SAchris

iTrader: (2)

I just installed a Monster stage 3 in the z28 with a new flywheel and slave cylinder. I bought ARP flywheel and pressure plate bolts. I put in a new pilot bearing and replaced u-joints and the transmission mount while I was at it. I used the energy suspension tranny mount that everyone suggested without the extra metal plate they give you.

Now I have a vibration that is RPM related. I start getting a vibration around 2500rpm and it vibrates to about 4500rpm then starts smoothing out. Right around 3000rpm is the worst, and it's pretty bad. Its definitely drive train related because I can do 80 in 6th gear and it's smooth because i'm only turning about 1800rpm.

When installing the clutch I was very careful with torque specs with the flywheel and pressure plate. I torqued the flywheel bolts starting at 30lbs per bolt in a criss cross pattern going up at 10lb increments to 75lbs. I did the same thing with the pressure plate up to 52lbs. I cleaned the flywheel and pressure plate real good with brake cleaner and installed the whole thing with latex gloves. Probably overkill, but I have a hard time not getting stuff dirty so I was extra careful. I kept the clutch disk in plastic until I actually put it in.

So where should i start looking?

Thanks in advance,
Chris

LilJayV10

iTrader: (39)

Do you have a stock trans mount you could put on there to eliminate the poly mount being the problem?

TB22

iTrader: (2)

I had the same issue after installing the Poly Trans Mount. The cd player would skip, the virbration was so bad. I ended up spending the $90.00 and putting the GM rubber mount back in and no more vibration!

SAchris

iTrader: (2)

It vibrates when I rev the engine in neutral and/or with the clutch disengaged. I don't see how this could be the tranny mount? That is an easy thing to check though if you guys still think that is what it is.

Chris

99french

iTrader: (7)

bump since i have the same issue but have to wait another couple weeks till i can tear it apart and figure it out

SNLPerformance

iTrader: (15)

If you install stiffer mounts into a car you will run into more NVH (noise vibration harshness). You will notice noises, etc. being transferred throughout the chassis.

If you have a question about our product call us at the shop - 817-750-2000, this will get you the correct answer immediately without having to wait for someone to post.

SAchris

iTrader: (2)

Thank you, but the clutch is the last thing I'm worried about. I was super careful installing it and I'm not at all concerned that the Monster is my issue. My z28 has 192k miles on it, so the list of things that aren't worn out is much smaller than the list of things that are. I used to drive a '90 Cummins diesel, so i'm not new to vibrations, but this is pretty bad for a car... even with a ceramic clutch. I don't want to bother you guys with things not related to your product.

I'm fine with NVH, as you call it, as long as i'm not going to permanently damage anything... i.e. the brand new monster clutch i just installed. It does seem like I should be able to fix this problem though...

The two things at the top of my list off the top of my heads were pilot bearing and motor mounts. I'm leaning towards ruling out the pilot bearing because when I pulled the old clutch out, the pilot bearing fell out in about 100 pieces. If it didn't vibrate that bad when the pilot bearing was basically non-existent, I don't think it would vibrate this bad with a damaged one. Even with a stiffer mount I don't think it would be this bad.

That leaves the motor mounts, which in all likelihood have 192k miles on them. I moved the engine all over the place getting the tranny in and out since I did this whole thing by myself. I wouldn't be surprised at all if I destroyed one or both of my mounts. I wanted to do motor mounts while I was doing all this anyways, but no one locally has motor mounts or can even get them. Because of that, I decided to wait. I'm going to do motor mounts unless some one has a better suggestion since I was planning on doing them anyways.

Which leads me to another question... Where is the best place to get motor mounts and which ones would you guys recommend?

I'll put them in then update this thread. Please keep any suggestions coming!

Thanks guys,
Chris

SAchris

iTrader: (2)

Also, just to be clear. Are you suggesting I ditch this mount and get a softer one, that I learn to live with nvh, or are you just playing devils advocate? lol...

Chris

99french

iTrader: (7)

i tried swapping back to a rubber trans mount and its stilll there just not as noticable. i am using the preload plate with my mount though and i just swapped it back in today and took teh rubber oen back to the parts store. i am going to cal SNL on monday and run some ideas past them. they are always really friendly and helpful

SAchris

iTrader: (2)

Cool, keep me updated on how it turns out.

I talked to a tranny guy today and he's convinced that my engine just has a vibration that I didn't notice with the old mount. Pretty much what SNL said. He said he didn't think engine mounts would do me much good. He said he would guess its either the harmonic balancer or the flywheel. Probably not the flywheel since it's a brand new Monster flywheel.

Chris

SAchris

iTrader: (2)

Could a misfire cause this by putting the engine out of balance? I get a few backfires when it's cold and it has a little hesitation when idling every once in a while. Will a misfire throw a code? The check engine light isn't on, but I haven't gotten it scanned.

Chris

99french

iTrader: (7)

i have tried plugs before and it worked one time. but no luck this time. might try a harmonic balancer before ripping my trans out seeing as how i still have the stock one from the factory.

dgcustomz

iTrader: (128)

What condition was your input shaft in? 99% of the times when I pull a trans with a grenaded pilot bearing the input shaft is destroyed. If your input shaft was damaged its probably tearing apart your new pilot bearing.

SAchris

iTrader: (2)

I thought about that, and checked it out. It seemed fine unless it was bent (which I doubt). There were no scores on the smooth part that goes into the pilot bearing or the splines. I cleaned it off real good to make sure.

Even if it did tear the new pilot bearing apart, I don't think it would cause this vibration.

I think I'm going to call SNL tomorrow and ask them a few questions about the pressure plate install. I want to find out if there is any way I could have installed the pressure plate onto the flywheel in a way that would cause it to be off balance but still work properly. The clutch functions exactly as it should. If I can rule out the clutch, then I'm going to move to the engine.

Chris

LilJayV10

iTrader: (39)

Also check the front bearing in the trans. I have seen if that bearing goes out or starts to go out it will make the input shaft walk around and will take out the pilot bearing.

SAchris

iTrader: (2)

When/if I have to pull the tranny back out, I will check that. I'm not too familiar with these trannys, is that something I could do without tearing down the whole thing?

I called SNL today and talked to one of their guys, Chris. He told me that the pressure plate can be clocked anywhere on the flywheel and not cause a vibration, so that rules out one of the possibilities in my head. I also ordered poly motor mount inserts and a poly mount for the stabilizer bar bracket on the back of the trans. I'm going to put those in and see if that helps at all. I still think I could have broken a motor mount while stabbing the tranny.

I also hooked up the z28 to a scan tool today to see if it was throwing any codes. I have been concerned that the last owner might have disabled the check engine light and it was throwing codes, but nothing came up on the scan tool. One more thing crossed off my list.

Chris at SNL said the only other thing he could think of is that possibly the pressure plate or something got damaged during shipping and is out of balance. He said if all else fails to pull the pressure plate off and send it back to them to get tested. I really hope I don't have to do that, but at least it's an option.

This is getting really frustrating.

Chris

SAchris

iTrader: (2)

Ok, so now i'm more confused than ever. I am sitting in my garage right now with the transmission out and next to me. All that is on the car right now is the Monster flywheel, pressure plate, and clutch disc. There is no vibration what so ever. The pilot bearing looks brand new and is in no way damaged. The input on the tranny looks fine, no splines are damaged and the smooth tip is smooth. There is a very small amount of play in the input on the transmission, but its barely noticeable when I move it around with my hand.

So am I just being super **** about this whole thing? Is there something else that I could be missing, or should I just put it back together and drive it? Like I said before, I'm not worried about the vibration I just want to make sure I'm not going to destroy a crank bearing or my rear main seal. Since the flywheel and pressure plate are all balanced, I shouldn't run the risk of damaging those should I?

Thanks guys,

Chris

BALLSS

Chris

first, you are not the only one to have to pull everything apart chasing some wtf issue and yes it is frustrateing.

Initially I thought you need to 180 the DS since you replaced U joints. When you said it vibrates in neutral and reved that took it out of the equation.

A harder tranny mount can certainly transfer more vibes as you found out after putting back in a rubber OEM type. IMHO the better direction.

The exploded pilot bearing "often" means the tranny input shaft is bent or the front bearing is wearing so the pilot bearing dies.

"Grounding" meaning something like drive train hitting exhaust or frame can be going on. Really check to see if anything is hitting

The FW??? I assume you have a stock replacement which is balanced as stock and not neutral. That would typically vibrate at all RPM's though.

Since this happened after a clutch install I would look at those componets. As frustrateing as that might be maybe you should take Monster up on their offer and return it for them to check out. I don't run their clutch but hear they have a good product. At least that would rule out the clutch.

Since the tranny is out take it to a known tranny shop and ask them their opinion on input shaft & bearing.

basically you need to back track your steps. The ride should be vibe free at any RPM's

You may hit that "ah ha" moment on something like grounding or find confirmation in your clutch and or tranny

Motor mounts are also something to consider. I run the black energy suspension ones, not red.

LilJayV10

iTrader: (39)

I know this is old. Did you ever figure anything out?

99french

iTrader: (7)

i did find a solution to mine if he didn't. a combination between my harmonic balancer that had **** the bed and it smoothed out some but not completely, so i found my factory trans mount and slipped that baby in and WHAMMO back o being silky smooth.