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Clutch Grumbling When Engauged
#1358381 Sun May 03 2020 03:26 PM
Joined: Apr 2009
Posts: 548
H
Shop Shark
I was trying to respond to a post with the same title and when I hit reply it said post deleted. Anyway I have a similar problem and was replying hoping for some input since this very troubling to me.

I also have a 1952 3100 235 engine with a similar sounding problem. I thought it was the throwout bearing which was brand new when I first assembled the truck. Everything was fine for about 2000 miles. Then it starting making intermittent noise when fully depressed but there were places in the pedal travel that no noise occurred. Seemed worse when cold. I replaced the throwout bearing with a NAPA made in USA bearing. It didn't feel any different in the way it spun in my hand than the one I removed. The rotating parts fit together close enough that I couldn't see how you could push additional grease into either one.

The second throwout bearing seemed to correct the problem for another 2000 miles but I am once again getting the intermittent noise. I made sure there was sufficient free play in the clutch linkage and both bearings were not in contact with the pressure plate with the clutch released. The problem occurs more often at first startup but can occur at other times too. Most embarrassing when at at stoplight and the driver across from you is just saying nice truck when this horrible noise erupts. I can get it to really make noise when downshifting unless my speed is very low. It rarely makes noise when upshifting.

The pilot bushing was new when I assembled the truck. The SM420 trans was rebuilt and the nose of the input shaft was clean without and burrs. I have wondered if it could be the pilot bushing making the noise but I can occasionally get the noise depressing the clutch with the trans in neutral. I would also appreciate any input about this problem. It is very discouraging to have this occur in an otherwise completely rebuilt truck. I am not up to the task of laying on my back and pulling that extremely heavy transmission out by myself again. The couple places that do manual transmission work in my area may have someone knowledgeable about working on these trucks but the people answering the phones do not give me any confidence when they do not seem to even understand what a torque tube is.

Re: Clutch Grumbling When Engauged
Hookalatch #1358433 Sun May 03 2020 09:40 PM
Joined: Sep 2011
Posts: 733
B
Shop Shark
If noise is easy to duplicate, find a safe place you can coast with engine off. Roll with transmission in gear, clutch depressed. Release bearing will not be rotating but input shaft will rotate in pilot bushing.


BC
1960 Chevy C10 driver 235 T5 3.73 dana 44
1949 GMC 250 project in waiting
1960 C60 pasture art
G.M dealer tech since 1980 & counting
Re: Clutch Grumbling When Engauged
Hookalatch #1358463 Mon May 04 2020 12:58 AM
Joined: Mar 2010
Posts: 139
L
Shop Shark
That was my post you referring to I went to do a edit but hit the delete button.
The best way I can describe the sound it’s like when a power steering pump is going out that grumble sound. My truck hasn’t been driven in 3 years just a little moving in the driveway.its a 52 with a 235 3 speed transmission w/od 3 on the tree new throw out bearing when I installed the transmission.
Robert

Re: Clutch Grumbling When Engauged
BC59 #1358522 Mon May 04 2020 02:07 PM
Joined: Apr 2009
Posts: 548
H
Shop Shark
Originally Posted by BC59
If noise is easy to duplicate, find a safe place you can coast with engine off. Roll with transmission in gear, clutch depressed. Release bearing will not be rotating but input shaft will rotate in pilot bushing.

Thanks, that's excellent advice. Since the noise is intermittent, no noise under those conditions won't rule anything out but noise will implicate the pilot bushing area. I will try this today. I probably should have been able to figure that out on my own but didn't. That's why this forum is so useful. If it turns out this is a pilot bushing problem one explanation for why it was quiet for 2000 miles after changing the throwout bearing is I lightly greased the input shaft when replacing the transmission. I am aware that the mileage isn't really a factor in either case but how often the clutch is released but the mileage is the only data point I have. Any additional ideas or advice are encouraged.

Re: Clutch Grumbling When Engauged
BC59 #1358566 Mon May 04 2020 07:44 PM
Joined: Apr 2009
Posts: 548
H
Shop Shark
Originally Posted by BC59
If noise is easy to duplicate, find a safe place you can coast with engine off. Roll with transmission in gear, clutch depressed. Release bearing will not be rotating but input shaft will rotate in pilot bushing.


I followed this suggestion and it turned out to be very helpful. The noise was barely happening and intermittent just driving the truck but when I did as suggested, engine off coasting in gear with the clutch depressed the noise occurs full time. There is also a slight vibration felt thru the clutch pedal any time the noise occurs as well which made me think it was the throwout bearing. So my problem is most likely the pilot bushing. Too bad I don't have a leaking rear main seal, maybe that would keep it quiet. Just to be sure, if the input shaft bearing in the trans was bad the noise would be there all the time wouldn't it?

Re: Clutch Grumbling When Engauged
Hookalatch #1358574 Mon May 04 2020 08:24 PM
Joined: May 2015
Posts: 2,630
Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums
If the input shaft bearing were bad, the noise PROBABLY would be there all the time. But if the input shaft bearing were bad (enough?), the tranny may tend to pop out of direct gear.


Kevin
First car '29 Ford Special Coupe
#2 - '29 Ford pickup restored from the ground up.
Newest Project - 51 Chevy 3100 work truck. Photos [flickr.com]
Busting rust since the mid-60's
Re: Clutch Grumbling When Engauged
Hookalatch #1358633 Tue May 05 2020 01:43 AM
Joined: Apr 2009
Posts: 548
H
Shop Shark
Thanks for the input guys. I don't drive my truck a whole lot so I guess I am just going to have to live with this for a while, keep driving a little, and hope for the best.

Re: Clutch Grumbling When Engauged
Hookalatch #1358734 Tue May 05 2020 04:37 PM
Joined: Sep 2011
Posts: 733
B
Shop Shark
I think you have confirmed the pilot bushing to input shaft interface is where the noise is coming from.


BC
1960 Chevy C10 driver 235 T5 3.73 dana 44
1949 GMC 250 project in waiting
1960 C60 pasture art
G.M dealer tech since 1980 & counting
Re: Clutch Grumbling When Engauged
Hookalatch #1358797 Tue May 05 2020 10:36 PM
Joined: Feb 2001
Posts: 1,129
D
Shop Shark
I had a similar sound from the clutch in my '40.

Was ok initially , Foot on pedal rattle noise , assumed thrust brg etc etc .

Turned out to be the wee flat springs in the clutch pressure plate , see pic , the curved end should be a lovely round shape , not the slightly flattened curve shown .

Attached Files
DSCF3911.JPG (86.3 KB, 58 downloads)
DSCF3912.JPG (94 KB, 56 downloads)
Re: Clutch Grumbling When Engauged
Dusty #1358810 Wed May 06 2020 12:03 AM
Joined: Feb 2020
Posts: 15
G
New Guy
When I worked in a GM shop in the 70's there was a big problem with pilot bearing noise in the S-10 pickups. The first GM fix was to install a modified corvette bushing which had 6 small grooves cut in side the bushing and evenly spaced. This prevented the input shaft from wanting to "grab" the bushing. It worked. Later they supplied a real bearing. Now every time I have to install a bushing when no bearing is available I cut the 6 shallow groves into the bushing. If it only works 1 time it's worth it.

Joe


just retired and finally making headway on my project truck. 1940 GMC AC152.
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