need to order a new set of coil-overs for the rear of a 2700-2900 pound car. (34 5W) would like to lower it slightly, old set is out of adjustment..... don't want the spring so strong it gives the car that "hiked up" rear look. Suggestions?
weight the rear of the car measure the angle of the shocks and the length extended and compressed and call a shock company and talk to a tech.
I just installed some 180# on my coupe. 30 degree shock angle. 2600 lb. Work great! Don't go too heavy!
I have bought from PRO_SHOCKS (Georgia) several times, I call and explain the car, and they tell me what to order, Right every time. Been very happy.
No way to figure it correctly without wheel scales. Once you have weight you are pretty much stuck with the coil that is going to support that weight. If you have the coils mounted behind the axle as opposed to in front of the axle you can get away with a lighter spring. It takes less spring to control the axle if placed behind the axle. Most fellas adjust their ride height by altering the shock mount and not by spring weight. Spring weight only controls your load not your ride height. The easy way is to get the correct spring weight is to get your weight at the wheel and call the shock company. Let them do the math and if it is wrong you exchange it for the correct spring. They very seldom get it wrong. The adjuster on the shock is not for making changes in ride height it is for preloading the spring to get the desired ride characteristics. Anyway if you want to adjust ride height you do it by altering your shock mount.
Sir, the strength or the rating of the spring will not determine the rake of your chassis. There is a small range of " pre-load ' adjustment with a coil over that will slightly change the rake. That is not the fundamental purpose of this adjustment. The shock mounts or mounting points wether on the rear axle tube or the upper mount will determine and allow you to make adjustments in your rake and the look of the car's stance. Again, this has its limits also. If the body of the shock or the dampening is fine, you might just need a new set of springs and fine tune the pre-load adjustment and all is well. You will need the weight on the rear axle as well as the angle of the shock in respect to verticle. Measure eye-to-eye mounting points AFTER you establish the look or the rake that you want. Suggestion here is to bring the car outdoors on the level ground and with the shocks unbolted, a friend or two and a jack and maybe 2 stands, set your car up for the look you want. Now the MOST important thing here is to STEP-BACK around 10-20 feet and sit down and check out the stance. Now take your eye-to-eye measurement again. TR
Porknbeaner has it right again. The geometry is also key here, (shock angle!) so be sure to mention it to the on-phone tech when giving weight and length specs. Not mentioned often enough, the mounting 'ahead or behind' the axle. Consider this.
Yea, damned shame there was a time when doing it was easier than telling it. "The times they are a changin'."
I want to add some info for the O/P, ROCKY, and all others playing along. This is where shock length's can actually get a little involved, more than we have already stated. A factor to be considered in the " percentage " of travel in inches for the compression and rebound of the shock tube. See after we hopefully established the rake or the look we want by my method of " setting up and stepping back ", we have determined our eye-to-eye distance or dimension. Now depernding on the particular car, how and where its used and driven, I determine the percentage of rebound and compression travel, using the available shock travel by design. This you can't change. Compression or bump travel is generally more than rebound or extension travel of the shock. lets pick a 60/40 ratio for example. If the shock you pick is 12 inches EXTENDED length, and 8 inches full compressed length, you have 4 inches of travel. { if there is no bump stop- I would reduce this by a 1/4" to 1/2" } Now 4 inches times 60% is 2.4", and 4 inches times 40% is 1.6", added together is your 4" of shock travel. This is where the adjustments are important and critical is setting your shock mounting points. At the stance or look you wanted, the shocks top and bottom mounting points must coincide and allow you to compress your shocks the 2.4' and allow them to extend the 1.6". Give or take an 1/8" is more than acceptable. The shock will compress sligthly with the weight of the car, you can fiqure this in with the springs spec's. provided by the manufacturer. A small book can be written here on the topic, and there is no way to cover all of the aspects of the correct way to do this. A good chassis guy, like a good engine builder, are worth thier weight in GOLD!! TR
I should add this. With just the shock body and no spring, compress the travel 1.6", and put a zip tie on the shock eyelet to eyelet. Now hold the shock up to the mounting points and locate. This will allow you to hit a bump and compress the shock your 60% or 2.4". and also allow you shock to extend or rebound after the bump your 40% or 1.6". If the shock in the example was 12" eye-to-eye, it would now be 10.4" eye-to-eye for locating the mounting point setup. TR
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