Fasterpatricks Custom Cobra

[strictlypersonl]

I'd feel more confident if you added some bracing to the rear dif mount so that the forces on the case were all vertical shear.

[fasterpatrick]

Just exactly where would the bracing need to be? There is more there than the car it came out of already.

I have a hard time believing that it will twist or roll with the t-shaped brackets already there. Draw me a picture. Patrick

[strictlypersonl]

Run a brace from the lower chassis bracket to the upper tube so that vertical forces don't tend to rotate the bracket down and forward. There's a lot of force on that bracket as a reaction to the wheel torque.

[fasterpatrick]

We all know that scratch building requiers dedicaton or a whole lot of money. I'm cheap so this is every bracket/tab to hold my rear suspension together. It took me a week of evenings in 90deg. heat to cut, drill, and finish the lot. But satisfaction rate is very high. Now to cut and bend the tubing and I could get it on the car this week, in the same heat. Patrick

[RACERAL]

You guys are amazing....

[mickmate]

Don't drip sweat on the bare metal. It's very salty and rusts it quickly...........

[fasterpatrick]

Huge piece of the puzzle was accomplished. Five days off from work and lots of time in the shop and victory was mine. Just some minor lose ends to finish up and it should be done.
The Accomplishment

The Aftermath

I'm not even going to clean-up tonight just shove every thing out of the way, and do that tomarrow. Patrick

[KarlCSX2498]

Hey Patrick, that all looks super. great job. you are brave to redesign and fab all the suspension pick up points and a-arms. Keep up the good work.
Regards, Karl

[Three Peaks]

Patrick,
That looks an awful lot like how I fashioned my rear suspension pieces for the 8.8 spindles. Looks great so far- what's next?

[fasterpatrick]

Big question? How much wheel travel is to much? right now without snubbers(rubber bumpers on the shaft of the shock) I'm looking at 9" of travel measured at the end of the axel. now I'm planing to use snubbers because I've pounded many an expensive shock into submission by slamming them at bottom. While this car is not an offroad buggy It will be driven alot and the roads here do take quite a beating. Potholes you need a guide to get across are quite normal. Just fishing for info so I can adjust bottoming point of shock. Any info helpful.Patrick

[Three Peaks]

Hard to say but I don't have anywhere near that much travel with my Edelbrock Cobra shocks. I think I only have around 4 1/2" total travel on my shock.
You could always use limiting cables to stop the axle travel before the shock bottoms out?

[hssss]

Patrick
I plan on using 05+ Mustang GT bump stops which are fairly long and can provide a secondary variable rate spring at near full jounce.

A couple of other possibilities would be to use something like the travel limiter on Fox mustang struts. Another possibility would be the pneumatic bump stop such as used on long travel offroad suspensions to eliminate the pounding of regular bump stops.
http://www.kingshocks.com/bumpstops1.html

[mickmate]

Hey Patrick, ERA is from potholed CT. They use 6" of travel for a road car. The originals use a pretty similar amount from what I can gather from my set up. Remember that's at the wheel travel, you need less at the shock. I have heard of originals twisting rear lower arms as a result of the anti-squat design running through too much travel. The front lowers also recieved a factory modification to beef them up with an angle back bone added to the tube for whatever reason. I think an excessive amount of travel will make it difficult to acheive minimal bump steer. Good stuff isn't it!

[KarlCSX2498]

Hey Patrick, I have CSX4000 suspension and on the rear suspension with the car in the air ........I have 8.5" of travel from the hanging position to the top of the travel. It appears that the rear shock has approx. 5" of travel.
Later, Karl

[mickmate]

Hey Karl are you using heims on the rear lower inners or that bushing over the threaded sleeve? I was curious how that bind-anti squat thing feels.

[KarlCSX2498]

hey nick, It is the box stock set up. The rear inner lowers have the sleeve. No heim joint. The heim joint is only rear upper outer & front upper inner. Not sure what you want? How does it feel? It just goes up and down in susp travel. later, Karl

[mickmate]

You know that angle difference between the upper arm (3 deg) and the lower (11.5 deg?) should cause a bind as they go through travel for the anti squat. I just wondered if you could feel it binding?

[KarlCSX2498]

I do not have everything cranked up tight yet. But for now it is a non binding travel up and down. I will let you know when everything is finished, tight and ready to go. Later

Nick, we should move these comments to another section. This one is for Patricks scratch build.
thanks

[Iggy]

Mickmate, I have tried to model the FFR IRS in solidworks. The theory is that the heimjoints bind on power and add to the antisquat. This may not actually be true. The front and back travel in different diameter circles, since one is 3 degrees lower, and the back one is something like 87 degrees off the side rails and is shorter.

The antisquat has something to do with the contact patch to instant center angle and the angle of the lower control arm. More angle on the lower arm gives more anti-squat. I will have to find my chassis book to actually remember what it said.

Iggy

[fasterpatrick]

Well spent a little time measuring and making adjustments to the mess. Found a few bugs , the center section was 5/32s out of center, fixed that, axles bound at full droop,needed new upper shock mounts to rectify that now they bind at full compress, not a problem once bumpstops are installed. Now the numbers, droop from ride height 4" total wheel travel till axels bind is 8 3/8" but doubt all that will be needed will make bumpstop addjustment with the body installed. No need to do that twice, will stop travel just before the wheels hit the body.
Full Droop

Full Compress(or at least to where the axels bind)

trying to stay cool: Patrick