Vibration at 2100 RPM

[mickmate]

Good point the mounts are halfway along the engine and the pipes hold it to some extent also but I'll make sure the beast is caged. Todays news from Lake Woebegone, the clutch has 3 fingers, 2 were pretty loose and had play in and out. The third didn't seem to move which seemed a little odd (uneven) to me. I noted fastener and pressure plate positions and pulled the clutch. I have the starter and motor plate back on to try the flywheel by itself tomorrow. If it shows vibration I'll pull that and try another flywheel. If it doesn't I'll probably still pull the flywheel, reassemble it to the clutch and start looking at balance of the assembly. Does that seem logical?

[vector1]

you know without the tranny on the rear that vibration might be a little more then you reckoned for. your more man then mine.

i'd remove the flywheel/clutch assy and check on the balancer clocked as it was removed. i think you'll find the culprit there. imo you really don't need to fire it up. now if i was there to watch.......

[mickmate]

now if i was there to watch

you'd be standing anywhere but in line with the rotating mass right. I've done crazier things.

[Three Peaks]

Nick,
I'm sure you know this,but without the tranny input shaft in place in the pilot bearing, there isn't much to keep the clutch disc centered on the flywheel while the motor is rotating. Might not help find your vibration if the clutch plate is flopping around and worse things could happen.....

Be careful out there......

Bob

[RICK LAKE]

mickmate Mick you found the problem with a broken pressure plate. If 2 forks are loose and one is tight the adjuster moved and is pushing the disc out of center, there is your vibration. Get a new clutch assembly and have the flywheel cut to give it a new surface. Most your vibration should be gone. Replace the pilot bushing too. Rick L.

[blykins]

Nick,

If you indeed have a broken plate, take pictures so that I can forward it to the appropriate persons. McLeod will want to get an RGA, but they are very reasonable about fixing issues.

[Jerry Clayton]

Before you chase the clutch/flywheel further, you should pull the front dampner off the crank to make sure that it hasn't sheared the key and/or turned out of phase with the crank. Also turn the front end of the crank back and forth to try to determine if there is a broken front web between the no 1 main and rod journal--

[mickmate]

I have run the motor with just the flywheel on it. Pretty good shaking (versus vibration) at 12-1400 rpm. At 2000 now it really smooths out. Removed the flywheel and spun on a wheel balance machine, it shows 0. With the clutch pressure plate on there it shows .25 oz unbalance. I have the clutch disc, PP and flywheel going to balance right now. We'll see what that reveals. Damper is tight on 3 allens and the centre bolt, all loctited on assembly. Timing is 16 deg and steady at idle so I'm thinking damper is OK.

[blykins]

The shaking at the lower rpm is probably just the cam on the engine....when it gets a little more efficient at the higher rpm, you get the smoothing out.

How did the pilot bushing look?

[jhv48]

If it has smoothed out at 2000 RPM and above, I think you have isolated your problem. The clutch assembly.

The roughness at off idle could just be your cam.

[mickmate]

Bearing in mind the motor is basically pivoting on the mounts halfway along it I was thinking it explains the shake as there's no trans or anything to tie the end down. Pilot bearing looks fine on bearing and shaft.

[jhv48]

Since you're probably replacing the clutch, replace the pilot bushing too. It's an $8 part that can cause you to pull the whole shebang apart again. Consider it $8 worth of insurance.

[vector1]

is the clutch disc something they can check by itself or maybe it doesn't matter. you know it spins independently of the pressure plate/flywheel.

[mickmate]

They took a small slug out of the flywheel to balance it. The pressure plate was drilled as deep as they dare on a clutch spring boss. They had been drilled on the other 3 already at Mcleod so it seemed obvious to me there was some balance issues from the get go with this PP. The balancers also shaved some off the housing on the same side to get it balanced. The PP doesn't sit flat to the FW without the friction plate in there. It also looks a little burned on about a third of the FW. I figured at this point we were onto something with the balancing so put it all back together. Same stinkin problem! I'm really not trusting this clutch at this point so I'm planning on trying another breed. Several of my trusted advisors suggest Centerforce so I think that's the next step.

