Reinforced lower control arms vs. upgraded/tubular lower control arms?

-
MRGTX

MRGTX

Well-Known Member
Joined
Sep 24, 2007
Messages
2,198
Reaction score
728
Location
CT, USA
Consensus around here seems to be that the stock LCAs have enough flex to introduce some slop into the handling, particularly when stiffer torsion bars are part of the equation.

It seems like a lot of you guys upgrade the stock arms with welded-on plates, upgraded bushings. etc. ad it seems that this does the trick.

That said, if you factor in clean-up, parts, labor (particularly if you're not an experienced welder), it's likely not much more expensive to buy "upgrade" control arms from QA1 (or others?)

What are the pros and cons of each approach?



F142744102.jpg

mopar-lower-control-arms.png
 
It depends and I see where you're coming from. If you don't have the welding ability or access to it or someone that does and you plan to run a sway bar and don't have arms with tabs (as you'd have to weld them on to do it right) and if your arms are possibly worn/rusty crusty/super sloppy then probably new tubular is the way to go. In the end its your call, time and money. I know time is not on my side so I spend more on things to save it.

If we knew your location you might be able to find a local to help you you out.
 
Last edited:
My time is basically worthless, so I reinforce my factory ones, those tubular ones I doubt are any stronger, I think they are designed to lighten your wallet is all!
 
MRGTX said:
Consensus around here seems to be that the stock LCAs have enough flex to introduce some slop into the handling, particularly when stiffer torsion bars are part of the equation.

It seems like a lot of you guys upgrade the stock arms with welded-on plates, upgraded bushings. etc. ad it seems that this does the trick.

That said, if you factor in clean-up, parts, labor (particularly if you're not an experienced welder), it's likely not much more expensive to buy "upgrade" control arms from QA1 (or others?)

What are the pros and cons of each approach?
Click to expand...

The weakest part of the factory control arm is the cast outboard end that holds the lower ball joint. Even a mild curb bump is enough to bend it. The weld on lower plate does nothing to address that, but it does help stop the flexing of the lower stamped sheet metal parts.

The cost of purchasing both upper and lower control arms is high, but they do strengthen those components.
 
Old MoPar stock cars ran a "C" Body inner, tied to a "B" Body outer, where the ball joint is located. They were boxed, like the pic above. "C" Body inner was used to use larger diameter T-bars.
Tossing a 3,900 car at 200 mph into a turn at Talladega puts a lot of stress on the lower arm and ball joint.
All this being said, I can't recall a MoPar failure during a 500 mile race.
 
I ran the QA1’s. I believe they are stronger. I just got tired of looking for a set of nice 46 year old lowers with sway bar tabs.
 
odcics2 said:
Old MoPar stock cars ran a "C" Body inner, tied to a "B" Body outer, where the ball joint is located. They were boxed, like the pic above. "C" Body inner was used to use larger diameter T-bars.
Tossing a 3,900 car at 200 mph into a turn at Talladega puts a lot of stress on the lower arm and ball joint.
All this being said, I can't recall a MoPar failure during a 500 mile race.
Click to expand...
Yeah, I was gonna mention that....I have YEARS of asphalt oval track experience with torsion bar mopars, and the only time I EVER bent one was from hitting the wall
 
a friend just put the entire set up in his charger.. said they he needed to use the QA1 sway bar. wasn't sure if he was mistaken or not.
 
abodyjoe said:
a friend just put the entire set up in his charger.. said they he needed to use the QA1 sway bar. wasn't sure if he was mistaken or not.
Click to expand...

Yeah, in that picture of the QA1's the sway bar tab looks too far in to use a factory swaybar.
Here's a pic of my lower arm with factory swaybar. You can see the tab is clear out past where the shock mounts.

IMG_1230.JPG
 
I would agree with Dano, if you have the ability to weld or a friend that does than go with the plates. You are the only one that can determine how much your time is worth. The Qa1 arms are very nice product and I recommend them all the time to customers that have bent or rotted out arms that need replacing. They are a great alternative, but from a performance stand point the only thing it may have over stock is strength slightly but from a geometry stand point there is no improvement.

Thansk
James
 
abodyjoe said:
will the QA1's use a factory style sway bar or do you have o buy a QA1 sway bar too?
Click to expand...
I literally just 2 weeks ago installed QA1 lowers and a factory sway bar. The drop links are perfectly lined up. No issues at all for me.
 
I had to move the mounts on the QA1 for my 69. They did not line up with the sway bar.
 
abodyjoe said:
will the QA1's use a factory style sway bar or do you have o buy a QA1 sway bar too?
Click to expand...

