Flywheel Balancing 1992 ZR1

[jerrydirks]

I have recently discovered that there are no weights in the flywheel and there is noticable vibration above 5000 rpms. I have the flywheel out of the car, were the weights meant for balancing only the flywheel or was the balancing performed for the flywheel and engine combined?

Would having the flywheel/clutch balanced alone be sufficient?

Has anyone had there engine and flywheel balanced in the car?

Any help is greatly appreciated!!!!!!

Jerry Dirks
1992 DRM 600 Minnesota

[WVZR-1]

Is it the same flywheel that you've had in the car and driven previously? Is your clutch "new"? Is the vibration "new" or you've not driven the car previously? I'll be interested in responses!

I'd be interested in how you accomplished the repair/rebuild/weld or whatever of your transmission case? I hadn't seen you get back to that thread.

[jerrydirks]

I am still sorting out the transmission repair. The flywheel was in it since the DRM mods....I think they did not transfer the weights. Clutch is stock. The vib was present before the broken trans.

Since I have the driveline in pieces I thought I would try to remove the vibration that has been present since I bought car last fall.

Thanks for follow up.

[Paul Workman]

I am still sorting out the transmission repair. The flywheel was in it since the DRM mods....I think they did not transfer the weights. Clutch is stock. The vib was present before the broken trans.

Since I have the driveline in pieces I thought I would try to remove the vibration that has been present since I bought car last fall.

Thanks for follow up.

One other item comes to mind, and that is the drive shaft balance. Were the U joints recently changed? I know how difficult it can be to keep those little "needle bearings" in place while installing new U joints; installing them is an art. ;) The FSM goes into some detail, but a drive line company could take your drive shaft and trans yoke and check the balance/rebalance as necessary. That would eliminate that part.

As for balancing the flywheel, it sounds like that too would be something you might want to send to a machine shop and have checked out.

Bottom line: BTDT and balancing that stuff made a huge difference on another project of mine (many moonz ago). From my experience, it is "SOP" to have the FW and pressure plate balanced together whenever a new clutch is installed. The trick is finding a place that can do the work.

Good luck. Let us know what ya come up with!

P.

[jerrydirks]

The flywheel and clutch that were in the care b4 the trans breakage were in it for 12 years, 14k miles. The drive shaft is new but the vibration followed engine speed in each gear.

Does anyone know if balancincing the rotating mass, flywheel, clutch, how GM approached the balance issue or should the balance be performed while on the engine crankshaft?

Thanks!
Jerry

[WVZR-1]

I was curious if the "original" DRM 600 package that I thought was a 368" and included a crankshaft might have the assembly balanced and there likely wouldn't have been weights? Don't know!
I couldn't imagine that critical an "operation" would have been "overlooked"! The balance of the driveshaft is an inexpensive "to do"!
I'd maybe check with DRM on the original build! If doing a new clutch I think most would agree, check the balance. Clutch assembly quality isn't exactly what it used to be! Confirm your "new" clutch is correct also, there's been some mispackaged goods around and assembly problems posted here and also on the other forums! Check the P/P with a machinists straight edge! I'd check the spring "color" if they're colored, if they're not all the same color it's a quick cause for concern!

* I believe the current DRM 600 is a "402"!

[jerrydirks]

This DRM was performed in 1996, dyno at 589 and 500tq is 385 CI. The inbalance was with the original clutch assy and flywheel. Driveshaft was new replaced before trans cracked. I believe that the vibration hastened the trans breakage.

Jerry

Does anyone know the purpose of the urethane that is applied to the trans and diff connections to the c channel???

[Jerry#397]

Jerry,

Don't know the details of the vibration you posted on but I will tell you that I had a vibration for a couple of years that I could not locate. Took the car to a restoration shop for a steering wheel pin replacement and while there had them check for the mystery vibration. Turns out that it was the Harmonic Balancer (believe GM calls it a Torque Dampener). Really a PITA to check it out with a mirror, etc. and to change it is another PITA. The "Dampener" also has balancing weights (pins) that must be replaced in the same slots on the new part.

It's worth checking, could be part of the problem.

Thanks,
Jerry

[Zr1 Destroyer]

Does anyone know if balancincing the rotating mass, flywheel, clutch, how GM approached the balance issue or should the balance be performed while on the engine crankshaft?

Thanks!
JerryNo...the lt5 is internally balanced meaning the crank/rods/piston were balanced and the balancer and flywheel were not used for the lt5 balancing. The only way the balancer could become out of balance if it was hit or the motor was removed maybe after rippie originally and the balancer slammed into the cross member...so I doubt the crank balancer is out.

If the pilot bearing went out or was damaged in the rear of the crank and car was driven for a while like that you will get a vibration since the front of the tranny shaft sits in it! I did my clutch in my first 90 zr1 and messed the pilot bearing up and it vibrated bad until I removed the tranny again to put a new pilot bearing in the end of the crank and the vibration was totally gone afterwards!

[Polo-1]

Yes, It's internally balanced. But it's also dynamic balanced with pins in the front dampener and the flywheel.
Part#10174322 for the front no longer available.....

Call Jeff I think he is working on replacements

[Jeffvette]

Yes, harmonic balancer pins are no longer available. I'll be weighing the ones I got coming in and will get sizing done. This will be a interesting write up for the registry newsletter dealing with the harmonic balancer.

[rkreigh]

check the balance on the flywheel and clutch assembly

the "tuning pins" for the balancer and flywheel for the dynamic balance should be transferred fromt the old flywheel to the same positions on the new one. but since that can't be done, the only way to do it again is having the rotating assembly balanced which really isn't feasible (or cheap) because you need the crank out of the engine.

the "goo" on the beam is an isolater under the c beam bolts

I believe it's purpose is to better secure the bolts and keep them from "digging in" to the soft alum

the bill boudreau beam plates do a much better job at that and stiffen the drive train.

on the balance problem, since the engine "should be" internally balanced I don't think you should be noticing a big difference with a new flywheel as the tuning pins really just are "fine tuning" the balance to achieve the legendary smoothness.

hopefully it's something else like the driveshaft!

[Jeffvette]

I have recently discovered that there are no weights in the flywheel and there is noticable vibration above 5000 rpms.

Jerry, Ron, brigns up a good question of the driveshaft.

Do you still get the vibration when sitting in neutral and revving the motor up?

[Jagdpanzer]

Does anyone know the purpose of the urethane that is applied to the trans and diff connections to the c channel???

The "goo" is applied to reduce the potential for "crevice corrosion" that can develop in the joint area where the aluminum C beam bolts to the aluminum transmission and differential housings. Because if it's galvanic nature aluminum is especially subject to this kind of corrosion. Its purpose is to keep moisture and road salt out and provide some level of dielectric isolation between the aluminum components and steel bolts. Otherwise this contact area could experience severe corrosion and pitting after a few years especially if the car is driven much in the rain or snow where road salt is used. However, most of us don't drive our Zs that much or if at all in such conditions so not using goo is not a big risk. I work in the marine industry and see this kind of corrosion problem quite frequently in ocean going ships and structures in sea water.

[USAFPILOT]

I have a vibration that comes on strong above 5K and really strong by 7K in neutral and while in gear. It is not the drive shaft. My car has 50K on it and has not had a new clutch, and has not been opened up to the best of my knowledge. Could my harmonic balance or flywheel just get out of whack on its own?

[rhipsher]

There is a technique to doing the half shafts. You have to take one of the caps completely off to get them into place. But there's a little more to it than that. I'm getting ready to do my half shafts in the coming week. Maybe I'll do a "TAH DAH" how to for it.:mrgreen: