Vibration in shifter

I have a RPM specific vibration that makes the shifter shake/vibrate at 3K RPM with the clutch in or out and the car still or moving. I am using a Spec stage one flywheel, PP and cluth disc. The rep said he would give me a return authorization for them to check the balance of the clutch assembly.
Does it sound like the clutch or are there other possibilities to check prior to dropping the rear of the car?

I had the same problem at 3000 RPM's. I pulled my TT out and found that the previous owner had done a very poor job rebuilding it. THE 4 internal bearings were not spaced out in the tube. I pulled my alum. flywheel and had it balanced anyway. My issue was the TT. Your car could have a miss or a balance problem at the flywheel or pressure plate. The job of getting to that flywheel is a PITA. Good luck

Remote, but check the harmonic balancer as well. Lots of harmonic balancer related issues on LS1tech. Run the engine while looking at the balancer for anything out of the ordinary.

But, I think you may be on to the culprit with the Spec clutch. A guy called Spec after having vibs at 3K rpm and they told him that their clutches are balanced to within a 0.5 grams. The guy took the assembly to a machine shop and they found out that it was off by 11 grams!!! Super vibrations im guessing!

Regardless, I dont want to lead you on preemptively. Its alot of work to get the clutch stuff out again....thats why I mentioned the balancer first.

Heres the thread... http://ls1tech.com/forums/ls1tech-sponsor-feedback/1371087-beware-spec-clutches.html

Arthropraxis wrote:I have a RPM specific vibration that makes the shifter shake/vibrate at 3K RPM with the clutch in or out and the car still or moving. I am using a Spec stage one flywheel, PP and cluth disc. The rep said he would give me a return authorization for them to check the balance of the clutch assembly.
Does it sound like the clutch or are there other possibilities to check prior to dropping the rear of the car?

Sounds like one of my posts, almost word for word!

I don't have it back on the road yet, but in my car I found that the forward-most TT bearing was not contacting the drive shaft, potentially allowing it to wobble all over the place. So I'm in the process of fixing that. I also replaced the FW (with a Spec unit) and got the FW & PP balanced together. And my DS tip was worn and undersized, so potentially it could flop around inside the pilot bearing. I had a properly-sized sleeve made for the DS tip.

And, now that 944-LT1 reminds me of it, my harmonic balancer had been replaced with an undersized crank pulley, so maybe that's part of the problem too...

Anyway, I hope the annoying 3K vibe is gone when I bolt it all back together. Fingers X'd.

Would the torque tube bearings have any effect on this when the car is not moving and the clutch pushed in? I will definately check the harmonic balancer. It could even be a tune issue, the fuel maps have not been reprogrammed yet. Acorad, your problem was more when the car was moving wasn't it?

Anthro, my vibes happened clutch in or out, car in motion or stationary, in gear or out.

So now that I think about it it does sound more like the FW/PP out of balance, since it also happened at rest, in gear, with the clutch in, so the DS/TT bearings weren't turning at all, only the FW/PP was spinning.

Although not having support from that front TT bearing probably didn't help when in motion.

My new, steel, heavy, Spec FW is replacing the lightweight alum McLeod FW. I wonder if the mass of the heavier FW, as long as it's balanced well, helps smooth out drivetrain vibes?

There is no visible wobble in the damper. I did mark the two sides to see if they walk from each other. Is there any chance this is normal harmonic vibration amplified through the poly motor mounts? Yes, I am in denial. I do not want to remove the clutch assembly.

Arthropraxis wrote:There is no visible wobble in the damper. I did mark the two sides to see if they walk from each other. Is there any chance this is normal harmonic vibration amplified through the poly motor mounts? Yes, I am in denial. I do not want to remove the clutch assembly.

Not likely, sorry.

This assembly was said to be balanced from the factory, sounds like the link you posted. Acorad, make sure you get yours checked for balance prior to installation. I am going to get the PCM tuned and scan for codes to see if I have any miss that could cause some of this before I remove the clutch assembly.

