front geometry
- Thread starter delreyss
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They do have a flawed design, but most street cars do, the real big problem is the bump steer issues with these cars. When the front wheels travel up and down they toe in or out, this happens because the tie rod pivot plain is not the same as the lower control arm. They make kits to correct this, you need a dual dial indicator gauge to check it. On my circle track cars it took many, many hours to get this right. You can't eliminate it,all you can do is try to move it to a travel that the car won't see under normal use, make sense? You need to know where your car sits at rest and the range the front end travels in under your driving style, then try to get it the best you can in that range. The next thing is the horrible camber gain/loss, on a race car I got this down by using a 1.750 taller lower ball joint, and 1.00' taller upper ball joint, this with a flat style upper control arm makes it better, but circle track dirt cars only sit 4' off the ground in the front, and run +4.5 degrees camber on the left front and -6.25 on the right front to keep a 12' wide tire flat in the corner.The idea is to never have the upper control arm go from pointing uphill to pointing downhill, the line between the ball joint pivot and the control arm pivot shaft is what im talking about, the taller upper ball joint helps prevent that from happening, but you can't get it at to much of an angle or you will create the same problem agian, guys who use a flat style upper on a street car will far worsen this problem, however most people that drive a car would never even notice it. Because you have two seperate pivot points in the front (lower/upper) the lower travels a larger arch than the upper, so at full droop the upper pulls the spindle in at the top, at ride height it pushes it out, and at full compression it pulls it back in, so you end up with loss of contact with the tire.The best control arm to help this is the upper and lowers from UMI, Hotchkis, that still drop the upper ball joint pad down, that with the longer upper ball joint only, helps out a bunch on these cars. You need the gauges to do this at home, most aligment guys know nothing about performance type tuning they are book mechanics. Allstar makes an adjustable centerlink for these cars that is great for tuning if combined with heim style outer rod ends for tie rods, as a set to compliment the control arms
man that sucks i just installed a flat tubular set of upper control arms from speedway a few months ago. im running moog 5606 springs speedway uppers with short ball joints and stock lower with poly bushing and new stock ball joints. running these flat tubular control arms they sit pointing upwards, comparred to stock where my ball joint where level with the bottem. the tubular control arm also put my ball joints at and angle at stock hight. any suguestions. thanks for the help
If you already own them, leave them but don't put the long upper ball joint in them it will only worsen the problem. If all you do is drive the car, the stock upper or correctly designed upper is not bad, they keep the angle decent, the flat style upper doesn't move the ball joint if its the same ball joint it just doesn't help the camber curve any unless the whole suspension is built around it. That is why they are race type control arms, that and the pivots will rattle in a short period if time. UMI/Hotchkis spent a lot of time and money to design and build their control arms for a reason, to help a street driven car handle better
No, the 1998+ S-truck (Blazer) spindles share the identical pivot/turn points as the GBody. The reason to switch is that they mount the caliper to plates called abutments; you can go to larger brake rotors by moving the calipers outwards using aftermarket (or fabbed) adapter plates between the abutments and the spindle. The stock GBody caliper mounts are part of the spindle casting. Check out liquidh8's postings - there were diagrams in his thread for different rotor diameter adapter plates.
If the 22s or 24s you show in your avatar require tall springs, that might be why your upper control arm geometry looks odd to you.
If the 22s or 24s you show in your avatar require tall springs, that might be why your upper control arm geometry looks odd to you.
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