lower arm control

**juxi** · 01-10-2015, 06:39 PM

i just bought a 2000 ss. The rear lower arms need replacement. But witch lca should i get boxed or tube ? the tube are less expensive and since my car will not see the drag strip that often i was thinking of getting those.
Are the worth the money or should i get the boxed?

**pajeff02** · 01-11-2015, 04:38 AM

Highly recommend a set of UMI tubular LCA's. As long as you are not lowered (and have no plans to be lowered) you can skip the adjustable variety and go with the standard LCA. Also recommend you swap out the panhard bar while you are at it.

Here's our car's UMI equipped back half (all non-adjustable, except for the torque arm):

**Naaman** · 01-11-2015, 04:00 PM

If you're looking just to replace them because they need to be there, get the most basic set you can get.

I've been doing some research on suspension parts and according to Sam Strano, the LCAs don't contribute significantly to the car's "handling." So if you're not looking for a handling upgrade, a standard set of polyurethane LCAs ought to be just fine, as Jeff said.

**35th-ANV-SS** · 01-11-2015, 04:14 PM

Tubular aren't as strong as boxed, but they'll work just fine for your application.

**Whamhammer** · 01-11-2015, 05:20 PM

Originally Posted by Naaman

If you're looking just to replace them because they need to be there, get the most basic set you can get.

I've been doing some research on suspension parts and according to Sam Strano, the LCAs don't contribute significantly to the car's "handling." So if you're not looking for a handling upgrade, a standard set of polyurethane LCAs ought to be just fine, as Jeff said.

What if a person is looking for a handling upgrade? Does one use the OEM arms, press in poly bushings, and box the arms in?

**Naaman** · 01-11-2015, 05:47 PM

Originally Posted by Whamhammer

What if a person is looking for a handling upgrade? Does one use the OEM arms, press in poly bushings, and box the arms in?

I'm not sure on that. Although, I believe FBJ does exactly that on his own cars. Manufacturers of LCAs will claim performance benefits, but then some racers/auto-x-ers don't use the rod-end/roto joints/etc and do just fine. I'm still trying to learn what how "28 degrees of rotation" translates into the car's ability to turn a corner or respond to steering input or whatever the benefit is supposed to be. And do I need that rotation on one or both ends of the LCA if I want "maximum" handling performance? I've asked before, but cannot get an answer that makes the performance benefits (if there are any) clear to me.

http://www.ls1.com/forums/f66/lcas-r...-combo-179588/

It seems like the rotating joint (rod end or roto-joint) allows for more tire contact during cornering, but according to folks "in the know," the LCAs need not be bothered with if "handling" is your goal (shocks, springs and sway bars, according to Sam Strano, are what make the most meaningful difference).

**35th-ANV-SS** · 01-11-2015, 06:13 PM

Yes, FBJ does just that. In fact, I sold him my OEM lower control arms so he could use them for that exact reason I believe.

Maybe he could provide some photos of what he does.

**Naaman** · 01-11-2015, 07:15 PM

I know he's posted photos of this exact thing around here somewhere...

**pajeff02** · 01-12-2015, 04:50 PM

Boxing the stock lower arms by welding in a steel plate is exactly how the factory started stiffening things up back in the day. Our '70 Olds W-31 has factory boxed lower control arms.

**Whamhammer** · 01-12-2015, 07:22 PM

Originally Posted by pajeff02

Boxing the stock lower arms by welding in a steel plate is exactly how the factory started stiffening things up back in the day. Our '70 Olds W-31 has factory boxed lower control arms.

I wonder how much stiffer a boxed in panhard and rr LCA's would be over a UMI rear set. I also wonder how much it would cost to buy and press in poly for the rear suspension.

**Naaman** · 01-12-2015, 07:44 PM

Seems like more trouble than it's worth. The basic poly LCAs from UMI aren't expensive enough to warrant the work, time, and parts of DIY, in my opinion. Kinda like changing your own oil: it costs just as much as to take it to the shop anymore (though I still advocate DIY maintenance).