They will, but I can only comment on the ones for the 73+ application. I run the QA1 LCA's on my Duster, and I use a Hellwig front sway bar that uses the factory mounting tab locations. I did have to shorten the end links compared to the factory LCA's with 73+ sway bar tabs, but the end links were in the correct position. I don't know about the 67-72 sway bar application, but I'm pretty sure there's only one QA1 LCA for A-bodies, and the tab is for a 73+ bar, so they won't line up with a stock 67-72 sway bar.

I pretty much agree with everything that's been said so far. The tubular LCA's are nice, they are lighter than the stock LCA's by a few pounds, and I would wager that they're probably a bit stronger than a boxed set of stock LCA's because of the way the ball joint mounts are attached. If you can weld and your LCA's are serviceable, ie, straight and not significantly rusted or damaged, boxing the stock LCA's will probably be more than enough for you.

I doubt anyone is going to really notice any kind of a handling difference going from a boxed stock LCA to a QA1 tubular LCA. I didn't, and I swapped from a boxed stock LCA to the QA1's. The difference in weight isn't big enough, and the difference in strength probably isn't needed for the vast majority of applications. As long as you've boxed the stock LCA's and taken the slop out of them at the torsion bar socket the differences will be pretty darn small.

There is a noticeable difference in one area, and that's the cross sectional height of the LCA's. The QA1's have a shorter cross section. What does that mean? It means more suspension travel. The difference is about an inch, although that's without any kind of bump stop. So, for a car that's been lowered (like mine!) you can gain back some suspension travel with the QA1 LCA's. Or at least, you could. I've seen an updated design for the QA1's that has a bump stop now integrated into the LCA, which would eliminate that change.

This is the old design, like the one's I installed
mopar-lower-control-arms-png.png

This is the new design, which would eliminate any change in suspension travel
img_2876-jpg.jpg


If you have the old design you can just add a bump stop to the factory frame stop, which is what I did. It takes away some of that extra travel, but not as much as the new design, so there's still some extra travel vs stock.

This is my set up, you can see the bump stop added to the stop on the frame, as well as the alignment with my Hellwig sway bar. And my fancy SPC adjustable control arms from Bergman AutoCraft. The upper bump stop is also much taller, this is to recenter the suspension travel around my lowered stance.
img_4412-jpg.jpg
 
Last edited:
Also the QA1’s do not have built in steering stops, but you could add something to them.
 
@MRGTX Honestly, you really don't need either.
a. The side loads are not about the t-bars, its much more about the use and the tires. So unless your putting this into some serious sticky R's, or dirt tracking, the loads will not be there.
b. The forces the act on the lca's are not twisting the arms to any great extent.

Tell you some things that do break; sway bar linkage and brackets, rims occassionally - and they certainly flex, and if the t-bar anchors aren't welded well or rust damaged, they break free - otherwise they're fine.

So if you want to put a strap across the bottom, go for it (unless you're ruleset says its not allowed). It's not going hurt, it may help a little. If its not convenient now, don't worry about it. Its not that hard to do later.

So that's my opinion. I've flexed rims enough to slice off the wheel weights, seen several road racers and autocrossers bust swaybar linkage - I should include myself but it was on Chevi. lol. There's classic photo of one of the Chrysler France e-body 'cudas with the rally rim busted.
 
Mattax said:
@MRGTX Honestly, you really don't need either.
a. The side loads are not about the t-bars, its much more about the use and the tires. So unless your putting this into some serious sticky R's, or dirt tracking, the loads will not be there.
b. The forces the act on the lca's are not twisting the arms to any great extent.

Tell you some things that do break; sway bar linkage and brackets, rims occassionally - and they certainly flex, and if the t-bar anchors aren't welded well or rust damaged, they break free - otherwise they're fine.

So if you want to put a strap across the bottom, go for it (unless you're ruleset says its not allowed). It's not going hurt, it may help a little. If its not convenient now, don't worry about it. Its not that hard to do later.

So that's my opinion. I've flexed rims enough to slice off the wheel weights, seen several road racers and autocrossers bust swaybar linkage - I should include myself but it was on Chevi. lol. There's classic photo of one of the Chrysler France e-body 'cudas with the rally rim busted.
Click to expand...

