Rear Suspension Problem

[Mystic_Cobra]

BACKGROUND:
I have a 96 Cobra that I drive agressively on the street daily and drive on track about 6 times per year, as well as a few dozen passes on the strip every summer. I've been upgrading slowly. I have a few common bolt-ons for the motor and have been working on the suspension/chassis lately. I am getting ready to put on H&R race springs with Koni single adjustable (yellows) shocks/struts. These are replacing tokico blues and H&R Sport springs. I recently added MM full length subframe connectors, and new poly bushings to the stock front control arms and sway bar. I also have MM CC plates.
My rear end is basically stock with 3.73 gears. I run 17x9 Cobra Rs with 275/40R17s. STOCK control arms in the rear.
I was getting into the corners hard enough on fast corners at Summit Point and Lowes and and rubbing the top of the left front tire in the fender well BADLY.

THE PROBLEM:
Now I am bottoming out the rear end. When I get on the gas hard in first and second gear the rear end will hit the MM bump stop. This seems to be getting worse as I improve the car, especially after adding the subframe connectors. My new aluminum driveshaft is also hitting the e-brake bracket in the tunnel. I can't move it, it's the part welded to the tunnel just below the console. I guess I am getting more power to the rear tires now. I figure the new springs, which are .4 inches taller according to specs, and significantly stiffer will help dramatically.
Will this solve the problem?
I know that I need to improve the rear end and I think it's my last and next project. THIS IS WHERE I WANT ADVICE.
Right now I'm thinking: MM lower standard arms and MM Panhard bar. Is this a good idea for a mostly street driven car ? What else do I need?
Do the springs resist the forces that push the back end of the car down on the rear end or is that the job of the control arms?

Jimmy Bost

[smashedheadcat]

It sounds to me like springs. If it bottoms out all the time now, it's probably springs. I'm not a suspension guy at all, but I don't think it'd be the control arms. If you still have the stock rear sway bar, check it and see if it's broken. That'd make some bangin' noises around the rear. I wouldn't think it'd bottom out with the springs you have on it when you hit the gas hard. That shouldn't happen. It just shouldn't.

[cobra96]

I'm looking at upgrading my shocks / struts and was wondering how you like the tokico blues? I know that they are not adjustable but have you had good luck with them overall????

[Mystic_Cobra]

I was happy with the Tokico blue/H&R sport combo. They were used when I got them but still good. They were fine until I got fast on the track.
I think they're pretty cheap from the new mustangracing.com site.

[tgentry]

Jimmy, my drive shaft was also rubbing. In my case it was worn out control arms. Steeda HD Uppers are less than $100 and might solve your problem. I'm running those with Pro3i street/race lowers and haven't had the driveshaft problem since.

For reference, I'm running Motorsport "C" springs, and I'm looking at stiffer springs too. Along with new inner fender liners ;-)

[Blown96Snake]

Jimmy,

I would highly suggest the MM rear phb and std. lca's. It is soooo much more predictable. The rear seems to stay planted better. The tires will get more grip when shifting into second (It takes more rpms to turn them over now). I also added rear coilovers and they feel great so far. I can't wait to see how they help braking in a few weeks.

The rear lca and spings work together so it could be a combination of the two...how many miles are on your car? The h&r race springs will probably make a huge difference. Enjoy

Dave

[Mystic_Cobra]

Ok, looks like I'm on track then. My Cobra has 115,000 hard miles on it. 33,000 in 23 months of ownership. More than 12 track days and more than 50 passes on the drag strip.

Also, what uppers would I use with this combo? I think MM suggests Ford uppers, that right?

What piece is that that allows you to remove the quad shocks?

[tgentry]

You can remove the quad shocks anytime, just be ready for wheel hop!:rotf:

If you want no hop or quads you'll need a torque arm, Steeda 4 link or something similar to positively locate the rear axle.

[Blown96Snake]

From my understanding....if you use the mm rear lca's, you can ditch the quad shocks...I did. I'll see if I can find some evidence...

Go to http://www.corner-carvers.com and search under "remove quad shock" and choose the "Remove quad shock w/ phb?" thread.

For some reason I couldn't get the actual thread address in my address window. Oh well...I hope that helps.

Dave

[Mystic_Cobra]

thanks for the tip. I seem to forget that there's a lot of experienced & knowledgeable folks over there.

For anyone else reading along, it was "remove quads"
Let's see if the link works for me.
http://corner-carvers.com/forums/showthread.php?threadid=2224&referrerid=0

[bolt-on]

I use Ford Racing LCL's and Ford Racing "C" springs. No bottoming and decent lateral control (no rubbing) with 17 x 9 wheels and 275/40 tires. The Ford LCL's are similar to the MM's except the spherical joint is at the torque box end. MM's PHB and T/A should cure axle movement problems, but require higher rate rear springs; and I wonder how streetable this combo would be.

[tgentry]

FYI, the reason for higher rate rear springs in a TA/PHB suspension is to make up for the lack of bind. Ultimatley there doesn't need to be much change in the actual wheel rate.