what is involved with a transmission upgrade (915 in a 84 911 upgrade to a G50)?

My 915 tranny is quite worn, and upgrading to the smoother shifting G50 is attractive. was wondering what is involved.

thanks.

 

just off the top of my head I would say after the transmision itself would be peddle cluster , hydraulic master and slave system for clutch , mounting points.....

not worth it in my mind ... i would rebuild the 915 for far cheaper..

 

It is a pretty involved job.

In the G50 cars the torsion bars were spread apart more and a different center portion to the torsion tube was used. This was to provide clearance for the greater length of the G50. Assuming you did this, then everything else is not too bad. you would need G50 sping plates, pedal cluster, shifter, clutch slave and master cylinders.

Also, if you get a used G50, it MAY not be in that brilliant shape either and G50 rebuilds are much more expensive than 915 rebuilds.

You will spend MUCH less money if you go for a quality 915 rebuild with a WEVO gateshift, billet side cover, and a nice shifter (WEVO or Rennshift).

It won't be as "modern" as a G50, but I suspect it would be a pretty acceptable (and lighter) option.

FYI I put a WEVO shifter in my 100K 915 and it has made a big difference. The shifting feels quite decent now. If I were to do a rebuild and put the above-mentioned goodies in, it would be that much better still.

 

If you want a G-50 tranny you should just sell your car and buy an 87-89 911. I know you don't want to hear that but converting is a project and a half. I think it might only make sense if you go to coil-overs and cut out the TB tubes and you really don't want to go there unless you're building a full on track car.

 

ok - got it. not worth the time/expense...

so what are we talking for a quality 915 rebuild? how much should I expect?

It's not like the car doesn't work well, it's just that on track, it can be a challenge to find the gears. And I'm not trying to have the best lap times, just a lot of fun....I miss shifted a few times this last session by going from 4th to 3rd instead of 5th.....so now I just run up to red line in 4th and don't risk and money shift.

of course, perhaps the real problem with with the linkages, etc and not so much the syncros...

but I really don't know that much about it, except that it is quite a bit more sloppy that the 993 G50..

thanks for the advice

 

Search for 915 rebuild and Peter Zimmermann on this board. He did a great write up on what a true rebuild should entail and some estimated costing. He also has a new set of DIY articles which are linked on a current thread here. You'll be well-served perusing both to make you and educated consumer, even if you don't DIY.

 

Just had my 915 re-built last Summer. Some things to consider to make it and the car better. First a Guard limited slip GREAT second would be a WEVO shifter which will improve smoothness and gear selection.

 

Search "Seine gate shifter" if you don't want to go the $$ wevo route - a few folks here use it including me. I had my tranny fully rebuilt and clutch done a little over a year ago and had the seine system installed with a factory short shift - shifts like a dream - no worrying on the track about $ shift at all.

 

I would be happy to help you with your 915 rebuild. We have a couple of options for you depending on what kind of time you have. We can either send you one to swap out your current gearbox with, (your current gearbox would become the core), or we can rebuild your gearbox if you would prefer to keep you original gearbox.

Rebuild cost is going to be around $2500.00 or so, it kind of depends on what we find internally, ie if you ring and pinion is damaged, that cost could be far more. This would be for new bearing, seals, synchronizers, gasket set, etc. Shipping would be in addition.

Let me know if I can help here, I would also recommend that you might want to take a look at the OS Giken before making a choice on a new LSD. Less expensive, more durable, in my opinion.

Erik Johnson
GBox Sales Manager
(303) 440-8899 work
(303) 895-4828 cell

 

OH Yeah, one last thing, I TOTALLY agree with the idea of looking into the Seine System setup for your shifter. I have it in my car and I absolutely love it. Took less then 30 minutes to install and I have never missed a shift since.

 

I think I read about a G-50 with a short case that is made specifically to replace the 915 in the early Carreras. But then again, I may have been dreaming....

 

THANKS - guess now I am in research mode. I think what would really help me is to drive a 915 equiped 911 so I know what it should feel like compared to the G50. I've had this car a while, but only tracked it recently. I'm usually in the E36 on track.

 

thanks for the offer. where are you located?

 

No one asked if the shift bushings have been replaced. I'd check the shift coupler adjustment, clutch cable adjustment, and change to Swepco 201 at the very least if not already done. I also have a Wevo Billet shifter, and I love it. In fact, I'm probably going to switch out my classic Wevo for chrome re-plating, and put the anodized Wevo back in. It's $$, but worth every penny.

He says the shifting is vague, not crunchy. If the shifter is balking that is one thing. But "vague" tells me you should look at the shift bushings.

 

Not sure how you can rebuild a 915 for under $2500 and actually replace parts? I have also seen the ads for the under $1500 exchange with Vertex and I am HIGHLY SKEPTICAL. I did a full rebuild, replacing all the sliders, dog teeth, bearings, syncros, etc. and it cost me more than 7K. (Including LSD, R & P parts) $1500 was the total labor for complete job-the rest is parts!
I also second the Guards torque biasing LSD, awesome, worth every penny. Same with the one piece Wevo bearing retainer. Do it right, but it will cost. My original lasted 225K miles, 25 years, and almost 50 races. It still shifted great! It was the damn speedo magnets on the differential that came loose that forced me to rebuild. Good luck.