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Lower control arm clunk from pivot point, fixable?

Posted By: conv440

Lower control arm clunk from pivot point, fixable? - 02/24/13 08:32 PM

My 1970 Challenger had a clunk when shifting from forward to reverse. The right LCA may have excessive wear at the pivot point between the torsion bar adjuster and the outer housing. Can I successfully squeeze the two outer parts against the pivot shaft in a press or is this LCA scrap? I really hate to replace it because they have the boxing plate welded in and sway bar mounts.

Attached picture 7601543-IMG_3617.jpg
Posted By: gregn96cuda

Re: Lower control arm clunk from pivot point, fixable? - 02/24/13 08:34 PM

Look here for what you need.web page
Posted By: conv440

Re: Lower control arm clunk from pivot point, fixable? - 02/24/13 08:52 PM

That is exactly what I thought the problem might be. The flex on the right side is worse than the left but after watching the video neither of them are as bad as the ones that Jim fixed. Both of mine are tighter than after Jim's the repair. Now I'm wondering if that isn't the cause of my clunk. The bushings are relatively new and there is zero play in them so I'm scratching my head.
Posted By: RobX4406

Re: Lower control arm clunk from pivot point, fixable? - 02/24/13 09:12 PM

Check the tubes in your K frame for cracking around the weld areas.

Strut rod bushings too.
Posted By: conv440

Re: Lower control arm clunk from pivot point, fixable? - 02/24/13 10:07 PM

Thanks, cleaned and checked the tube but no apparent problems. Weld is solid.
Posted By: larry4406

Re: Lower control arm clunk from pivot point, fixable? - 02/24/13 11:29 PM

I have had bad u-joints "clunk" when going from forward to reverse and vise versa. Why do you suspect the control arm?
Posted By: GODSCOUNTRY340

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 01:15 AM

Check your strut rod bushings.
Posted By: autoxcuda

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 01:42 AM

Yes, you can tighten the halves of the LCA around the pivot housing.



BUT there still can be wear between the OD of the pivot housing and the halves of the LCA stampings. Tightening the halves together will not fix that looseness.

I have that problem with my LCA's. I clamped and weded the halves together in the above picture about 16 years ago in 1997. But now there is noticable movement between the pivot housing and LCA stampings.

This is the same set of LCA's as pictured above on the left, just painted black and 16 years later...



Attached picture 7602019-LCAtoFrameClearance1b.JPG
Posted By: conv440

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 02:42 AM

Quote:

I have had bad u-joints "clunk" when going from forward to reverse and vise versa. Why do you suspect the control arm?




Funny you mention that. I am starting to wonder if the clunk was not LCA related but I've eliminated several other potential problems. The U joints and the trans yolk were both toast and causing 'other' clunks. Those got fixed last year.

Quote:

Check your strut rod bushings.
Quote:



Strut rod bushings are poly and fairly new. Have them out too but no apparent wear or problems.

Autoxcuda, yes I was wondering about the tolerance on that as well. Mine don't seem exceptionally worn but there is some play. Wondering if a few choice blows with a chisel all around the circumference would stake the outers into the inner. That fix might be only temporary if it worked at all.
Posted By: JohnRR

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 04:04 PM

Quote:

My 1970 Challenger had a clunk when shifting from forward to reverse. The right LCA may have excessive wear at the pivot point between the torsion bar adjuster and the outer housing. Can I successfully squeeze the two outer parts against the pivot shaft in a press or is this LCA scrap? I really hate to replace it because they have the boxing plate welded in and sway bar mounts.




How do you know it's the control arms ? Do you feel the clunk in the steering wheel ?

How much backlash is in the rear end ? Is the car an auto or 4 speed ?
Posted By: VincentVega

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 04:12 PM

That's usually strut rods. Check the big nut torque, perhaps the bolts to the LCA. any big clunks from the axle between coast down and putting power on? (backlash?)

KFrame loose? (yikes). Sector shaft loose? Idler arm?

