69 Barracuda Clutch Shake Help Needed.

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TimS

TimS

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Got a problem with my 69 Barracuda I'm trying to resolve. I think I'm on the right track but would just like some other opinions. Car specifics are:

69 Barracuda Formula S Fastback, All original 383 HP, 4 speed, 3.23 SG rear. Original cast bell housing.

Past history by 30 year previous owner, car was put on jack stands some years ago after smoking the clutch, so a new clutch was needed. I bought the car last October and at that time shakes at a dead stop take off only. Put in the new clutch last week. A street Mcleod with Borg and Beck pressure plate from Brewer's Performance. Resurfaced the flywheel. All seems good on the rack. Good motor/tranny mounts. No binding linkage. Car does fine down the road once you get it rolling. Will take off fine in 2nd gear and in reverse form a dead stop but still shakes like crazy at a dead stop from 1st gear, even easing out. Yesterday I set the cars mercy brake and let out on the clutch while in 4th gear. Car dies pretty quickly. Then put the car in 1st gear eased out the clutch and throttled the car. Car wants to raise up with the brake set. But as soon as you let the brake out and start moving at all it shakes. BTW. If you are rolling much at all in 1st gear and take off easy. It won't shake. I'm leaning toward bad leaf springs and/or pinion angle incorrect.

Has anyone ran into this condition with a stick car and bad pinion angle? Car runs, drives, rides very nice otherwise. Only shakes violently form a standing stop take off in 1st gear.

Any suggestions would be greatly appreciated. Thanks.
 
I had this problem with a previous car many years ago in my younger, stupider days. Turns out I bent a clutch disc getting over exuberant putting in a transmission in by forcing the transmission in with the bolts instead of ensuring it slid all the way smoothly. Lesson learned.
 
So you had it before, and you still have it after?
Are you running a pilot bushing or bearing? What is the condition of it? Condition of the fork pivot? Condition of the fork? Release bearing? Bearing retainer tube? Assuming acceptable start to rule out items with easy stuff.
I think I'd start by verifying both spring clips are correctly on the clutch release bearing. Secondly, determine whether the release bearing is in contact with all three cover fingers at the same time when pushed forward, by hand, using the outside of the clutch fork. Third, going around the fly wheel diameter, determine the disc and cover plate ring mismatch is the same all the way around.
Being "new" don't necessarily mean it's "good". Although unlikely, possibility is there for a disc that has a fat area or a cover that has weak springs or stretched eye bolt.
And don't overlook a bad u-joint in that easy check stuff.
 
Take a good look at the flywheel. If the clutch was smoked it probably needs to be resurfaced. The shudder is caused by the uneven surface of the flywheel.
 
Daves69 said:
So you had it before, and you still have it after?
Are you running a pilot bushing or bearing? What is the condition of it? Condition of the fork pivot? Condition of the fork? Release bearing? Bearing retainer tube? Assuming acceptable start to rule out items with easy stuff.
I think I'd start by verifying both spring clips are correctly on the clutch release bearing. Secondly, determine whether the release bearing is in contact with all three cover fingers at the same time when pushed forward, by hand, using the outside of the clutch fork. Third, going around the fly wheel diameter, determine the disc and cover plate ring mismatch is the same all the way around.
Being "new" don't necessarily mean it's "good". Although unlikely, possibility is there for a disc that has a fat area or a cover that has weak springs or stretched eye bolt.
And don't overlook a bad u-joint in that easy check stuff.
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I put a new pilot bushing in. Double checked the fork springs and throw out bearing along with pp finger contact. Based on my test yesterday, I think the clutch area is good.
 
Did you soak the bushing in oil and wipe dry prior to installing it?
Is the input shaft whole and the original length?
You mention it is all original, how sure are you? Lots of 833's have been modified over the years and the shafts cut. What about BH run-out? How is the ride height and does it have original type shackles? Just guesses for you to ponder.
If you need an angle on the pinion Myself or other could surely measure ours for you.

