Opinions? 901 vs 915 Options

[dekman]

I'm still on the fence....Spoke with John Williamson(OTTO) and he said he has run 380hp against a modified 901 for 7 years(hates the 915). Spoke with Roger Sheridan and he said he now has a modified 915(x $14,000) and it works OK .... but previously used a 901 with problem. Both men preferred the 901 box! (modified with 904 main shaft and intermediate plate of course...weakest area=ring & pinion). My goal is to use either a 3.6 or modify my 3.0L to get ~300-320hp. Adding torque to the 901 box is a factor, I know but? Any opinions appreciated......... (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif)

[Jeroen]

just curious... did they give any specific reasons why they didn't like the 915 box?

you could just run the 914 box 'till it pukes and decide if you need a 915 then

[John]

If you have a bunch of 901/914 boxes, then stick with that, and keep rebuilding them.

How are you going to use the transmission?

We found that the mainshaft/pinion shaft could flex allowing 4th gear to seperate far enough to rip teeth from the fourth gearset.

I am assuming it is because of torque and not horsepower. We were driving the trans with a stock 3.2.

I/we destroyed 4 4th gear gearsets before going with a 915.

This car was track only and was abused in DE events with 2 drivers for about 8 years before failure started occuring on a regular basis (even with different trans cases).


My street 914/6 (3.2) will start out life with the last trans I rebuilt for the track car (with the billet intermediate plate). This trans hasn't been used since rebuilding as we went 915 before trying it out.

Eventually, I will switch to the 915 for my street car just to make it that much more robust and allow the use of stock flywheel and clutch with my 3.2.

It seems that some people don't care for the way a 915 shifts, but if it is properly set up, I don't have a problem with it.

just my $0.02

[914-8]

I like my Vellios 915 a lot!

The factory pumped at least 231 hp through the 915 in production cars, and always overbuilt the trans by a decent margin.

Lots of guys have used 915 with 300-350 hp 911 engines with no problems, for lots and lots of miles. Some birds have blown 915s up on high hp 911s, but it always seems to be a result of multiple high rpm clutch drop drag strip use (why?!?).

915 also has many better/easier/cheaper clutch options than the tiny 901 clutch.

[Wild 6]

I have owned two 914s, one with a 901 and one with a 915 Wevo gearbox. There is no comparison between the two. Once the Wevo shift linkage was adjusted properly, It shifted almost pefect.

Now the 915 can be a little more difficult (notchy) to get into a gear, but it is not vague like the 901. It is also expensive.

[Series9]

I'm one of very few people who have run a 3.6 against a stock 901, Vellios 915 and WEVO 915.

The 901 is just not an option for me. Although I like the shifting and the pattern better, I also like childishly doing burn-outs with the RS. I put that kind of power in my car for fun, not so I would have to baby the tranny.

Between the Vellios and WEVO conversions for the 915, there's no comparison. Get the WEVO. The shifting is much more precise and it's an all-around higher quality kit.

Keep in mind, I have over $7k in the complete conversion (includes shifter, drive shafts and 911 hubs).

[East coaster]

It should be referred to a 91$, not a 915! (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

I've got 9K into my 915 and that does not include driveshafts, linkages, or shifter......ouch! I am hoping it works real well though. Also, thanks to the genius who did my wevo conversion, I now have a defunct tranny cooling system (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) Sorry.......this one still pisses me off!

[Britain Smith]

One problem with the opinions on the 915 is that people think that they can just slap it in and complete the conversion. That is simply not true. While the 901 was built with a version specifically for the 914, the 915 was never a mid-engine transmission. Now that companies like WEVO around making OEM-quality products for the 915, one is able to utilize the benifits of a 915 in a mid-engine config. I bet you that there are not many 911 guys that would take a 901 over a 915 and it helps that the conversion is fairly straight forward. If you take a 915, slap on a WEVO sideshift kit, and install it in your 914 with some serious power I am betting they you will never go back...ever! To enhance the experience, add a WEVO Internal gateshift kit, a PSJ, and a shifter to have the ultimate set-up no questions asked!

