CPP control arms caster angle?

[osdmike]

A friend of mine own this Chevelle -66.
We are wondering about the control arms.
The control arms were allready mounted when the car was purchased.
Are they mounted backwards, or....?(see pics.)

http://www.pixbox.se/alb_show_id1169128_page0.html (http://www.pixbox.se/alb_show_id1169128_page0.html)

It seem to be a problem to get a correct caster angle.
We have put a lot of shims(se pic.), but it´s not enough.
What´s wrong here?

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[Roadbuster]

Looks like the upper arms are swapped left and right.

See Popular Hot Rodding install: http://www.popularhotrodding.com/tech/0705phr_front_end_rebuild/photo_10.html

Looks like that bend in the upper arm should be toward the front.

Jon

[killer69]

Sure looks like they are backwards.

[osdmike]

I found this info from CPP "Car Suspension Component Instructions"

6472TCA-UK (http://www.classicperform.com/Instructions/PDF/6472TCA-UK.htm)

So it looks that the C-arms are correctly mounted.

But I still don´t understand why all shims are needed to get a decent caster angle.

Any thoughts?:hmm:


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[sik68]

Perhaps it is the lower arms that are swapped Left / Right? I think so because look at the angle that the spring and shock are making...seems wrong in comparison to the way the shock mount is oriented. But maybe I'm wrong because it looks like the bump stop is in the correct spot....

[6'9"Witha69]

Something is definitely backwards!! If not the uppers, then the lowers, as stated. The top of the upright should be tilted toward the rear, nor forward as seen in those pics.

[osdmike]

I checked with CPP "Car Suspension Component Instructions".
Bump stops should be on front tube. So lower arms are OK.
Also seen in "Popularhotrodding"-link above.

:dunno:

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[Roadbuster]

I found this info from CPP "Car Suspension Component Instructions"

6472TCA-UK (http://www.classicperform.com/Instructions/PDF/6472TCA-UK.htm)

So it looks that the C-arms are correctly mounted.

But I still don´t understand why all shims are needed to get a decent caster angle.

Any thoughts?:hmm:


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They are installed correctly according to the document you referenced.

Thinking about this, I now remember that the CPP upper arms copy the factory geometry. The factory castor angle is nearly zero on these cars, so to get a decent amount of castor you need to use a lot of shims.

The Popular Hot Rodding article mentions replacing the upper studs with bolts pointed outward for header clearance. The photo does not show the shims they needed to get a 'modern' alignment. http://www.popularhotrodding.com/tech/0705phr_front_end_rebuild/photo_09.html

You have to look close but this shot does show the amount of shims they have on that car:
http://www.popularhotrodding.com/tech/0711phr_1968_chevy_chevelle_big_block_swap/photo_19.html

[osdmike]

As you mentioned,..I have also read about that the caster angle is nearly zero on CPP c-arms.

So , now we are looking at adjusable c-arms.
(SPC or similar)
That will solve the problem, I guess.

Anyone have experience with these?

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[Roadbuster]

I have the SPC upper arms from SC&C. They work very well and are easy to adjust in as much camber and caster as you want.
Contact Marcus at SC&C. :)

Jon

[GenPac]

I have the SPC uppers as well with tall BJs and OE lowers. I have 7.8-8.9 deg of caster (1.1 cross) dialed in right now. Almost as much as I can go without clearance issues with the back of the fenderliner.

[osdmike]

OK! I´ll look into that
I guess the SPC uppers will work fine with the CPP lower,right?

Thanks for the info.:)


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[JRouche]

I have the SPC uppers as well with tall BJs and OE lowers. I have 7.8-8.9 deg of caster (1.1 cross) dialed in right now. Almost as much as I can go without clearance issues with the back of the fenderliner.

Wow, 8-9* of caster is a whole lot of spindle tilt. You have power steering huh? I have some SPC uppers and I use 5.5* caster. But its a diff type of car and manual steering. But the 5.5* is still 5.5* more than the stock suspension would allow. Its a much better setup.

Im curious. With the huge caster and tall BJs have you checked the camber gain. Im wondering if you could over camber it in a turn with that much caster? Whats your static camber. And camber gain if you measured that?

Also, with that much caster how does the tire look in the fender opening. With 5.5* it set my tire back almost an inch. I had to pull some caster out from 6* because of fender interference. JR

[JRouche]

OK! I´ll look into that
I guess the SPC uppers will work fine with the CPP lower,right?

Thanks for the info.:)


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They should work fine as long as the CPP lower arms are the same length as stock and they position the ball joint in the same area as stock. Meaning not forward or rearward. Ill assume they are built to pretty stock ball joint locations. JR

[GenPac]

Wow, 8-9* of caster is a whole lot of spindle tilt. You have power steering huh? I have some SPC uppers and I use 5.5* caster. But its a diff type of car and manual steering. But the 5.5* is still 5.5* more than the stock suspension would allow. Its a much better setup.

Im curious. With the huge caster and tall BJs have you checked the camber gain. Im wondering if you could over camber it in a turn with that much caster? Whats your static camber. And camber gain if you measured that?

Also, with that much caster how does the tire look in the fender opening. With 5.5* it set my tire back almost an inch. I had to pull some caster out from 6* because of fender interference. JR

IIRC static camber is 0°

[silver69camaro]

With that much caster, you've moved the outer tie rod pivot point by quite a bit. You should probably adjust that to get bumpsteer back to acceptable levels.