Rebuilding a 915 transmission.

The fact that my second gear will grind when shifted up from first at anything more than 2000RPM is really bugging me. It makes shifting from first to second on accelerating to cruising speed sketchy, as i always have to wait a good second, maybe two seconds...not a very sporty way to drive in a 911.

how much does it cost to have a shop replace the second gear synchro ring (all other gears are fine...shifting down from third into second is also no problem)? and when that work is done, should other things also be done at that point?

are there other causes that might be responsible for this?

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1976 911S Targa

Well, it might be a worn sychro hub, or a worn synchronizer ring, but there is a POSSIBILITY that it is just old, dirty gear oil, too! I would recommend a couple of 'quick' changes with Castrol or Valvoline or Quaker State SAE 75W-90 gear oil ... change the oil, drive the car a week or two (200-500 miles) ... chnage it again and see if the shifting improves, ultimately, if the grinding, or whatever (I usually call that a 'graunchy' shift!) gets noticeably better after two gear oil changes, then change it again to SWEPCO 201 gear oil, and your 915 will probably shift smooththly for a long time! Seriously, gear oil gets neglected probably more than even brake fluid by MOST 911 owners, and the 915 transaxle suffers/complains by making inappropriate noises when you shift certain gears, and 1st and 2nd gears seem to complain most often! If you change your gear oil twice a year with regular gear oil, or once a year with SWEPCO, you can be assured of a much more satisfactory shifting transaxle!

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Warren Hall
1973 911S Targa

hey warren,

as it appears to me, you really are exceptionally aware and active here...quick replies and deep knowledge all over the place...thank you!

i will pick up my car from having the rear tires put on and aligned today, and will stop by the transmission place to see whether i can't get a quick oil change in the transmission...i saw an earlier post that you replied to, suggesting something similar, and had alrady started to rack my brain to figure out whether an oil-change could indeed have been overlooked in all of the work that was recently done...

let me start there and let you know about the results.

cheers,
till

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1976 911S Targa

I would recommend checking the clutch free play adjustment and the shift linkage bushings/adjustment after you change the gear lube(it's the easiest to do first).Our 1987 Turbo uses Swepco and it shifts pretty well but I don't try to "speed shift" it as it was never designed to be shifted that way and I use new bushings every two years. Good luck.

allright, i'm back...went to bring the car by the shop, had a good chat with Don (the porsche mechanic) while he gave me free information and changed the trans oil...

the plug had a considerable amount of synchro-flakes on it (amounting to about the size of a nickle), but neither one of us was too surprised about that...after all, i had driven it for about 1300 miles with quite a few occasional "graunches", as my main-man warren would say, since Don had topped the trans off with a bit of fresh oil...he admitted to not having changed the fluid, as much as filling it up last time...considering how dark the oil that came out was, i suspect that it had been driven for quite a while with sludge inside...

and, as i pulled out of the garage, i already noticed a big improvement...it still does grind a little if i shift aggressively, but already i can sense a big improvement...i'll drive it like this for about 500 miles, and do another change then...just like warren says...

gotta listen to the wise men, kids...

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1976 911S Targa

Till, I believe my post is the one to which you were refering(transaxle oil). I have the exact same problem with 2nd gear. I am now going to change my gear oil and see what happens. Thanks for pulling more info out of Warren. Mark

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aaarrrggghhh....

took my baby onto the freeway, and if i wind first up into the 5K RPM + range and shift into second, then graunchyness is definitely still a problem...if passing past 5000RPM, a 1.5 - 2 second wait before shifting is still necessary...well, i'll see how this develops...

to get back to my original question: how much does a full rebuild cost? how much to replace the scond gear synchro, the synchro hub, etc.?

do i even want to know?

hey mark, i hope that we can both get this smoothed out one day...guess we're just not fully satisfied while our babies cry and groan...

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1976 911S Targa

I know that it costs around $2,000 for a total rebuild of a transmission in a 1974. I believe that is the 915...someone correct me if I am wrong.

This rebuild was done by a professional Porsche/BMW only shop. To me, this is quite expensive, but the transmission did come out of the shop like it was brand new, needing to be broken in a little.

Paul

I had a similar problem with my 78SC into second I adjusted my rear coupler behind the seats and it fixed my problem, It took many tries to get it right but it shifts like butter since adjusting a year ago.

well all these coupler and link/bearing adjustments certainly sound like the next step to try before sinking yet another 2000 buckeroonies into my sweet lil' ride...that'll be the next step...

but why would this only happen at certain RPM's, and only shifting up from first? if it is due to extenal adjustments, shouldn't it happen both on down and upshift, and at any RPM's?


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1976 911S Targa

there are prices all over that vary for rebuilds...try www.motormeister.com, or pick up excellence mag...I have seen prices for rebuilt 915 trans's for $900-$1200 all over the place...one guy in Conn. even has a 2 day turn around as well as a good guarantee

My rebuilt trans, done and paid for by the original owner of my car right before I bought it from him, cost almost $3,000 at Andial!

Brian

As somewhat of an answer to the question of why the transmission would be moody at certain rpms...
when the engine/transmission is running at the right speed and you shift and let it comd down a little, the synchros will be in lign and won't have to really be used when you shift.

Like, when you are shifting from 1st to 2nd...the engine is going about 4,000rpm in first, you push in clutch and let engine get down to about 3,000rpm, it will be easier for you to shift into gear.

Paul

i checked out the http://www.motormeister.com site (thanks 77911s) and was surprised to see that the prices for rebuilding my 915 transmission ($795) and my 2.7L engine ($3,195) were much lower than many posts would suggest...

of course R&R will add to that, but is there something wrong or suspicious about these rebuilds? has anyone had experience with motomeister, or does anyone know anybody that has? are they neglecting to mention costs that will occur in most cases? what makes this different than the usual 8-10K engine rebuild that keeps on being quoted as the "rule of thumb"?

4K for rebuilding both seems like an enticing deal when the time comes...or am i missing something?

oy weh, the questions keep on forming in my sleepy little head...



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1976 911S Targa

I'm currently compaigning a 2.7 that was built by MotorMeister, and I can tell you they did a very good job of putting this monster together. There were no "gotchas", and their after sale support has been absolutely phenominal. Both Roy and Lee are ready and willing to talk to you, at any time, about your engine and are willing to provide any information you might need to solve any problem that might arise. MM delivered what I wanted, when they said they would, and most importantly, on budget. Would I use them again? Absolutely. How can they offer these prices? This is all they do. They don't align cars etc, etc. . .They also work off a volumn price break. If you have any other questions, let me know, and I'll be glad to talk to you about my experiences with MM.