New Clutch = Lots of Vibration

I got a new stock duty clutch kit and SM flywheel from South Bend Clutch (SB). Put it in and the first time I fired it up I had a lot of vibration, more at some RPMs. SB had me check the injectors. All cylinders were contributing equally so the source of the problem should be the new hardware, not the engine. SB sent me a new clutch and flywheel. When I pulled their first Throwout Bearing (TB) off I notice two rings had separated from it. Turns out, the TB they sent me gets pinched by the Pressure Plate (PB)- thats what broke the rings off.

Pinched defined: The TB has a lip that sticks out ahead of the TB by about 1/8". That lip has to fit inside the hole made where the PP fingers come together. When the TB pushes the PP fingers in that hole gets smaller, to the point where the TB lip has zero wiggle room, or is even constricted some. That I believe is why it broke those two rings off.

I can't see the slightly damaged TB having enough mass to cause my significant vibration. Next, I put the new kit and flywheel in and I still have the vibration, maybe not quite as bad as before.

When I pulled the Trans I have to raise and lower it 1 - 1 1/2" which in turn moves the engine on its mounts. Maybe that busted a motor mount to break which would explain my first observance of this vibration occuring right after I put the clutch in. But, it looks like the motor mounts are good.

I torqued and double checked all bolt in this job.

Any ideas on what might be causing this vibration?


Thanks,


BigRedWeather

BRW, those engine mounts are quite resiliant......have you checked the rear crossmember mount?

How did you remove the rear crossmember? There are 12 bolts total---if memory serves---- for the crossmember and horns that bolt thru the member to the upper frame.....any chance one of those are in a bind?

What play if any does the input shaft have?

Did you replace the pilot bushing in the flywheel.....the SB kits use a Kevlar pilot bushing.......

geonc said:

BRW, those engine mounts are quite resiliant......have you checked the rear crossmember mount?

Click to expand...

Yes, it looks good.

geonc said:

How did you remove the rear crossmember? There are 12 bolts total---if memory serves---- for the crossmember and horns that bolt thru the member to the upper frame.....any chance one of those are in a bind?

Click to expand...

I count 10 bolts, including the two that old the transmission to the cross member. No, those bolts all slid in nicely and I torqued them down with no binding. Another thing, I have not put the transmission back in twice and had the same result twice. I can't see me getting that cross member in odd ball, twice in a row. It was very straight forward to put in.

geonc said:

What play if any does the input shaft have?

Click to expand...

South Bend asked me to check this. It would move back and forth about one 1/128th of an inch.

geonc said:

Did you replace the pilot bushing in the flywheel.....the SB kits use a Kevlar pilot bushing.......

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Yes, they sent a new Kevlar pilot bushing. I ran the first clutch kit for about 500 miles while they/we were trying to decide how to attack the vibration. When I pulled it out the pilot bushing would allow the aleignment tool to move a little more than the new pilot bushing would. Translation- as expected, the pilot bushing had been worn some by the vibration.

Thanks for the ideas. I a little stumped as to how I can get this vibration. More ideas are most welcome.


BigRedWeather

Getting down to input shaft or bearing issues mebee ........

What kind of play do you have?

Is there any chance the input shaft is pushing the pilot bearing into the flywheel too deep when you bolt the trans up? I've seen this on Mercedes 4000 truck engines a few times....Very simular vibration description. The 4000 uses a spacer behind the pilot bearing to set/hold the pilot bearing in place. Are you positive the pressure plate is centered on the flywheel?...Just thinking of the usual problems I've seen guys run into.

GEONC I have about 1/128th of an inch play in the input shaft. South Bend had me call a tech line to see what the spec was for this play. They couldn't give me a number, but said it should be "very little." I think mine is definitly within that.

BigRigTech said:

Is there any chance the input shaft is pushing the pilot bearing into the flywheel too deep when you bolt the trans up? I've seen this on Mercedes 4000 truck engines a few times....Very simular vibration description. The 4000 uses a spacer behind the pilot bearing to set/hold the pilot bearing in place.

Click to expand...

I don't think that's possible. Both times I have put the clutch kits in the truck, I have pushed the trans to the engine with hand pressure, after I got them all lined up. I couldn't have been pushing the pilot bearing to deep into the flywheel.

When I pulled the first flywheel off, the pilot bearing was in its proper place in the flywheel.

BigRigTech said:

Are you positive the pressure plate is centered on the flywheel?...Just thinking of the usual problems I've seen guys run into.

Click to expand...

Yes, the PP is centered on the flywheel. When I put the PP on the flywheel, it didn't have two guide pins like my original flywheel did. I went from a 12.5" flywheel to a 13" flywheel with PP to match each flywheel, per the recommendation from South Bend. I called South Bend on this and they said this PP/flywheel aleigns on the eight bolts, and does not need/use guide pins. I would feel better knowing that two pilot pins were holding the two in the exactly correct orientation, but the eight bolts give the PP very little wiggle room. Also, after the first PP and flywheel had run on the truck for 500 miles (with a lot of vibration coming from somewhere) I looked at them and could tell from the lack of marks on the flywheel that the PP had not moved at all on the flywheel.

Keep the ideas coming. I'm still at a loss for what could be causing this.


Thanks,



BigRedWeather

it is a possibility that the flywheel is out of balance, I had thst happen with a luk before.
seems like 1 in 1000o have that problem. in a different truck it may have worked just fine.

Double-S-Diesel said:

it is a possibility that the flywheel is out of balance, I had thst happen with a luk before.
seems like 1 in 1000o have that problem. in a different truck it may have worked just fine.

Click to expand...

Since I have observed the same vibration at the same RPMs with two flywheels from South Bend, I don't think they both could be out of balance. The first one was one that had been in a truck for 2 months, resurfaced and sold as refurbished. The second was a new one. I don't think they could sell me 2 in quick succession that were out of balance.


Thanks,


BigRedWeather

My goal is not to rule out every post offered here. I greatly appreciate every post. I have to respond with what I observe on the actual truck.

Please post if you have another idea. Maybe one will be the solution.


Thanks,


BigRedWeather

Still have vibration...

If I am:
-driving
-standing still in neutral with the clutch in
-standing still in neutral with the clutch out

I still get a little vibration at +-800 RPM and significant vibration at 2400+ RPMs. If you felt it for the first time you would say "Get this thing to the side of the road- something major has just gone wrong."

I checked the torque on all bolts between Engine, Trans and Trasfer Case. All were within spec. Those that were at the bottom end of the spec I took to the top end of the spec.

This truck used to run smooth until the new clutch. The only change is that it has a knew South Bend LUK clutch kit and I have gone from a dual mass to a single mass flywheel. From what I know, the dual to single mass flywheel couldn't be causing all of this. (Actually, the first rebuilt clutch kit SMF caused even more vibration. When it got back to South Bend they said the flywheel was properly balanced when I had it. They sent me another new clutch kit SMF and it is causing less, but still too much vibration.)

The problem is that I am getting really bad vibration at 2400 RPM, right where my truck is getting its best acceleration. I am also concerned about what other damage I am doing to bearing from the Engine on back.

Any more ideas on where this vibration could be coming from?

BigRedWeather

test

Test of a link

http://www.oilburners.net/forums/showthread.php?t=33633&highlight=vibration