My take on Lower control arm brace

[Will F.]

I wanted to put a traditional set on my car for ever. I just could not see spending so much money for some bent SS and a couple bushings. At least will tools and skills to build my own. So I thought I would share the progress of how my arms are coming out.

My idea was to make these adjustable with a center turnbuckle so that I could get not only the control arm where it needed to be but to also have the ability to ad a bit of caster angle by pushing the lower ball joint forward. Obviously it can not go much but when talking in Deg a little goes a long way.
Just like others before I plan to use the same two mounting points. Rear control arm bolt and the lower shock bolt. The tubes are currently way too long but I need to find the angle from rear bolt to front bolt before I can cut the radius and tig weld them together.
53132

[Lwanmtr]

Just my 2 cents..but if its supposed to be a brace, having that bit in the middle seems like a weak point where it would want to bend and possibly break under pressure.

[Bitsyncmaster]

The other adjustable links I've seen were built with larger components. I don't know the loads that arm sees.

[Will F.]

This is at least a billion times stronger than the control arm . hahah The center tube is actually .2360 thick and overall diameter is 1.00. The center turn buckle is grade 9 and the thread length is 1.75 long and fully tapped into the tube for full depth. You would have far worse issues if you bent this. lol Unlike the Z bent SS braces everyone gets 4-500$ for this carries the load directly from point to point completely eliminating any flex. Here are a few more pictures showing its construction. 531445314553146

[Will F.]

The other adjustable links I've seen were built with larger components. I don't know the loads that arm sees.

Well considering it has nothing at all right now, and is completely relying on the sway bar to keep the arm straight the loads cant be too great.

[Bitsyncmaster]

Well considering it has nothing at all right now, and is completely relying on the sway bar to keep the arm straight the loads cant be too great.

Are these for the front or back? I was assuming these are the rear lower control arms.`111

[Nicholas R]

This is at least a billion times stronger than the control arm .

A Billion?

Are you planning to put these on both sides of the control arm or just one?

[Will F.]

Are these for the front or back? I was assuming these are the rear lower control arms.`111

My plan is to put them on the rear of the front control arms. Since most of the load is pushing the arm back. I believe the arm sees very little forward deflection unless doing some extreme reverse maneuvers. While driving forward just the drag along is probably moving the control arm back, this is what gives this car so much bump steer.
While

[Will F.]

A Billion?

Are you planning to put these on both sides of the control arm or just one?

Yes , One Billionnnnnnnnn hahah Obviously not but I wanted to make it sound grand.

I plan to just put one on ear side on the rear of the front control arm. I don't see the advantage of both sides. Most modern control arms ( although much wider) are only mounted at two points in a triangular fashion. This is still going to have the sway bar mounted is the factory location. but like I said I don't believe this sees extreme loads. I mean how hard can you really push a car with 90 WHP .

[louielouie2000]

My plan is to put them on the rear of the front control arms. Since most of the load is pushing the arm back. I believe the arm sees very little forward deflection unless doing some extreme reverse maneuvers. While driving forward just the drag along is probably moving the control arm back, this is what gives this car so much bump steer.
While

The deflection between braking & acceleration is pretty eye opening:


https://www.youtube.com/watch?v=CMHO4Aydk04

[Will F.]

The deflection between braking & acceleration is pretty eye opening:


https://www.youtube.com/watch?v=CMHO4Aydk04

Although it is true there is deflection both ways its still far worse backwards. Your video is prof of this. The arm looks almost twisted while applying the brakes. Still this singular arm is going to control the arm from deflecting for and aft just from the way it is attached to the control arm.

[Gruffalo]

Wow, that video is an eye opener! Where will you attach the brace ? To the frame? And how will you achieve a straight line of suspension travel, the brace being a radius arm (in effect).

Definitely rooting for this one!


2015 VW e golf
2005 BMW 120i
1987 Porsche 928 S4
1981 Delorean dmc-12
1980 Fiat bertone X1/9

[Will F.]

[QUOTE=Gruffalo;223921]Wow, that video is an eye opener! Where will you attach the brace ? To the frame? And how will you achieve a straight line of suspension travel, the brace being a radius arm (in effect).

Definitely rooting for this one!


It will mount the same as all the other designs. From the rear control arm mounting bolt to the lower shock mount bolt. That way it utilizes factory mount points and makes reverting back to original very easily.

