gretchen/jason Posted March 9, 2008 Share Posted March 9, 2008 So the question being to keep rear end squat to a minamum would it be bettwr to get stiff springs say from AZ car or the tokico adjustable struts . I have new KYB struts in the rear and tokkico lowering springs all about 1 year old . Im trying to stiffen up the rear end to eleminate squat to get better tire grip/grab . The front end raises up fast enough allready so its ok on that end . Jason Quote Link to comment Share on other sites More sharing options...
johnc Posted March 10, 2008 Share Posted March 10, 2008 Shocks control transitional behavior. They can slow down the squat but ultimately the car will squat "X" amount based on the load transfer to the rear and the rear spring rate. On a drag car you get the most load transfer at launch and less as the rate of acceleration drops over distance. The question is: are you trying to control the rate of squat, total squat, or both? Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 13, 2008 Author Share Posted March 13, 2008 I would say im trying to controll total squat . As it is it squats down very easy not much effort needed . the front raises up nicely i was told by someone that if i stiffen up the rear " keep it from squating " that i would get better traction when i launch . Not really sure ive never dealt with this issue before . Jason Quote Link to comment Share on other sites More sharing options...
1 fast z Posted March 14, 2008 Share Posted March 14, 2008 Yea, because with squat, all motion inertias aside, you get negative camber, which in turn reduces tire contact. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 14, 2008 Share Posted March 14, 2008 Total squat is controlled by spring rate. You would want to increase your rear spring rate without affecting your current ride rear height. We need to know: 1. The spring rate of the springs currently installed on the rear of your car. 2. What is the uninstalled height of the springs currently installed on the rear of your car. 3. How many inches of squat you're seeing now on a good, hard launch. From this we can calculate a new spring rate and height and see what's available. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted March 14, 2008 Share Posted March 14, 2008 Whats nice about coilovers is that you get CHEAP springs. You can buy springs from summit for about 35.00 a peice if I remember, so you can almost stock a few different rates/lengths and use for testing. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 15, 2008 Share Posted March 15, 2008 Whats nice about coilovers is that you get CHEAP springs. While a great idea in theory, it sometimes doesn't work out well in practice. For example, a customer brought me a set of 4 "silver" springs purchased from Summit Racing for $150 total. When I installed these springs and adjusted the ride height the lower spring perches were off by as much as 1.125" side-to-side. I pulled the springs off and tested them. One 250 lb. in. spring initially tested at 272 lb. in. and then settled down to 268 lb. in. then next two times. The other started at 241 lb. in. and settled at 236 lb. in. That's a 12.8% difference between the two springs. The difference between the 225 lb. in. springs was 10.7%. If you were drag racing and running the "250" lb. in. springs in the rear there would be a 12.8% difference in how each side of the car squats under acceleration. You would spend a lot of time trying to tune the launch around this difference and it would be confusing if you didn't know what the problem was. If you were running the 225 springs up front and happened to put the soft spring on the same side and the soft rear spring, you would be pulling your hair out! Its even worse if you're trying to tune a road race car with this kind of spring rate difference. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted March 15, 2008 Share Posted March 15, 2008 I have purshased a "few" sets, and the R1 springs (some brand) seem to work well. Measured on a bathroom scale and a arbor press. Possibly just a weird batch. I have had bad springs from another well known z car supplier with terrible results as well. I now have about 30 different springs I have picked up from different places that I test with. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 15, 2008 Share Posted March 15, 2008 FYI... I didn't mean to imply that all cheap springs are bad. Just be careful and if you can test them before putting them on the car, you'll be better off in the long run. Aslo, be aware that cheap springs will take a set so when you test them, test them at least 3 times and use the last tested numbers as the rate. One nice thing about Hypercoils is that they individually test them at the factory and then a person scribes the spring rate on the ground end of the spring. When they leave the factory within 1% of rate specified. If you test them later (even a decade later) and they are 2% or more off the factory rate, they will send you a new spring. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 15, 2008 Author Share Posted March 15, 2008 For all the searching ive done i can not find the spring rate . I bought them from MSA and they dont know either . All i know is they ar Tokico progressive rate lowering springs . They measure 12 inches long unistalled and i get about 1 1/2 to 2 inches of squat on a good launch . The spring has a number on it i havent been able to locate yet it is 5022-r Jason Quote Link to comment Share on other sites More sharing options...
johnc Posted March 15, 2008 Share Posted March 15, 2008 That's a Tokico part number so its probably the lowering spring from the HP Advanced Handling Kit. The spring rate is around 140 lb. in. If you go with the Arizona Z Car rear OEM springs you'll be getting a spring rate around 200 lb. in. That should cut your squat in half. Adding in a set of adjustable Tokico Illuminas will let your stiffen the rear the reduce the rate of squat so the car will stay up through most of the first 60'. By doing this and not changing the front springs and shocks, the car will tend to oversteer on corners. If what you're building is a mostly and drag car and you don't drive fast on the street, then its not ann issue. Otherwise, I suggest you get the complete spring kit from Arizona Z Car (185F 200R) and a complete set of Illuminas. The adjustability of the shocks will give you a way to tune front lift and rear squat - at least a little bit. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 15, 2008 Author Share Posted March 15, 2008 Cool thanks for the info ill contact az car next week . I do drive the car to work sometimes and of course to car shows , i really buillt it for th wow factor and its just plain fun with a supercharged 383 lets say a toy i always wanted . Jason Quote Link to comment Share on other sites More sharing options...
johnc Posted March 15, 2008 Share Posted March 15, 2008 BTW... I sell the Illumina shocks for a pretty reasonable price. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 15, 2008 Author Share Posted March 15, 2008 I will contact you for the struts when i get some extra money , i also purchased my cowl induction hood from you very nice hood . I let it sit for about 4 months before i installed it only to find out it wasnt tall enough for my air filter . Im not knocking youre product its great but with my supercharger i had only 3/4 of a inch between the carb flange and the bottom side of the hood i know a guy who is great with fiberglass im going to see if he can rasie it about 5 more inches make it about a 9-10 inch cowl scoop . Jason Quote Link to comment Share on other sites More sharing options...
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