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Control Arm/Torque Arm Compatibility

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ChrisM

Mostly harmless.
1,180
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South Carolina
Hello all, questions about the various rear/trailing arms/links/whatever. Would non-adjustable Boss 302 spherical LCAs and a non-adjustable Multimatic UCA, plus a one piece driveshaft and Cortex coilovers play well together? The recommendation is always to have adjustable arms somewhere for pinion angle but not sure if it's necessary. I don't see the racecars running adjustable arms, though I could be wrong and I understand they are set up to run those combinations. The second piece to this question, would a Cortex torque arm + non-adjustable Boss 302 spherical lower arms, along with a one-piece driveshaft work together and might that be a better option than the above setup?

I'm really trying to keep all my pieces within the Cortex/Ford Racing families. I've scoured as many threads as I could and noted a couple mentions where the non-adjustable upper and lower control arms have been used together but no follow-up. I noted one thread that mentioned Filip sent an email stating that non-adjustable arms were fine in conjunction with the torque arm since the individual was running Cortex coilovers. I honestly don't think I would notice much of a difference going with the torque arm and I really prefer simplicity over making drastic changes.

For reference, I already have the Cortex coilovers. I'm just trying to bring my hodgepodge of parts under one banner, or as close to one banner as possible.
 
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Pretty much any of the combinations you mentioned will work fine as long as you don't slam the car on the ground height wise.

What parts do you already have on hand?
 

Grant 302

basic and well known psychic
I don't see anything wrong with the lack of adjustability, aside from the potential for noise and vibration from driveshaft harmonics. IOW, I don't think adjustable arms are necessary, but will depend on what you'll tolerate pinion angle and noise wise.
 
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Norm,

You might want to elaborate about thrust angle. I suspect you are giving a reason for using adjustable lower control arms.

OP, its best to tell us what you already have on the car and possibly your goals.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
Thrust angle.

Norm

Norm,

You might want to elaborate about thrust angle. I suspect you are giving a reason for using adjustable lower control arms.

OP, its best to tell us what you already have on the car and possibly your goals.

Thrust angle as in making sure the axle is "square" so that when you accelerate you are going forward instead of having the axle at a wonky angle to the rest of the car. At least that's what I'm guessing.

No goals except my own OCD that wants all the same brand parts and to have a dependable track day car. I already have all spherical bearings on my BMR arms and they are fine, but I've got a bunch of random parts on the car. It's more like "if I were to do it over what would I do differently?" Well, I would have just gone with all the non-adjustable Ford Racing stuff from their FR500/Boss 302 programs, so that's what I'm doing now.
 
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If you already have BMR upper and lower control arms with spherical bearings, there is no reason to swap them. The BMR components are quality pieces. You are not going to gain anything with the Ford arms. The money is best spent elsewhere. Are the BMR arms adjustable? If so, I definitely recommend keeping them.

You can use adjustable lca's to change the thrust angle and make sure the axle is square with the cars center line. An adjustable upper will let you fine tune pinion angle.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
If you already have BMR upper and lower control arms with spherical bearings, there is no reason to swap them. The BMR components are quality pieces. You are not going to gain anything with the Ford arms. The money is best spent elsewhere. Are the BMR arms adjustable? If so, I definitely recommend keeping them.

You can use adjustable lca's to change the thrust angle and make sure the axle is square with the cars center line. An adjustable upper will let you fine tune pinion angle.

Yep, already have that done. Pinion angle was good already. Had to square it up a bit though.

Not really looking to "gain" anything from any of it, if I even do it, except to satisfy my own wants and desires. :rolleyes: The torque arm might have some advantages from what I understand though.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
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5-10 Years
a few miles east of Philly
Thrust angle as in making sure the axle is "square" so that when you accelerate you are going forward instead of having the axle at a wonky angle to the rest of the car. At least that's what I'm guessing.
Yes.

If thrust angle changes by more than just a tiny bit for any reason (when swapping LCAs, it can), you'll notice it as the steering wheel being not quite centered when you're driving down a flat and level road, or that you can hold the steering wheel straight and follow a gentle highway curve without moving the steering wheel at all. The proper fix here does not involve tierod toe adjustments (though I suspect that's the way most people - and most alignment shops - deal with it).

You can also adjust both LCAs in the same direction (longer or shorter) to make pinion angle changes without even touching the UCA, something you might want to consider just from changing the OE rubber-bushed LCAs out for LCAs with stiffer bushings or sphericals.

Just because some components can be adjusted doesn't mean you always have to be tinkering with them for street or most HPDE purposes (shocks & struts perhaps excepted). One or two iterations ought to get you close enough until you've got a clearer idea what you might like even better.