[dmcjohn]

Someone (in Germany I think?) used a similar design at one point - to use a solid tubular link between the back of the front lower control arm and the frame bolt. They went a step further and welded a bracket onto the frame to put the link in double shear at the frame. However, I believe they removed the brace again after testing.... I'll have to try and find that thread.

My only concern with making the lower control arm completely unable to deflect backwards by using a solid link like this (rather than the flexible one offered by Ed Uding), is that it would seem to me that you are introducing tension into the system.

The sway bar is mounted to the front frame extension and to each lower control arm. If you picture removing the lower control arm / spring / shock from the car, and just leaving the sway bar attached to the frame extension - as you lift it up and down it pivots on that frame extension mounting point, and the ends of the sway bar travel up and down in an arc, not in a vertical straight line.

Now put the suspension back in place, along with your solid link, which causes the lower control arm to travel straight up and down and does not allow any rearward deflection. The swaybar end is bolted to the lower control arm, which now prevents the sway bar from traveling in the arc - therefore there is now tension in the system as it goes through upward motion. So as the suspension compresses, and does not allow the sway bar to travel in an arc any longer, what is happening to the sway bar? Does the sway bar bend to mitigate (and over time will this cause metal fatigue)? Maybe the sway bar bushings are able to compress enough to take up the strain, without causing the sway bar to bend? I don't know, but I imagine this is why Ed's solution allows the braces to flex somewhat.

I'd love to see a solution which fully triangulates the lower control arm like what you are proposing here, so long as the movement of the sway bar is taken into account. On later mode Lotus Esprit's, I believe they added a very similar brace as what you are proposing, but (please correct me if I am wrong) they did this in conjunction with making a slide bushing on the end of the sway bar, so that it was able to still travel through it's natural arc while the lower control arm was prevented from deflecting backwards any longer. Maybe another solution would be a different sway bar mounting to the lower control arm using a drop link rather than a direct attachment.

Thanks,
John

[Josh]

Someone (in Germany I think?) used a similar design at one point - to use a solid tubular link between the back of the front lower control arm and the frame bolt. They went a step further and welded a bracket onto the frame to put the link in double shear at the frame. However, I believe they removed the brace again after testing.... I'll have to try and find that thread.

My only concern with making the lower control arm completely unable to deflect backwards by using a solid link like this (rather than the flexible one offered by Ed Uding), is that it would seem to me that you are introducing tension into the system.

The sway bar is mounted to the front frame extension and to each lower control arm. If you picture removing the lower control arm / spring / shock from the car, and just leaving the sway bar attached to the frame extension - as you lift it up and down it pivots on that frame extension mounting point, and the ends of the sway bar travel up and down in an arc, not in a vertical straight line.

Now put the suspension back in place, along with your solid link, which causes the lower control arm to travel straight up and down and does not allow any rearward deflection. The swaybar end is bolted to the lower control arm, which now prevents the sway bar from traveling in the arc - therefore there is now tension in the system as it goes through upward motion. So as the suspension compresses, and does not allow the sway bar to travel in an arc any longer, what is happening to the sway bar? Does the sway bar bend to mitigate (and over time will this cause metal fatigue)? Maybe the sway bar bushings are able to compress enough to take up the strain, without causing the sway bar to bend? I don't know, but I imagine this is why Ed's solution allows the braces to flex somewhat.

I'd love to see a solution which fully triangulates the lower control arm like what you are proposing here, so long as the movement of the sway bar is taken into account. On later mode Lotus Esprit's, I believe they added a very similar brace as what you are proposing, but (please correct me if I am wrong) they did this in conjunction with making a slide bushing on the end of the sway bar, so that it was able to still travel through it's natural arc while the lower control arm was prevented from deflecting backwards any longer. Maybe another solution would be a different sway bar mounting to the lower control arm using a drop link rather than a direct attachment.

Thanks,
John

Excellent information here. Thank you for contributing this John!

I have a project coming up this winter, which will use sway bar end links (like most cars) to get around this issue.

[Gruffalo]

Regarding tension... I understand John's point, but that tension must be negligible compared to the load on the sway bar when braking, as seen in the video.


2015 VW e golf
2005 BMW 120i
1987 Porsche 928 S4
1981 Delorean dmc-12
1980 Fiat bertone X1/9

[Lwanmtr]

Any energy from the suspension moving has to go somewhere, so as was mentioned earlier, the sway bar is designed to take the energy in a certain way, as is the frame...if you force that energy to move in a different direction it could cause stress in areas not designed for it. I'm not an engineer, but the frame and suspension parts were designed to work together in a specific way, altering that can cause problems. For certain you will need to make your mounting point on the frame more able to withstand basically the energy of the whole car pushing and pulling on it during braking and acceleration.

