Engine Vibration when Clutch is dis-engaged

Have a Butler 461 balanced Rotating assembly installed in a 67 400 block. I used a new PRW flywheel, new Clutch assembly on a M20 Muncie. I had this trans on a 350 Pontiac before the 400 change over and never had this vibration. I did re-use the original 1968 harmonic balancer, which looks good. When driving with the clutch engaged I feel no vibration, when I push the clutch in I feel vibration. It doesn't matter if I'm in gear or not, or what speed I'm going.  Any suggestions?
Thanks  

So, you don't have the vibration with the engine running and the trans in Neutral.  The first thing that comes to mind is dirty mating surfaces.  Next a bad clutch plate and or a throughout bearing. I think it would be a good idea to pull the clutch and inspect.  If you don't find any physical damage make absolutely sure everything is meticulously clean before you reassemble.  Also, inspect the rear seal for leaks before you put it back together.

If you need to put in new parts go for the best you can afford.

When you first noticed the problem what kind of driving were you doing. Do you drive it in where it could get sand or mud in it - is the cover in place?  Is there anymore you can add to the description of the problem.

I wish I had a magic answer but there are a number of thing that can cause the condition. I think a visual inspection is the place to start.

Milt  

there is a good chance that old harmonic balancer needs replacing, but I don't think that's the big issue here..
It sounds as if there is a problem with the throwout arm/bearing and how it engages w/pressure plate. There are specific dimensions for the height of the mounting stud in the bell housing. Too far down and the clutch may not disengage completely, too far up and you might be pressing the diaphragm fingers in to far. If the throwout bearing isn't on the arm in the right position, you could possibly be off set in the contact pattern with the fingers.  
Jim,

1968fb

It would help to know the following. Is your clutch cover a diaphragm or 3 finger style? What brand is it, mcleod, hayes, centerforce or zoom etc? What brand and type is your disk, organic, glass, carbon fiber. Just the make and p/n is enough.

What exactly do you mean by vibration? What I think you mean is that if you depress the clutch the clutch pedal pulses biut the engine does not actually vibrate. Is this correct? If not please explain the problem in more detail. If you just lightly depress the clutch pedal until it barely touches the cover fingers or blades etc does it pulsate [vibrate]?

If you determine that the problem is actually in your pedal as I described then you most likely have one of two problems.

If you have a diaphragm cover than the problem is most likely the flywheel. It is not surfaced square. Happens sometimes. Debris gets under the flywheel from poor cleaning of the table surface and though the newly machined surface is flat it is not square to the opposite side. This will always cause a vibration that increases with engine rpm though irrespective of whether the clutch pedal is depressed or not.

Without the above info I can only make an educated guess. I have encountered and repaired similar problems many times.

If you have a diaphragm cover with the above described condition then the problem is in the finger height. I have encountered this problem on about 30% of all new covers irregardless of mfg. you can check this by doing one of two things. Take the cover to a competent clutch rebuilder and have the finger height checked or get some type of depth gauge and check the finger height with the disc and cover installed. Check the height from the highest point of the finger to the disc. The fingers must not vary more than .015 between all three. In other words, if the tallest is 2.015” for example and the lowest is 2.000 than that is the maximum difference they can be out. I set mine up to within .005. Sorry this may sound a little confusing.

If they are out you can either get some shims from the company of mfg or from the clutch rebuilder and do it yourself however it is obviously much easier to have the rebuilder do it but make him show you that it is correct. The mfg can also do it for you but this takes time and shipping expense and since they didn’t do it right in the first place...  

It could be just a bad throw-out bearing????

Bob  

1968fb

Pepsi1is absolutely right. I was basing my opinion on the assumption that you replaced it along with the rest of the clutch assy however if your pedal "pulses" and makes no grinding noise than it is back to the things i mentioned. Even if you do find the bearing to be bad and your pedal was still "pulsing than you still have the additional problem of the clutch cover or pressure plate.  

