My saga continues. This sorta follows a thread I had a couple weeks ago about balancing. I found my internal assemby is neutral balanced. I then took my NEW oem dual mass to have it neutral balanced so it would match up. I think I now have a nice paper weight.

The guy seemed to know his stuff, but had never before seen or worked on a dual mass. The stock flywheel has a good sized weight cast onto the engine side. Off the shelf this was no where close to neutral, so he starts drilling holes to basically remove this cast in weight. Well, he struck oil drilling, literally. It appears a couple of the holes entered a cavity between the masses. Then when he spun it some grease appeared in the holes. Now I can't say I really tried to move the two masses to see how it felt before this operation, but now it does not take a lot of effort to move the two masses relative to each other. I looked a little in my service manual. It appears the two masses are on bearings, and I assume the grease I see is for the bearings. I'm not worried that much of the grease came out, and I think it would be possible to fill the holes by welding or inserting a plug to keep more grease from coming out and then rebalance. But I'm concerned about the ease of movement between the masses. But I can't see how the hole would affect this unless the internal cavity was pressurized or something.

Anybody have any experience or knowledge to share here. Is this thing junk? I'm going to be pi$$ed if this guy ruined a brand new flywheel. :mad

 

Jeff you got mail.

Here something else. In the Helms manual they talk about a test for the dual mass flywheel. If you can move the two masses, along the outer edge, more than 1 1/2" (I think it is) replacement is needed.

Here's a dual mass for sale: http://forums.corvetteforum.com/zerothread?id=733890

 

Yeah, I think if I do need a new flywheel, I'll consider a single mass. Although I'd like to know the magnitude of the increased "noise" everyone talks about with lighter single mass flywheels. On the other hand, has anyone noticed any problems with the dual mass in higher power applications.

 

The ZR1 seems to do okay. They have the dual mass. As far as the noise from a single mass aluminum wheel, I helped a friend swap out clutches and he had a Fidanza aluminum wheel and the only noise you get is from idle to about 1500rpm. It sounds like a loose front spline rattling inside a pilot bearing (even though that's not what is happening). Really, you'll be the only one that notices it.

 

Jeff, I feel your pain. I brought a dual mass flywheel to a "good" guy to get it neutrally balanced. He started drilling and on the 4th hole struck oil. While he was a good motor guy, he had no idea what the proper technique was for removing the weight material.
I then got an F-body single mass to use. After the noise bugged me enough I plunked down the money for a new dual mass and with the old broken flywheel in hand went to someone else for them to try balancing it. We came to conclusion that using a mill is a much better wey of removing the material.

I've been using my neutrally balanced dual mass flywheel for over a year and love it.

Hope it works out for you.

-Mike

 

Mike, I'm guessing you trashed your flywheel. What I'm trying to figure out if there is any damage done other than leaking the grease (internal bearing lubricant) out. I'm sure it will all sling out over time. But I don't see why the holes can't be tapped and filled with a plug to keep the grease inside. Then have it rebalanced of course. The flwheel doesn't have excessive lash between the masses. I'm just not sure if it is now easier to move the masses than it was before since I didn't try it. I'm trying to find out if this one can be repaired before tossing it. They aren't cheap.


[Modified by Jeff Hickman, 2:50 PM 1/26/2004]

 

not that it's any consolation to you now, but that guy knows how far he can drill now. (i had the same thing happen to me, but with the original, so it wasn't a brand new part i had just bought. i elected not to use mine.)

fwiw, too, i had the steel camaro flywheel with the stock vette disk, and the noise under load was deafening. i now have the fidanza Al flywheel (Al absorbs more shock/vibration) and a sprung hub disk, and the refinement took a giant leap. it's more than livable this way. as mentioned earlier, just a bit gear clash noise under 1500rpm.

 

Tell that "good guy" he just bought you a new dual mbutt flywheel. It's shot, end of story. I have had a similar deal with a "good engine guy", that couldn't admit he didn't know everything about everything. It was an expen$ive lesson. Don't roll over, let this guy pay to learn. Why PAY to let the turkey learn at your expense? Sorry, raw nerve. :cheers:

 

After reading the Helms Manual a little bit more, I agree, your dual mass is history. Part of the inspection of the flywheel is to check for any leaks and if there is one replace it. I wish I had better news for you on this. How about making a deal with this "good guy" 50-50 on a new wheel? Where on the flywheel did he drill? I've seen them drilled on the outter ends, with the drill pointing to the center of the wheel, perpendicular to the crank shaft.

 

He was drilling into the cast-in counterweight: the bulged up area on the engine side of the flywheel just inside the ring of holes where the "fine-tuning" balancing weights go.

I'm really in a bind with the situation. This was sorta a side job type of deal so I have no company with $$ backing to go after. IE, no guarantees or anything. This sucks. I shoulda just shipped it off to have done, but was trying to save time by not having to ship it out.:banghead:

I read the same thing you did in the manual. It mentions leakage from the seals. So to me that meant if the seals are shot they are not servicable. However, my "leaks" can be fixed by plugging the holes. So then it wouldn't leak anymore. But I don't know how this would affect it's operation. I e-mailed ZF doc; waiting for a reply.