Help : Need coil over shocks asap

[coinop101]

Hi

I need to replace my existing rear coil over shocks ( no spec.on the existing type of shock or spring ). I'm looking at QA1 shocks with a 14" extended and 10 1/2" compressed . I don't know which spring pressure to order ? I have a big block up front and a standard 9" rear end .
Any insight on what your running .

Thanks
Peter

[john chesnut]

It is important to get the right length of shock. Sorrry if I am going over things that you already know. You need to have 60% of the shock travel available for compression. So, set the frame height at normal ride height and then measure the distance between the upper and lower shock mounts to establish the shock length at ride height.
Most Cobras are around 2500-2700lbs. I would use a 500lbs spring in the rear. The length will depend on the shock length. You want to use as long a spring as possible to eliminate coil bind and you want there to be a little tension on the spring when the suspension is at full droop or use an axle limiting strap to prevent the spring from popping out of its seat.
For the shock length that you have specified you can use between an 8 and 10 inch spring.

[ZOERA-SC7XX]

500 seems a bit much. I'd try 350's to start with and see how it behaves. You may end up buying several spring sets until you're satisfied with it. The beauty of coilovers is you can change and adjust to your hearts content. Why not just keep your existing springs?

[Tim Brewer]

500 is way too much, I have 300 and it feels very good and doesn't boyyom at all.

[RICK LAKE]

coin101op Peter What are you looking for from the car? roadracer? cruiser? 1/4 mile? caddie ride? You would have a different setup for each one of these driving styles. Which QA1 shocks are you using? What is the spring rate of the front springs and weight of the car. What size tires are you running? You can run a higher spring number rate with a lower profile tire. You will get a harder ride but handling will be better. Does the car have front and rear sway bars? All this needs to be added into what you are looking for. You can see why I am asking for a little more info. You have single spring and shock in the rearend for each side. A 350-400 would be the choice without knowing anything else. This would include 2 people in the car with a 375 total wieght. Again looking for a little more info. Rick L.

[dlampe]

You can't simply say 500 is to much. With a target wheel rate of somewhere between 275 and 300 for performance driving, 300 might be right if the shocks are perpendicular to the axle. If they are at an angle, it will take more spring.

Measure as John suggest and if the shocks are stright up and down, go with 300lbs. If they are at an angle, give us some idea what the angle is and we can sort it out for you.

[Cobra #42]

Dean, Glad to see your talking about spring rates and roll centers.I remember when you were new to this disease called performance driving, the more you learn, the more the fun. db

[Tim Brewer]

You're right about the shock angle, the greater the angle, the higher the spring rate will be needed due to the increased leverage.

[coinop101]

Thanks
I talked with QA1 and purchased their DR 4855P single adjustment shock . They told me to try a 250# spring ,soI am . AS to all of your postings , I will try the 250 # but expect to go up ( 300# to 350#) depending on feel . I will also measure shock angle .
Want to thank all of you guys for your input .
Peter

[john chesnut]

Sorry, I had a brain cramp when I made the post. I run 350lb in the front and 300lb springs in the rear of my Cobra. I bump the rear up to 500lb when I race on a banked track. Again, sorry for my goof. john