#21  
Old 02-07-2020, 09:51 AM
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Each joint cap due to that small area of contact may now be crushed and pinching the needle Bearings?

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Old 02-07-2020, 10:05 AM
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The caps in the last photo look too small to me and the strap does not look right.

  #23  
Old 02-07-2020, 10:07 AM
crustysarge crustysarge is offline
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Quote:
Originally Posted by 70gtojosh View Post
The gap between the cap and U joint may cause a vibration but I don't think that explains the driveshaft hitting the bolt heads. Have you considered or inspected for a extreme/bad axle wrap up condition? There is a lot of movement coming from somewhere.
I agree. I can't get my head around how much movement there is to allow the shaft to hit the bolt heads and the shaft hit the pinion yoke.

The 10 bolt is on the stock leaf springs and I checked everything back there. Short of putting on old school traction bars or maybe new springs I don't know what to say.

I plan on swapping the pinion yoke for good measure.

  #24  
Old 02-07-2020, 10:33 AM
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Originally Posted by crustysarge View Post
Take a look: Could be the problem. Have to wait until I get new straps from the States.
Is that a 1310 u-joint mated to a 1330 yoke. Or maybe a 1330 to a 1350 yoke?

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Old 02-07-2020, 10:49 AM
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I wouldn't be driving the car with that gap, let alone at 90mph, and I've driven some shady **** back in the day.

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Old 02-07-2020, 11:02 AM
crustysarge crustysarge is offline
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1350 joint and 1350 yoke. I put in 1350 yoke when I did the rear a few years back. I measured caps this morning to be sure...

Car is parked for now. I agree, not feeling safe.

  #27  
Old 02-07-2020, 11:17 AM
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Looks like the only thing that has prevented disaster are the tabs holding the caps from sliding back and forth in the yoke. Cause it looks like the straps are only just keeping the caps from falling out of the yoke ... rather than actually holding them tight.

Lucky you decided to investigate before you had a shaft trying to beat it's way through the floor boards

  #28  
Old 02-07-2020, 11:42 AM
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FWIW, I'd say you have a companion flange problem for sure by looking at the back lit image, possibly a poorly machined flange, and possibly mismatched straps.

I'd also be looking at the angles, and that the angles are caused by broken leaf springs causing the excess movement. I had a 76 T/A that had both main leaves broken right thru the main leafs at the center bolt holes. On a hard launch the rear axle moved enough that it actually would stretch the emergency brake cables applying the brakes side to side making the car swerve side to side under acceleration. I damn near put it in a ditch doing a burnout with it on the street.

On a hard shift under power the rear axle wrapped up enough that the driveshaft would bump the floor. Because the spring was clamped at the break you couldn't notice that the main leaves were broken inside of the rubber insulator. My car also had rear U joint problems caused by the angles going way out of spec because of the broken spring leaves, actually broke a rear U joint during a burn out even after I found the broken springs, and corrected the problem. The extreme angle damaged the joint, and I never realized it until it failed later on.

Your car could have bent the driveshaft if it was putting the U joint into bind under acceleration with broken springs, something else to be aware of and check during troubleshooting your problem. Second Gen cars do have more spring wrap than most people know about, clamping the front half limits some of spring wrap, also transfers some of the movement from the axle wrapping up to the chassis, making the car much easier to drive under acceleration.

Just something I've run into on my own car years ago and replacing the main leaves and rebuilding both springs with 2 hefty homemade clamps on the front portion of the springs solved the problem. I have no way of knowing if your main leaves are broken, but your problems are some of the same ones I had experienced with my own car.

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  #29  
Old 02-07-2020, 11:49 AM
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Went back down in the pit and spent some inspection time, look at the pic, the yoke shield has been rubbing on the snubber above it. That is pretty big movement. I also found the driver's side leaf spring wrap around clamps loose, all three of them. You could see they had moved, that tells me the spring has really been moving to force the clamps open. The rear of the same spring looks like it has an area on one of the leafs that has bulged or warped.

Might be time to swap the 43 yr old springs. Stroked 455 must be too much for them.
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  #30  
Old 02-07-2020, 11:52 AM
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43.year old suspension parts like to balk at 480 plus ft lbs of torque multiplied by a 2.48 first gear!

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #31  
Old 02-07-2020, 12:29 PM
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Quote:
Originally Posted by steve25 View Post
43.year old suspension parts like to balk at 480 plus ft lbs of torque multiplied by a 2.48 first gear!
hehehe, yeah, and I do run it hard... crap, now I gotta go study springs.

  #32  
Old 02-07-2020, 01:27 PM
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Quote:
Originally Posted by cdrookie View Post
I wouldn't be driving the car with that gap, let alone at 90mph, and I've driven some shady **** back in the day.
I agree. Wrong straps, possible wrong joints? Have never seen a driveshaft yoke chewed up like that...except when a u joint broke and it spit the shaft out of the car. But IN the car? WTF. Also, sarge, if you are ordering new straps, I would order new bolts as well. Yours are all buggered up from using open end wrenches or pliers or whatever on them. Bolts are cheap. Lives aren't.

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  #33  
Old 02-07-2020, 02:31 PM
crustysarge crustysarge is offline
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Gonna get new Strange forged yoke with U Bolts.

  #34  
Old 02-07-2020, 03:09 PM
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Originally Posted by 73LeMans View Post
That's why I said "for example". The length was exaggerated to illustrate the point that you can have proper angles at the trans and rear end, and still have vibration/driveline issues.
Yes I see that. But if he has the trans down in the rear and the pinion down in the front it will be tough to make it OK. Billk

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Old 02-07-2020, 03:50 PM
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If you correct the issues brought up so far, and still have vibration, you might find that you have insufficient driveshaft diameter and material for the length.

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  #36  
Old 02-07-2020, 05:21 PM
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It will be a few weeks before I get new parts over here. I will follow up and let everybody know what I find and how things work out. Thanks to all, helped me stay on course and get out my "I don't want to work on it" rut.

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Old 02-08-2020, 05:45 AM
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Please do follow up. Way too many threads like this end up with the OP never posting the solution of the problem. Hope you find the answer.

  #38  
Old 02-08-2020, 07:21 AM
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It's good that your not going to drive it as you where lucky things did not go badly amuck, but I would like you to confirm the overall driveshaft length at the tranny end while you have time.

The combination of shaft lenght and front yoke lengh should allow the whole assembly once centered on the output shaft of the tranny to go in deeper by 3/4" without bottoming out and slide out by 3/4" before dropping of the end of said shaft.

You will need to jack the car up in such a way to have the rear end at normal ride height to get accurate info on this.

And keep at it, you'll get worked out!

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #39  
Old 02-09-2020, 12:01 AM
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Quote:
Originally Posted by steve25 View Post
43.year old suspension parts like to balk at 480 plus ft lbs of torque multiplied by a 2.48 first gear!
Actually, the load seen at the suspension parts is 480 lb-ft times 2.48 first gear times 3.73 rear axle ratio = 4440 lb-ft or 2220 per leaf spring.

Add a clutch dump in 1st gear and that total could easily double for a half-second or so, provided there's enough traction at the tires.


Last edited by hgerhardt; 02-09-2020 at 12:06 AM.
  #40  
Old 02-09-2020, 09:16 AM
crustysarge crustysarge is offline
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Any suggestions for new springs?

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