-Britain

[lapuwali]

IMHO, the 3.6 would kill the 901 a lot faster than a modified 3.0 would. Any modifications other than a turbo to the 3.0 will gain you HP, but not much torque (that is, it wouldn't raise the torque PEAK very much). Peak torque is primarily a function of engine size. Peak HP is primarily a function of peak engine speed.

Torque, not HP, is what kills gearboxes. HP causes faster wear, but it doesn't bend and break parts.

So, keep the 901 and modify the 3.0. If you go with the 3.6, look to a 915.

[Wild 6]

QUOTE

To enhance the experience, add a WEVO Internal gateshift kit, a PSJ, and a shifter to have the ultimate set-up no questions asked!

That's the ticket!

I have two 915 Wevos with the internal gate shift. I may be putting one up for sale. I can't decide if it's just too extravagant to have a spare 915 Wevo gearbox (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) just in case.

[GeorgeRud]

I have one of each in my cars ( a Vellios 915 and a 901), and much prefer the 915. I always figured that there was a reason that Porsche went to the 915. It was the early 70s when they developed it, and money was tight for them, but they still changed to the 915 - must have been some reason.

I definately agree that setting up the linkage is a major part of a successfull installation.

[J P Stein]

Ask Gary Chapman how much it costs to have a top flite shop to set up a 915 for a 914.....tho I don't think he has the final tally as yet (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)
I figure he is gonna have more in his trans that I have in my engine/trans combo. I just bought a 914 GA side shifter from Brad Mayher (sp?) that was ugly outside, but sparkling inside
for 400 bucks.

Do the math.
If ya got a big motor and do a lot of track/AX, maybe a 915 can be justified, otherwise.......well, bragging rights are worth something.

[Series9]

QUOTE (J P Stein @ Mar 31 2006, 07:25 PM)

....well, bragging rights are worth something.

For me, (childishly) the burn-out rights are worth something.....

[campbellcj]

I have one of Otto's 'big buck' 901's and no probs so far; of course I'm only hammering it with a low-torque 2.2S/6 and it's a track car so 1st gear gets almost zero use. I didn't even think about a 915 or other options for this car -- no reason to -- and I doubt I would/will even with a significantly more stout engine. (A V8 or turbo-6 would be exceptions but I have no plans to go that route). Otto definitely knows his way around the early Porsche transmissions...

[dekman]

Keep those opinions coming....really appreciate it! Really.... thanks to everyone! My engine builder just returned from Tahiti(surf bum)...he thinks I should put the 915 Wevo in too! Also entertaining building a 3.8(have 3.6 long block with cracked case) but putting it in a 3.2 case. Why? So it will look more original and can use original sheet metal. New question: 50mm PMO's or Injection? (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

[EMRoadster]

QUOTE (Britain Smith @ Mar 31 2006, 10:46 AM)

To enhance the experience, add a WEVO Internal gateshift kit, a PSJ, and a shifter to have the ultimate set-up no questions asked! -Britain

Ok, dumb question from a Porsche newbie:

What is a PSJ?

[dekman]

PSJ = Precision Shift Joint (see Windrush Porsche Racing Transmissions) (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[John]

QUOTE

My engine builder just returned from Tahiti(surf bum)...he thinks I should put the 915 Wevo in too!

ROTFL

He wants to get another trip to Tahiti on your bill.......

[dekman]

Actually John he tried to talk me out of it...he said my 3.0L with the 901 was a good/balanced combo. "BUT" at the WCC 2005/streets run, a 3.6 kept pulling away from me on the straight (I think it was" Wild 6"). A seed was planted. Then recently at Laguna Seca against a new Caman S , I kept up with him for about 5 laps(till the diff broke). I realized that with ~100 more hp I could take him easily...and so here we are. (IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)