I'm confused. You say there's no twisting forces acting on the LCA, and then you follow that by saying the sway bar brackets break. Well, the sway bar tabs on the LCA aren't mounted on the centerline of the LCA (from pin to ball joint), so, yeah, the sway bar tabs are introducing twisting forces on the LCA. The force applied by the sway bar primarily acts in the same plane as the motion of the LCA, but since the tabs are basically a lever between the centerline of the LCA and the endlinks where the force is applied, well, a component of that force will twist the LCA. The bigger the sway bar, the bigger the force acting to twist the LCA. Boxing the LCA will improve the rigidity of the LCA, so the tabs are less likely to flex the wall of the LCA that they're attached to.

The other thing is that the slop between the LCA body and the torsion bar socket/lever does allow the LCA to flex about on the socket. Jim Lusk's video on installing the reinforcing plates highlights that area of slop. Inputs from the strut rods, sway bar, and hard braking/acceleration will move the LCA around on the socket a little if there's space there. Using the plates you can tighten up the joint that's formed by the torsion bar socket/lever and the LCA itself. A strap across the end of the LCA does the same thing, it's not so much to add strength, but improve tolerances.
img_2790_zpsj1t3mbyg-jpg-jpg-jpg-jpg.jpg





You're right, neither of those things is a huge deal by itself and with all season tires and stock size sway bars it probably doesn't make a big difference. But as you add better tires, bigger sway bars, harder bushings (poly/delrin) that stuff does become more significant. The plates are inexpensive and pretty easy to install, so though they may not pay huge dividends like other modifications I think they're a good addition. It's not something you install and afterward go "wow, what a difference!", but it does help match the components to work better with other upgrades.
 
The links themselves is where I've seen breakage, not the tabs. When I write "brackets" I'm refering to the bar-mounting brackets on the K-frames. This is on the early style ones that are attached to the front weld flange. A third attaching bolt or welding those makes a big difference.\

I basically agree with you on any slop on the LCA bushings, and thats where all the forces are; vertical loads, a portion of for-aft from braking, and yes any twisting from the leverage applied to the sway bar tab.
 
72bluNblu said:
They will, but I can only comment on the ones for the 73+ application. I run the QA1 LCA's on my Duster, and I use a Hellwig front sway bar that uses the factory mounting tab locations. I did have to shorten the end links compared to the factory LCA's with 73+ sway bar tabs, but the end links were in the correct position. I don't know about the 67-72 sway bar application, but I'm pretty sure there's only one QA1 LCA for A-bodies, and the tab is for a 73+ bar, so they won't line up with a stock 67-72 sway bar.

I pretty much agree with everything that's been said so far. The tubular LCA's are nice, they are lighter than the stock LCA's by a few pounds, and I would wager that they're probably a bit stronger than a boxed set of stock LCA's because of the way the ball joint mounts are attached. If you can weld and your LCA's are serviceable, ie, straight and not significantly rusted or damaged, boxing the stock LCA's will probably be more than enough for you.

I doubt anyone is going to really notice any kind of a handling difference going from a boxed stock LCA to a QA1 tubular LCA. I didn't, and I swapped from a boxed stock LCA to the QA1's. The difference in weight isn't big enough, and the difference in strength probably isn't needed for the vast majority of applications. As long as you've boxed the stock LCA's and taken the slop out of them at the torsion bar socket the differences will be pretty darn small.

There is a noticeable difference in one area, and that's the cross sectional height of the LCA's. The QA1's have a shorter cross section. What does that mean? It means more suspension travel. The difference is about an inch, although that's without any kind of bump stop. So, for a car that's been lowered (like mine!) you can gain back some suspension travel with the QA1 LCA's. Or at least, you could. I've seen an updated design for the QA1's that has a bump stop now integrated into the LCA, which would eliminate that change.

This is the old design, like the one's I installed
View attachment 1715139489
This is the new design, which would eliminate any change in suspension travel
View attachment 1715139490

If you have the old design you can just add a bump stop to the factory frame stop, which is what I did. It takes away some of that extra travel, but not as much as the new design, so there's still some extra travel vs stock.

This is my set up, you can see the bump stop added to the stop on the frame, as well as the alignment with my Hellwig sway bar. And my fancy SPC adjustable control arms from Bergman AutoCraft. The upper bump stop is also much taller, this is to recenter the suspension travel around my lowered stance.
View attachment 1715139491
Click to expand...
That's sweet
 
I’ve seen a set of QA1s break on a b body. Unless real destructive testing is done you really can’t comment on strength with any certainty.
I’d venture to guess I’ve done more open track events than anyone here while using stock lower arms that are boxed using my pins and bushings without failure. Track driving puts a who new level of stress on front end parts. This is one reason why I made the hardware to use delrin bushings on the SPC arms I sell. The rubber would slide out of the arms...
 
You must log in or register to reply here.
-

Back
Top