[ballsout1]

finally got my pro-street// bracket chevette to the track. it wound up going 6.9 @ 95mph off the trailer but it was a bit of a handful because i beleive the rear coil overs are sprung to lightly. ``i`m not 1000% sure but i`m pretty sure. i`d like some input. anyways the car is fairly ridgid chassis wise. huge sub frame connecters out of the back half roll bars teid in nicely into steel plate etc. you can lift the car anywhere and still open the doors etc. even on the rockers. anyways the left front wheel comes off the ground a foot or so and from the back the right rear drops enough for that whhelie bar to hit when its was set about 5 inches off the ground. when this happens the car goes right. its contollable sort of but a handfull. i`m gonnna order at least one stiff coil over spring for the right rear....or maybe just two stiff ones for the back....car weighs about 2500 lbs... any ideas other than this??? any idea on what spring rates? car tracks nice when its in third gear. spooled rear, solid motor mounts. leaving on two step set at 3000....real mild vortec 383 in it. ladder bar rear with diaginol bar.

[ericnova72]

You really need to know the actual static weight on the rear tires to pick a spring, but I would venture 110 or 125 lb springs to be in the ballpark.

Spring should be the same both sides,.... not one side stiffer, that will give you a handling nightmare.

Shock compression and rebound rates will be important also.

Any preload dialed into the passenger side or set dead nuetral?? Sounds like you need to preload the pass side ladder bar.

[cal1320]

Don't buy springs yet. Spend $30 on the book ''Door Slammers'' by Dave Morgan. TONS of info that will help you. Learn the ins and outs of chassis setup.
Sounds like a fun ride.

[ballsout1]

right now on a wim before we went to the track i had put the pass side coil over mounting one hole higher than the drivers side..... sorta pre loading right? when you speak of "loading the bar" is that done with the rod end adjustments or moving the front mounting holes for the bar or the rear threaded adjustments near the axle on the bars... remembering back i think theres these three things that can be messed with. my season is over here even for test and tune but i want to make a change ready for preseason next year and have a few back up plans if the first one doesent pan out.

[cal1320]

Start by putting both ladder bars in the center holes on the x member. Later you can adjust this (top holes hit the tire harder(more weight transfer), lower holes hit the tire less hard). Preload is made with the where the driver side ladder bar attaches to the chassis. But in order to add preload you first need the chassis in a neutral condition. Put the car on the ground with driver in the car and loosen the front ladder bar bolts. If you cannot pull the bolts out by hand, adjust the bars until you can. (reset your pinion angle). Once its neutral, lower the front drivers side 1/4 to 1/2''. Jack up the ladder bar and reinstall bolt. You now have preload
Check your shocks also for proper travel. Topping or bottoming out will affect the chassis. Shocks should be same spring rate and even. Ride height should be set at the lower adjustable shock mounts. NOT the spring platform. Use the spring platform to raise the spring rate and center the shock travel if needed. There is more to this, but thats the short version straight from the book.

[Tony@AirRideTech]

Keep in mind... The only way you are going to change the spring rate is if the shock is topped out and you keep compressing the spring or if you simply change the spring. If you are just running the spring up in relation to the shock but the shock is not topped out then you are only changing spring/ shock relation.

I had a guy approach me at the Dallas GG show with a C10 almost same exact scenario as you that wanted me to take a good look at the chassis to see if I could figure it out. What I found on his was A. Not only running a cheap coil over but one of the rear coil overs was blown anyway offering no dampening. After looking at the front end (Coil-over MII), he was running the control arms way uphill towards the spindle trying to get the front end down a couple of inches which was in turn running the tie rods way out. So what was happening is the rear shock was giving way on one side causing the truck to sqaut to hard to one side then when he would lift, the front end would settle inducing bumpsteer. Changing the front and rear coil overs to a quality piece and adding a set of drop spindles to correct front end geometry was all it took.

What I am getting at with that little story above is to start out with the simple pieces... like his truck, just having a blown or inneffective shock on one side can cause issues.

[ballsout1]

good info guy`s i doo appreciate. i do have the upward tie rod ends and there is a bump steer issue i had identified while the car was being constucted ... thats actually a slightly different issue than my inquiry. i have actually limited the front end upward travel some time ago with the concern of the bumpsteer and realistacally now again i will add less upword motion to 1 offset some bumpsteer { which isnt the big problem here} and 2] help settle the rear action. i`ve got two different manufacturer shocks in the back... one was blown when i got it so i replaced it with a 3 way adjustable comp engineering unit on the one side i`ll get the same one for the other side and the springs are not pre loaded at all...as in completely loose when the car is lifted off the ground by the frame...i can scrunch the springs by hand abit when there out. i`m gonna try a set desighned for a 1500 lb rear weight next spring and test from there...i think ....and then possibly work with the bar adjustments. i`m all ears though to any other input.

[cal1320]

Lets talk shocks. Before you install the springs on the shocks ,extend them fully and write the length down (eye to eye). Compress them fully and write the length down. The difference is the shock stroke. For a drag only car I used 1/3 for compression and 2/3 for rebound. Extend the shock, compress it 2/3 rds of the stroke and write down the length. This is the shock ride height (not to be confused with the chassis ride height). Measure your shock mounts eye to eye and adjust the mounts to this measurement. Make sure at this time you have bump stops installed that will not let the shock bottom out at full compression.
With car full of fuel and driver get front and rear weights.
Get the above info and post it. We can then choose what springs you can use.