Norm
 
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I prefer Ford racing stuff, but just because I do doesn't make other brands inferior, BMR and others seem to be a quality product, if you have them installed and properly adjusted, I'd just go with it.
You will rarely see me bad mouth any decent products out there, it's hard enough to make a living in this business especially with all the internet experts critiscizing virtually everything from every brand. We all have our preferences that doesn't make the others junk. I forget the names of the trailing arms on my GT500, they were on it when I purchased it, but they are the suspension components from hell, so once I lowerred the car I took it to the alignment shop, did my thing and left them.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
Yes.

If thrust angle changes by more than just a tiny bit for any reason (when swapping LCAs, it can), you'll notice it as the steering wheel being not quite centered when you're driving down a flat and level road, or that you can hold the steering wheel straight and follow a gentle highway curve without moving the steering wheel at all. The proper fix here does not involve tierod toe adjustments (though I suspect that's the way most people - and most alignment shops - deal with it).

You can also adjust both LCAs in the same direction (longer or shorter) to make pinion angle changes without even touching the UCA, something you might want to consider just from changing the OE rubber-bushed LCAs out for LCAs with stiffer bushings or sphericals.

Just because some components can be adjusted doesn't mean you always have to be tinkering with them for street or most HPDE purposes (shocks & struts perhaps excepted). One or two iterations ought to get you close enough until you've got a clearer idea what you might like even better.


Norm

Norm, I have adjustable LCAs and a non-adjustable UCA. I went that route because the LCAs are easier to reach. I had a shop take a look at them after I installed them and they were able to correct the thrust angle with them. The pinion angle was fine. I haven't touched them since. They were definitely worth the money. I might consider the BMR spherical differential bearing to get that final rubber bushing out of the rear end.

I prefer Ford racing stuff, but just because I do doesn't make other brands inferior, BMR and others seem to be a quality product, if you have them installed and properly adjusted, I'd just go with it.
You will rarely see me bad mouth any decent products out there, it's hard enough to make a living in this business especially with all the internet experts critiscizing virtually everything from every brand. We all have our preferences that doesn't make the others junk. I forget the names of the trailing arms on my GT500, they were on it when I purchased it, but they are the suspension components from hell, so once I lowerred the car I took it to the alignment shop, did my thing and left them.

The BMR control arms have been stellar. I may have to reconsider and just go with all the BMR equipment since I'm already invested in some of it (with the exception of my Cortex coilovers and watts link).
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
I changed out the poly bushings for spherical on my LCA's and went with the spherical BMR UCA..... Was surprised that ride and noise was pretty good. At least better then I expected. The only poly I have left is in the UCA to the axle. THAT does squeak horribly. Will be re greasing it this weekend, probably make that spherical soon if the squeak comes back.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
I changed out the poly bushings for spherical on my LCA's and went with the spherical BMR UCA..... Was surprised that ride and noise was pretty good. At least better then I expected. The only poly I have left is in the UCA to the axle. THAT does squeak horribly. Will be re greasing it this weekend, probably make that spherical soon if the squeak comes back.

Yeah, I have all spherical bearings except for the diff bushing. Even my watts is all spherical. The whine from the gears drives me bonkers sometimes but whatever...racecar. The roll bar amplified it. Seems to just resonate everywhere now.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
I had the gear whine before switching to spherical. At the same time as the sphericals went in, had the rear redone with all new bearings... now it just whirrs instead. Big improvement, probably why the extra noise is not that much of a deal after the whine.
 

ChrisM

Mostly harmless.
1,180
1,419
Exp. Type
HPDE
Exp. Level
3-5 Years
South Carolina
Another interesting thing I noted was the difference in the lengths of the upper arms between 2005-2009 and 2011+. I believe the 2011+ are longer. I've seen one post that says that as long as you swap out the UCA mount on the 2005-2009 cars you can switch to the newer, longer arm. I'm no scientician, so I'm not entirely sure how that specifically is better, but my best guess is that the longer arm would mean less dramatic changes in angle as the control arm goes through its motions. I'd assume this leads to fewer changes in the roll center.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
The UCA - in conjunction with the LCAs - defines the side view instant center and from there the anti-squat percentage, but has nothing to do with the geometric roll center height. A longer UCA slows down SVIC migration (movement) and changes in anti-squat.

The geometric roll center is defined by the PHB in conjunction with the LCAs - it's actually a 3-D construction. But for most practical purposes the height of the PHB at car centerline is close enough, assuming that the midpoint of the PHB is on or very close to the car centerline as well.


Norm
 
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FWIW, I've worked on Ford 9inch, Dana 60s, Chevy 10 and 12 bolts and the Ford 8.8 seems to be the most prone to gear whine than all of them.I don't know if it's the design, or some harmonics, but as long as the pattern is good you should be fine, the gear pattern is the ultimate decider on what's right and wrong. I can definately see where having rod ends or a non rubber bushing would cause this to be exagerated.
 
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