Porsche G50/52 advice?

I currently own a G50/03 with LSD in unknown condition, and have just been presented an opportunity to acquire a G50/52 with 38K miles for around $5K USD. Both boxes are '91 models.

Whichever box I settle on will be going to CMS for addition of a side shifter, other mods & probably an overhaul or at least a freshening up.

Is the G50/52 definitely the stronger and more desirable box to start with and would it be worthwhile springing for it at this price point, or once the box has been through Bobby's shop, there's really little difference between them? (I've been trying to contact Bobby for a few days, but haven't heard from him as yet)

The 50/52 does have longer gear ratios than the 50/03, which might be another advantage.

TIA,

John

John,

Much stronger. This is the Turbo box. Bigger r&p. Joel (jmracecar) has all the hands on experience with G50's and their intimate differences.

Cheers,

Russ, thanks for that confirmation. I thought it might have a stronger r&p than the G50/03 but wasn't sure. Hopefully jmracecar will chime in, also.

Best,

John

I am interested in using a Rotary Mazda in front of a Porsche gearbox. I know that the adapters are available. I intend to use the gearbox in the inverted position ala a GT40 setup.

The target power from the engine is 350HP and about 300Ft/lbs of torque.

The car's target weight is 1900 lbs, and on slicks.

I NEED a LSD in the box and prefer a Quaife.

Can I use a less expensive 915 gearbox? I am not hard on power-trains. No drag racing.

What do you guys think. What would be a fair price for a used 915?

Howard, I believe the 915 should be able to handle 300 lb of torque but don't rely on me. I was offered a non lsd box for $1,000.00. Price dropped a week later to $800.00. I don't know if it is still available.

I would be interested in the 915 box if you arent going to take it . Could you get me the contact info?

Howard,

915s are on eBay all of the time! (use the Porsche tranny search at the bottom of GT40s.com Links) They have been trying to ride the shirt tales of the 930s and G50s, but I have seen fully rebuilt, nice looking ones for $1,500.00 I would consider that a max price.

Since you aren't far away, give the Kennedys a call. If anyone should have a feel for the capability it should be them. You can talk to them about the adapter as well.

Lynn

Great, I'm in the research phase still so I don't need one right at this moment. I would however like to run down a couple of California Porsche gearbox shops, norcal is better, so I can talk to someone local.

Anyone have a recommendation. I know all about Kennedy. Good people and great products. I'm the kind of guy who likes to talk to several sources before I make a decision. They are at the top of the list thought. They are the adapter source I would like to use if I follow through on this.

JohnC
CMS\Bobby has recently had phone problems, possibly the reason for not returning your call. Very reliable and straight forward. Keep trying and his recommendations will be spot on.

Howard
I run a turbo Wankel in an off-road car, 485rwhp, Fortin sequential. Let me know where I may help. As mentioned above, if a G50\52 is an option, Bobby @ CMS would definitely be one to consult. I was with Bobby two weeks ago and he mentioned the 50\52's are readily available. (If I were an SPF buyer I would seriously consider one over the ZF)

Roy, I don't know where you are located, but the trans was local to me so I called the seller this morning regarding its availability. Unfortunately he sold it two weeks prior.

JohnC- YES the G50/50 is definitely stronger than the G50/03. From that standpoint it is a no-brainer. Where it becomes a brainer is determining what condition it is really in. How many miles, how used, was it ever rebuilt? We really can't know without asking someone we trust who knows, if possible, otherwise we can only determine fair value by opening it and taking it apart. Not much help I know.

Let me try it this way. I'd rather see you run a good G50/03 than a bad G50/52. But I don't know you or your style or goals or budget. Some people would rather buy two G50/03's and run one while they rebuild the other. Other people would rather get the stronger box. As mentioned above, yes bigger diameter ring gear, and the bellhousing is reinforced internally, and is larger obviously to house the bigger ring gear.


Re: the 915 boxes, everything is smaller in there. Porsche brought out the G50/00 to handle the 3.2 liter Carrera in 1987 which made 230 hp. While you may be able to put 300 ft lbs through it, it will not last. It has these really cute little bearings in it. Perfect match for a four-cylinder non-turbo motor.

The G50 has larger bearings and it has Borg Warner cone style synchros. It has a 1" input shaft where the 915 is only 3/4". However, the G50 shares the differential with the AUDI 01E and is smaller than the 915 along with the ring gear diameter. /the 915 has a 7 7/8" ring gear and the G50 I'm told is 7 3/8". I have also been told that the gears are the same width in the G50 and 915.

Renegade Hybrids and Rod Simpson Hybrids both state that the 915 will take 450 HP and be very reliable. (no drag race starts) I haven't seen anything an HP capacity on the G50.

I think the 915 Ring and Pinion is stronger but the G50 bearings are bigger. The G50 has better synchros and can have 6 spds.

I don't think, however that the G50 even comes close to the strength of the 930. The 930 has a much bigger ring and pinion and has wider gears than the G50 and the 915.

I would always choose the 930 over either. The 915 is much less money than the G50 and I'm not convinced that it is much stronger than the 915. You could buy a few 915's for the price of one G50 so you could have a few spares.

The standard G50 is not as strong as a 930 in certain ways, I agree there.

Note that the G50/50 series would be stronger yet than the 930 box in most respects (except for the ring gear diam). It seems a lot of the hype around G50's got out there without drawing much distinction between G50/0x and G50/5x boxes. It's still the same old equation, the turbo boxes were stronger. The G50/5x is the Turbo version of the G50/0x, and is the evolution of the 930 gearbox obviously.

I agree with most of your points, but not with those who claim reliability putting 450 hp through a 915. The shafts flex and separate, and the bearings wear fast. The syncros were terrible in those boxes too, not so much in terms of wear, but just in vague shifting. No comparison to a G50. You can fix some of the 915 bearing weakness with the Wevo steel bearing plate, but with machining it into the case, you are spending G50 money or 930 money. SmartRacing Products (Smart Racing Products - Home of SmartStrings, SmartCamber, and other quality performance auto parts) has all the Wevo upgrades for the 915 boxes. Their internal shift gate also makes an improvement, but again you're spending 930 or G50 money once it's all in.

A 915 may appear to be reliable for awhile with 300 or 400+ hp, but are they taking them apart and checking them? What kind of track hours or street miles are they claiming, and who is checking the gearboxes after those intervals?