Rear lca recommendations

[Champale]

Like Norm, I am not seeing the spherical end despite the possibly typical ebay misinformed description.

The WL LCAs have bushings that have a little more give than the poly bushings, which can bind at full articulation. I used to have the Steeda billet alloy non-adjustable ones with poly on one end and spherical/heim on the other and I can't feel a difference, to be honest. The Steedas are beautiful, though.

 

[Midlife Crises]

Installed this set of BMR adjustable arms today. Easy to do. Don’t remember what brand the solid ones are But they are 10 years old.

 

[JEWC_Motorsports]

https://trackmustangsonline.com/threads/suspension-failure-you-guys-should-see-this.5413/

 

[Juice]

Pretty much why I'm skeptical of aftermarket suspension products. Except from maybe Maximum motorsports, those guys actually race test there shit.

 

[Midlife Crises]

Seems like all the ranting about suspension parts failure is based on one Whiteline UCA breaking. Haven’t seem pictures of BMR or UMI failures.

 

[JEWC_Motorsports]

There have been many Whiteline UCA's and LCA's fail. Most of what people run now are the swaybars and thats pretty much it.

 

[Champale]

I had one of the early WL UCAs that cracked within 100 miles of use and thankfully I caught it before it broke free. Not good.

But WL really went to work and re-engineered their stuff and I have no qualms about the current LCAs they sell (I bought mine about 2 years ago). They seem very sturdy. BTW Vorshlag used their stuff for years on their incredible 2011 GT track car.

 

[Enfield]

Pretty long record of Whiteline failures. Wasn't going to mention, but IIWII.

 

[1950StangJump$]

Installed this set of BMR adjustable arms today. Easy to do. Don’t remember what brand the solid ones are But they are 10 years old.

View attachment 77331

You have a picture of the new ones installed? The bushings on either side of the spherical end are sized differently, and the instructions weren't terribly clear which side the longer ones should be on.

I'm pretty sure mine are on correctly, but want to see what you did.

 

[Midlife Crises]

I did not take a picture of the arms mounted but the long spacer goes on the inside at the axel end.

 

[1950StangJump$]

I did not take a picture of the arms mounted but the long spacer goes on the inside at the axel end.

Here is a picture of how mine is installed - note the position of the larger bushings on the inside of the spherical end. Is this what you meant?

 

[Midlife Crises]

Here is a picture of how mine is installed - note the position of the larger bushings on the inside of the spherical end. Is this what you meant?

View attachment 77351

That is exactly what I mean. Looks real familiar by the way!

 

[Doug Huggard]

After replacing front control arms and upper rear control arm rear bushing, and installing new shocks, wheels, and tires, I went for a test drive. The car handled overall much better, but on turn-in about half the time it felt like the front and rear axles were fighting each other. Stringing revealed that the passenger rear is toed in about 2mm, while driver rear is toed out a similar amount. Fronts are just where I want them: toed in about 1/16". Side-to-side rear toe is 0, as one would expect. Wheelbase is about 3/8" longer on driver's side. There is also a buzzing vibration that suggests a binding driveshaft at about 35mph and again at about 70.

These symptoms suggest a problem with rear lca's. The car came with J&M nonadjustable rears; I haven't checked the condition of their bushings and don't know whether I need to, or should just replace the arms with something adjustable. Should I bother with having an alignment tech check the whole chassis for kinks or bends first? Given the rather consistent nature of my measurements, I'm leaning toward just installing the lca's and having a tech set the rear toe and pinion angle afterwards.

No drag racing or hard launches contemplated, so I guess that arms with somewhat stiffer rubber bushings would best serve.

All suggestions welcomed, tia

Enfield

 

[Enfield]

I'm not a fan of LCAs with polyurethane bushings at both ends, and I'm not aware of any adjustable-length LCAs that use OE rubber-style bushings. Better than poly/poly is if one end uses a spherical joint, which does not have to be a metal-on-metal rod end.

What is it about the poly/spherical arm that makes you a fan, Norm?

Spohn arm looks a lot like the BMR unit that seems to be popular on here.

Enfield

 

[Norm Peterson]

What is it about the poly/spherical arm that makes you a fan, Norm?

It comes from understanding how various kinds of structural connections work - I was a civil/structural engineer by education and most of a career (I'm retired these days).

Ideally, you don't want the LCAs or the UCA to carry any loads other than pure tension or pure compression. But depending on the details of the end connections (to the axle on one end and to the chassis at the other) those are not the only loads that those arms can see.

The main problem comes when the joint only permits rotation about the centerline axis of its inner sleeve, where the actual motions of the axle involve rotation about other axes. Think roll due to cornering here, where the body rolls more than the axle does (yes, the axle "rolls" a little based on lateral load transfer and tire vertical flexibilities). Point being that these arms need to release the torsional joint moments or else they start turning the rear axle into a virtual sta-bar that can in some cases (like the Fox chassis) be as stiff as the real physical one. That throws off the front to rear roll stiffness balance, and can make for noticeably more lateral head-toss as you cross a drainage gutter at an angle.

One spherical joint is enough to eliminate those end moments and the resulting forces, because it is equally free to rotate about any resulting axis up to the point where it runs out of angular travel. Ford mostly solves this force/moment problem by specifically using soft-ish rubber bushings which will deform in the off-axis directions without building up large forces. Polyurethane's higher stiffness puts those forces and moments back to being relatively large - on most forums this is loosely described as 'bind'.

If you're only going to drag race or never take corners all that hard, poly is at least sort-of do-able, though the head toss will still be there. And at the strip a little extra rear roll stiffness actually helps a stick-axle car. But for a wider range of uses, it's not the hot tip (just the cheap one for those looking for firmer fore-aft axle location and who aren't aware that there's more to this than first meets the eye).

There are a few DIY modifications that you can make to polyurethane bushings to put some compliance back into them without totally destroying their fore-aft stiffness advantages. You won't get all the way back to OE rubber softness, but you could probably get 75% of the way there without compromising bushing durability too much (side note - as long as they can be made to last, poly bushings really should be considered 'wear items' whether you modify them or not).


Norm

 

[Enfield]

So in some cases a poly/spherical LCA combo might actually contribute to a smoother ride?

And how about motions that are carried through the upper control arm? Right now it has poly at the rear and oem rubber at the front. Not really looking to do any more with the UCA, as getting that rear replaced was rather tedious.

Thanks for the explanation. Retired here, too, and planning to take some tours around our great country in the GT soon.

 

[JEWC_Motorsports]

Poly/Poly works fine as long as they are maintained properly and the proper grease is used.

 

[Norm Peterson]

Poly/Poly works fine as long as they are maintained properly and the proper grease is used.

IF you don't do much hard cornering.


FWIW, there are more effective ways of keeping poly bushings from squeaking than endlessly re-lubing them and waiting for the squeaks to return . . . one of those ways also eliminates the 'clunk' that is another fairly common downside of poly.


Norm

 

[Norm Peterson]

So in some cases a poly/spherical LCA combo might actually contribute to a smoother ride?

Certainly over significant one wheel bumps. I suspect a bit better generally, though I don't know how noticeable the difference might be over any given stretch of road.

And how about motions that are carried through the upper control arm? Right now it has poly at the rear and oem rubber at the front. Not really looking to do any more with the UCA, as getting that rear replaced was rather tedious.

The UCA is an even worse place for poly/poly than in the LCAs. The angular movements and off-axis rotations are exaggerated because the UCA is much shorter than the LCAs.


Norm

 

[Juice]

You guys are making me spend money lol

Not many options for poly/spherical LCAs. Tons of poly/poly lmao