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Posted by: peteinjp May 8 2023, 10:41 PM

As some of you may have seen in http://www.914world.com/bbs2/index.php?showtopic=364676 I thought I was shimming the pivot only to find that I need to replace stuff. I contacted Kennedy and they have a 215mm stage 1 PP and matching components good for 230ft/lbs which will give me a bit of wiggle room with my 2.7.

Just wondering from anyone else is running this setup with a 901,how heavy the clutch feels and how light the assembly feels when shifting. I’m looking to keep it light as it was with the aluminum PP and stock flywheel that was in there or just a bit lighter.

Thanks-

Pete

Posted by: Superhawk996 May 9 2023, 08:04 AM

Pete

I can’t comment on the KEP clutch

However I will take the opportunity to note that you’re on the path of typical American style hot rodding. What do I mean by that?

Hot rod the engine for more HP & torque
Start blowing out clutches as the 1st weak link
Fix / upgrade clutch
Start blowing out CV joints (usually 2nd weak link)
Fix / upgrade CV joints to larger 911 / 930 joints
Start blowing up the transmission.
Replace 901 with a 915 trans

You’re already well past the limit of the limit of a 901 trans. I’ve never found the actual torque spec for a 901 that came from the factory but it seems to be accepted that it’s in the 150 lb-ft range.

https://rennsportsystems.com/letstalk/4-how-to-make-your-porsche-faster-transmissions-clutchessscluct/

This isn’t to say that 901’s aren’t mated to engines making more torque than that (V8 SBC, 3.0L +, etc) but doing so comes at the price of long term durability and the need to baby the 901 especially in 1st gear.

So, what I’m saying, is carefully choose where you want the “fuse” to be. In my opinion, the clutch is a good fuse. Cheap and easy to replace. If you’re going to have to baby something, the clutch is easy, it gives advance warning (smell and slip), and usually doesn’t fail catastrophically leaving you stranded like broken CV’s or a broken tranny can.

Food for thought.

Posted by: SirAndy May 9 2023, 08:34 AM

I've been putting ~270 lb-ft through my stock 901 for 15 years now.
That includes AX and track days with 10" full racing slicks.

The key to making this work is to know its limits.
No first gear burnouts for me, but i can lay down 30 feet of rubber taking off in 2nd gear.


As for KEP, they made me a custom clutch/pp setup that can handle the torque (and then some) while still usable on the street.

Tell them what you need and they will make it for you. Make sure you mention that this is for street use and you don't want a heavy duty racing clutch.

Posted by: Superhawk996 May 9 2023, 08:51 AM

And a great data point on what is possible with some due care.

The interesting thing is we know the factory would have put more than 150 lb-ft into a 901 when racing. But we also need to remember that the reason the 901 is a dog leg 1st is that when racing you pretty much only use 1st gear once and then the rest of the race it would be working in 2nd thru 5th.

@http://www.914world.com/bbs2/index.php?showuser=179 any guess how many miles over those 15 years? And is that with bone stock 901 as in Magnesium intermediate plate?

Pete ,

With respect to your original clutch / flywheel that is overheated, I’m wondering if some of that didn’t come from putting the car on a chassis dyno before the clutch and the flywheel and pressure plate had some time to bed in before it was used hard? Do you know how they arrived at the 190 lb-ft number for your engine; chassis dyno or engine dyno?

Posted by: Steve May 9 2023, 08:56 AM

My first six was a 2.7 with webers, headers, etc. with a stock 2.0 six flywheel and clutch. I was in my 20's and drag raced every car I am came across, autocrosses, up and down hills in San Francisco, etc. and never had a problem with the clutch.

Posted by: peteinjp May 9 2023, 11:35 PM

Thanks guys- all great advice and info. The car has axles etc already and it pretty well balanced in general. That said I'm more of a back roads burner than a drag race type and having read up on the this awesome forum about the 901 I am easy on 1st- usually... at least until the clutch is out- haha.

