Thanks for at least trying to help me out. I just bought this 99 FRC with an 427 stroker motor. I was told it had a aftermarket clutch in it. I was sent the invoice from the previous owner that has all the motor work done and it says in the invoice that it has a Ram 902100 dual disc clutch. I was also told it has an adjustable clutch master cylinder in it.

OK here is where it get interesting. The guy that I bought it off of said the clutch was changed out and didn't say to what. I see a blue SPEC sticker under the hood. I was having a hard time getting it in gear at mid/high rpm. I did some more searching on the forum here and found Tick performance. I ordered an adj. master and put it in last night. Seems to have helped out quite a bit. The car still moves just a little at 5000+ rpm when the clutch is pushed in. I have the peddle adjusted all the way to the stop so there is no free play. It engages at the top of the peddle.

The car also has a vibration at about 2500-3500 rpm. The shifter vibrates and you can feel it in the car It has the vibration going down the road going through the gears, setting at a stop clutch in, clutch out, it doesn't matter. Its still there at that rpm no matter what.

Wondering what I should look at or check next. Searching I found people with vibration issues while in gear but not out of gear. Any ideas? Worn pilot bearing? Loose flywheel? I am going to call the shop that built the motor Monday and see if they have any ideas also. The motor has approximately 4000 miles on it sense new.

Thanks
Will

 

OK, Talked with previous owner. He said it has a RAM dual disc clutch. I guess it was not switched out. I am going to call the shop that installed it and see what they think and will post back up with the results.

 

Do you get the vibration with the setting still and reving the engine up to the problem rpm range?

 

I get it even if I am setting in the driveway with the clutch in or out.

 

The flywheel and or pressure plate assembly is out of balance. If you continue to operate it this way it will damage the engine if it has not already.
I recommend you start by removing the bell housing inspection cover and see if you see any obvious damage to the clutch.

 

I talked with the shop that did the motor build and install. They are saying from my description that they think its the torque tube bushings.

I have a 99 FRC. Does this mean I have the 10mm bushings on the 57mm torque tube? or possibly the 12mm bushings in the 63mm torque tube?

Thanks
Will

 

Quote:It has the vibration going down the road going through the gears, setting at a stop clutch in, clutch out, it doesn't matter. Its still there at that rpm no matter what.

 

I believe 99s had the 10mm bolts. Based on you description I do not believe the torque tube bushings are the cause of the vibration. Once the clutch pedal is depressed, the drive shaft should stop turning (unless the pressure plate is not disengaging correctly). The flywheel and clutch rotate all of the time when the engine is running.

 

Something else I noticed today was that when I am setting still Clutch out, in neutral, I push in on the clutch and start to put it in first gear and the car moves forward just a little bit while its engaging. Weird.

 

No surprise here. The propshaft would be spinning. It has enough inertia to continue spinning even though you push in the clutch. As soon as you force it into gear the spinning propshaft energy will try and move the car some before the rotation stops.

As far as the imbalance damaging your engine, not likely. It might harm anything attached to the engine like accessories, brackets, coils, injectors, etc..

 

An imbalanced rotating assembly will cause premature main bearing wear along with other cycle fatigue failures. Ever wonder why the manufacturer goes to great lengths to balance the rotating assembly. Go ahead and run it imbalanced, at high speeds and under heavy loads, you will find out, good luck.

 

So if the shaft is still spinning then the clutch is not fully dis engaging correct? I need to adjust the tick master more.

 

Please show your source of this premature main bearing wear and fatigue failure of what components due to imbalance. What quantity of imbalance are you speaking of?

 

The propshaft would have been rotating. How quickly after pushing the clutch in did you try to put it into gear? If more then 30 seconds then yes, you may need to adjust the Tick. But if less then 30 seconds then the shaft may very well have still been spinning causing the car to move.

 

Experience and sound engineering practice, choose your own source, there are literally thousands available. Balancing is an integral part of any manufacturing, service, or repair procedure for rotating assemblies. I can't believe anyone would ever argue such an accepted practice.

The OP will make his own decisions on whether or not he will operate his engine with an imbalance. He should not be mislead as to what the risk are in doing so by opinions.
As far as how much imbalance is too much, if you can feel it, it's too much.

 

Ok, let’s at least keep it on track here, we are talking LS1.

I'm going to make an assumption here that since you are in the Corvette forum that you at least have owned or do own a Corvette. Can you tell when you have your engine running other than by the sound? ALL LS engine have some level of vibration, even yours. The level of vibration capable to do internal damage would destroy the engine mounting system way before harming crankshaft bearings or any of the reciprocating components. Have you ever lugged the engine? The vibrations from the engine can be quite violent but the LS engines keep running without any impending doom.

NONE of my post has EVER been misleading on risk factors. Your comment "If you continue to operate it this way it will damage the engine if it has not already. THIS comment by you is misleading. The engine would be shaking so bad it would be hard to drive before there would be any fear of internal engine damage.

I'll take you up on "choosing your own source" and point out a few engines that were designed with KNOWN imbalance and have no unusual failure rate due to their imbalance design. Have you ever heard of a company called Harley Davidson? I suggest taking an in-depth look at their 45° V-twin. This is not an optimum design that any good engine designer would choose. Any design is faced with compromises and in the case of the Harley Davidson; the original design was compromised so it would fit into the existing motorcycle frame. The vibration level was put second to fitting the engine. You may also want the check out Ward’s 10 Best Engines of the 20th century, namely the 3800 90° GM V6 engine. This engine, rated as one of the best had a imbalance design.

Let me be very clear here. If your LS series engine is shaking you need to investigate why. I am not suggesting that it is OK to ignore vibrations that seem to be over the norm. If an engine vibration due to an imbalance issue is discovered, for example after a clutch change, chances are it has something to do with the clutch or flywheel. The level of this vibration would have to be very extreme before harm to the crankshaft bearings or reciprocating components. For a comparison, one might think the engine would come out of the vehicle due to the shaking well before damage to the internal engine components would occur.

 

Well, what-ever the vibration issue is, I am going to just put some parts together and replace everything at once. Clutch, slave, remote bleeder, resurface flywheel, torque tube bushings, and maybe upgrade to the 63mm torque tube all at the same time. That should take care of the vibration issue.

Will

 

When my TT bushings were going it felt like I was running over rumble strips under moderate acceleration. Didn't feel it on light or heavy acceleration.

 

Will,

After rereading your first post it sound like your clutch might not be fully disengaging. You may already know this, but most likely the clutch disengagement issue is separate from the vibration issue. I also do not believe that the imbalance you are feeling has anything to do with the propshaft. If you can still feel the vibration with the trans in first gear setting still with the clutch in, the propshaft would not be rotating. That would indicate that the vibration would have to be from something else like the engine, flywheel, clutch assembly or a combination of each. Has the car always had this vibration since you've owned it, or is it something new?

It sound like you have a good plan going with getting all the items together to do in one shot. Keep us posted.

 

I seem to get sucked into the pointless diatribes with you for no reason other than the entertainment value.

LS engines, like most modern V-8s are in the "not supposed to shake and vibrate" category.