G-body 4 link control arm questions

[SSninja]

Quick question that I'm hoping one of you guys can answer for me:

I'm planning on picking up adjustable upper and lower rear control arms from UMI, along with a Watts link (Just waiting for the next sale to come around).

I think I have the upper arm sorted out (Roto-joint on the frame side and new rubber bushings on the axle side:

http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_71&products_id=373


For the lower arms, do I want to use a roto-joint on both ends, or only a roto-joint on one end with poly on the other?

Option 1 (From Spohn as I don't see a poly/rotojoint option from UMI now that I look):
http://www.spohn.net/shop/1978-1987-GM-G-Body/Suspension/Rear-Lower-Control-Arms/Rear-Lower-Control-Arms-Tubular-Adjustable-with-Spherical-Poly-Combo.html

Option 2:
http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_70&products_id=379

[UMI Tech]

I'd definitely choose UMI. :) Give us a call to help you decide.

Seriously though, we have great feedback on our poly/Roto lower combo. And we do have all combinations of poly/Roto/rod end.

And you mentioned Watts link?

Thanks for considering UMI.

Ramey

[SSninja]

Hey Ramey,

The only Rotojoint/poly lower arm that I see on the site isn't adjustable:
http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_70&products_id=365

The double adjustable lower arms advertised are either rotojoint or rod end on both ends.


My question is really this: Do you want to have a rotojoint on BOTH ends of the lower control arms? In my mind that would allow the frame side to pivot as well as the lower part of the axle side...Not sure if this is what you want the rear end to do?

[UMI Tech]

Hi Dave.

The upper arms on a GM 4-link act as the lateral locator. Double roto would be exactly the same as double rod end and would work fantastically on the lowers.

ramey

[SicMonte]

Do these adjustable lowers allow for beter pinion angle adjustment?

If so....I NEED THESE!