tranny options, 915, 930, or G50 Options

[smrz914]

Hello,

So my situation is that I'm going up to Chico for school and want something with higher gearing. I have a 914 w/ a 350 putting out about 280hp/330tq. I was considering doing a 915 but it seems that it wouldn't be much of an upgrade to the 901. A 930 would be nice and I'v heard that the gearing is good for a v8. A G50 seems really expensive and really overkill. I would like to do as much of the work myself so that I can keep the cost down. So I would like to know what is entailed in doing the different transmissions, the issues with the different ones and what needs to change. Thanks.

Paul
'72 5.8 918

[LvSteveH]

The tranny options you are considering are of course not for the faint of heart. They all have serious obstacles and compromises unless you have $10K around to just pay to have it done. Even then, a cable shifter leaves a lot to be desired. The Wevo setup for a 915 allows for conventional shifting without the cable and is very well sorted and regarded in racing circles. The down side to the 915 vs. 930 is that the stock gearing isn’t ideal for a V8, so a ring and pinion swap is usually recommended, and the 930 is good for more horsepower. In a V8 application, I’d think the 915 is good to around 500hp, the 930 anywhere north of that. Transmission are a funny thing, you can get the toughest tranny in the world, and some drivers will still blow it to bits. On the other hand, in all forms of racing, there are drivers that can make relatively stock or conservative parts last and last and last, when others need to upgrade. I’ve heard Robby Gordon is very easy on his equipment. It’s all about how you drive it. I recently saw a 914 can-am car with a 280hp 3.6L Porsche six in it, running a completely stock 914 gearbox, not even the billet intermediate plate. It even had huge slicks. It’s a recipe for disaster, literally one bad shift and it’s all over for the tranny. If the driver is capable from preventing that bad shift, and has the driving and clutch finesse to keep the shock loads to a minimum, then why upgrade? You didn’t mention having any problems with the longevity of your current tranny, and your horsepower and torque ratings aren’t extreme, I’d say stay with what you have. At minimum, if you cut corners, you are looking at close to $5000 for the upgrade. If the gearing is that big an issue, why not upgrade the 4th and 5th gears on your current trans? If you are ambitious enough to want to jump into the world of 930’s and 915’s, then digging into the 914 trans shouldn’t be anything too dramatic. There are some excellent online resources available on how to set the gear stacks back up, and Pelican even sells the special tools necessary. Don’t get me wrong, I’d love to have all the bullet proof parts out there, but everyone has a budget, and until it proves necessary, I’d spend the money where you know it’s needed. Good luck. (IMG:style_emoticons/default/driving.gif)

Steve

[smrz914]

Thanks for the reply Steve. My first tranny didn't last. I'm on my second and have been very nice to it so it has lasted. So i have been talked out of the tranny swap. I'll rebuild mine w/ taller gears and an internidiate plate. Are there any tech articals on this kind of thing. I have 2 trannies that i have taken appart. One that I broak and one that I had laying around. Where can/should i get gears.

Paul

[Brad Roberts]

Hey Steve.

You really need to think this thru (with money in mind) Building a 901 with tall gears and billet plate will run you close to the same as installing a 915 and you know it wont last either. Nothing you do to a 901 will make it last behind a SBC (unless you dont drive it) The 915 is better only because it is marginally stronger and has a little taller ratio's.

The 930 box is the end all. I'm doing a car right now and we will have 5500$ in it for the conversion.

B

[LvSteveH]

Brad,
Have you heard anything from Wevo on the conversion kit for the 930? Of course I'd love to have a Limited slip 930 behind the V8 project I'm working on, but it's largely a matter of money. I'm going to keep the 901 for now, and stay mild with the motor, in the 300hp/300ft lb range. That way I can get the car together, drive it, and work up to the high dollar stuff. From what I can tell, the 901 will do ok, as long as I don't beat the piss out of it, which of course some people are prone to do with a 300hp 914. I'm not going to put much tire under it with the 901 trans, to keep the stress to a minimum. The Can Am car I saw had a 12" slick with a 914 box. In Paul's case, as a student $5500 may be out of reach to do the 930 conversion, I know it is for me all things considered. I totally agree with you on the 915, being a waste of time and money when compared to the 930. I think Scott at Renegade is of the same opinion as well. If Wevo comes through with the kit, that will be perfect. In thinking about it I will probably also be interested in the 5th gear conversion they talked about for the 930. If you are going to have a 600hp 2000 pound car, why not enable it to go 180mph, even if you never actually go that fast. Remember the GMC Syclone? Quarter mile in 13.6, 0-60 in around 4.5 sec, but only 126 mph top end. In a real race a stock nissan maxima would spank it on the top end. It's almost as important to win the bench races as it is the real ones.