I hope you get working and that it works out fine....just giving my thoughts on doing a radical change like that.

[Patrick C]

Someone (in Germany I think?) used a similar design at one point - to use a solid tubular link between the back of the front lower control arm and the frame bolt. They went a step further and welded a bracket onto the frame to put the link in double shear at the frame. However, I believe they removed the brace again after testing.... I'll have to try and find that thread.

Ed Uding did this before switching to his more flexible braces. The frame was unable to handle the strain, as I recall.

As Ed said in this thread (please remember english is not his native language): http://dmctalk.org/showthread.php?6880-Lower-Control-Arm-Braces&p=100689&viewfull=1#post100689


It is not the same concept, your set is only the rear support that will stress the bold and frame in the end.
This is what we start with, after test and calculation it was not the way to go.
The force is a lot more thane you think, it is still a wonder that all the stock lower arms there.
Rust and bend metal , make it more weak thane it shoot be.
Call it what you like, as long you don,t call it Same concept.

Ed Uding
Delorean Europe

[Josh]

Any energy from the suspension moving has to go somewhere, so as was mentioned earlier, the sway bar is designed to take the energy in a certain way, as is the frame...if you force that energy to move in a different direction it could cause stress in areas not designed for it. I'm not an engineer, but the frame and suspension parts were designed to work together in a specific way, altering that can cause problems. For certain you will need to make your mounting point on the frame more able to withstand basically the energy of the whole car pushing and pulling on it during braking and acceleration.

I hope you get working and that it works out fine....just giving my thoughts on doing a radical change like that.

Wut?

The stock suspension setup is very poor, it can easily be improved upon.
Due to the sway bar triangulating the suspension (which is a stupid design) the lower control arm needs to follow an arc, adding in braces hinders this movement.

John covered this pretty well.

[Will F.]

Someone (in Germany I think?) used a similar design at one point - to use a solid tubular link between the back of the front lower control arm and the frame bolt. They went a step further and welded a bracket onto the frame to put the link in double shear at the frame. However, I believe they removed the brace again after testing.... I'll have to try and find that thread.

My only concern with making the lower control arm completely unable to deflect backwards by using a solid link like this (rather than the flexible one offered by Ed Uding), is that it would seem to me that you are introducing tension into the system.

The sway bar is mounted to the front frame extension and to each lower control arm. If you picture removing the lower control arm / spring / shock from the car, and just leaving the sway bar attached to the frame extension - as you lift it up and down it pivots on that frame extension mounting point, and the ends of the sway bar travel up and down in an arc, not in a vertical straight line.

Now put the suspension back in place, along with your solid link, which causes the lower control arm to travel straight up and down and does not allow any rearward deflection. The swaybar end is bolted to the lower control arm, which now prevents the sway bar from traveling in the arc - therefore there is now tension in the system as it goes through upward motion. So as the suspension compresses, and does not allow the sway bar to travel in an arc any longer, what is happening to the sway bar? Does the sway bar bend to mitigate (and over time will this cause metal fatigue)? Maybe the sway bar bushings are able to compress enough to take up the strain, without causing the sway bar to bend? I don't know, but I imagine this is why Ed's solution allows the braces to flex somewhat.

I'd love to see a solution which fully triangulates the lower control arm like what you are proposing here, so long as the movement of the sway bar is taken into account. On later mode Lotus Esprit's, I believe they added a very similar brace as what you are proposing, but (please correct me if I am wrong) they did this in conjunction with making a slide bushing on the end of the sway bar, so that it was able to still travel through it's natural arc while the lower control arm was prevented from deflecting backwards any longer. Maybe another solution would be a different sway bar mounting to the lower control arm using a drop link rather than a direct attachment.

Thanks,
John

John Thank you for this. This is excellent information. I wonder if the use of spherical heim joints would allow more of an arc then just a polyurethane bushing. I do however agree with Josh "
I have a project coming up this winter, which will use sway bar end links (like most cars) to get around this issue." having a sway bar with an end link is definitely a far better way to go, not to mention would add worlds of tunability. But this in turn would also require a 2nd brace on each side. At this point I would probably be easier to just make a custom lower control arm, and use the outer points of the original lower control arm mounting. That way there is a true triangular set up, and would achieve none of this arching that is cause by the sway bars attachment style.

