Vibration in clutch pedal

[Lu Blunt]

recently had the clutch replaced in my 79 k30 350/sm465/np205. The wrong size throw out bearing had been used and destroyed the clutch n the front snout of the trans. All was fixed. Drove fine the first 50 miles or so then the vibration started growing. Drove it another 50miles back to my mechanic. The vibration is a lot worse at higher rpm. It feels like ur running over the rhythms on the side of the highway. Like a hard pulsing vibration can be felt in the steering wheel and especially the clutch pedal. No noticeable vibration from trans shifter or tcase shifter. Truck shifts great. It's like it right between my feet or right behind the engine. I took it the mechanic immediately thinking there was a problem with the new clutch n didn't want to ruin it. Been at the mechanics a month now he's tried everything he can think of but the vibration is still there. I told him it never did this type of vibration before the clutch work. He's having a trans tcase specialist come look at the truck. I feel like it's clutch related n I'm about out of patience. Spent the last month haulin firewood in my daily driver instead of the work truck. He's an old family friend n wouldn't do me wrong but **** happens. U guys have any ideas as to the problem ?

 

[CSFJ]

Bolts still tight in the flywheel? And did they resurface your original or replace it? If they replaced it, is it verified to be the correct one? The 400 had a counter weighted flywheel, both will bolt up iirc.

 

[Lu Blunt]

I mentioned the fly wheel n he said it was resurfaced. After having a transmission builder drive the truck they decided on the rear drive shaft as the cause of vibration. It will be rebalanced on Monday. Should I consider a one piece aluminum rear drive shaft?

 

[bucket]

Doesn't sound like the symptoms of a prop shaft. That would be speed related, rather than engine rpm related. You also would feel it in the shifter.

 

[Lu Blunt]

I agree. I think it’s something to do with the recent clutch job. It did not do this before the new clutch. The vibration didn’t feel like it was coming from behind the transfer case, I felt it right behind the engine. Plus I have had front drive shaft rebuilt n new ujoints in the rear drive shaft and that was bearly over a year ago

 

[bigcountry78]

Did you ever find out what was going on? I’m having some of the same issues.

 

[Lu Blunt]

No luck yet. Been driving the truck pretty regularly since the new clutch. Kept thinking the vibration was the clutch assembly or possibly the clutch arm return spring. Found a decent return spring to replace the broken one. Helped alittle. Found if I hold the clutch pedal like an inch or two down (not enough to engage it) I can keep the vibration to a minimum. Drove like that for 5k miles or more. Recently the vibration has gotten so bad I can barely drive it. Looks like the trucks headed back to the shop. Not sure what else to do.

 

[bucket]

Sounds like it's been a clutch problem this whole time.

 

[dvdswan]

New parts can be bad. Has the new pressure plate been placed on a lathe to check for vibrations or warping? I would think if the clutch disc was missing any material you would see it. Was the pilot bushing replaced?

 

[B.K. Cunningham]

Input shaft bearing retainer. 25 bucks. Mine was rubbing and off center. Pedal was doing the same thing, push in a inch and it would quit for a while. Finally broke, I thought it was the clutch too.

You must be registered for see images attach

 

[Lu Blunt]

Not sure if the pressure plate was checked for vibrations. Also not sure about the pilot bushing. I will have the input shaft bearing retainer replaced when everything is apart. Hopefully have the truck in the shop this next week

 

[Lu Blunt]

The mechanic who did the clutch work has since retired n closed shop. I had the truck in another shop oct 2019 to have the drums rebuilt. While it was in I asked about the clutch pedal vibration. they said it was ok and didn’t seem interested in looking at it. I continued to drive the truck till about about month ago when the clutch quite engaging. Finally found a good shop to work on the clutch. He’s going to have a parts list and quote Monday. Said the failure could have been the wrong clutch or wrong throw out bearing. He will know more when he looks up the correct parts vs what’s in the truck. Also said the engine leaking oil on the clutch did not help things. The 350 has definitely seen better days and I’ve been wanting to swap in a big block for a long time. I have the hd big block leafs upfront already. Seems like a good time to do swap while everything is apart. I’m leaning towards a GM Performance crate motor. What do you guys think?

 

[bucket]

Well, if it fits in your budget then I'm certainly not going to talk you out of a crate GM big block! That's the route I would go if I could afford it.

 

[Turbo4whl]

.... The 350 has definitely seen better days and I’ve been wanting to swap in a big block for a long time. I have the hd big block leafs upfront already. Seems like a good time to do swap while everything is apart. I’m leaning towards a GM Performance crate motor. What do you guys think?

"There is no replacement for displacement" You have my vote for a Rat motor. Small issue is getting a crate engine you will still need all the accessory mounts for alternator, P/S pump etc. The sm block dizzy will still work.

 

[Craig 85]

I replaced my engine with a stock GM rebuilt 454 due to emissions BS. 3yr/100k warranty, although I'll probably have less than 3k on it when the warranty runs out. I went this route as I didn't want any issues like having to send the engine out to some far off place to have a possible warranty repair/replacement work done. I can go to the local Chevy dealer. The nice part is my replacement block was a 1990 and had a 4 bolt main.

454 LE8/L19 GM 12339193