Transmount?
Posted By: Jim_Lusk

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 04:33 PM

Quote:

My 1970 Challenger had a clunk when shifting from forward to reverse. The right LCA may have excessive wear at the pivot point between the torsion bar adjuster and the outer housing. Can I successfully squeeze the two outer parts against the pivot shaft in a press or is this LCA scrap? I really hate to replace it because they have the boxing plate welded in and sway bar mounts.




Watch this video...

http://youtu.be/Nwes-SP8u4w
Posted By: VincentVega

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 04:39 PM

heh, arc welding with exposed skin...
Posted By: JohnRR

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 04:47 PM

Quote:

heh, arc welding with exposed skin...




Working on his tan , I do it all the time ...
Posted By: autoxcuda

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 06:02 PM

Quote:

....

Autoxcuda, yes I was wondering about the tolerance on that as well. Mine don't seem exceptionally worn but there is some play. Wondering if a few choice blows with a chisel all around the circumference would stake the outers into the inner. That fix might be only temporary if it worked at all.




You can pinch the back and weld a strap to hold it like I pictured. I don't think a few blows around that circumfernce would hurt anything. That's a good idea. And if the noise went away and came back, at least you could narrow down the source better (I'd chisel it again in the car to see if it would go away again to confirm). And/or you could also put lube in the circumfernce joint and see if that gave any temporary change.
Posted By: RobX4406

Re: Lower control arm clunk from pivot point, fixable? - 02/25/13 06:56 PM

Quote:

Quote:

....

Autoxcuda, yes I was wondering about the tolerance on that as well. Mine don't seem exceptionally worn but there is some play. Wondering if a few choice blows with a chisel all around the circumference would stake the outers into the inner. That fix might be only temporary if it worked at all.




You can pinch the back and weld a strap to hold it like I pictured. I don't think a few blows around that circumfernce would hurt anything. That's a good idea. And if the noise went away and came back, at least you could narrow down the source better (I'd chisel it again in the car to see if it would go away again to confirm). And/or you could also put lube in the circumfernce joint and see if that gave any temporary change.




Be careful with pull from welding if putting straps across the arms.

Posted By: Jim_Lusk

Re: Lower control arm clunk from pivot point, fixable? - 02/26/13 12:48 AM

Quote:

heh, arc welding with exposed skin...




I don't do a lot of welding so I don't worry much about it. It's the shoes that catch on fire that make it real fun....
Posted By: conv440

Re: Lower control arm clunk from pivot point, fixable? - 02/26/13 06:03 PM

The straps look like a great idea. I'm going to add the straps and then heat and beat the outer shell. There goes my OE Gold Certification!
You guys are making me feel guilty so I guess I better dig out my welding jacket and find some shoes that aren't made out of nylon.
Posted By: autoxcuda

Re: Lower control arm clunk from pivot point, fixable? - 02/26/13 06:14 PM

Quote:

The straps look like a great idea. I'm going to add the straps and then heat and beat the outer shell. There goes my OE Gold Certification!
You guys are making me feel guilty so I guess I better dig out my welding jacket and find some shoes that aren't made out of nylon.




You won't need to heat the shell. Just clamping it in a vise near the end will tighten it to however tight you set the vise at.
Posted By: conv440

Re: Lower control arm clunk from pivot point, fixable? - 02/26/13 06:20 PM

I was going to heat the metal and give a few whacks to the rear outer shell to try to close the tolerance between the torsion bar mount and the rest of the arm. Same place you are experiencing some slop in your earlier post (looseness/gap/wear).
Posted By: autoxcuda

Re: Lower control arm clunk from pivot point, fixable? - 02/26/13 06:34 PM

Quote:

I was going to heat the metal and give a few whacks to the rear outer shell to try to close the tolerance between the torsion bar mount and the rest of the arm. Same place you are experiencing some slop in your earlier post (looseness/gap/wear).




Oh ok. That could use heat.
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