The 901 is:

Completely rebuilt by Gordon Ledbetter
A, E, KA, Q, and Y gears.
930 GT ZF limited slip from Guard Transmission
904 factory main-shaft
Heavy duty bearing plate
Side shifter conversion
All new parts inside (synchros, bearings, operating sleeves, etc) where needed
Lightweight high torque starter
Rebuilt CV joints, Sway-A-Way 930 axles

Tags said the "fuse" is an idea that I have ascribed to in the past. On my old land cruiser it was in the front hubs rather than having a CV bust or an axle twist up. Easy trail fix.


The dyno work was on an engine dyno. Steves comment is a great data point as well and has me leaning towards the idea that the clutch was slipping due to adjustment issues rather than all out power. Though I noticed that he now has a 916 conversation...


I think I figured out that the PP I took out is a in fact a Kennedy stage 1 unit. Its nice and light with an aluminum foot (the actual pressure plate) I'll be checking in with them and if so I'll use or replace with the same.

Pete

Posted by: Steve May 10 2023, 06:35 AM

The 2.7 started pulling head studs and a 3.2 from a wrecking yard was cheaper at the time. The 3.2 has a nine bolt flywheel, so you are forced to go KEP. I ran a stage 2 with the KEP until the 916 trans was ready. Only reason for the 915 gear box was for the street, I hated the 901 gears with the 3.2.

Posted by: Superhawk996 May 10 2023, 07:43 AM

I tend to agree given engine dyno information. .

The thing that is puzzling is I thought your initial issue was a lack of release travel. However, it could have been original owner experienced the same issues and had the clutch too tight initially - trying to get proper clutch release - and that lead to slipping? I could see that being a strong possibility.

Good news is you’re on a path toward getting it sorted.

Posted by: peteinjp May 10 2023, 09:43 AM

Yep- I hope so. You guys have been a great help! Thanks

Pete

Posted by: slivel May 10 2023, 10:35 AM

KEP clutch/disc. 9 bolt flywheel. 257 lbs/ft torque and 901 gearbox with billet intermediate plate. Also have three-point gear oil spray over R/P and gearset driven by Tilton pump and cooler. The 901 has served me well for many years but I don't abuse 1st gear.

Posted by: peteinjp Jul 18 2023, 12:09 AM

Just to follow up- the new KEP stuff is posted here:

http://www.914world.com/bbs2/index.php?showtopic=364676&st=60&gopid=3090059&#

Posted by: tomeric914 Jul 18 2023, 12:47 PM

Get the Stage 2 pressure plate. I've run the stage 2 on a 3.0 for 13 years now. Not heavy at all.

Posted by: peteinjp Jul 18 2023, 05:56 PM

I got the stage 2- but thought I ordered the stage 1. Anyway I got exactly what I wanted I was just confused.

Good to know you can get it to last so long!

Pete

Posted by: Krieger Jul 18 2023, 06:30 PM

I replaced mine after 10 years because I was in there. I bought the same stage 2 package.

Posted by: Robarabian Jul 18 2023, 07:05 PM

This comment is for trans handling power only.

In my suby conversion, 2.0 turbo, dyno at 300 hp to the wheels, kept the TQ number at 250. Power comes on a bit linear and then hits hard when you are finally moving. Everything above 3400 RPMs all the way up to 7200 redline.

Transmission seems to not care. I don't do burnouts either, but once it is rolling it will take 250 no problem. The tuner and I agreed not to bring the torque number in earlier and to limit it at 250 as we could have easily changed curves.

I agree with the fuse comments though, there is always a weak link in the system.

Posted by: peteinjp Jul 19 2023, 05:10 AM

How did the surface look when you took it out? Any hairline cracks in the surface coating?

Posted by: Krieger Jul 19 2023, 08:04 AM

No cracks. I had the flywheel resurfaced.