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Unread 08-31-2014, 12:18 PM   #1
Chewtoy
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1976 CJ5 
 
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Location: Post Falls, Idaho
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Heavy shudder under acceleration

I just picked up a shudder that I have been fearing is clutch related due to other threads I have been reading so I am asking for confirmation of where to look.

1. it only happens when the clutch is out and under acceleration
2. goes away if I back off the throttle.
3. goes away if clutch is in.
4. 1st gear nothing, 2nd gear a little vibration, 3rd and 4th has a heavy shudder.
(T18 tranny so not much time spent in 1st)

Tranny mount is fairly new, but I have no idea if the motor mounts have ever been changed. Motor mounts.... we are talking the rubber between the solid frame piece and the motor right?

304 w/ JYEFI, and just moved to 35" tires and 4.30 gears. I am guessing from this thread that I need a heavier clutch and clean fly wheel and maybe new rubber motor mounts?

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Unread 08-31-2014, 12:22 PM   #2
Mike Romain
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A worn clutch just slips under load. If a clutch is going to shudder, it does it in 1st usually. I would be looking at those mounts real close.... I have torn new ones apart under heavy torque, some are junk.
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Unread 08-31-2014, 12:31 PM   #3
LumpyGrits
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Ck for broken motor and tranny mounts.
Lube your drive shaft slip-spline and U-joints.
LG
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Unread 09-01-2014, 05:59 PM   #4
Chewtoy
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Turns out the the bolts holding the mount to the trany spacer (between the T18 / D20) were loose. so I tightened them up and took it for a run and that got rid of most of the shudder. Got it back in the garage to look for other causes and one of the bolts was loose again. Long story short the threads in the adapter are striped.

So now what is the best way to repair it? it was 1/2 inch threads, so use a 5/8s tap or bigger? Maybe a helicoil?
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Unread 09-01-2014, 06:07 PM   #5
RenoF250
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Quote:
Originally Posted by Mike Romain View Post
A worn clutch just slips under load. If a clutch is going to shudder, it does it in 1st usually. I would be looking at those mounts real close.... I have torn new ones apart under heavy torque, some are junk.
If you get oil on a clutch it will slip and shudder. It does it most under the most torque which may not be first gear.
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Unread 09-14-2014, 05:20 PM   #6
Chewtoy
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Ok got the tranny mounts fixed and still getting a shudder on acceleration, but not as strong. I greased the slip joints but there are no zercs on the u joints.

So what exactly am I looking for to see if the u joints are gone? I can roll the drive line back and forth a bit until the gears in front or in back bind up. There seems to be a little movement in the double cardan joint before the gears move.
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Unread 09-14-2014, 05:43 PM   #7
adman02
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My motor-to-tranny bushing was out of round on the inside diameter which caused a shutter starting out in forward and reverse. Could be that.
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Unread 09-14-2014, 05:45 PM   #8
RenoF250
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Quote:
Originally Posted by Chewtoy View Post
Ok got the tranny mounts fixed and still getting a shudder on acceleration, but not as strong. I greased the slip joints but there are no zercs on the u joints.

So what exactly am I looking for to see if the u joints are gone? I can roll the drive line back and forth a bit until the gears in front or in back bind up. There seems to be a little movement in the double cardan joint before the gears move.
I would suspect your clutch/flywheel surface has problems.
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Unread 09-14-2014, 06:07 PM   #9
LumpyGrits
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Any form of 'play' in the U-joint is bad.
Did you by chance do any driveshaft work(R&R)before the shutter started.
LG
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Unread 09-14-2014, 06:47 PM   #10
RenoF250
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Quote:
Originally Posted by RenoF250 View Post
I would suspect your clutch/flywheel surface has problems.
I was thinking your shutter was when you were letting the clutch out. Sounds like the problem is when the clutch it out and you accelerate. It the engine running well? My truck was shacking on accel so I changed u-joints and carrier bearing, turned out to be the PS injector harness was loose so those cylinders were misfiring.
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Unread 09-14-2014, 07:33 PM   #11
Chewtoy
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Well this summers jeep events went like this.

Driving down the freeway I had a large vibration suddenly start and after I pulled over to investigate, all power was gone to the rear wheels. Got the rear drive shaft out and found the output shaft nut had backed off and allowed the yoke to come off. Ok could have been worse, the output shaft splines and yoke splines looked pretty good so I unbolted the CV joint from the yoke and put it back together torquing to 140 ftlbs. Put the drive line back in and drove it a few times and things were going ok.

a few drives later and the shuddering started. Per this thread, I checked the motor and tranny mounts to find the threads on one of the main tranny mounts stripped. Got that fixed this weekend and the shuddering is still there to a lesser degree.

The shudder is very light in 2nd and heavier in 3rd and 4th and only under acceleration. I dont feel anything when engaging or disengaging the clutch.
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Unread 09-14-2014, 07:52 PM   #12
RenoF250
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You might want to have the driveshaft checked, perhaps it got bent when the yoke came off.
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Unread 09-14-2014, 08:37 PM   #13
LumpyGrits
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Bad engine mount.
Ck the P/S mount.
LG
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Unread 09-20-2014, 03:57 PM   #14
Chewtoy
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Well I found the cause of the vibration.
img_2014092040787.jpg

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Unread 09-20-2014, 04:05 PM   #15
LumpyGrits
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Maybe you should check ALL of the u-joints.
Some grease from time to time is good-
LG
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