Beginner question, flywheel on 3.6 conversion
 

My 911 has a 3.6 conversion (in a '78) mated to a 915 transmission. It's a 964 (out of a '90). Unfortunately I cannot ask my uncle, who build this car, any questions about it as he passed, and I have a TON of questions :(

It has a lightweight flywheel. Is the flywheel specific to a 964, or the tranny, or is it specific to the "shortened bell-housing" conversion? I can't seem to find an answer.

Thanks for any help.

Probably a custom flywheel. https://patrickmotorsports.com/collections/patrick-motorsports-parts-kits/products/flw-22536dmefw-pmp

The flywheel is partially specific to the engine and engine Motronic needs(ie the 60-2 teeth and partially specific to the 915 transmission(225mm clutch). A 964 would have a 60-2 & 240mm clutch and stock it would have been a dual mass unit weighing ~40#.

You don't have a shortened bell housing, that mod is specific to g50 transmissions

Thank you Bill, so it could be any LWF for a 964 as long as it worked with a 240mm clutch?

No, the 964 would have originally had a 240mm clutch but that is incompatible w/ a 915, so the conversion flywheel has a 225mm 915 size friction surface,

A lwf for a 964 would still have a 240mm friction surface for the clutch and would likely weigh ~12# vs the ~10 for yours.

Question: Why do you ask this question - problems or just curious ??

We have the 3.6/3.8L 964 engine with the 915 and a conversion flywheel . . . 5 years racing (100+ hours and one engine refresh) and clutch is still good . . .

Regards,

Since the conversion, the car had a stalling issue. I am working with Steve Wong to solve the issue (and I think we can) but I like to have a backup plan. Since I am not going to track it, I could throw in the towel and uninstall the LWF.

Yep, Steve is the right guy to help you . . . he did a Dyno tune chip for us on our new 3.8L engine back in 2012 . . . also there is a little trick in starting off from a stop with the LWF - keep the revs up . . . ha ha . . . but I think you have figured this out . . . one more thing we have learned is on the engine warm up keep the revs up at 1500-2000 to improve oil flow to the cams and lifters - we had some wear when we did the engine refresh . . .

Wish you the best,
Regards,

There's more than one way to skin a cat, LOL. Back in '92 I put an
'89 964 into my '80SC. In '89 the 964 motor came with a single 240mm light weight flywheel, not the dual mass heavy one. There were no conversion flywheels available back then, so I took the stock the 964 light weight flywheel to my local machine shop and had it redrilled for a 915
225mm pressure plate. It all worked out perfectly. I have never had
any of the light flywheel problems in the last 27yrs.
Back then you had to be quite creative with a 3.6 conversion, as there were no "conversion kits" on the market, but it all worked out.
I also retrofitted a stock on engine oil cooler to the 964 motor, and with
the combo of the on engine cooler plus a Carrera front cooler and fan, she runs cool as a cucumber.
By the way, that '89 single mass 240mm flywheel is still available
from our host.

Thanks for the info, uwanna, Roy, and Bill. I have never worked with clutches or flywheels (yet) so this is very helpful.