Positive caster on Tubular Upper Control Arms

[tonyvol]

Hey guys, I'm looking to buy upper control arms for a 67 camaro and want to see what you guys thought about tubular upper control arms. Some manufactures state that they have positive caster built into their arms and some don't. Are the one's that have more positive caster built in better than one's that don't? For example Hotchkis has +1 positive caster where as Speed Tech has +4. What do I need to look for to find the best tubular control arms?

Thanks,
Tony

[Bryce]

Try the search function, there are a ton of threads wiith this exact same topic.

[David Pozzi]

Some like Hotchkis & DSE have added caster built into both the top AND the lower A arms. This keeps the spindle centered and lessens the chance the tire will contact the wheelwell splash panel to the rear of the tire. Global West, Speed Tech & some others have the caster built into the upper arm. BMR and Ride Tech have some good arms, but I don't know if the caster is split or not.

[tonyvol]

Thanks guys for replying back.

Bryce, I did a search before I posted but didn't find the answer I was looking for.

David, so... what do I need to look for in a good set of tubular control arms? Is the one with more caster built in better than one that has less?

Thanks Again Guys,
Tony

[SR71]

I am a big fan of the sc&c spc adjustable uppers. you can adjust them to fit your needs.

[JRouche]

Thanks guys for replying back.

Bryce, I did a search before I posted but didn't find the answer I was looking for.

David, so... what do I need to look for in a good set of tubular control arms? Is the one with more caster built in better than one that has less?

Thanks Again Guys,
Tony

Hey Tony. Im not sure about the arms for the Camaro, I have a Nova.

Im curious why you are looking for so much caster? I did also. Because everything I read, no hands on knowledge for me, said you really cant go too far with caster as long as its within reason (say 7-10 degrees).

A large caster is good cause it supplies some camber gain in a turn for cars lacking (our cars) and there really isnt any neg issues besides possible tire clearance and steering stiffness. Guys with lots of room and power steering have it solved.

So I bought some SPC control arms for the uppers. And I modified my mounts and the way I can tune the suspension. I did the alignment with my home grown jig and ran the front suspension through many variables. Mapped it all out on paper using various caster settings with the intention of keeping the camber and toe at a set number.

I didnt want the camber (and toe) to travel unexpectedly, I wanted a nice curve (a straight line would have been perfect but there will be some camber curve issues). So after ALOT of changes, upper arm length changes, shim changes and combined changes I found the best camber curve when the caster was at a lower number. I forget, I can go look but I think it was around 3 degrees of caster.

Setting it there gave me a consistent camber change that was somewhat linear from static ride height through the entire compression range (the outside tire that is taking the load) of my car.

When I tried to stuff in more caster the camber was erratic. It would rise fast for the first inch of compression and dwindle off for the last 2.5 inches. Or the other way around, slow camber change at first and a fast change during the last part of the compression depending on how much caster I dialed in.

I wanted a car that was predictable throughout the compression of the loaded tire so I dialed in the 3 degrees from what I saw when running the suspension and documentation I made.

Best thing about the adjustable upper arms and using shims also? I have a wide range of changes that I can make and if I get board I have my paper still and know what amount of turns for the arms should be and what shims to use for a specific number. Then I can just make the changes, break out the alignment jig and re-align it for the changes. Yes!!! I like to play with my car. Not a race car, its MY toy.

But I have to add. My car is an adjustable car to the point of adjusting yerself off the road if you take large steps. I have a parallel four link (with the full compliment of adjustments there), a watts link that has more adjustments than most, adjustable sway bars front and rear, adjustable upper control arms that are shim mounted for more adjustments. The only thing thats NOT adjustable is the springs. They are air springs. But the shocks are double adjustable also so thats one extra noodle in the mix. And the adjustable bumpsteer links from baer.

With that many adjustments you really NEED to make a folder and document the changes you make and follow up to write how it changes the handling of the car. I happen to like to keep a few folders for my car.

I think you will be ok. You have some great info from the other guys. Just try not to get too set on one set of numbers, like a high caster number. You can still hit the sweet spot without having to use a heavy caster.

I think David hit it on the head. Try to use some upper and lower arms that work together. The folks (there are a few) that produce the arm sets have done the homework. Id pay the money for their parts and the homework they did...JR

[tonyvol]

Thanks SR71 for the great advice. Also, nice car you have.

Thanks JRouche for the great write up. Thanks for taking the time to explain suspensions in a way that I can understand.

Tony

[badazz81z28]

I like the design of the SC&C arms, but they do not have bump stops.