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Old 02-05-2009, 07:44 AM
  #30607  
Jeremy Otis
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Join Date: Aug 2007
Posts: 234
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Originally Posted by Trips
Don't thank me yet... I only asked a question so far... this should help...

First, with the ProStrut front end on my GenX I run the 045 springs, the 050's would probably be better on a low grip track, but for carpet I think the 045 would be the way to go. The 050's are the stock spring on the ProStrut front end, so switching to 045 should get you some more steering.

Second, be sure you don't have any preload on the front spring. It's easy to screw the kingpin too far into the steering block and compress the front spring when you put the eclip on. You'll want to loosen the brass setscrew, get the kingpin back into the ball (my allen wrench is real short, so I have to lift the kingpin out of the ball to get to the setscrew) and with the kingpin in the ball hod the car upside down, slip the spring onto the kingpin, then holding thh steering block against the lower ball, adjust the length of the kingpin so that the e-clip groove is JUST clear of the end of the spring. Lock the setscrew back down, and install the eclip. There should be no slop, but the least little pressure on the bottom of the kingpin should start the spring compressing. When the car is sitting on its wheels, you should see a slight gap between the steering block and the top of the ball in the lower arm. If the car's own weight doesn't have a little compression gap there, the kingpin is set too short. It can be a fiddly process, sometimes it'll take me almost an hour to get the kingpin lengths set just right.

Make sure the balls in the lower arms are installed with the little shoulder facing UP... if they're not, the front end won't be working right.

One other thing... there shouldn't be any friction at the upper arm... no binding at the hingepin, and the upper pivot ball mustn't be too tight. With no spring, if you push up on the kingpin, the upper arm and steering block should fall back down of their own weight. If they stay up, find the friction and get rid of it. Some of the CRC upper arms are tight on the hingepin out of the mold. When the upper arm is off the car, I put a hingepin in it. If the hingepin won't fall out of the arm just of its own weight, I open the holes in the arm up with an .080 drill bit on low speed. Or an .080 reamer if you can get one. If the arm is free on the hingepin but still binds on the car, you might need to give the teflon shims a swipe or two on some fine sandpaper, like 600 grit. They usually break in after a few runs, but they can be a little tight when you first build the front end.

Friction and preload in the front end can make the car steer like you're running two or three spring rates too heavy, so whatever time and effort it takes to get the front end friction free is well spent.
Hey Trip,

I agree with you to a point about spring settup. I think it is crutial to get the kingpins measured to the correct length but you also have to take into consideration that after a few runs the springs will compress/settle a bit. Now all of sudden you have to much play between the e-clip and spring. One way to eliminate this problem is to take a new spring and compress it and hold tight in your fingers a few times to settle it in. After you do both springs measure with calipers to ensure the are exactly the same. Now put the FE togather per your instruction.

Jeremy
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