Paul, there are some good tech articals on Pelican, and if I recall Red Beard, on the Pelican BBS is working on a book for rebuilding porsche trannys. He has a web page up with the basics of doing a complete rebuild, very helpful, I think someone on here just used the info to swap the 3d and 5th gears for improved autoX ratios. If you have to pay through the nose for taller gears for the 901 box, of course it would make that route less attractive. If you already went through a tranny, then maybe saving for the upgrade will be the best bet for you. If you aren't having fun with the car because you have to stay out of the throttle, then that's your answer. I hope you are avoiding using first gear at all costs. From what I've heard, it should only be used going up the driveway or something. It should never be used for a spirited launch, start in second when ever possible.


Steve

[TMorr]

Steve,

The 930 Sideshift is not a high priority for us at the moment.
Since it was discussed on this BB last, we have investigated some of the packaging issues and can confirm that preliminary progress is being made.

The 930 Sideshift product, when ready, will initally be a 4 speed only version. Some of the time spent now is in the packaging of a 5 speed solution, although the internal components for a 5 speed version will take quite a lot longer for us to design and source.

I am leaning towards a 5 speed with a dogleg first, like the 901. This offers the best use of the existing package for the top 4 gears where maximum torque needs to be accommodated.

The 915 version took just about 11 months start to finish, we save some time by sharing technology although I would not really say the work we have done so far on the 930 is as "started" as it should be for the clock to be running......

We have about 6 weeks of busy schedule allocated to other projects, then the 930 should make it onto our board as an open file - work in progress.

All technical specifications and market ideas go into the mix, so feel free to contribute if you specifically wish to impact on a feature or solution with special merit.

Regards

Hayden PTBT

[LvSteveH]

Hayden,
Thanks for the informative response. It’s great to hear that you still have interest in pursuing the 930 project. Obviously the 930 is of primary interest to the V8 crowd, at what point is it worth considering something more unique like a hewland? Given the need of an adapter plate anyway, it isn’t as far out as it might initially appear. In fact I’m sure they’ve already got a setup for the chevy V8, because it is very popular in offroad racing. I would guess the price tag would be around $10k if purchased new, and somewhat less for used. There is of course something pleasing about staying with Porsche parts when possible. I just look forward to the day when the tranny becomes a non-issue. Maybe I’ll trip across a Ferrari trans with the F1 paddle shifters at the local pic-a-part! All electric, no linkage issues, woo hoo. Thanks again.

Steve

[Brad Roberts]

Thanks for the update Hayden.. I'm getting 2-3 calls a week about 930 boxes for mid-engine use. The word is spreading that we can do them now... the word is also spreading that we may have a real solution for shift linkage in the near future.

Steve.. you cant run a Hewland on the street. They have straight cut gears that whine like crazy... and no true synchronizer for upshifts. The Hewland equivilant of the 930 box would run you close to 14k dollars new.

I recieved a call today from a guy with a Tube frame V8 kit car having trouble shifting his 930 box...

B

[TMorr]

No Worries Steve,

Brad, let's not let the tail wag the dog, we have success with our R&D process and that means it will run pretty slowly compared to the enthusiasm of the potential market, but I appreciate you fielding those calls and leaving my time free to actually work on the R&D... thankyou.

FYI an equivalent Hewland Transmission to a 930 unit would be the DGC, a cool $20,900 with a LSD.

Our solution will be road car oriented (unlike the DGC) but the competition capability of the 930 unit is also widely understood.

Regards

Hayden PTBT

[LvSteveH]

Thanks for all the great information, I generally see the hewlands used, so I didn't have a good barometer for the new cost. It’s nice to see all the ideas bouncing around, I’m sure the end result will benefit greatly from it. I wonder if the value of 930 boxes will shoot up because of the renewed interest, and new potential applications. I’ve been keeping an eye out for one, but just can’t manage to justify the expense yet. I can’t afford to stockpile them like the 914 trannys, so when I get a 930 box, it needs to survive for the long haul, maybe someone will part out a super clean low mileage original car…. I won’t hold my breath. Have a great day.

Steve

[Brad Roberts]

No worries Hayden.

I learned my lesson on opening my fat mouth early. I didnt tell the guy when anything would be done and I sure as hell didnt tell him WHO..LOL


B