Thanks for all the suggestions, The throw out brg was replaced along with the Centerforce Dual Fiction clutch assy along with the fly wheel. I did check alignment and it was within limits of Centerforce's recommendation. Guess I'm pull the trans and start inspecting the clutch assembly. Just to note i do have a small rear main leak, any thoughts on this causing the vibration?
Thanks Again for the advice.  

hello  Unfortunately you have left some critical info out. I personally can not help you any further unless you answer all the questions I asked.  Please keeep in mind I as well as others are not there and it is hard enough to answer solve some problems by remote even with good info. I also think you totally misunderstood my post. Please read it again very carefully.`lots of info there. The answer to your problem is most likely in my reply.  I have no idea what alignment you measured. Was it the finger height I mentioned? The only other blind guesses I have are bent clutch disc or bad rear main bearing. Your detailed answers to my questions will help pinpoint the problem.  Thanks  

vibration when the clutch is DEPRESSED ...


does it vibrate when the car is stopped and the transmission in gear??? stopping the clutch disc from spinning...

or only when the transmission is in neutral..  clutch depressed..

if only when the transmission is in neutral and the clutch is depressed.. i would aim for pilot bearing backed out of the crank.. or input shaft bearing on the transmission being extreamly worn..  

an oil leak onto the dual friction material might make it stick to the cover.. or build up dust in one spot.. where it was slung off in another..

when the transmission was out..  did you wobble the input shaft  end to see how much radial play there is..


i came up with a easy way to check alignment if you have a decent hardware store nearby..

remove one of the flywheel to crank bolts.. measure the distance from the crank bolt to the alignment ring on the bell housing.. either weld 2 bolts head to head.. so you can use a lock nut to position the bolt into the back of the crank..   and a pair of nuts on the backward facing nut to hold a properly selected flat washer just a few thousands from the edge of the alignment ring.. so you can rotate the crank.. and work your way around with a feeler gauge between the flat washer and the inside of the alignment ring..   yep.. low buck.. but not everybody has proper fixtures to mount a dial indicator to the flywheel..

i also had used double nuts on the end of a long bolt and a piece of pipe to hold the washer tight against the underside of the bolt.. . with the upper nut tightened to pinch the pipe into the washer.. the lower nut to hold the bolt steady in the back of the crank..  

Ok, more info on my issue.
~The vibration is not felt when the car is stopped, in gear or out with the clutch depressed or not.
~The vibration is still felt when driving and with the engine shut off, does not matter if in gear or not.
~When the clutch is depressed all the way to the floor is  when its felt, if I release ~ 1 inch it goes away. In gear or not. Makes me think that it is a rotating issue.
~I'm not familiar with the wobble check on the input shaft but I do remember I thought their was quit a bit of play (radially) How much is too much?
~Could the drive line be a factor?
~Everything is new from the transmission forward ( except harmonic balancer and pulleys)I made sure everything was clean before assembly, took a depth measurement on the fork arm which was correct. everything lined-up when installed????
 Again thanks for all the help guys!  

do you have jack stands that have deep enough grooves in the top to secure the rear axle  while you run it thru the gears with the rear end supported on jack stands...


warning.. use extreme care... people have been snagged by the rotating driveshaft... and wrapped up around it..  one guy got a mattress wrapped around his when he ran across it..


could you have a wheel balance issue..

or belt separation happening to the tires...    can you run your palm around the tire tread..  make sure there are NO LUMPS sticking up from the tread.. please look first to make sure the steel belts are NOT EXPOSED or showing that will make your hand into a pin cushion as you have an OOPS moment..  ending in a  Darm moment. without the R..

if your car does the hula dance at 5 MPH.. the tires have issues..  

lets try this again...


there are several articles on muncie transmissions rebuilding around the various magazines on this site..

even though this is a race mod.. pay attention to the shift rings with the modifications to the spine shapes to prevent kick outs..




http://www.circletrack.com/drivetraintech/ctrp_0804_racing_transmission_build/viewall.html

what i am thinking is you either lost an input bearing..  an output bearing.. or the roller bearings in the back of the input shaft that locate the output shaft front end...  

