Suspension travel question

DocDirk · #1 (**permalink**) 02-13-2009, 08:13 PM

I'm still working on my West Coast build and noticed that the rear arms stabilizing the 9" Ford rear end attach to the frame at a point that has a horizontal top section where I would expect it to be open. This appears to me to limit the spring and shock / axle travel. The photo is of the left rear. This chassis came with that installation but the manufacturer has been building these for years and I don't imagine he designed it this way without a reason. I'm a near-complete auto amateur, so I'd defer to his expertise if I could get him to answer my phone calls / messages / emails. Can anyone shed some light on this? I'm tempted to cut off the top of this attachment point to allow for vertical travel...otherwise I think I'll be getting a pretty swift kick in the rear over most any bump requiring rear suspension travel. ....what am I missing here?

Thanks!

Dirk

mickmate · #2 (**permalink**) 02-13-2009, 08:26 PM

You should see where the suspension is on travel now, it may be at the top and that's a deliberate stop. That radius rod sure is stopping it's travel. Is it upside down? It looks like the holes are off center and that would give it some clearance.....

Tim Brewer · #3 (**permalink**) 02-13-2009, 08:36 PM

Just remove your springs so you can bottom out the suspension and see what bottoms out first, the trailing arm, or the shock.

427mudflap · #4 (**permalink**) 02-13-2009, 09:06 PM

It looks like you should replace the rectangular tube control arms with spherical rod ends and threaded tubes, you might need spacers on each
side of the rod ends.

DocDirk · #5 (**permalink**) 02-14-2009, 11:40 AM

Thanks for the replies! Mickmate, the suspension is viewed with the car on three wheels, the left side frame on a jack and the left rear wheel removed. There's no added stress on the suspension at this time at all.... meaning that the square tube has no place to go when the car gets loaded or and/or hits a bump. I'm so tempted to cut out the top side of the attachment at the frame to give it up and down travel, but hesitate because I'm not a professional builder and these guys ought to know what they're building... I'm a bit hesitant to drive this thing over anything but a perfect surface, concerned that the arm/attachment point might even do some damage if it has nowhere to go... Anyone know of a good chassis / build shop in N. Calif.?

Thanks again!

Dirk

glenview289 · #6 (**permalink**) 02-14-2009, 02:09 PM

If that is a solid axel car, pick up the both sides and if the suspension arms go down together you may need to dial in more spring on the coil overs, heavier springs, or longer springs.

Bill

CHANMADD · #7 (**permalink**) 02-14-2009, 03:28 PM

So.. When the car is on the ground..can you bounce it up and down in the back??
john

DocDirk · #8 (**permalink**) 02-19-2009, 01:01 PM

No, I checked and the rear end doesn't have any suspension travel with bouncing it while at rest - the rear control arms are actually up against the frame mount at this position. There is room between the rearend and the frame bumper above it so I suspect there will have to be modifications made.... even different springs/shocks I would suspect would leave me with limited travel and an unhappy potential impact on both sides...at which time the suspension might be expected to adversely affect the handling? Chassis build shop is likely going to be my answer.

Thanks for all replies

Dirk

mickmate · #9 (**permalink**) 02-19-2009, 07:47 PM

Those guys are builders, they are not professional builders. You are seeing a problem for sure. I think the radius rods was a good suggestion if they are put together properly. Those 2x4 radius rods are scary looking. The bottom one has a bend in it, take a look at whether it's been welded and ground down there (without fish plates) or whether they've just been bent. You need a good local race car or fab shop to look at it. See if those arms are Mustang or something you can replace with good aftermarket ones. If I can help let me know.

kitcarbp · #10 (**permalink**) 02-23-2009, 12:15 PM

Dirk, If the control arm needs to be modified or replaced to give you more upward movement, you can buy the arm ends with bushings installed and have a 3/4 " or larger rod made with these threaded into each end. Air Ride Technologies has them; "Radius Arm Rod Ends, its on their web site. Any good custom chassis shop will be familiar with this and its not a lot of money for the parts. I priced it out for about $150 per side in materials using 3/4 inch rod with ends. You must use good quality Chrome Moly Steel, there is a lot of lower cost junk out there, be careful. Speedway Motors also has the parts to make custom radius arms.

It might make just as much sense to modify the existing West Coast radius arms. The important item to check is how much clearance do you have in the rear wheel wells when the suspension is fully compressed and touching the axle bump stop (once radius arm can travel. I cant check mine yet because I dont have a body yet.

tcrist · #11 (**permalink**) 02-23-2009, 01:01 PM

Looking at the WCC web site, your trailing arms do not look like the ones pictured there. When did you buy this kit and did you get it from a dealer?

Terry

DocDirk · #12 (**permalink**) 02-23-2009, 02:10 PM

Yes, Terry, it's an actual West Coast. I bought the kit from Vern Redel (West Coast Cobra) and took delivery in April of 2007. I'll zoom over to the website to check if there are pictures of a different setup on his example chassis or elsewhere. I've heard other West Coast owners mention that their kits weren't identical. Thanks for the information.

I'll definitely check out the alternative chrome-moly rods on the web and get this beast up to a chassis professional in March. It's at the upholsterer's right now, I had to try my hand at that art as well and found out it's not as simple as I had imagined....doh!

Dirk

P.S. OMGoodness, I just check the West Coast Website photo of their rear suspension and on the version with outboard coilovers (which I have) the rectangular control arm is attached to the frame by a mount WITHOUT a top to allow it full travel......Sheeeeesh!

Camarofreak69 · #13 (**permalink**) 03-25-2009, 12:38 PM

Quote:

Originally Posted by DocDirk

Yes, Terry, it's an actual West Coast. I bought the kit from Vern Redel (West Coast Cobra) and took delivery in April of 2007. I'll zoom over to the website to check if there are pictures of a different setup on his example chassis or elsewhere. I've heard other West Coast owners mention that their kits weren't identical. Thanks for the information.

I'll definitely check out the alternative chrome-moly rods on the web and get this beast up to a chassis professional in March. It's at the upholsterer's right now, I had to try my hand at that art as well and found out it's not as simple as I had imagined....doh!

Dirk

P.S. OMGoodness, I just check the West Coast Website photo of their rear suspension and on the version with outboard coilovers (which I have) the rectangular control arm is attached to the frame by a mount WITHOUT a top to allow it full travel......Sheeeeesh!

Hey Dirk,
My name is Ryan I'm from UT. I work at a race fab shop and we have worked on one of these West Coast Cobra Cars. We have pretty much solved the problem of the suspension travel and the problem with the jerkyness of the rear. We fabbed up some new upper arms and replaces some of the pieces of the lower arms and also modified them so they don't bottom out. We are currently selling new upper set that are made up of butch tie rod ends and butch D.O.M. with polly bushings. They are priced at $400 shipped anywhere in the country. That also includes instructions on how to modify the lower arms so they don't have any clearance issues. If you are interested call (435) 865-0885 and we'll give you more info ask for Drew or Ryan.