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sticky clutch???? long post
#44351 Mon Jul 19 2004 02:50 PM
Joined: Jul 2002
Posts: 189
D
dave s Offline OP
Member
The clutch in my 49 3600 has been sticking. Sometimes when you push the
pedal it takes 2-3 seconds to release. I have adjusted several times. When I
have the proper amount of free play (3/4-1"), it does not disengage
completely. I adjusted to take out some free play and that works until you
drive for 10-15 miles and then shifting becomes harder. This weekend I took
it to the car wash to try to blast off another layer of grime on the tranny,
and on the way home it would not disengage at all. Pulled the drive line,
tranny, clutch. The input shaft had gear oil on it. To my surprise their is
no sigh of a rear mail leak. The pressure plate face was very dirty and
sticky. The spines on the input shaft were VERY dirty and the grooves were
filled with a brown sticky substance, that I assume is dried gear oil. I
cannot see anything wrong with the clutch. I am planning on replacing the
throw-out bearing which was very dry. I have cleaned up the pressure plate
with lacquer thinner and emery cloth. I have a good clutch disk from my
other truck ( the one that came out is sticky too). I have cleaned up the
spines on the input shaft with lacquer thinner and emery cloth and lightly
dressed them with a file. The top of the spines was rough. The clutch disk
now slides freely on the spines. I took off the nose cone of the tranny. It
does not have a seal and the shop manual does not show one, only the nose
cone and oil slinger. The nose cone has a hole in it about 1/4" in dia. that
points down. This hole is also shown in the shop manual. I'm thinking that
that is where the gear oil came from on the input shaft and pressure plate.
How do I keep it from happening again? Could the transmission been over
filled at some point causing the oil to come out? I have an input shaft that
Gary Perry sent me. I don't know what it came off of, but would suspect a
bigger truck. the nose cone on it is longer and does not have the hole.????

The pilot bushing feels ok when I push the spare input shaft in it. no slop)
I've lubed the bushing w/30w. Do I need to replace it??

Re: sticky clutch???? long post
#44352 Mon Jul 19 2004 05:26 PM
Joined: Apr 2000
Posts: 487
R
Shop Shark
There should be a breather on the top of the trans case, much like the one on the rear end. Check to see if it's clogged up.


'67 GMC 3/4 292 4spd
Re: sticky clutch???? long post
#44353 Mon Jul 19 2004 07:38 PM
Joined: Jan 2001
Posts: 142
T
Wrench Fetcher
Is there a breather on the 3 speeds also? Because I seem to have a extra ordinary amount of leakage out the front.

Re: sticky clutch???? long post
#44354 Mon Jul 19 2004 11:40 PM
Joined: Feb 2004
Posts: 22,595
H
'Bolter
Just about any manual trans will have a breather somewhere. Overfilling and/or a clogged breather will force oil out anywhere it can find a route, and if there's no front seal, that's the easiest vent.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: sticky clutch???? long post
#44355 Tue Jul 20 2004 01:03 AM
Joined: Jan 2001
Posts: 142
T
Wrench Fetcher
If that is the case. Does anyone know where the breather is on a 3 speed?

Re: sticky clutch???? long post
#44356 Tue Jul 20 2004 04:16 AM
Joined: May 2004
Posts: 62
H
Member
Dave,

Sounds like your crank shaft is walking a bit to far due to failing main thrust bearing. You adjust it to work right the in a few miles it is all out of whack.

Get a dial indicator and set it up on the flywheel and with a pry bar try to move the flywheel/crank shaft front to back on the bearing axis. If you see the dial indicator move over .008 thousands, the thrust bearing is giving up.

I had a 235 1st. series doing the same thing you are desctibing and I found .045 thousands crank end play! It raised hell with the clutch adjusment and leaked at the rear main seal. It was still running.

Rebuilt the engine with a new crank and bearings. Fixed the clutch problem.


47 Fleetmaster, Hotrod 6, 5 Speed
50 Sedan Delivery, 327, 5 Speed
Re: sticky clutch???? long post
#44357 Tue Jul 20 2004 02:40 PM
Joined: Jul 2002
Posts: 189
D
dave s Offline OP
Member
Interesting thought on the crank. I don't have a dial indicator, but perhaps a feeler gage???
The shop manual does not show a breather and I don't find one. Could it vent out the top plate where the shift lever comes thru??

Re: sticky clutch???? long post
#44358 Wed Jul 21 2004 03:38 AM
Joined: Mar 2001
Posts: 317
G
Member
If you have the Granny-Low 4spd, with the shifter that comes up through the floor (NOT "Hurst" linkage), then yes the shifter tower IS the top vent.....................the hole in the bottom of the "bearing retainer" that the throw-out bearing rides on.....that is normal and is part of the ventilation. Overfilling the trans will result in oil flowing out at this point....usually not onto the clutch, but on a steep hill......I can see it happening.

Discard old clutch and PP, they are contaminated.
DO check crankshaft end-play..............if excessive, you will have bigger fish to fry besides a clutch job.


*** GMC ***
Re: sticky clutch???? long post
#44359 Thu Jul 22 2004 04:32 PM
Joined: Apr 2000
Posts: 487
R
Shop Shark
Looks like I spoke to soon, without checking my memory or the facts. My book doesn't show a breather on those 3spds and it's been thirty years since I've had one apart. The original 3 spd for my '67 did have a breather on the top of the tail housing. It's the later all-syncro type.
You mentioned a 1/4" hole and the oil slinger. Is there a slot on the bearing retainer(nose cone) that lines up with a hole under the bearing? The oil thrown off by the slinger should return to the trans through that hole.
Checking the crank end play without a indicator??
If the thrust bearings are really worn and we're talking about a runing, but semi tired six then you can try this. With the fan blade, turn the engine forward, then back. The cam gears are cut at an angle. The valve springs will try to keep the cam from turning. The crank gear will walk up and down the taper on the cam gear and push the crank in and out. If the engine is gummed up or locked up or the end play is within specs, you won't see anything.


'67 GMC 3/4 292 4spd
Re: sticky clutch???? long post
#44360 Mon Jul 26 2004 06:48 PM
Joined: Jul 2002
Posts: 189
D
dave s Offline OP
Member
Update:
I used the old pressure plate(cleaned up and polished with emery cloth) and the disk out of my 50. I compared the disk to a new one at Chevy Duty and saw no appreciable wear. It works fine, I'm pleased.
The carrier bearing on the front drive shaft was ok, but the rubber support around it was history. Jim Carter carries the support, Chevy Duty doesn't. The trick is to install the rubber support in the bearing carrier and then install the drive shaft with carrier bearing, it won't go together any other way.
I didn't have access to a cherry picker, so I pulled the tranny on a floor jack. Installation was harder, it fell off the jack 3 times. I finally set a 2x8 on step ladders just outside the doors of the truck, running thru the cab and hung a come a long from an eye bolt thru the 2x8. It helped a lot. I wasn't able to see the end play describe above so I'm assuming that the thrust bearing is ok. The truck drives much better, the only problem is a slight wheee sound when I engage the clutch from a stop. it sounds like the throw out bearing (new) spinning up. It only makes the sound pulling away from a stop, not when you are shifting.


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