its probably not going to be pretty inside there.. but all the parts are available either new or used ...

here is one on the alignment of the bell housing...

http://www.circletrack.com/drivetraintech/ctrp_0404_bellhousing_alignment/viewall.html

you could have a bent drive shaft..  tight or wasted U joints..  loose output shaft bushing in the muncie allowing excess side clearance...    one thing.. when replacing the tail shaft bushing.. please test fit the drive shaft yoke into the installed bushing before installing the seal... polish the drive shaft yoke smooth surface.. if there is debris.. use something like a diamond file to remove any high spots before polishing with some 400 grit wet or dry paper and some soapy water..  or spraying clean with some carb clean or brake cleaner.. the fit should be tight..  tail housing bushings mushroom slightly at the edge when installed so i at least normally have to scrape mushroomed sections or the ID slightly to get the clearance right..  

Thanks waynep71222,
I went back and looked at the oil leak I have that I think is my rear main, I'm now 2nd guessing myself b/c I had the same leak in the same area before the engine swap. Could be I have a loose input shaft bushing. looks like I have several things to inspect once i remove the transmission.
Thanks  

1968fb

Thanks for the additional detailed info.Another question, are you saying the vibration is felt in the pedal only or do you feel it in the seat also? Your description doesn't clearly define anything to me just yet. It does not sound like it is necessarily related to your clutch by your description. If your pilot bearing was excessively loose or the disc was bent it would chatter when you leave from a dead stop. Does it do this? You also said you did not have this problem with this same trans with a 350 hooked to it. This eliminates the possibility of it being a worn rear drive shaft bushing. At this point it’s up to you to eliminate anything that is different than before. Is this motor in the same non vibrating car? Same driveshaft? Rear yoke on differential? Same tires? Etc. It now sounds like a u joint or out of round [bent] driveshaft. Is this possible? If this driveshaft did not vibrate before and your rear yoke is the same then it sounds like tires. Did they sit with weight on them for a long time? Are they different tires than before? If everything else is the same and was ok before than that only leaves the tires or tire balance or rims if they are different.

The splined transmission shaft typically feels fairly loose it may wobble about 3/4 of an inch. If you have a front transmission leak you will see it on the trans where the seal is but by the time it got to where your rear main is it would have splattered all over everything first before it finally got there.  

there is a special tool to unlock the nut that holds the input shaft in the middle of the front bearing... under the front retainer..

i don't have that tool anymore.. it walked away..  next time i have to build on.. i will have to revert to either channel locks or make one out of some steel strap.. after grinding i would harden it by heating and quenching ..   perhaps just thinning the heck out of an open end wrench..  i don't recall the size right now..

you will need a wooden dowel or a plastic one to support the countershaft bearings while reloading them and dropping the loaded countershaft into the case... then slipping it out.

do check the driveshaft for straightness..

i had a friend with a seville milan convertible.. 79 seville shortened 28 inches..   he had a terrible vibration..  i finally got him to go with me to have a new driveshaft made.. its only 32 inches long as i recall and one end is a double cardin joint.  it was so smooth afterwards.. he went out and bought new tires.. i warned him to only use floor jacks to lift the car.. do not let the tire shops use those rubber padded short lifts.. as i  think thats what bent the prior driveshaft.. nope.. he comes back in 3 days and the vibration is back... i looked and the shaft was bent... i could see the blue impact mark on the driveshaft tube... the tire shop said it was not their fault.. and the driveshaft shop wanted another 260 bucks to build another..   no warrantee on bent shafts... he took the new receipt  and drove from my shop.. i told him to NOT go to that tire shop... but he drove right back there ... i parked across the street..  they put the car on that stupid rack and were just about to lift if when i drove into their lot and stopped them... calling them STUPID..  they were trying to prove to him that they did not bent the last new one..    i had them back it off and showed them the dented paint in their lift..