Vibration Damper and L/W Flywheel (993)
02-23-2006 | 01:34 AM
#1
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Instructor
Joined: Jun 2001
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From: Africa
Vibration Damper and L/W Flywheel (993)
We are having an interesting discussion with a customer and I need a little input.
His 993RS is fitted with the non-damper l/w single crank pulley. Before he took delivery the engine was rebuild by Porsche and a l/w flywheel setup (non DMF) was fitted.
The question now is - should one fit a vibration damper pulley on the front of the crank to compensate for the new l/w flywheel setup?
We have several 964/993 engines running the Clubsport type l/w flywheel, and sofar have had no problems.
Would there be a difference btw a road and a pure track setup? i.e. use vibration dampers only for a road engine?
Regards
Tom
His 993RS is fitted with the non-damper l/w single crank pulley. Before he took delivery the engine was rebuild by Porsche and a l/w flywheel setup (non DMF) was fitted.
The question now is - should one fit a vibration damper pulley on the front of the crank to compensate for the new l/w flywheel setup?
We have several 964/993 engines running the Clubsport type l/w flywheel, and sofar have had no problems.
Would there be a difference btw a road and a pure track setup? i.e. use vibration dampers only for a road engine?
Regards
Tom
02-23-2006 | 12:45 PM
#2
Burning Brakes
Joined: Jul 2004
Posts: 1,100
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From: Land of Milfs and honey (SoCal)
The harmonics of running a motor without dampners and a lightweight flywheel can destroy the crank, rod bearings and even snap a crank. I have seen this on VW motors when kids buy and bolt on a $130 light weight pulley set on a cast crank. I have never encountered these problems on a car with a lightened flywheel, I never recommend light weight crank pulleys on a street car.
A race car that will have its engine rebuilt frequently is another story.
However, porsche motors have 1 rod journal sandwiched between a main, with a forged crank and are extremely strong, and if the motor has been balanced properly, I dont think It would hurt anything.
A race car that will have its engine rebuilt frequently is another story.
However, porsche motors have 1 rod journal sandwiched between a main, with a forged crank and are extremely strong, and if the motor has been balanced properly, I dont think It would hurt anything.
02-23-2006 | 05:53 PM
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The only 993 that uses a crankshaft damper is the 993 CUP, I suspect that they used the damper as an expediant due to the early date of their manufacture not out of necessity.
The 964s did need a damper because of their less robust cranks, a very few of the 964RS cars do run w/o them( 2 oy of ~20 that I have seen and spoken w/ the owner) and the only downside I have heard of is increased NVH
The dual mass fly wheel was a refinement of the earlier rubber center clutch, the goal of both was to reduce gear rattling at idle. Never had either in any of my cars and can't say that it was ever an issue. The dual mass is a heaver m/f
The 964s did need a damper because of their less robust cranks, a very few of the 964RS cars do run w/o them( 2 oy of ~20 that I have seen and spoken w/ the owner) and the only downside I have heard of is increased NVH
The dual mass fly wheel was a refinement of the earlier rubber center clutch, the goal of both was to reduce gear rattling at idle. Never had either in any of my cars and can't say that it was ever an issue. The dual mass is a heaver m/f
02-24-2006 | 12:39 AM
#4
Burning Brakes
Joined: Jul 2004
Posts: 1,100
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From: Land of Milfs and honey (SoCal)
I think the DMF is around thirty pounds, where a lightened one is around 10-12. that damn DMF is expensive, rattles in the 964's and turns on a CEL for misfires in a 993, so I tell most people to put a light weight one in as a replacement and save the cash
The one in my GTI is 7 lbs.............that with the big cam and the fat chip means tempermental running at idle when its REALLY cold out on first start up.
The one in my GTI is 7 lbs.............that with the big cam and the fat chip means tempermental running at idle when its REALLY cold out on first start up.
