Excessive vibration from lightweight flywheel?

I am experiencing a small vibration at approximately 1900 rpm that goes away at 2k rpm but comes back with a vengeance at 3500 rpm and goes until pretty much redline. It has this vibration in any gear and is dependant on rpm and load. (It gets slightly worse with a load on it.)

I ordered a Spec Stage II+ clutch upgrade with the G60 Eurospec flywheel (supposed to be 14 lbs) to replace my stock clutch and DMF, received it, and had it installed by a very trusted TDI guru. Problem is, I didn't actually make sure I got the correct flywheel when it came in the mail. It turns out that instead of the 14 lb flywheel, I was sent the ultra-light-weight flywheel (I think 8 lb). Unfortunately I did not discover this until it was installed and mentioned this vibration to the guru. The guru drove my car when it had over 500 "nice" miles on the clutch and said that his upgraded Jetta had the same vibrations, just not nearly as pronounced. (He has a stock weight G60).

I really wasn't too worried about the extra vibrations from a SMF but this seems pretty severe compared to what I was expecting.

My question is, should I worry about it? I read up on it and general consensus was that a light-weight FW won't hurt anything, but no one mentioned the kind of vibrations that I am experiencing, or, for that matter, I don't think I saw ANYONE with an ultra-light-weight SMF on a PD. I can easily get used to it, but I just don't want to ruin anything...

I should also mention that the passenger drive axle was replaced at the same time, could that possibly be a contributing factor?

This is on a 2005 Jetta with RC Stage 1.
Thanks

Well... ive helped someone install an 14pound flywheel and vr6 clutch in his golf tdi and it has some viberation at idle but none throughout the rpm range while driving... it almost sounds like your flywheel could be unbalanced... the more true the flywheel is in centrifical balance is what i was told helps with the viberation at idle but... ive not seen it beyond that...im personally installing an g60/vr6 flywheel setup in my PD in a few weeks before i get RC3 tuning and ill see what i have.. but im running stock weight.. i got them from junk yard and had the machine shop resurface and rebalance them... be amazed how bad they can get one of the flywheels i had they had to take almost half a pound off on one side for it to rotate balanced.

What year is your car. I got little vibration on my 04/golfTDI on hwy speeds.

MY vibrations are in the steering, it comes & goes . The car has been to VW dealers about 8 times & they saw the vibration on the steering wheel.

I made sure I sat right be side the mechanic in passenger seat so he could witness this annoying vibration.

Brought it back to the shop they checked the whole car & everything is perfect.

My Rotors , motor mounts , shocks, struts, axle, drive shaft, wheel bearing balancing of tires are all in line according too Vw. They wanted to charge me for an aliment but couldn't guarantee me the vibration being gone.

I still have my stock clutch & tried different new set of tires rims but still the annoying vibration. They even drove the car in mid air on the hoist to see if anything is bent but Vw say its perfect everything.

You say you replaced the passenger axle , I would bring it back to whoever installed it to double check that because I don't really see how the fly wheel could cause the vibration.

Maybe I'm wrong, but is your car still under warranty because I notice these Goofy dealer want to shy away from the warranty work & rather wait till your warranty is over .

Let me know if the vibration is on your steering wheel.This could maybe solve my problem that Vw dealer say the vibration is A mystery & cant figure out .

You also stated the vibration gets worse with load..... ummmm & you said you changed the axle makes me wander that s probably your problem right there maybe.

Let me know PoochiePD

Yes I realized its A 05/PD

Yep an '05. It has about 86000 miles on the odo and has had RC for about 60k of those miles. The guru (I don't know if he cares if I use his name, I don't see why I shouldn't, but meh) and I changed out the axle because we discovered the old one was worn when it was all apart for the clutch job. He said it was possible that the new drive axle was not perfectly balanced and could be causing the vibration or be producing some sort of resonance.

Since the vibration is present in EVERY gear at certain RPM's and simply is more noticable under load it would make more sense to me that it's more of a pre-transmission thing. I figured I would get some opinions from other club members before swapping out the axle again.

Also, I DO feel the vibration through the steering wheel, but then again it is so high speed that it actually shakes the whole car. Not quite a "shake the car apart" vibration, but definitely noticable.

The fly wheel wont shake the steering wheel in my opinion. The axle will.

Not directly but possibly: flywheel causes engine to shake, which causes tranny to shake, vibration gets transferred through axle, then hub assembly and steering linkage back up to steering wheel...

or...

engine shakes, goes through mounts to frame, from frame to body (including firewall), from firewall to steering column mounts to steering wheel.

I might have made the steering wheel shake seem like more than it really is. I'll stick with calling it more of a "heavy resonance". It's easier to feel it through the floorboards and seat than it is through the steering wheel.

There are certain engine speeds that many aircraft engines aren't supposed to stay in, just for the reason of devestating vibrations.

Since you have a much lower weight flywheel now I would bet you are causing the vibrations to be exagerated or brought into a lower rpm range that woundn't have been felt with a heavier flywheel. The dual mass was there to absorb an aweful lot of shake, rattle and roll I think option number 1 form your above supposition is the more correct path since people tend to hear gear rattle with even the stock weight G60.

This might be worth a read, has an intersting bit on a german sprots car and lighter flywheel. http://www.eng-tips.com/viewthread.cfm?qid=175442&page=8

Are you running any type of poly dog bone mount. That combined with single mass flywheel cause a lot of vibration in my golf.

I didn't even think of that...

I did stiffen the dog bone slightly by removing about 1/4 inch of the metal from the inside column (can't think of the term) which compressed the stock rubber more when I tightened it down. It made a noticable difference in transmitted vibrations but I have since gotten used to it.

