Suspension dilemma

DocDirk · #1 (**permalink**) 02-14-2009, 10:49 AM

Hello Norcal folks! I'm coming close to almost kind of nearing the part where I might someday soon .....oh well, I guess it'll never actually be FINISHED, but driveable...I hope so!! Anyhow I posted a question on the All Cobra Forum about my suspension and haven't yet figured out if I have a problem. The rear control arm is attached to the chassis at a point which includes a horizontal top, this limiting vertical motion. I include here a photo of the left rear assembly with the car on three wheels, the frame on a jack on the left rear. The rectangular control arm is at its upper range of travel even without a load on the car such as passengers or a bump in the road

I cannot get a response from the manufacturer so I'm hoping someone might be familiar with an answer to this query or perhaps steer me to a good build shop in N. Calif. where I might get a professional answer if it's not obvious from just looking at it. I'm tempted to cut the top out of the attachment point to give the arm more vertical travel but I'm not a pro and assume the folks who built this chassis did that for a good reason....

Thanks for any replies and I hope to see y'all some day soon!

Dirk

tmareina · #2 (**permalink**) 02-14-2009, 12:48 PM

I can't imagine why the top plate is built like it is. Cutting a portion out to allow travel would seem like the answer, but, call Tom Lucas at FE Specialties, in Sac. He might know a solution...he set up my suspension and did a great job. He is an advertiser on this site.

Good luck

Tom

jrjmac1 · #3 (**permalink**) 02-14-2009, 12:58 PM

You may have enough travel once you have the wheels on and body height adjusted with your coilovers when the car sitting on the ground. I would check that before doing any cutting on you suspension.

John

Don · #4 (**permalink**) 02-14-2009, 01:17 PM

DocDirk:

From the West Coast web site, might want to contact a builder/rep:

http://www.cobrakit.com/Dealers/Dealers.htm

FWB · #5 (**permalink**) 02-14-2009, 02:24 PM

i talked to someone about a year ago with the same situation on his west coast. he had dog bone style upper arms fabricated, west coast didn't seem to have an answer for him. i will check my notes to see if he mentioned where he got them made.

Fred

FWB · #6 (**permalink**) 02-14-2009, 02:47 PM

i looked but i don't have any further info except the thread link. go here and try to send him a message. i'm sure he'd tell you where to go to get new arms.

West Coast upper trailing arms hitting frame

Fred

Rick Parker · #7 (**permalink**) 02-14-2009, 03:54 PM

The lateral link must be able to travel through the entire pivoting arc without restriction. Does the other side have this same appearance? 2 solutions: 1. Convert to high quality rod ends with threaded tubes and replace upper and lower links. 2. Remove upper rectangular link and taper the end and weld a cap over the removed section, this is above the pivot point.

wanab5150 · #8 (**permalink**) 02-16-2009, 01:05 PM

I would remove the spring and check the actual shock travel with the control arm attached before I did anything else. Is there is a bind somewhere other than just the top of the control arm? If so, it's probably not just the top arm, but a combination of issues.
I would not cut the gusset on the control arm pivot. There should not be much (if any) side to side torque on that joint from what I see, but it has the gusset for a reason.

I'm sure you checked to verify that the control arm is does not have an off center hole where the control arm is bolted into the pivot on the frame. Does it have a specific top and bottom? Have you tried rotating the control arm 180 degrees just to see if there's a difference? Could the arm be backwards?

The rod end solution would be more sano but you would have to shorten the control arm as necessary. You probably don't need the adjustability, but regardless, the rod ends should extend the control end far enough from the gusset to allow full travel. If the strength of the box control arm is not necessary I would just replace it with a pair of rod ends and link. From the photo, it looks like a guide more than a strength member. BUT..it's just a photo. tom

DocDirk · #9 (**permalink**) 02-18-2009, 05:59 PM

Yep, it's a guide as far as I can see, but I don't understand chassis physics anyhow. There's no suspension travel with the car at rest on the rear tires and there is a lot of spring/shot travel left. The mounting hole is centered on both sides and the arm is symmetrical. Perhaps if I search for other West Coast owners to survey them for this issue it will become clearer.

Thanks for the posts!

Dirk