upgrade the 901 or get a 915 ?

[Sandeep]

All,

I currently have a stock 914 gearbox behind my 2.0 turbo (~250 fwhp, ~300 ft lbs tq) and am upgrading the 2.0 to a 2.4 (~300 fwhp, ~330 ft lbs tq) this winter.

I have a line on an aluminum 8:31 RP 915 aluminum box, complete and am wondering if I should buy this box or upgrade the 901.

The 915 has a AZ 1st gear (3.182), HX 2nd (1.883), NT 3rd (1.261), QP 4th (0.962) and a TM 5th (0.759).

It has an 8:31 R&P ... a little low maybe ?

I am going to circuit race my beetle next year so any thoughs / suggestions are appreciated.

Thanks !

Sandeep

[wrenchnride247]

IMO, 915. By the time you "rework" the 901 (not cheap) a stock 915 will handle it. I have asked questions to several Porsche gearbox rebuilders, and have gotten quite a shock on different rebuild prices. (ONE gear stack is about $850) Matt, at Carquip, in Colorado, has been very helpful. He said the 8:31 is way stronger than the 7:31 in early 915's and 901's. The 915 tranny is a little longer, but with bug@5speed nose cone it's alot easier to fit in a T1.

[DORIGTT]

How has the 901 been doing for you? I've seen the video of you doing a couple burnouts and I wonder how it's been working for you.

[GS guy]

I'd also be interested in hearing how the 901 is holding up Sandeep. Was it overhauled prior to the installation?

I'm kind of in the same situation - except my application is mid-engine. Will be running a 914 trans - but fully rebuilt, 1st locked out/removed and billet intermediate plate. Rebuilding the 901 is crazy expensive (~$500 just for first gear parts - I'm using that for the billet int. plate instead!) - but considering converting a 915 to mid-engine, it runs a bunch more $$$. So I'm sticking to the 914 for now - anticipating ~250hp and similar torque from my 2.0 Suby turbo. Thinking (and hoping) the 914 will suffice in my case.

Jeff

[Sandeep]

Thanks for the responses. I'm still trying to figure out the clutch setup right now for the 915 as well. I have a WBX 228mm FW and a kennedy stage 2 PP with 6 puck solid disc.

By the time I buy the 915 and sell the 901 I figure I'll have about $800 into the 915.

Can I make the 901 hold 300hp / 330 ft lbs by spending ~ $800 ? I would not have to worry about shifters / clutch / fw issues becasue I already have a working solution for the 901, just need to make it stronger.

OTOH, I could sell the 228mm setup and get a setup to work with the 915.

If I keep the 901, I'll be hitting 230 kph (143mph) in 5th @ 6000 rpm (Been there done that ) but if I get the 8:31 915, I'll be hitting 245 KPH (152 mph). The 901 is geared higher so I would have a better chance to keep the engine in a usable power band on a racing circuit and a better chance of using all of the gears.

You will notice that when I did the burnouts in 1st gear, I was rolling with street tires. 1st gear seems fine but I would not attempt this with slicks. I'm using a stock 901 with no mods and am pretty happy with this box. I just feel that I'm on the limit right now and don't want to destroy this box.

Sandeep

[wrenchnride247]

Yes stock gearing is taller on the 915, but Jake is setting me up with a cam that will work with stock 915 gearing to save me some $$$. (to build 915 like I want is 4K!) The 901 will be fine if you change the intermediate plate out to a aluminum one, like GS guy mentioned in his post (about $1500 I think). Your 228 FW & PP will work with 915, but not sure about the clutch disc splines working. If you get a late model 915 the clutch arm will need to be "flipped" as it is a "pull type", and you need a "push type" for T1. You can use a late T3 t.o.b. using Bug@5speed conversion guidance tube. (pictured below) This info comes from Martin and Alex. I have some of their parts for my conversion, top quality service, and craftsmanship. To do the "complete job" they have more stuff I didn't get.

[Zman]

I have both, in one car with one of Jake's 2270 Torq kits I have a 901 out of 914. Perfect gearing. As you can see don't have near the power or torq you have. In another car 2270 roller, I am putting the 915 model with the same gearing that came in the 76 912E. I believe this is the 915 tranny you want. It was geared special for the 912E. Sorry, I need to look up the gears in it I have them at home. Racers love that box and the gearing. I have Martin's kit on both of them. Well worth the money IMHO.

I like the 901 from the 914, but have a nice shifter for it from Martin. I went with an aftermaket porsche shifter for the 915.

Find a good 915 and you probably will not need to do anything to it, just check out the gearing that came in the 912E, most of the guys on the track running the 911 sixes, have changed to that gear box or gear ratio. If you can find one with the right gears and in good shape, you save youself much money. They are hard to find.

Just think hard about a good shifter as well.

Gary

[Sandeep]

I pulled the trigger on a 915/62 8:31 RP aluminum box. The gearing is lower than the 901 I am replacing but I think that will be good as I felt first and second in the 901 were too high and needed to be longer with my setup.

The gearing in this box will put me almost on par with a 997 Carrera S, which is what I want to keep up with on the street and circuit. 237 kph @ 6000 rpm (915 5th) vs 245 kph @ 6000 rpm (997 6th)

I'll be looking into a shifter from BAFS as well as some other items now.

Searching the forums now ...

Sandeep

[DORIGTT]

What was your clutch disc, PP and flywheel situation? I've got a 901 and have been wondering what setup to use.

Thanks

[Sandeep]

For a T4 up to 180 ft lbs - stock 914 215mm fw/pp/clutch

I used a 228mm wasser fw/Kennedy satge 2 pp/ 6 puck solid clutch and could not tell the difference in pedal pressure. You also save a few lbs on the complete setup vs a 215mm setup.

The stock 228mm setup holds 200 ft/lbs, stage 2 pp with stock 228mm clutch holds 273 ft lbs with no increase in pedal pressure over a stock 215mm setup. The 6 puck clutch increases the holding power to 341 ft lbs.

Sandeep

[DORIGTT]

You're telling me I can use a stock WBX flywheel and an upgraded Kennedy clutch package? Was the clutch for the 901 trans or for a VW trans?

Also, what starter were you using the 901 starter?

The reason I ask is that I've been given some (apparent) mis-information regarding what needs to be done to put a flywheel/clutch in my WBX / 901 setup.

Thanks

[Sandeep]

The information I provided was to connect a T4 with 228mm wasser FW/PP and VW clutch to a 901 gearbox using the stock 901/914 starter.

The 901 spline and VW splines are the same as I was able to use a 210mm bus clutch with the 901 in the early days.

I am not sure if this information will be correct for a WBX motor as I have not used one.

Sandeep

[Steve C]

Hi

The WBX uses the same splines as the usual bug etc spline.

Steve

[DORIGTT]

The WBX according to Kennedy also uses the same flywheel as the T4. So I can get by without spending the $350ish that Kennedy wants for their flywheel when I can use what I've got now!

That's alright in my book.

When you say VW clutch, are you saying the Wasser clutch, T4, or T1 clutch setup?

[1303R]

i have a wasserboxer turbo (when working) fitted to a 901. the 215 didn't hold, am now using a standard 228mm wasser flywheel and clutch. spigot bearing fitted to the wasser crank, as per type4 conversion, had an issue with the starter not throwing out enough thou (porsche) and did some mods to it to gain an extra few mm throw. i've made my own release bearing using bit's of an early beetle bearing welded to later type, i did try a 901 bearing, did work but was on the limit of how much throw it had.