Bill Wagner

I put up a post a little earlier about a DMF failure that I suspect I'm having (I was kind of hoping...well maybe praying...someone would post something like "Oh...I know what that is...just tighten this bolt at such-and-such location and the problem will be fixed"...this is called WISHFULL THINKING, FWIW).

In any case, I suspect my DMF, which is a Freudenberg is hosed. I've been tied up working a lot lately, so I haven't really been following this board all that much. Here are my questions:

1. Has ANYONE come up with a non-DMF replacement that actually works on a C4 without DME mods/replacement?

2. Assuming it is the DMF, I'll likely replace the clutch etc. as well. Anything else I need to be aware of? How much do you figure it will run in terms of $$$?

3. Is this a "must replace immediately" thing, or can I drive around with the car in this state for a while? The reason I ask this is that I may not be able to take the car in for weeks. I don't like the idea of letting it just sit there unused for weeks on end and would like to take it out for at least a 1/2 hour drive once a week to keep the battery charged, flush condensation out of the system etc. etc. I'm more concerned with doing further damage to the driveline/clutch assembly.

Thanks in advance,

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Adrian

Dear Bill,
You have answered this question yourself many times in the past. If the silicon fluid leaks out of the DMF you are going to get stranded. The more vibration you have in the transmission line the more potential damage or accelerated wear that may occur. I have never seen a major catastrophic failure because most people get them fixed immediately.
You have a 1991 C4 which means the only not intrusive problem causing solution is to replace the DMF. I recommend you get a LUK but you will have to ask for it. The parts catalogue clearly shows the LUK only for the C2.
Ciao,
Adrian
911C4

PS: To answer question 1. The answer is No unless you install a Paris-Dakar transmission and this very expensive and totally impracticable.

Kevin

Bill;

I think that all of us in this forum have reached this situation that you speak of right now. Maybe not with the clutch issue, but other issues, like leaks and so on. Cheer up. Do not drive it, replacing your mainshaft bearings will make you sick. This is what will get knocked out. The pilot bearing can only hold things together for so long before it starts to fail.

Madridcab

Adrian, I read somewhere that Porsche continued with the Freudenberg unit in the C4 until the end of 964 production, due to "resonance compatibility" with the G64 gearbox or something like that? Does replacing with a LUK unit have any negative side effects (noise, rattles etc..), or just prolonged life? By the way, is the unit used in the 993 the same DMF, or are there various alternatives in terms of LUK manufactured DMF´s?

Rocket Rob

My Dual Mass Flywheel failed on my car back in '95 (approx 50K miles). I replaced it with the LUK and have not had problems with it since. I have 165K miles now.

Adrian

Dear Madrid,
Yes Porsche did continue with the original unit slightly modified. The secondary flywheel mass was slightly different. I have not heard of any complaints from people who have installed LUKs into their DMF C4s. To the best of my knowledge there is only one type of LUK. Remember the Turbos also had Freudenberg DMFs and failures are almost unheard of. Again it had a different secondary mass I think plus a few other minor differences. A problem I do not have of course being a SMF guy,
Ciao,
Adrian
911C4

Bill Wagner

General information for those interested:

I took my car to the shop and when I got home I (unfortunately) had it confirmed that the DMF had gone bad.

FWIW, in the past, Pelican Parts was selling the Freudenberg ONLY, but now they're selling two flywheels for 964s (Pelican part numbers M-114-012-01 for $818.40 and M-114-012-02 for $857.65). I'm about 90% certain that the unit ending in "01" is a Freudenberg and the one ending in "02" is a LUK. In the description, the "02" says it fits the " Carrera 4 (1990-94), C2 (1990-94), Carrera (1995-98), Carrera 4 (1995-98)" whereas the "01" says it fits ONLY the Carrera 2 (1991-94).

I thought I would post that info because a few years ago Pelican was only selling the Freudenberg. Their prices seem to be reasonable in my opinion...but I'd confirm that you're NOT getting a Freudenberg if you order from them...it 's not worth the $40 difference in price.

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johnfm

Sounds like a good time for the RS light flywheel...

...I'm sure you have searched the archives for the usual concerns re: stalling.

Bill Wagner

johnfm:

Yeah, I looked at the lightweight units. The head mechanic mentioned the lightweights as a possibility but even he mentioned the stalling problem.

To bad a solid flywheel from the '89 C4s won't work.

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914und993

There is an 'intermediate' weight, single mass flywheel that has been available from Andial. They took an RS lightweight flywheel and added a custom designed/milled mass to it, such that it is pretty much intermediate in mass between stock and the lightweight RS.

This supposedly tames the stalling problem in the 964, while giving you a single mass flywheel and the improved response of a lighter one.

Chip

JasonAndreas

Why not just go with a modified eprom? The only change required is to increase the rpm value that the injectors are reenergized at after the fuel is cutoff, there is no reason to screw with the idle speed control valve or to add more weight back onto the flywheel.