If it is all original it would be nice to see it posted here Show "YOUR, REAL" 383/440 '67-'69 Barracudas...NO CLONES please
 
Possible transmission mount, rubber is broken? A tough this to see as it sits, easy and worth taking off the trans X member to check. Trans is bouncing under load and settles down once you get going, Just a thought :)
 
Daves69 said:
He did already according to his post.
Click to expand...
I missed that.
I'd take a look at the U-joints as well. Make sure that there is no excessive play or any binding. Also wondering if the bell housing is correctly mated with the block. Misalignment can cause engagement issues.
 
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The block to Bell, yes...but not so much like what you describe, Misalignment Block to Bell can cause bad wear or breakage.....Im not so sure how accurate the factory was in aligning the block to bell?
Good luck, hope you find the issue! Let us know what it was if you do. Lots of good ideas mentioned here, pick the cheap and easy ones first, I do...cause I'm cheap..lol
 
I know he said the flywheel was resurfaced, but... I've heard of and experienced the "1st gear shudder" several times, and the cause was always (IIRC) the flywheel needed resurfacing, and for whatever reason wasn't.

I won't install a new clutch anymore without a resurface, just won't do it.

I do remember an occasion where motor mounts aggravated the situation, but the root cause was flywheel surface.

I'd have the flywheel surface checked, or swap the flywheel if an alternate was avail, and or check flywheel runout while it's mounted on the crank.

hope it helps..
 
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1969383S said:
Did you soak the bushing in oil and wipe dry prior to installing it?
Is the input shaft whole and the original length?
You mention it is all original, how sure are you? Lots of 833's have been modified over the years and the shafts cut. What about BH run-out? How is the ride height and does it have original type shackles? Just guesses for you to ponder.
If you need an angle on the pinion Myself or other could surely measure ours for you.

If it is all original it would be nice to see it posted here Show "YOUR, REAL" 383/440 '67-'69 Barracudas...NO CLONES please
Click to expand...

I'm sure the transmission is original. I texted the guy I bought it form on Saturday and he said when he put the car on stands 15 years ago I did not shake like it does now. I did add some aftermarket shackles to the car to raise the rear an inch before I put the new clutch in. It did still shake with the stock shackles but it still had the old clutch in it. I guess that is something to ponder.

Angle should be somewhere between 5 and 7 degrees negative. The angle finder I ordered should be here today so I'm anxious to see what that ends up being.

The previous owner in his pics showed the car on stands. It had been that way for years and the rear stands were supporting the rear axle housing at each end it appears. Just a thought, but sitting that way straightening the springs out maybe changed the angle a bit.
 
TimS said:
I'm sure the transmission is original. I texted the guy I bought it form on Saturday and he said when he put the car on stands 15 years ago I did not shake like it does now. I did add some aftermarket shackles to the car to raise the rear an inch before I put the new clutch in. It did still shake with the stock shackles but it still had the old clutch in it. I guess that is something to ponder.

Angle should be somewhere between 5 and 7 degrees negative. The angle finder I ordered should be here today so I'm anxious to see what that ends up being.

The previous owner in his pics showed the car on stands. It had been that way for years and the rear stands were supporting the rear axle housing at each end it appears. Just a thought, but sitting that way straightening the springs out maybe changed the angle a bit.
Click to expand...

The issue you are describing is actually called clutch chatter. Can you post a picture or two of your clutch linkage? Also, curious how you verified the motor and trans mounts were good, especially the driver's side. They can look perfect, but be completely broken.

Longer shakles are not the proper way to raise the rear of the car. Fresh leaf springs are relaticely cheap. It's important to lubricate the rubber pivot points ie shakle bushings, shock mout bushings etc with synthetic disc brake grease. It allows the suspension to move much more freely b reducing sticktion at those mounting point. It noticibley enhances how smooth the suspension works.
 
The only reason I asked about the pilot bushing is some times people make the mistake of greasing it and that usally leads to grease flying out and contamminating the clutch.

