting through there.

One problem I have is that on one of my fuel injectors it keeps slipping out of the sleeve. I am now sorry that I lubed the o-rings with dow corning silicone

Peter Zimmermann

James: Re: slippery injector. You can slightly re-bend that injector line, without losing its shape, in order to put a little pressure on the injector. If the sleeve is tight, and your injector o-ring is new it'll get tight as soon as you start the car (heat will do wonders).

About your trans. When you remove your M/S and P/S from the diff housing you will find metal shim(s) under the clamping plates, take good care of those because they determine your final pinion depth. You will find it helpful, before you pull the shafts from the case, to remove completely the bolt that holds the 1/2 shift fork. Then remove the detent plug for the 3/4 shaft from the case. Now you can pull the shafts out together without all the fork apparatus getting in a fight (the 3/4 rod & fork will slide from the case, and the 1/2 fork will slide off its shaft). I have found, on occasion, that if you gently spread the 1/2 fork after you take its bolt out it will make removal easier, but you must be gentle if you do this! Have fun!
Pete

SeattlePorsche

Pete, Thanks for the advice and encouragement. I am having alot of fun doing this. A question for you: Why isn't it important to remove the detent plug and detents from 1/2 also?

If I remove the 1/2 shift fork, is there any concern on reassembly? I mean the length of shaft protruding from the shift fork? Or does it just find it's final position on reassembly by itself. If necessary I will measure things with my caliper. Thanks!

Peter Zimmermann

James: After the P/S and M/S are on the bench then you can remove the 1/2 shaft and its detent parts (if you leave the 1/2 shaft in the case it's easier to pull the M/S and P/S. No need to measure anything because the detent will locate its neutral position at assembly. However, this is when special tools come into the picture: You need the long socket to loosen the nut on the M/S, and you will need the M/S holding fixture (for your vise) and the holding fixture (for the bell housing) to disassemble & torque the M/S nuts x 2. You will also, during re-assembly, need the holding plate to re-set the shift forks. Depending on if your P/S bearing race is loose, after that is fixed it's a good idea to re-set pinion depth, backlash and diff pre-load. Pre-load should be checked in every instance. For that part of the job you will probably want to use Mr. Walker's services - the tools to do the diff cost me more than $3K 25 years ago! Regarding shift forks, I never look at them because on more than half the 915s that I've repaired (that had already been worked on by someone else) they were set up wrong anyway. It's best to apply the procedure in the manual rather than rely on them having been done correctly by someone else. A correct set-up is crucial because that adjustment allows the linkage to function as intended. A last thought for now, it looks like you work clean, which is a huge plus! Just lay out everything as it comes off the shafts, upside up, etc., to avoid confusion later. I'm so careful with this procedure I don't wash a part until it's ready for assembly. That way the individual gear set needle bearings all end up exactly where they were, etc., and you don't end up with gear noise that wasn't there before.
Pete

SeattlePorsche

Thanks! Yes, I am even going to make sure all the needle bearings go back in the correct orientation just to make sure.

I will plan on having my differential pre-load checked.

SeattlePorsche

Hi Guys. Good day today. Fixed a heart attack waiting to happen. Put in a temporary pacemaker emergently. Had a big journal club meeting. And then...took out my shafts baby!! Had to giver a go. Took out the bolts for the springs and detentes for 3/4 and 1/2. Springs came out with a magnet, but the detentes wouldn't. But I tilted the diff on it's side and 1/2 detente fell out. So I tried it again and 3/4's fell out. Removed 10 bearing retainer bolts and spring washers, 13mm. Then the pinion and main shafts pulled out easily.

Good news, the bore for the pinion shaft (3/4) race is very tight. The race for the main shaft (1/2) came out with the shafts, but it looks tight. I couldn't put it back in easily. You can see the single retainer bearing shim that determines pinion depth.

Here is the inside of the differential. Here is the lonely diff. Here are the forks for the pinion and main shafts for recall later. Shafts on my workbench now. I could inspect the dogteeth better and first gear on the main shaft still looks like the only one with broken teeth. Not all are broken. Some are worn less than others. Which might explain why sometimes I could get into 1st easily, and other times would get grindage. Here is my highly technical diagram. I believe in simplicity...

SeattlePorsche

Would this be a good thing to replace my bearing retainer plates? It is a solid piece. The current bearing retainer plates are 2 separate pieces. The G50 transmission has a one piece retainer plate, at least that is what the web page says. Worth doing?

http://www.wevo.com/Products/Transmi...ngRetainer.htm

Peter Zimmermann

James: You must have been tired - you got those shafts backwards! 1/2 is on the P/S, and that is the race that came out, as usual. That means that a support shim must be made and installed - the bearing race requires about .004" press, which means it absolutely can't be put in by hand, or come out with the shaft. The bearing for the M/S is almost always still tight, so that's no surprise. FYI: When I refer to the P/S as the 1/2 shaft, that's because first and second both have their gears with synchros on that shaft. Same for the M/S, it has 3/4 gears with the synchros/slider. Better call Mr. Walker and find out what method he uses for fixing that loose bearing race (the part number for that bearing is 999 110 146 00). About the clamping plates, the loose race starts wearing away the lower (P/S) plate, and the darn thing is currently NLA. I haven't had to restore one yet, by adding weld on the worn race surface and then machining to the correct depth. The last two 915s I've had apart the clamping plates were still OK, but definitely have yours looked at. I'm not aware of a one piece plate for the 915.
Pete

SeattlePorsche

Pete, Ah gee, Dadgummit. I hate it when I get the anatomy wrong! Thank you for catching my error. I looked at those diagrams over and over and still got it wrong. Part of my problem is that I have so many sources with different nomenclature. (input, output, pinion, main, 1st gear, 1st gear fixed, etc.) I am still not sure what is what. Correct me, but that biggest gear with the broken dogteeth is 1st, right?

Pete, this is good advice. Today is my "friday" and I have the day off tomorrow so I think I will bring everything to John. That big nut on the pinion shaft looks like something I'll leave for John. Plus, as for deciding which parts I will replace, I am better off letting John examine them for me. Something tells me there is more to it than just looking at broken dogteeth. If John isn't so busy he usually doesn't mind me watching. This might be as far as I take it. John knows I like to play amateur mechanic and I am sure he will tell me what I can do. I think I will have fun just reassembling the 915 and filling it with Swepco. As for the big race that fell out, I will get it fixed properly.

As for the one piece plate for the 915, please click below. It looks like an improvement over the original and wevo has a very good reputation. I am cautious about putting in non-stock things, but this seems reasonable. What do you all think?

http://www.wevo.com/Products/Transm...ingRetainer.htm

Thanks!