Need quick advise: 915LSD or G50?

eimkeith · 01-05-2006, 06:06 PM

for my 3.2 in my '77 backdated to '72 911.

I've got the opportunity to go either 915 w/LSD or G50 w/out LSD (but with shifter and linkage) for approximately the same price.

opinions?

the G50 WILL require torsion bar housing work (or rear coilovers and less torsion bar housing work) and a hydraulic clutch setup (pedal cluster also). Is it worth it? I may turbocharge the 3.2 (build a 3.3 efi) in the future.

Is the weight difference a factor? I've gone to the trouble of shaving the sunroof and backfdating to save weight (but remain all steel)

Opinions?

Dantilla · 01-05-2006, 06:25 PM

I've got a Quaifed 915 with a 7:31 R&P in my 3.2 powered 1973 coupe.

Couldn't be happier.

Bill Verburg · Bill Verburg's Garage

As long as the 915 is an 8:31 w/lsd that would be my choice.

herman maire · 01-05-2006, 06:43 PM

I am in exactly the same boat, and also have to decide quickly. Like tomorrow.

Same 2 options rebuild my 915 with WEVO parts and limited slip and hope for the best with the 915 behind my turbo motor.
or
Go with a G50 with shifter linkage and pedal assembly ect.. and just build a extremely durable drive train from the get go while the car is already striped.

Im going coil over in the rear anyway.

My only problem is how I reinforce the torsion bar? If you have any ideas let me know.

As I am writing this I think I made up my mind.

I vote G50.

Im still working out what flywheel and clutch to use.

Hopefully others who have succesfully completed the conversion chime in.

If I was not after big HP I would keep the 915.
Since big HP is in the cards im going G50.

I think the difference in weight is 20-30 lbs. I am not too woried

Bill Verburg · Bill Verburg's Garage

for a turbo motor, yes G50 especially if you are going to coil overs any way. For normally aspirated 3.2 - 3.6 in an earlier chassis 915

Porschekid962 · Porschekid962's Garage

I am pretty sure Patrick Motorsport makes a shortened bellhousing for the G50 that does not require cutting the tbar tube for fitment into an earlier chassis. Go for it if the price is right. Unless the 915 comes with helicoiled sideplate cover studs, reinforced sideplate cover, reinforced main bearing plate, then the G50 would be the choice. The 7.3:1 r&p is awesome in a light car trust me, my old man has one its like lightning. All about what kinda driving you will be doing.

best of luck, ryder

aigel · aigel's Garage

So, no LSD in the G50? If you track the car, you WANT LSD. If you can't get it with the G50, go 915.

George

herman maire · 01-06-2006, 06:30 AM

Keith
Where you at?

I will ask a few more questions for you.

In my case I will be putting a LSD in my G50.

When mounting a G50 to a 3.0L motor can you get away with the stock 3.0l flywheel.
What are the prefered set ups ( clutch , flywheel ect..) with a 3.0l

also

Would a G50 clutch pack and a 3.0l flywheel work together?
Or what does work?????

anybody have any info on this????

lvporschepilot · 01-06-2006, 08:29 AM

I thought the g50 weighs close to 50lbs more. Not to mention the extra hydraulic assemblies needed. I am a 915 w/LSD man all the way. Especially the wevo version. wow.

herman maire · 01-06-2006, 11:52 AM

Anybody have any opinions on this mod..... Or ideas please share

I know there have been many Treads on the G50 Vs 915 and both are great trannys in there own right. I am just after a really durable set up for a turbo RSR.

and willing to take a small weight penalty, but hopefully the added durabilty offsets that even if the last place I want more weight is in the rear.

Bill
915 question-
How much stronger is the 8:31 compared to the 7:31 Ring /pinion? If I did stick with the 915 would my stock 72 915 with 7:31RP be a good tranny to WEVO.
Or get a later 8:31 tranny?

Bill Verburg · Bill Verburg's Garage

Quote:

How much stronger is the 8:31 compared to the 7:31 Ring /pinion?

Lots, I posted the theoretical calculation a while ago. It's in there somewere.

I have been seeing failures of 2^nd and 3^rdeven in n/a G50s. This is under race conditions but the point is that none of them are totally bullit proof.

lvporschepilot · 01-06-2006, 12:49 PM

Bill said it best. None of them are totally bullet proof but, if you do have the means, I would suggest wevo's version of the 915. They shift so quick and accurate that it actually changes the body dynamics. Check it out on their website. Real jewelry.

dean · 01-06-2006, 01:58 PM

Quote:

Originally posted by lvporschepilot
I thought the g50 weighs close to 50lbs more. Not to mention the extra hydraulic assemblies needed. I am a 915 w/LSD man all the way. Especially the wevo version. wow.

My G50 weighed 20lbs more than my 915 that I took out.

Dean

eimkeith · 01-06-2006, 05:25 PM

so is running a 915 in a turbo (3.3l) application entirely out of the question?

Or will some of the WEVO mods strengthen that thing up to take the increase in torque?

I like the lighter weight and lack of modification (torsion bar housing swap, hydraulic system), plus the economy of the 915. However, if it is destined to puke on me when I tturbocharge, then I should consider the work involved with the G50...?

daloff · 01-06-2006, 05:56 PM

Put a 930 transmission in and then you don't have to make the mods if you are concerned about strength. The G50 is by far a better shifting and overall better setup. The costs to maintain the G50 is more (parts much higher) If you are running this as a street car I would just use the 915 and be done with it.

eimkeith · 01-06-2006, 06:11 PM

street/weekend track car.

lvporschepilot · 01-06-2006, 07:12 PM

The wevo 915 is supposed to take up to 400bhp comfortably. It is also supposed to shift much faster than anything on the road.

RoninLB · 01-07-2006, 05:28 AM

The Wevo 915 costs super big bucks.

eimkeith · 01-07-2006, 05:58 AM

what is super big?

tom1394racing · 01-07-2006, 06:14 AM

Some additional info on this subject:

I had my 915 with 7:31 rebuilt by Gary Fairbanks here in CT. We put in a set of short gears with ZF limited slip. We also replaced the gearcase with a '74 mag case because of the input shaft seal problem that is unique to the '73 cases. Other than the Wevo shifter and coupling, he recommended no other mods for my 280HP RSR clone. We discussed the side cover upgrade and the Wevo shift gate as well as a cooler. He recommended against spending the extra money even though the plan was for 80% track/20% street. He has been rebuilding 911 gearboxes for at least 20 years and I know many of the members of this board have used him.

BTW.....The Wevo shifter/coupling make a HUGE difference in the shifting.