Sure sounds like a clutch issue and not pinion angle.
 
If you have access to GoPro camera mount it under the car and get some video. May be invalueable to help you see whats happening.
 
1969383S said:
The only reason I asked about the pilot bushing is some times people make the mistake of greasing it and that usally leads to grease flying out and contamminating the clutch.

Sure sounds like a clutch issue and not pinion angle.
Click to expand...

My pinion angle question really is derived from a couple of guys sticking their head under the car and saying it appears the angle is positive. I'm just moving forward in verifying that angle with a finder just to rule it out. 5-7 degrees is still not much even to the eye and I also still have not run into anyone that actually has had an issue in the past with pinion angle being positive causing clutch chatter.
 
FWIW ..................

PilotBushLube.jpg
 
Guess I never read past line 1.

Capture.JPG
 
Got my angle finder today. I get 5 degrees negative. Measured my 71 Cuda 340 4spd car with 8 3/4 and got about the same thing. The 71 has no issues. Has anyone here actually have or know of a situation were positive pinion angle caused take off issues only. Everything I have read about the subject suggests I would have vibration at various speeds as well. I don't have that at all. Very smooth driving car other than take off at standstill in 1st gear.
 
1969383S said:
How is it in reverse?
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Perfect in reverse. You can stomp it going backward and no chatter at all. Takes right off. I've worked on/restored Mopars only for 40 years and haven't ran into this situation. I'm a bit stumped at the moment. When I measured the pinion angle last night I did it on the u joint and left it bolted to the pinion. I'm going to drop the drive shaft off and measure pinion only tonight after work. But as I said my 71 measured close to the same in that same spot. I had a shop check the clutch PP fingers to bearing and just in general. All looked good to them in the clutch area. Local Napa did resurfaced the pressure plate before new clutch install. Maybe something up with that as suggested earlier in the thread.
 
TimS said:
Got my angle finder today. I get 5 degrees negative. Measured my 71 Cuda 340 4spd car with 8 3/4 and got about the same thing. The 71 has no issues. Has anyone here actually have or know of a situation were positive pinion angle caused take off issues only. Everything I have read about the subject suggests I would have vibration at various speeds as well. I don't have that at all. Very smooth driving car other than take off at standstill in 1st gear.
Click to expand...

5 degrees negative in relation to what? What is the angle of the transmission centerline and the angle of the pinion centerline?
 
I have run into "heavy duty", and "hi performance" clutches that are very finicky about flywheel finish. Just saying it is refinished doesn't mean the friction material likes that finish. Grippy materials and heavy duty hub springs can jump violently w/a mismatch and lite loads. Some discs will do this cold, and cease once they've warmed up,even OE ones when it's damp out.
 
jbc426 said:
5 degrees negative in relation to what? What is the angle of the transmission centerline and the angle of the pinion centerline?
Click to expand...

I should have specified. What I measured about 5 degrees negative was the drive shaft angle toward the pinion as it was still hooked to the yoke. I unhooked the drive shaft from the rear pinion and rotated the pinion yoke around so I could attach the magnetic angle finder to it. I got 2 degrees positive that way. I'm going to do the same thing with my 71 Cuda and make sure I see a difference. That car has an 8 3/4 with 4 speed, and if I'm doing this right, should be negative at that spot. The 71 does not chatter. Just comparing.
 
Killer6 said:
I have run into "heavy duty", and "hi performance" clutches that are very finicky about flywheel finish. Just saying it is refinished doesn't mean the friction material likes that finish. Grippy materials and heavy duty hub springs can jump violently w/a mismatch and lite loads. Some discs will do this cold, and cease once they've warmed up,even OE ones when it's damp out.
Click to expand...

Even after I've gotten this one warmed up, it still chatters violently. I went as far as putting the car in 1st gear, setting the mercy brake and easing out the clutch, throttling the motor to heat up the clutch.
 
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