Will a '70 901/911 trans handle a strong 3.0?

Just curious - can a 901/911 trans deal with the torque of a 3.0 with carbs? Car (70T) would be mostly street with a little track thrown in for spice.

[Tyson Schmidt]

Yes, but that's extremely driver-dependant.

Very little built-in margin left over with that drivetrain combo, but if you're nice to it............????

Just don't be a hero in first or second.

Thanks Tyson - what would be involved in a 915 transplant into the 70?

[Shaun @ Tru6]

Originally posted by Mark Wilson
Thanks Tyson - what would be involved in a 915 transplant into the 70?

Got a big hammer?

[911pcars]

Originally posted by Shaun 84 Targa
Got a big hammer?

But that's all you'd need (and a 915 gearbox and shifter and matching driveshafts/CVs).

Sherwood

Thanks Sherwood(and Shaun),
I have the 915 box and driveshafts. Will the shafts bolt directly to the 70 hubs?

[Shaun @ Tru6]

Depends on the year of the 915. I think a 74 is a bolt-on. later 7:31's may be as well. When you get to 8:31's, I think you'll need to change hubs or flanges or both?

[Joe Bob]

Ask the the 914 weenies.....


OK....yeah....I had a 901 with a 3.0 and pounded the crappoutta it....the 1st gear burnouts are what killed it....took 3 years....

BTW....I have a early 915 in the garage....$900......

[briankim912]

I've got a 901 paired with a 3.0 that's carb'd. It's held up fine so far.....but as they say, as long as you're easy on it in 1st and 2nd....

-Brian

Cool - so sounds like I can get by for a while with the 901. I even have an extra 901 in the garage for a spare. Thanks.

Next question - Is the 901 to 3.0 a straight bolt up?

[911pcars]

Originally posted by Shaun 84 Targa
Depends on the year of the 915. I think a 74 is a bolt-on. later 7:31's may be as well. When you get to 8:31's, I think you'll need to change hubs or flanges or both?

Mark,
I'll have to concur with Shaun. The early CV joints were 4-bolt, the later ones were 6-bolt. It's a matter of matching the CV joints with the gearbox drive flange on one end and the axle stub flange on the other end......or vice versa. The overall axle length may also be a factor. It's easier if 7:31 parts are used throughout (gearbox, axles/CVs and control arms) or all 8:31 parts.

Sherwood

[Grady Clay]

I will agree with Tyson and say no.

With a 3.0’s torque, the question is; How Long?

With a great original set-up, new parts, proper oil cooling and regular maintenance rebuilds a type 901 or 911 will last acceptably long using a high revving 2.8S. A tourquie 3.0 is over the top IMHO.

Sure it will work. The question is how long.

Porsche engineers, in their usual early ‘70s conservatism, thought 2.2 liters the limit for the 901/911. They would have preferred to use the 915 with the ’70 2.2 but it wasn’t ready. On the other side, Porsche waited too long before introducing the G50 (950) transmission in the beginning of the “only profits count” era. It didn’t take much time for the G64 to show up for larger engine applications.

What to do?

With a 3.0 and larger, use a 915. If you have the opportunity, use the G50 or G64. (Remember, these last two require much modification.)

Best,
Grady

[Joe Bob]

901 to a 3.0....no. You will need an early flywheel or you can get one built by Kennedy Engineered Products in Palmdale CA....I've seen them build a new flywheel cheaper than a used one has sold for. They also can do larger clutch faces and supply discs, pressure plates and TO for excellent prices.

I've been doing business with them since 1975. Class act....

[Shaun @ Tru6]

Originally posted by 911pcars
But that's all you'd need (and a 915 gearbox and shifter and matching driveshafts/CVs).

Sherwood

When pounding the transmission tunnel, it's good idea to have a core nose to push up into the sheetmetal to check for fitment.

Mike - thanks, I have 2 - 901 flywheels at my disposal. Have to see what shape they're in tho.

[Grady Clay]

Mark, et all,

This an entirely different issue from the choices among 901, 911, 915, G50 and G64 transmissions.

Using a 215 mm push-type clutch with a 3.0 simply invites too regular clutch replacements and possibly a failure at an inopportune moment. It certainly isn’t appropriate for track use.

A type 911 transmission is designed for use with a 225 mm pull-type clutch common from ’70 to ’89.

I still think you are peeing on a live wire using a 901 with a hot 3.0. It may be a very painful experience, waste valuable parts needlessly, and be an expensive “learning experience.”

Someone give me a counter argurement.

Best,
Grady

[Joe Bob]

KEP can put a 225 or a 228 clutch package together.....unless you are a dedicated racer...it's fine. Keep the burnouts to minimum....even a 915 has it's limits.....

[Scooter]

Originally posted by Grady Clay
I still think you are peeing on a live wire using a 901 with a hot 3.0. It may be a very painful experience, waste valuable parts needlessly, and be an expensive “learning experience.”

Do you feel the same way if the engine is not a "hot 3.0"? Thanks in advance for your reply.

I'm buying a 3.0 with a nice rebuilt 915. I was just looking for the path of least resistance to get this little orphan car back on the road. If I use the 911, it will be temporary while the car is getting back road worthy.

[island911]

Originally posted by Scooter
Do you feel the same way if the engine is not a "hot 3.0"? Thanks in advance for your reply.

It isn't likely to matter. Torque is the issue, not HP. Peak Torque isn't going to change too much for a 3.0.