Rear Suspension Failure - Rear Trailing Arms

[Tramsey]

Does the CC kit not use a trailing arm back to the lower wishbone? I have a broken wishbone and it looks like there were no trailing arms/radius arms installed. Seems like there needs to be another link to keep the trailing arm from rotating about the inner fulcrum mounting point, which mine did and failed in the weld area of the tubular section where it mounts to the yoke. I scanned the manual but did not see anything addressing a rear trailing arm.

Thanks for any info.

[65cobraking]

Hi Tramsey,

Give Nick Acton a call I believe he has the answer for you.
Acton Custom Enterprises Custom Metal for Cobra's
603) 279-0241 Shop
(603) 254-4105 Nick Cell

Regards,
Mike.

[Tramsey]

Thanks Mike. I sent him an email.

[RICK LAKE]

Tramsey A giveway car from years ago at Carlisle had the same problem at a R&G event.If the welds broke on the lower trailing arm. Not enough ampage for the welding of tube to yoke end. Need to have the joints triangled for better support and strength or go to aftermarket lower arms from billet aluminum. Do you have any pictures?? Sorry for your breakage. The other car caught on fire for breaking a hole in the fuel tank. Car was repaired. Rick L.

[Tramsey]

I just got it off the car. You are right, it failed right through the weld. Not enough heat into the weld, very little penetration. Luckily the car was at a stop when it broke and there was no other damage. I'll post some pics if I get a chance.

[Thor maine]

The best setup is to use a "watts link" set up, on the top of the hub. And a trailing radius rod system on the lower dog bone.

[RICK LAKE]

I know that Peter B built a great car as near perfect to a Shelby as possible, and the car is and was. The problem is who did the welding on the lower arms for the rearend?? School in PA did the give away car or that was what was in the mag about the buildup. There should be added gussets to the arms from the tube assemblies. Any good welder can do this for couple bucks. Speedway sells premade plates for this. Over years, the stress on the rear arms may crack the welds. You may not see this until too late. No body wants to end up as a fire ball and the gas tank is right there. Rick L.

[redmt]

Originally Posted by Thor maine

The best setup is to use a "watts link" set up, on the top of the hub. And a trailing radius rod system on the lower dog bone.

Do you have any pix of the radius arm?

[65cobraking]

Nick makes a kit to convert a standard jag hub into a watt's link set up.

Mike.

[redmt]

Originally Posted by 65cobraking

Nick makes a kit to convert a standard jag hub into a watt's link set up.

Mike.

YEP!! Nick makes a beautiful setup for the Watts. What I have been interested in is seeing a setup for trailing or leading ares to the outboard side of the wish bones.

[CHANMADD]

Check my gallery.......not the prettiest, but they have been there for a lot of miles. Without them
you also get a lot of wheelhop. With them no axle tramp at all. Also switch the controlarms left to right so that the littletab is facing backwards so no extra welding or fabricating on the arm. John

[mickmate]

There were quite a few arms cut and welded from XJ6 and other widths made shorter to E type length as they were getting harder to find. There is some info on installing the Watts the lads mention here Contemporary Cobra Watts Linkage

[bill37341]

Tramsey- You might try the trailing arm system that I used. Like Chanmadd suggests, reverse the lower wishbones left to right. QS Components sells a high-misalignment spacer for their 3/4 inch rod ends. Use the spacers to reduce from 3/4 to 5/8 inch. This will allow enough angle of the rear rod to align with the center of the wishbone. It also allows use of the 5/8 bolt in the wishbone, and a 3/4 inch trailing arm. Speedway sells a 3/4 rod in varying lengths for about $15. Mine was 24". I'm not familiar with Contemporary's frame, but you will need to tie the rear end of the rod to the frame using another rod end. Be sure that the rear end of the rods align with the pivot points of the inner wishbones. They should be 9 1/4" apart. Will try to post some pix. good luck, Bill.

[Tramsey]

Thanks Bill. Unfortunately the CC frame does not have an outboard section of the frame that I con run these arms to. I'm still studying the geometry. The Watts link setup by Nick looks the most promising.

Thanks for everyone's input. This is a great forum. Lots of useful info and helpful folks.

[mickmate]

We just saw this again recently.

A watts linkage is the answer but in addition I would add gussets like this.

or tubular braces like this

Be sure to alternate the welding so you don't bend the arm as the weld cools/shrinks.

[Dominik]

The point you guys raised is the weld, and Peter B, while building a fantastic replica, used E-type wishbones which came at the correct length.

The trailing arm, as used for XJ6 is not needed. It is rather detrimental if mounted in rose jointed assemblies. The original rubber mount compensates for change in length under suspension movement. If mounted rigid, it may actually break something - like the weld...

Remember, the XJ rear suspension is mounted in a cage - in rubber.

As a side note: I wouldn't be surprised that load in cornering actually assist turn into corners with this Jaguar design (the Porsche 928 followed a similar idea).

It does not apply for a solid mounted differential like we have. The Watt's linkage is a good idea.