[blykins]

Did you get in touch with McLeod? They should make good on the pressure plate.

As for Centerforce, I'd rather run an Autozone clutch than a Centerforce. I'm afraid you'll have more problems out of the C/F than anything else. The weights will more than likely have to be removed for proper behavior and I wouldn't count on it holding the power that the engine is making (with or without the counterweights).

If you do want to try something else, I would suggest a RAM clutch....but I would let McLeod make good on the current setup. McLeod is among the best of the best in my opinion.

[RICK LAKE]

mickmate Mick 2 things, Unless you are beating on the car hard, get a diaphragm clutch assembly. 2,600 pounds if you are driving normal. You didn't say what the HP and torque of the motor is? This is also important for buying a clutch. 2,800 pounds would be the max for your car.
I am reading they rebalanced your flywheel?? Did they resurface the clutch side?? If yes, make sure that the PP bolts don't go through and hit the block protector plate. They could be too long now. I have seen this happen.
As for clutches, IMO centerforce sucks. If you look at some of the old threads about clutches , you will find that they have no idea about how this clutch is to work with the sliding weights. I got the gold one and had nothing but problems shifting the car over 3, 000 rpms because of the lockup weights on the PP. Many calls. everything was to blame but their parts. Ended up buying a 2nd trans from G-Force after the richmond 6spd was to be the problem. It was not. $6,500.00 dollars later and still a shifting problem with another new trans. Turned out the weights where loading the PP and not letting the trans unload and shift. I broken the clips in the shifter 2 times. I figured out the weights where causing the problem. I removed them and have not had a problem with the clutch in 10 years. With the 400hp 452 motor the clutch holding was fine, With the 482 motor the clutch slips if I hit the throttle and not roll on and off. I will end up with a multi disc clutch with motor 498. The street twin is going to be the way to go for a car on the street. For the track I may go to a smaller multi disc 8" setup.
I don't HATE Centerforce for there products, I hate them for the stupid tech end and giving out wrong info and not knowing how there own product is to work. Alot of guys are running the CF clutches without weights and having no shifting problems. A HTB bearing may have worked with the weights but the one I installed leaked from the banjo fitting. ERA uses a master and slave setup with a modified fork. I feel the engage and release is quicker than a HTB setup for racing.
You know you can go out and buy a cheap 11" clutch and get many years out of it for 1/3 the price of some of the stronger clutches. The last thing about this is, It's alot cheaper to replace the clutch assembly than the rear end of the car. Clutch is a sacrificial part of the car for the drive train, just like the torque converter for a car with an automatic. These parts absorb the abuse. Good luck with the new clutch assembly. Rick L.

[Jerry Clayton]

did a little calculating--- the weight is added to the after market flywheels at aprox 4 1/2 inch radius---the weight and bolts for the 28oz wheel weigh 186 grams which is aprox
6 1/2 oz. My balancer came with info that 1/4 oz 4 inch radius would be 7 lbs at 2000 rpm----so 26 of those 1/4 oz would equal 182 lbs at 2000 rpm--at 4 inch ---

by the way--that 1/4 oz at 4 inch changes dramicly as rpm increase
7 lb at 2000rpm
28 at 4000
83 at 6000
112 at 8000

so multiply all those by the 26 factor and you have a pretty good shake

[madmaxx]

The reason for the harmonic balancer is to balance torsional forces not out of balance rotating assembly forces. As your crankshaft rotates it acts as a torsional spring. The harmonic balancer dampens the torsional forces. In other words it helps the crankshaft to not "twist" as much. It acts as a gyroscope for your crankshaft. Google harmonic balanecer and you will find some pretty interesting write ups.

[Jerry Clayton]

Madmax----I was speaking of my balancing machine as a balancer not a harmonic dampner

[mickmate]

Changed to a Fluidampr today. It needed the spacer machining 1/2" shorter and a March 1971 4 bolt pulley. First couple of drops through 2100 RPM I thought it was gone but some smooth road and a couple more tries and sure enough it's just like it was. I'm going to try the new clutch next week. This is driving me (and more importantly the customer) absolutely nuts.