I'm sure that's a contributing factor...how light is the flywheel in your Golf? Does it vibrate at higher RPM's at all?

If you still have the stock rubber inserts I doubt that is causing it. The poly inserts vibrate alot with a single mass flywheel.

I was running a 12lb. I had no vibration once I put the stock rubber mount back on.

I worked on the car.

I'm going to swap out the axel again to see if and rule out that as the issue. This is a serious deep rumble. it's definetly engine related. It's not the typical bad axel vibration you feel in the steering. It's down deep in the car. I've never really seen anything like it either.

I was a bit worried about the flywheel when I installed it since it was so light. But, since the box was open I assumed he looked at it and it wa ok with him. I run the 14lb version and while it has some similar vibes it is nowhere near this one.

way to step up and admit you did the work...

I don't know if you were being sarcastic or not but...

JasonTDI is my number one trusted source on TDI's. There is no doubt in my mind that the work he does is top-notch and the problems I am having are in no way his fault.

The only reason I didn't mention his name before was a question of etiquette. If I am having problems that I don't feel are the fault of the mechanic, should I even bother to mention the name? I decided not to simply because people might see the problem, see the mechanic's name, and unfairly associate the two.

you mod you accept the consequences of muddeling with the design. flywheels are desisgned to smooth out combustion pulses and absorb the varring fources of the engine power output and smooth it out so that it doesn't destroy the trans gears clutch or shake he driver out of the car. this is why they are heavy.

PoochiePD said:

I don't know if you were being sarcastic or not but...

JasonTDI is my number one trusted source on TDI's. There is no doubt in my mind that the work he does is top-notch and the problems I am having are in no way his fault.

The only reason I didn't mention his name before was a question of etiquette. If I am having problems that I don't feel are the fault of the mechanic, should I even bother to mention the name? I decided not to simply because people might see the problem, see the mechanic's name, and unfairly associate the two.

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no sarcasm at all, I was actually commending him on stepping up.

I am just a lurker here I have been wrenching on my own oil burners for a long time and when I found this forum I have taken the liberty to read just about everything and its pretty clear who the people that know what they are doing happen to be.

the fact is that no matter what the make or model when you start bolting togather combinations that have never been tried before you can end up with strange things like this vibe you are trying to hunt down. being that Jason just installed(and I would guess correctly)the parts you selected and provided the result is most likely something neither he or you could have predicted.

The fact that he stepped up and put it out there that he did the work says alot about him and the service he does for the TDI community.

its a bummer that you have the vibe...whats worse is that the flywheel will in all likelyhood need to come out to get rid of it...IMHO. Flywheels dampen the single shock load as each cylinder fires. the heavier the flywheel the less perceptable each individual ignition becomes, hence the lighter the flywheel the more so. the higher reving the engine is in its powerband, the more cylinders the engine has and the better the rotating mass is balenced the less weight is needed in the flywheel...I guess you happen to have found the limits for your application.

I do hope you get it squared away.

Thom

buckweat diesel said:

my 2 cents a 14 pound flywheel or even 8 pound is too light for a diesel that is a daily driver in my opinion (did u have the flywheel clutch preshure plate balanced? that will cause a big vibration if it was not done)

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I have installed alot of clutches and never had one balanced and never had any issues. I would say well over 100 clutches.

Thank you for all of your responses.

Assuming the upcoming axle swap does nothing, I will replace the flywheel I have now with a standard weight G60.

...and the site I ordered my clutch/flywheel combo from BETTER take the flywheel back and reimburse me, since they're the ones that sent me the wrong one in the first place. True, maybe I should have double-checked the parts closer...but they screwed up first.

The axel did not do the job. Clearly not the problem. He has a stock eurospec single mass coming and we will try that when he gets back in 2 weeks. I've done plenty of 14lb ones in cars with no issues, just not in a stage2+ RC-PD car. Also the clutch itself was one of SPEC clutches starge 2+ 430 ft lb jobs with the 4 arms and the ceramic pucks for contact to the PP and flywheel.

The company that sold him the parts is under the assumption that I bent it on install. If that were the case you'd feel it everytime you pressed the pedal in and the car would shake constantly. Clearly some sales guy with his head in his bottom.

I just had another custom get a 7lb one sold to him from autotech. I made him call them for return shippment.

New update.

Problem solved.

We finally got together on a date that worked for both of us and tore it apart and installed the new stock weight single mass eurospec (20 lbs or so) Problem solved.

From this I HIGHLY suggest not using a light flywheel in the PD cars.

If I had a nickel for everytime I told someone this over the years I'd be rich.

Don't use lightened flywheels on Diesels. Two problems, first is the obvious harmonic vibrations, and 2nd is the overshoot between shifts. There are accel and decel maps that need reworked for this. You can try an experiment by recoding your 5spd car to auto maps 00001 (torque converter is heaver). It will overshoot between gears. Kind of like too much rpm hangtime. It's very cool to flatline the decel map - the motor drops rpms like a semi with jakebrake.

good work jason!

I dont have any vibration from my 12lb flywheel. But its noisy as hell. I will be changing soon.

Thanks Jeff!

We should try that with mine and the 14lb one I have! I need to up the boost again on mine.....

They aren't that loud actualy. For a VE car theyaren't too bad but NEVER for a PD.

IMO you lose a bit of smoothness going from a DMF to a single mass flywheel. If you lighten the flywheel you lose more. I've been in a number of ALH cars with lighter flywheels (usually 14 lb) and they do transmit more engine pulses than the stock flywheel. And my Golf with the DMF is noticeably smoother than my wagon with the G60/VR6, even at stock weight.

You want to reduce rotating mass? Buy lighter wheels. But leave the flywheel alone.