Quadcammer

anybody have the part numbers for the correct parts to do an LFW conversion on a 993TT with basically no engine mods?

thank you kindly.

No HTwo O

Oliver, have you seen this:

http://p-car.com/gearfaq/

It might guide you. I can look at my receipt from last year too if you need.

Droops83

Does depressing the clutch pedal in the RPM range that the vibration occurs make a difference in the feel through the shifter? What about if you coast down in neutral instead of in gear? Does this happen at 3900 down to 3700 in any gear? If there is a difference with the clutch engaged or disengaged or in/out of gear this can help to isolate the potential issue.

I agree with others that a DMF that is just starting to fail could cause this issue. The trans mount is pretty easy to check with a big pry bar. You can also disconnect the front driveshaft from the transmission by sliding the clamping sleeve forward to eliminate the possibility of anything forward of the transmission being the cause.

Quadcammer

Chris, thank you for the suggestions. Trouble is, if i push the clutch the revs drop immediately, same story as in neutral.

That said, I'll try these things and see.

Droops83

Ha, of course the revs will drop when you push the clutch in, I had that thought as I re-read my post. The main reason that i suggested this is that if the vibration only occurs in gear while coasting down (try just barely touching the clutch pedal while the symptom occurs), this points to something in the powertrain like the DMF or transmission, as opposed to a road speed-specific driveshaft or axle shaft issue. Try coasting down in different gears and see if it changes.

Quadcammer

I was a bit confused on that one haha.

I will give it a try.

On the other hand, performed the one wheel up LSD test and even at 75lb ft of torque on the lifted wheel, it would not spin.

If i have to do the LFW, i'll most likely be doing a tranny rebuild...it needs at least a third gear synchro.

sigh...

Droops83

75 lbs and the lifted wheel would not spin??? Are are sure that the parking brake was not engaged, or that the transmission wasn't in gear? Stock Porsche LSDs are pretty wimpy, the breakaway torque specs are often in inch-lbs, not ft-lbs. Porsche's specs are also using a torque wrench directly on the differential unit itself when it is removed; with the leverage on the wheel it should take even less torque than the spec to turn the wheel.

DM993tt

do a guard pack in the diff

osugasman

PM Sent. --Brian

Quadcammer

well, took it out for the rennlist drive and the vibration happened a few times but not every time. NO real rattle when shutting it off.

What is the worst case if the DMF completely ****s the bed? Potential for other damage?

thanks.

my plan is to let this go on as long as possible, then drop the motor, refresh the turbos, do the vc gaskets, and do the clutch/flywheel, etc.

Droops83

How long did you say that this noise has been happening? When the rubber dampener on a dual-mass flywheel starts going bad, it usually degrades progressively and gets worse over time. If this noise has been happening for awhile and has never gotten any worse, that leads me to think that it may be a normal resonance issue with the aftermarket engine mounts. We have seen a number of cases where aftermarket engine mounts transfer normal vibrations to the body and it sounds like bad chain tensioners at certain load/RPM, especially in older 911s. Did this noise start soon after you installed the stiffer engine mounts?

Droops83

Oh yeah, forgot to mention that a truly bad DMF will often cause false misfire codes in 993s, as their misfire detection system is not too sophisticated and mainly relies on the crankshaft position sensor only. Newer cars with distributorless ignition systems will compare the crank position sensor signal with the camshaft position sensor to eliminate such false alarms. Loose alternator and fan belts can cause the same thing, BTW.

osugasman

What happens if you drive around with clamping sleeve slid up drive shaft and secured down with the panhead screw? Shouldn't be a problem, right? Poor man's RWD conversion??

If you spin the front wheel with AWD, shouldn't the other front wheel spin also due to the front diff?

--Brian