Moparts

LCA's worn out/junk?

Posted By: 83hurstguy

LCA's worn out/junk? - 03/19/20 01:20 PM

I am new to Mopar, we are working through our first front suspension rebuild on a '70 Challenger. We put new bushings in the LCA, put it back on the car, and realized we still have a bunch of play out near the spindle.

Take a look at this video... the LCA hole appears to be oversized where the torsion bar sleeve passes through it, and it has slop there. Is this a common issue with these? I'm assuming it's not fixable, the arm is junk and we'll need a replacement? There's no play from the new bushing that's on the pin in the K-member from what we can tell, it's all in this area.



Thanks in advance!
Posted By: burdar

Re: LCA's worn out/junk? - 03/19/20 01:37 PM

Pretty common. The LCA isn't "worn out". It was just built that way. (sloppy) Those two pieces don't move independently from each other once the ride height it set. My Dart LCA was the same way. I welded a small strap to the back side to tighten things up. Not sure that it actually does much of anything but it made me feel better. Once there is a load on the LCA from the torsion bars and the strut rod is installed, my guess is that movement will go away.
Posted By: Kowal

Re: LCA's worn out/junk? - 03/19/20 02:16 PM

I just had to pull one because the bushing had failed. A friend had a NOS piece, with the stock tag still on it. Similar slop. I think your piece is fine.

If you are replacing the bushings, make sure you research carefully online. There is a sequence to inserting the bushings. Shaft first, then the bushing in to the control arm...but you have to make up a fixture so you are inserting the bushing by pressing on the outer shell of the bushing, not the shaft. If you use the shaft to insert the bushing you risk separating the rubber material from the shells. The bushing that I had that failed had only about 2K miles on it, when the car was restored they seemed to have damaged the bushing on the one side. The picture attached is what literally fell out of the LCA, that is not after any work by me to remove.

Attached picture 792E8DD0-3CEB-4107-B202-AA99B89F9D05.jpeg
Posted By: DaveRS23

Re: LCA's worn out/junk? - 03/19/20 02:47 PM

The LCA bushings are easy to damage or destroy without some experience with them. If those involved aren't familiar with the slop being posted about, then they may not be familiar with the bushing install. Might be best to have someone more familiar with them review the bushings.

Where in Illinois are you? Anywhere near me? I'm in Benton 62812.
Posted By: 4406bbl

Re: LCA's worn out/junk? - 03/19/20 03:48 PM

Ya they are kinda loose there, the only upgrade is a set of bigblock lower arms as they have a sleeve belled out there and tend to be less worn. I have an nos bigblock arm and it is looser than my 40k mile originals so maybe a vendor thing. I have seen the nonbelled arms get pretty loose there, would think it could cause a phantom clunk under certain conditions. I change then to the better arms if I have them.
Posted By: 83hurstguy

Re: LCA's worn out/junk? - 03/19/20 03:49 PM

Thanks everyone, appreciate the feedback. They were clearly put together wrong when restored a while ago, because the rubber bushings had failed by squeezing out like posted above (I didn't take any pictures of the "before" condition).

We replaced the rubber bushings with the firmfeel delrin bushings. They are one piece solid bushings, and they pressed into the lower arm using what I could consider to be reasonable effort.

We are in the south Chicago suburbs (Mokena, IL). We've done control arm bushings before on GM cars, so it's not my first rodeo with bushings, but my first experience with Mopar stuff.
Posted By: Jim_Lusk

Re: LCA's worn out/junk? - 03/19/20 04:55 PM

Yes, that slop is normal, but it can be made tighter.

https://youtu.be/Nwes-SP8u4w
Posted By: 83hurstguy

Re: LCA's worn out/junk? - 03/19/20 06:33 PM

Thanks Jim! Ironically I had found your video a bit ago, thanks for sharing (and for putting that together!)
Posted By: Mopar Mitch

Re: LCA's worn out/junk? - 03/19/20 08:50 PM

I'm also using the Firm Feel Delrin LCA bushings.. still to hit the road and track (road race track)... this summer!
Posted By: DynoDave

Re: LCA's worn out/junk? - 03/20/20 01:08 AM

Originally Posted by Jim_Lusk
Yes, that slop is normal, but it can be made tighter.

https://youtu.be/Nwes-SP8u4w


Good stuff. Thanks for sharing that. up
Posted By: Jjs72D

Re: LCA's worn out/junk? - 03/22/20 06:49 AM

Originally Posted by 4406bbl
Ya they are kinda loose there, the only upgrade is a set of bigblock lower arms as they have a sleeve belled out there and tend to be less worn. I have an nos bigblock arm and it is looser than my 40k mile originals so maybe a vendor thing. I have seen the nonbelled arms get pretty loose there, would think it could cause a phantom clunk under certain conditions. I change then to the better arms if I have them.


I think that you are ill informed. There were no "big block" suspension parts other than larger torsion bars.
Posted By: 83hurstguy

Re: LCA's worn out/junk? - 03/23/20 01:34 PM

Quick update for closure - we put the tension on the torsion bars and the slop was taken up.

Ironically, without tension on the torsion bars, the torsion bar sleeve didn't have the side-to-side slop that you could fix by cutting the arm apart and re-welding (shown in the video above), it's only radially around the torsion bar sleeve. I'm guessing if you hit a good bump it could cause the arm to migrate a bit, probably something to fix long-term.

Thanks again to everyone for the help.
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