**35th-ANV-SS** · 01-12-2015, 08:21 PM

I'd agree with that for the majority of people out there. In the case of FBJ, he likely has plate steel laying around the garage he can use so it would essentially be a fraction of the cost vs. buying new. $20 for OEM LCA's bought off someone (or free if you have them already) and a few hours of your time vs. $190 for boxed control arms, whereas standard tubular versions are only $110. Boxed will definitely be much stronger too. I don't think it would be too difficult assuming you had material and equipment to do it; that would be where most people would fall short.

**pajeff02** · 01-13-2015, 03:00 AM

Originally Posted by Whamhammer

I wonder how much stiffer a boxed in panhard and rr LCA's would be over a UMI rear set. I also wonder how much it would cost to buy and press in poly for the rear suspension.

I have installed several sets of bushings on our older cars. They kind of suck to do -- I generally get the torch out and heat it up to knock out the rubber insert, cut the shell so it can be collapsed for removal, run the control arm through my blast cabinet and paint it, and then press in the new bushing. I have a set of oak blocks I made that keep the arm from collapsing as the bushing is pressed in. It is kind of a pain and unless I am doing a pure restoration the aftermarket arms with the greaseable poly bushings are far superior imo.

**Naaman** · 01-13-2015, 03:24 AM

Originally Posted by 35th-ANV-SS

I'd agree with that for the majority of people out there. In the case of FBJ, he likely has plate steel laying around the garage he can use so it would essentially be a fraction of the cost vs. buying new. $20 for OEM LCA's bought off someone (or free if you have them already) and a few hours of your time vs. $190 for boxed control arms, whereas standard tubular versions are only $110. Boxed will definitely be much stronger too. I don't think it would be too difficult assuming you had material and equipment to do it; that would be where most people would fall short.

Yes, I wasn't including FBJ in my statement, either. In cases like his, where someone is already set up for it, and they enjoy doing it or it brings a specific sense of accomplishment, etc, then, by all means, I say have at it. If the goal is simply to get/keep the car on the road or achieve a performance end-state, I'd just as soon buy the parts.

**Whamhammer** · 01-13-2015, 06:36 AM

Originally Posted by pajeff02

I have installed several sets of bushings on our older cars. They kind of suck to do -- I generally get the torch out and heat it up to knock out the rubber insert, cut the shell so it can be collapsed for removal, run the control arm through my blast cabinet and paint it, and then press in the new bushing. I have a set of oak blocks I made that keep the arm from collapsing as the bushing is pressed in. It is kind of a pain and unless I am doing a pure restoration the aftermarket arms with the greaseable poly bushings are far superior imo.

FBJ, are you saying that the UMI tubulars are stronger than the boxed in LCA's?

In a nutshell, I like to drive some spirited and twisty backroads now and then and I would like to improve the smile factor if I can ( for a reasonable price).

**Whamhammer** · 02-12-2015, 08:13 AM

Originally Posted by Whamhammer

FBJ, are you saying that the UMI tubulars are stronger than the boxed in LCA's?

In a nutshell, I like to drive some spirited and twisty backroads now and then and I would like to improve the smile factor if I can ( for a reasonable price).

Sorry, I meant to aim that question at PA Jeff

***SMWS6TA*** · 02-12-2015, 08:23 AM

Jon has shown this in the past about that question. Box are stronger than tube if the same metal is used in both.

**theorangeguy** · 02-12-2015, 08:26 AM

Originally Posted by SMWS6TA

Jon has shown this in the past about that question. Box are stronger than tube if the same metal is used in both.

yea, I dont really know of a way to make a tubular design stronger than a box without using some type of exotic crazy expensive metal. Due to the way the metal can bend, boxed is stronger most of the time because it eliminates a lot of flex that "could" occur in a tubular design.

***SMWS6TA*** · 02-12-2015, 08:33 AM

It also has something to do with the wall thickness. Tubular needs a little more material to match the same strength as a box. Like I said, Jon explained it all to me 5 yrs ago when I was asking the same questions.

**Whamhammer** · 02-13-2015, 09:41 AM

Originally Posted by SMWS6TA

It also has something to do with the wall thickness. Tubular needs a little more material to match the same strength as a box. Like I said, Jon explained it all to me 5 yrs ago when I was asking the same questions.

So are the tubalrs at least stronger than factory/ stock? If not, whats the value proposition for them?