Thanks Anthro, I did get the new Spec FW & the PP balanced together. The PP is not Spec, it's a Clutch Masters unit. The speed shop said the assembly was really close as it was, before they added the balancing weights.

Wow, what a nightmare. How many miles did you get on it before the vibration started?

The vibration was there from the start but attention was on everything else running right. It is in such a small window 3K-3100RPM that it can be missed if the car is revved quickly through it or shifted prior to that RPM. Now, I hope it is the clutch and not an internal balance issue.

Have you figured out the issue yet? I have the exact same problem with my ls2

I have not had my clutch kit balanced yet, so not positive that is the issue. It is safe to say the issue is in front of the torque tube in a rotating assembly. That leaves the flywheel/PP, vibration damper or crank. I can't see any deviation in the damper, hopefully, it is the flywheel.

Well I have the same issue, with spec stage 2 clutch flywheel and pp... My TT is a Constantine unit, so I seriously doubt that is my issue. So for me, it seems like it has to be the clutch. Mine goes in on the 15th, so I will update you with my results.

I have a similar problem between 2500 and 3000 RPM, the vibration completely disappears above 3K.

When I first installed the motor it was really bad and I started to look at my PP, Clutch and flywheel, they have not been balanced. Once I started tuning the motor the vibration began to disappear, the vibration is very difficult to feel when the motor is cold but is more pronounced when warm.

I had a discussion going on EFILive (my PCM software) and I was told the vibration could be the motor missing, LSX motors have to be perfectly tuned to perform well. I'm still working on this issue, at this point its very difficult to feel the vibration but I know its still there.

I got the clutch assembly out today. There was a hot spot on the flywheel and PP and my slave cylinder is leaking. There is some fluid on the bottom of it. The fittings going into the slave were clean and dry. Looks like I need another slave, after 200 miles. I am going to get one from GM parts direct PN 89059282 for a C5 Corvette. After doing some reading on LS1tech.com it seems the aftermarket slaves wear quickly.

Where did you get the bad slave cylinder from?

Greg Sloan. I got Sloaned. I was trying to help a new vendor/small business out and got bent over. Who knows where he got it from.

He sure got famous real quick and the SLOAN effect is still hanging around on current vendors as well. A vendor said an email with the info needed would be in the email the following day and then would follow up with a part being sent as it was being finished and on its way shortly, instead I got SLOANED. It sure is frustrating.

Looks like mine may be the fact that my oil pan is resting on the power steering rack... So now we need to figure out if its just a loose motor mount, or maybe a broken motor mount.

@zeusrotty : what oil pan do you have and were did you get it? What motor mount set up are you using? Did you trim the crossmember enough for clearence or where do you think the problem is?

I am looking for an oil pan as I am about to sit the engine in for mock up and practice installing and removing . Information is always good and if certian pan makers aren't quality one I'ld like to stay away and just do it right the first time.

I'm using a modified Moroso oil pan, first and second pictures are without spacers, third pic has 1/4" spacers under the feet of the engine mounts.

Tehone wrote:@zeusrotty : what oil pan do you have and were did you get it? What motor mount set up are you using? Did you trim the crossmember enough for clearence or where do you think the problem is?

I am looking for an oil pan as I am about to sit the engine in for mock up and practice installing and removing . Information is always good and if certian pan makers aren't quality one I'ld like to stay away and just do it right the first time.

I originally bought my car converted. It looks like it is just the stock oil pan that has been modified. I think Erick's pan needs to be added to my list. I will snap some pics tonight to see if anyone has some insight on what I need to do.

https://s245.photobucket.com/albums/gg57/zeusrotty/?action=view&current=743842bc.mp4

As you can see, the oil pan is resting on the rack. Any ideas on why? Should I just shave down the rack a little? Wait till closer to the end of the video to see what I am talking about.