jet911

There has been much discussion regarding 915 tranny rebuids and how the tranny shifts afterwards. I've just had the 915 tranny in my '86 911 rebuilt by a local non-dealer mechanic. He stated to me that he had 20yrs experience, worked in the p-factory in germany (he is german) and I noticed that he has several porsches in his shop all the time, so I had confidence that he was reputable. The reason for the rebuild was that the 1st syncro was shot (could not down shift into 1st) and the 2nd gear was difficult to shift into up and down with some occasional grinding. When I received the bill, I was charged for replacing the 1st and 2nd syncro hubs and rings, the needle bearings and a new clutch totaling about $2500 which I thought was reasonable. My question/concern is this: After looking at the bill I noticed that the sliders had not been replaced. I'm not happy at the moment. I've put about 300 miles on the car since the rebuild. About 1/3 fo the time upshifting from 1st to 2nd, I cannot get it into 2nd and about 50-60% of the time when down shifting from 3rd to 2nd, I cannot get it to engage in 2nd. He told me to drive the car for 1,000 miles and it should break in. Is this acceptable? I can understand shifting may be stiff, but I'm very concerned about not being able to get it into gear at all on many occasions (and concerned about bending the stick shift rod or using such force as to cause other damamge). Could the problem be because the sliders were not replaced? Everything I have read says that the dogteeth (syncro hub) and sliders should both be replaced at the same time. Also he did not use Swepco201 which seems to be manditory in these trannys (he used Castroil 80W90 Hypoid oil GI-5). Opinions please from folks who have had 915 rebuilds. Is this acceptable? Does it take 1,000 miles to break in? Did new Porsches off the lot from this era have the same problems? I find it hard to believe that a new car would have shifting problems.

Thanks in advance,
Jim
'86 911

Alan Herod

I believe this is normal, as is the first fill with something other then Swepco for break-in purposes. My shop said to replace with Swepco after the first 1,000 miles, but, I did not change it until after two track events and probably 2000 miles when it started to become less stiff. It is shifting very nicely now and behaved as you described during the first thousand or so miles. The rebuilder also said that it would be easier to shift when driving it hard and this also proved to be correct. If it was driven too moderately it did not want to even go into second. Mine was gone into because it would not go into fifth as was discussed on Rennlist years ago.

jet911

Alan,
Thanks for the input. I went back to my mechanic and we talked for quite awhile. He told me to be patient and drive it for 1,000 miles and I would really notice a difference. He has given me a 12,000 mile, 12 mo warranty as well. He also told me that after the 1,000, he would be happy to change to swepco 201 if that's what I wanted to do.

Regards,
Jim
'86 911

druck

This is a perfect case of penny wise pound foolish.
You've taken the engine out,disassembled the box and only replaced 1st and 2nd synchro's? Why not replace all synchros,dog teeth, brake bands, sleeves and seals? Now you have a fresh box. Doesn't make
sense.
Confused,
verbus

jet911

Just passed 300 miles on the rebuild and patience is the key. The tranny is already starting to loosen up. It now down and upshifts into and out of second nearly everytime as I expected it should have when I picked it up. It still is a bit stiff on some shifts, but a hell of alot better than immediatley following the rebuild! I suspect it will only get better. He also said after the 1,000 mile break in, we will drain the tranny and fill with Swepco201. Just thought I would update in case anyone else has same questions. This mechanic knows what he is doing!

Regards,
Jim
'86 911

gerry100

Jim,

How many miles on your '86 when you neeede tranny rebuild?
My '86 has 90K and second is a little stiff. I've just replaced the bushings in the shift linkage and am still fine tuning the adjustment but I'm curious long term.

Gerry

jet911

verbus -
Don't want to be defensive here, however I went by the advice of the mechanic (Porsche factory trained master mechanic - maybe he's a fake - you know you can't trust those Germans - Oh wait I'm German!). I had no issue with 3rd, 4th and 5th. They all did and do shift perfectly! In fact, I did ask him about replacing all syncros, bands, dog teeth (hubs) and sliders (after reading a few posts on this board that talked about doing that during a rebuild). He said fine no problem, he would do that if that is what I wanted as it meant more money in his pocket! However he restated it was not needed. That all components in 3rd, 4th and 5th looked basically new with no "visible" wear. According to him and the way the tranny shifted, only the 1st and 2nd were bad. All seals were replaced. I guess I could have had all the gears and shafts replaced as well and paid $10K for the true rebuild, you know, since the box was apart might as well replace "everything," whether needed or not! I don't believe that by not replacing 3rd, 4th and 5th, it will change anything, or have any effect on 1st and 2nd. He did give me a 12 Mo. 12K mile warranty as well. He seems very confident in his work.

verbus, I was asking for input about break-in, not to be called foolish.......for taking the advice of a mechanic with 20 - 25 years of Porsche experience.

