RS Clutch + LWF noise ?
04-23-2018, 02:26 PM
#32
Instructor
I also did this mod and get the "rattling sheet metal" noise at low RPMs that appears to increase as the transmission warms up. Could this be alleviated by service on the transmission or a different transmission fluid? I have RS mounts, RS clutch, LWF, and the function first transmission mount inserts.
04-23-2018, 02:37 PM
#33
8th Gear
Join Date: Feb 2018
Location: Toronto, ON
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I have an LWF too and I notice that my revs bounce when I shift into nuetral when coming to a stop or starting the car up. It is very intermittent and the rev bounce does not last for long. I was told by few air cooled mechanics that this can be attributed to the LWFW. Anyone else experiencing this ? - On the other hand, the shifts are smooth and the engine spins up like a jet turbine haha 
04-23-2018, 02:40 PM
#34
I also did this mod and get the "rattling sheet metal" noise at low RPMs that appears to increase as the transmission warms up. Could this be alleviated by service on the transmission or a different transmission fluid? I have RS mounts, RS clutch, LWF, and the function first transmission mount inserts.
04-23-2018, 03:37 PM
#35
Instructor
Thing is, people like jakfrost, MDamen, and @chsu74 don't report sheet metal rattle when driving, only some new sounds when idling with neutral engaged. The difference between the charming noise in neutral and the scraping metal noise is really stark when pushing in second around 2K. There must be some kind of wear in the drivetrain that is worsening this. Anyone have ideas?
04-23-2018, 05:07 PM
#36
Rennlist Member
gear noise
Did this with my (missed) '95. Noise not a real issue but occasional rev fluctuation on quick stop a bit disquieting even after much ECU and ISV "tweaking". For a '95 993, I would recommend Steve Weiner's midweight flywheel adaptation in 100% hindsight.
04-23-2018, 07:23 PM
#37
Three Wheelin'
Thing is, people like jakfrost, MDamen, and @chsu74 don't report sheet metal rattle when driving, only some new sounds when idling with neutral engaged. The difference between the charming noise in neutral and the scraping metal noise is really stark when pushing in second around 2K. There must be some kind of wear in the drivetrain that is worsening this. Anyone have ideas?
04-24-2018, 11:24 AM
#38
Thing is, people like jakfrost, MDamen, and @chsu74 don't report sheet metal rattle when driving, only some new sounds when idling with neutral engaged. The difference between the charming noise in neutral and the scraping metal noise is really stark when pushing in second around 2K. There must be some kind of wear in the drivetrain that is worsening this. Anyone have ideas?
04-24-2018, 11:32 AM
#39
Burning Brakes
It makes for an interesting "shuush" noise when first disengaging the clutch under certain loads & lower RPM ranges. Even though I expected to hear it after the upgrade to a LWF, it was still a bit surprising the first few times I heard it. Now it's just part of the the "language" of the car. I don't mind it at all...it's kind of a unique and cool signature sound to me now.
04-24-2018, 12:03 PM
#40
Rennlist Member
I just had an RS clutch and LWF installed, and its' noisy between 1700-2000 RPM. This is the factory part, not an aftermarket part. The engine spins up and down more freely and the bottom end torque has improved which is very nice and my shifts are much quicker (RPM matching to gear selection). But it sounds like rattling sheet metal. Not irritatingly loud, but the other day I had my wife in the car and she (again) questioned my obsession with Porsche 993.
The dual mass was both quiet and seemingly smoother even if it did weigh 40+lbs. I can’t believe Porsche would design something that is unnecessarily noisy, or is it that our 3.6 engines have some inherent harmonic imbalance at that RPM range that the dual-mass overcame because it was also a harmonic balancer?
Is this typical ? Does anyone have a 'quiet' RS/LWF ?
The dual mass was both quiet and seemingly smoother even if it did weigh 40+lbs. I can’t believe Porsche would design something that is unnecessarily noisy, or is it that our 3.6 engines have some inherent harmonic imbalance at that RPM range that the dual-mass overcame because it was also a harmonic balancer?
Is this typical ? Does anyone have a 'quiet' RS/LWF ?
hahaha like jumbo shrimp, smart cars and motorcycle safety?
04-24-2018, 12:49 PM
#41
Instructor
To complicate this further, it must also be related to driving style. I tend to accelerate hard every chance I get �� so if I'm slowing down before a corner incline in San Francisco, and speed up into the turn as usual, I will now look like I'm learning to drive stick and ruining my shiny 911. If I rev up to 4K in first, then I avoid this issue most of the time.
Perhaps gear oil viscosity and levels make a difference. Can anyone who has the nice raspy sound of the LWF say anything about the transmission oil they're using?
Perhaps gear oil viscosity and levels make a difference. Can anyone who has the nice raspy sound of the LWF say anything about the transmission oil they're using?
04-24-2018, 03:32 PM
#42
Addict
Rennlist Member
Rennlist Member
This is my 3rd 95 993. Second with LWFW / RS clutch.
Yes. I get the rattling bolts sound in neutral and idle. Goes away when depressing clutch pedal or when on the gas. Never really understood why. It just does.
Yes, I get throttle bounce sometimes when decelerating. The onboard computer expects the slower speed of the dual mass flywheel and thus thinks it has time to catch the throttle as the whee slows down. Since the lighter wheel slows down faster, it can slow down too slow before the computer reacts, thus stalling.
Chips are supposed to help, as is cleaning the ISV, as is adjusting the ISV as well.
I still get some stalls, but recently rebuilt to a 3.8 and thus I'm changing my chip. We will see if it helps the latter issue any.
Yes. I get the rattling bolts sound in neutral and idle. Goes away when depressing clutch pedal or when on the gas. Never really understood why. It just does.
Yes, I get throttle bounce sometimes when decelerating. The onboard computer expects the slower speed of the dual mass flywheel and thus thinks it has time to catch the throttle as the whee slows down. Since the lighter wheel slows down faster, it can slow down too slow before the computer reacts, thus stalling.
Chips are supposed to help, as is cleaning the ISV, as is adjusting the ISV as well.
I still get some stalls, but recently rebuilt to a 3.8 and thus I'm changing my chip. We will see if it helps the latter issue any.
04-24-2018, 07:28 PM
#43
RL Community Team
Rennlist Member
Rennlist Member
light weight non-dual mass flywheels are widely discussed on this board as a replacement option.
I researched the non-dual mass lightweight flywheel option and found that if you replace the flywheel with a lightweight single mass flywheel be aware that you should expect a good bit of additional noise, per Luk testing data and Rennlist postings. Some who have done this like the concept and throttle feel of the simpler flywheel and feel it is a good tradeoff for a perception of improved performance. Others have found the noise bothersome.