[Patrick C]

At this point I would probably be easier to just make a custom lower control arm, and use the outer points of the original lower control arm mounting. That way there is a true triangular set up, and would achieve none of this arching that is cause by the sway bars attachment style.

This is exactly what Rob Grady's car is running. Prototype, triangulated LCAs from Legend Industries. Basically an upper control arm that has been cut, and then welded to a cut lower control arm.

See photos here:
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-MvpQfff/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-j2ZVWkP/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-272F3NT/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-d3465Sb/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-6Jp3CwK/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-tMD38N9/A
http://photos.grenexmedia.com/Events/Delorean-Mid-Atlantic-Club/2008-Spring-Social/i-rLKmQpV/A

[Josh]

At this point I would probably be easier to just make a custom lower control arm, and use the outer points of the original lower control arm mounting. That way there is a true triangular set up, and would achieve none of this arching that is cause by the sway bars attachment style.

that is the plan!

[Will F.]

Ive been thinking of this all weekend. The argument was made that the arm needs to move in an arc to prevent any extra stress. But if you look at the way the lower control arm is mounted it is a long bushing in the rear. If indead it is moving in a arch that means that that fixed bushing is also being pushed a pulled on. This just proves the poor design in the front suspension. If your truly worried about the slight arch the control arm is making in what is prob less than +2 -2 inches from center then any of the braces being sold are not going to work. I stand behind my thought that A custom lower A-arm needs to be fabricated to triangulate the setup and a sway bar mount with an endlink of sorts.

[dmcjohn]

I stand behind my thought that A custom lower A-arm needs to be fabricated to triangulate the setup and a sway bar mount with an endlink of sorts.

100% agreed - I would love to see a proper true lower wishbone developed with a modern mounting point method such as a drop link for a sway bar, rather than trying to develop bolt on solutions for the existing setup, which is always going to have to have compromises.

[David T]

While the design of the front suspension leaves a lot to be desired, it was designed with a basic goal in mind. The frame and suspension was designed by Lotus Engineering and their motto is "add lightness". They always try to make every part do at least 2 things. If you think the front suspension on a Delorean is bad you should see how they did the rear suspension on an early Lotus. They used the half-shaft as the lower control arm! It's not too bad until things get worn. When that happens it gives the car some peculiar driving characteristics! For a street car the front suspension is not that bad. Ever watch the wings flex on an airplane during flight? They move up and down and twist a LOT! Inspect the front suspension for worn, loose, missing, or broken parts. Makes sure the flange on the edge of the lower control arm is not bent or all banged or bent up. Make sure you have complied with the recalls. If you are tracking the car you may want to consider some kind of upgrade to the front suspension but if you are driving on the street what the car came with is adequate.

[opethmike]

While the design of the front suspension leaves a lot to be desired, it was designed with a basic goal in mind. The frame and suspension was designed by Lotus Engineering and their motto is "add lightness". They always try to make every part do at least 2 things. If you think the front suspension on a Delorean is bad you should see how they did the rear suspension on an early Lotus. They used the half-shaft as the lower control arm! It's not too bad until things get worn. When that happens it gives the car some peculiar driving characteristics! For a street car the front suspension is not that bad. Ever watch the wings flex on an airplane during flight? They move up and down and twist a LOT! Inspect the front suspension for worn, loose, missing, or broken parts. Makes sure the flange on the edge of the lower control arm is not bent or all banged or bent up. Make sure you have complied with the recalls. If you are tracking the car you may want to consider some kind of upgrade to the front suspension but if you are driving on the street what the car came with is adequate.

The frequently occurring broken lower control arms would disagree with you.

[David T]

The frequently occurring broken lower control arms would disagree with you.

After 30 + years you would expect things to start breaking. We also don't know the history on all of the ones that broke. There could be other influencing factors like it got bent from improper towing, a previous accident, striking a parking bumper or other road hazard, etc. That is why I said it should be inspected along with all of the rest of the suspension. We have seen TAB's break. Does that mean we should redesign the rear suspension? IMHO a good through preventative program should catch most things before they fail. That starts with getting the car into the best shape you can. Keep up with maintenance and do yearly inspections. I doubt most owners can say they do that so it should be no surprise things break. You worry about the lower control arm. I would worry more about a rotten frame that the LCA attaches to! That is a much larger and more common problem. Or brake fluid that looks like old gear oil. Or tires over 10 years old. Point is there are other, more common problems to fix that most owners are oblivious to.