I think the whole topic of twisting forces is definatly overated, the over engineered lower arms wont even notice the differnce

later models used a single pair of springs. I think, as strange as it sounds, people look at the tubular arm and figure it will want to twist around. If your really worried you could make a double shear bracket by running some flat steel from each wishbone pivot bolt, Essentially triangulating one side of the arm. If you utilise the pivot bolts theres no welding required and its all removable so ypu can easily return it back to original

Last edited by KLR250 (5/20/2011 12:03 am)

OK ... I'll throw my two cents worth. Yes there will be forces applied to the lower control arm with only one shock mounted BUT what the LCA is going to twist ?!? steel ... really ... the only way that any motion in the LCA could exist is if the mounting points allowed that motion. I know that you are running the UHMW bearings and that pretty much eliminates any movement. 

If that doesn't instill any confidence lets try this ... you are sitting at a stop light listening to your favorite tunes when suddenly a camaro pulls up next to you, he (or maybe a she) looks over at you at smiles. We all know whats going to happen ... 1st gear pedal to metal and blow the doors off that camaro. Well while that is happening the wheels are trying to rip the LCA's right off the car. I'm pretty sure that the LCA's are going to do their job and the forces imparted are going to be far greater than one little shock

One last visual .. I built custom LCA's for my IRS and I asked myself if I was going 100 MPH (I love going fast!) and had to slam on the brakes suddenly would the LCA do it's job ... I have no concerns ... but the point is if you were running stock or semi-stock in your case do you think that the forces applied during a panic stop would be greater than running one shock ???

One last thought, the LCA's were designed by Jag to handle the forces from a variety of inputs ... the shocks, I'm guessing, were designed to dampen only one force ... the up and down motion of the vehicle.

Last edited by Joe (5/20/2011 8:20 pm)

Read this! He is not the only one that broke a LCA at Club Cobra. My personal opinion, if you can't afford to do this right you should not be fooling around with something as critical as your suspension. Sure hate to be a dead bargain hunter! One more point, some run with only the LCA and two shocks. This is truly an issue, adding an upper watts link is very important.


"broken rear control arm..help "

"yes thats right 4th ride in our new cobra and the rear driver side control arm cracked is and making the wheel rub ever so slightly on the body.the wheel is about 1 inch forward.. where do i get a new one or do i have it reworked? the car has a jag rear end. are the control arms jag or cc? i need help bad....thanks.."
http://www.clubcobra.com/forums/contemporary-classic-forums/104598-broken-rear-control-arm-help.html#post1052216


http://erareplicas.com/427/shorten.htm

Last edited by Ralphy (5/21/2011 5:04 am)

I was still thinking about the twisting forces on the LCA this morning when I remembered that you designed your own sway bar configuration. I had to go back and look at the photos ... nice job by the way. That sway bar is trying to twist both of the LCA's right off the mounts. I am pretty sure that the forces from the sway bar far exceed anything a single shock is going to exert.

Ralphy wrote:

Read this! He is not the only one that broke a LCA at Club Cobra. "broken rear control arm..help "

good read, it sounds to me like it wasn't just a trailing arm issue and  the guy who thought it was a an XJ6 arm that had been improperly narrowed to fit an xke probably hit the nail on the head.  when I did mine I not only used gussets but I also sleeved the tuba and once I had it tacked in place deferred to a pro to weld it all up

Ralphy wrote:

My personal opinion, if you can't afford to do this right you should not be fooling around with something as critical as your suspension. Sure hate to be a dead bargain hunter!

I agree, if decisions are being made by cost and not quality you are in the wrong hobby.    In my case I am trying to do both, build the best quality unit I can but also not spend more than I need to. that is the whole reason I started this thread before just arbitrarily going to one shock

Ralphy wrote:

Daze I think I came to the answer to the question. Coilover in front or back?
With the load being behind the axle you will have a twisting motion of course around and down, rear of the axle. Hard acceleration pulls forward at the pavement twisting your wishbone even more. Add the extra load from weight transfer and you get even more load. Coilover should be in front not rear. What do ya'll say?

I could be mistaken but I think thats backwards, as your car move forward the front of the tire will be moving down pulling the top of the hub forward, this would cause a counter clockwise twisting (when looking at the drivers side wheel)  having the shock on the back would cause a clockwise twisting which should counter the accelerating twisting motion... right?????

Originally I was thinking "in the back"  there was no logic to it other than the fact that I was wanting to get the shock as vertical as possible and there is not a lot of clearance between my most outer front mount on my sub structure, and the underside of the car, but  after reading your post (before I pictured it in my head.... not sure if it's right or wrong) I tried mounting my single coil over in the front and it just barley cleared, and I can see some advantages of doing it that way:

1.  may or may not counter twisting, jury is still out on that one
2.  the sway bar is in the back so the sway bar will provide some counter balance to any twisting to the coil over creates
3.  the trailing arm is in the front:
       a.  I can make a tab off of the trailing arm that goes on the front side of the shock to help eliminate single sheer
       b.  The way my trailing arm pivots with the wish bone, it is like making the wish bone twice as wide and with the shock in the front and attached to both the trailing arm and the wish bone it will be "centered" roughly, so there will be no twisting
6.  I can use the upper shock mount on the Mustang to  bolt in bracket to put the upper mount in double sheer

thoughts???

"equal and opposite" 
when I was thinking about it I was picturing the twisting of the axle and tire, and from the drivers side that would be counter clock wise.  What I should have been thinking was "every action has an equal and opposite reaction"  if the energy being put in to the system was rotating in a counter clock wist motion than there would be clockwise twisting to compensate.  Thanks for talking it through ralphy.  I am really good a visualizing things but when the visualization also has movement it complicates things.  After seeing the picture you posted I went back to the xj40 thread and the OEM units also had the springs in the front which only strengthens the "mount them in the front" position.  what did you think of my other reasons to mount it in the front??
1.   counter twisting during acceleration (jury is in mount it in the front )
2.  the sway bar is in the back so the sway bar will provide some counter balance to any twisting to the coil over creates
3.  the trailing arm is in the front:
       a.  I can make a tab off of the trailing arm that goes on the front side of the shock to help eliminate single sheer
       b.  The way my trailing arm pivots with the wish bone, it is like making the wish bone twice as wide and with the shock in the front and attached to both the trailing arm and the wish bone it will be "centered" roughly, so there will be no twisting
6.  I can use the upper shock mount on the Mustang to  bolt in bracket to put the upper mount in double sheer

also you are so close to posting pictures directly in to the thread.  all you have to do is add [img]before the direct link to the picture and [/img]after it.

Ralphy wrote:

I think the upper watts link Mickmate came up with has a lot of merit.

I like the pic

I totally agree!!!!  I was on contact with Mickmate trying to come up with a way to modify his kit to make it fit in my car, but there is just not a lot of room between my sub frame and the tire.  I may revisit it with him, at some point because I think it is a stellar piece of engineering.  You still didn't answer my question what were your thoughts on my other reasons to run the shock in the front???

Daze, in what I have recently read. Why don't you try something like the Klaus Arning CMT design? I'm liking the design because what I have read it has toe control, anti squat and is the original design of the 427 AC Cobra. Gotta work on where I can fit the rear shock and this rear shock works.

http://mustangirs.com/pdf_articles/t5_technical_drawing.pdf
http://www.mustangirs.com/pdf_articles/racecar_engineering_2008-10.pdf

Last edited by Ralphy (5/24/2011 5:10 pm)

The whole thing is so adjustable call me. Check your mail.

Last edited by Ralphy (5/24/2011 5:42 pm)