Maybe in the end I am foolish. Foolish for buying a car that I am not that impressed with! An M3 will blow the doors off this car, in the straight aways, top end and in the corners! Or maybe I just don't know how to drive a Porsche......... Oh by the way, my first autocross with the P-car, I took 3rd in my class out of 14 drivers.......

Regards,
Jim
'86 911

jet911

Gerry,

The car was a two owner car. Both the individuals were in their 60's. The car has 78,000 miles on it. The original owner had three P-cars. I found out after the fact that this car was used mostly for Auto Crossing. Everything (was)/is very strong on the car except 1st and 2nd, and hopefully, the tranny will now perform as it should. IMO, 2nd gear is always stiff at times. 2nd from what I have read and have been told by my mechanic, seems to be the achilles heel in this trannies. He told me that while working in the P-factory, the majority of warranty work on these cars was replacing 1st and 2nd syncros and dog teeth. By the way, he told me that even in the factory during the 80's, they did not replace all the syncros in all gears (as some want you to believe is necessary), during a warranty rebuild. Take this info for what it is worth, i.e., me and my mechanic - Alex's opinion. I'll probably get trashed for that opinion by some on this board!

Good luck!

Regards,
Jim
'86 911

Andreas Langhoff

Hi,

I have no experience with a rebuild 915, but I still have the original 915 on my 1972 911S. Main issue for proper shifting seems to be the proper adjustment of the shift linkage. Since I set the linkage properly up I have no complaints at all and also shifting into 1st works fine, with sometime slight noise.
I am driving my car very harsh sometimes up and down alp mountain roads, only drawback of the 915 is that sometimes I cannot engage 3rd gear under very harsh driving in bends, probably because the engine/tranny block is moving too much in the mounts.
I found that it is important to shift in a clean way, e.g. Z-wise: To shift from 2nd to 3rd push the lever forth, TO THE RIGHT and forth again, like a Z.

Try adjusting the linkage properly, and replace all the shift bushings also I am sure you will enjoy the new feel.

Concerning gear box oil, I use normal 90 grade oil. Oil does not seem to be critical: Once I put some molycote (Molybdan Disulfate)additive in the gearbox, only for a little while I could feel the slightly longer gear sync time needed, a couples of weeks later all worked fine again, shifting remained smoother though!
(Don't do this on limited slip diffs)
Remember, a Porsche is just like a sqeezed beetle, it is only just faster! Enjoy

Alan Herod

Geez Jim, I was going to come to your defense, because I didn't see the value of the "penny wise pound foolish" comment. What are you expected to do now besides feel bad. My trans was rebuilt at 150K miles because it quit going into fifth gear for no apparent reason. On exploration there was an internal alignment problem. I had some more stuff replaced for preventive maintenance, but I had twice as many miles on it as you did. Truly in terms of synchros, the weak link is second. After 150K miles third, fourth, and fifth were showing very little wear. Change the rest of them in another 16 years when you have another 78,000 miles on it.

jet911

Andreas & Alan,
Thanks for the insight, it is appreciated!

Best Regards,

Jim
'86 911

gerry100

Hey wait a minute -

I just picked up on the M3 comment - Elvira (black 3.2 coupe) and I just got back from a two day DE at the Glen. We definitely corner with M3's of all ages ( at least in the Novice group)and when I develop some skills and get my exit speeds up we'll be OK in the straights. Our cars have more ultimate cornering ability when the driver is ready IMHO.

Besides I got a good workout steering out of "the boot"

jet911

Gerry,

OK, I was a little quick there....and taken back by verbus' comments. P-cars and M3's are IMO comparable in cornering and upper end. I do believe however, they are quicker out of the hole and in the low range. I'll have to go back and check it out in my Panorama, but an article in one of the last couple of issues talked about BMW dominance in several European races. Sorry, just fact!

Don't get me wrong, I love my 911, i.e., the total package. I did not buy the car for performance only (although it certainly was part of the reason). The primary reason was I love the lines, style and overall look. IMO the 80's 911 is one of the most beautiful cars ever made......

Regards
Jim
'86 911

Drew Theodore

M3 faster in straight aways? yes
M3 faster on top end? probably
M3 faster than 911 in corners? You do not know how to drive a Porsche.
There are other cars faster than your 911 in straight aways and top end that cost alot less than a M3 if that is what you are looking for.

druck

Jim,
You're a defensive lad. It's a saying. Save a little now, pay big later. FYI, synchros go for $24 each. Yeah I guess that would've gone way over budget.
Brake bands even less. Dog teeth can be a tad pricey. If M3's are passing you, maybe you should stop lifting.
Be well,
verbus.