info on shock settings

[fishman1]

Hi GUys

I am looking for some reading info on setting up shocks...i have single coil over adjustable qa1 same shocks on the front.... a ladder bar car and also affetcs of tire pressure...just trying to do some fine tuning and if i have a referson to go by will help out........trying to fiure out why the car is loading and unloading, does a spin on the tires, so not sure about stiffening the shocks or lossening them , go up with tire pressure or down...more i think about it the more i confuse myself..........thanks in advance.

[fishman1]

somebody must have a link were i can do some reading up on this stuff............thanks

[fla1976]

Hope this helps.

http://www.dragstuff.com/techarticles/video-suspension.html

[fishman1]

Hope this helps.

http://www.dragstuff.com/techarticles/video-suspension.html

Thanks but i already found that site......what i am looking for is basically is affect of air pressure for my application on the tires.......trying to find the normal air pressure i should be running for my application and also i have coil overs in the front and the back with just one way adjustments.....my take is setting the back stiffer will not let the tires hit so hard and softer settings will let the tires hit harder.......i am trying to figure out if i have my shocks set wrong or my air pressure or i am launching at the wrong rpm as the car loads up and then unloads for a instance and a small spin.

The car weight is 2600 lbs with me in it
wheel base is 94 inchs
rear tires are 32x14x15 with 7 to 8 psi in them
launching at 4800 rpm and torque stall is 5800 rpm
tranny is a 1.76 powerglide
motor is 383 sbc peak torque at 5300 rpm 525 ft/lbs
peak hp is at 6700 rpm 600 hp
car is 55 wieght to front and 45 to back

The other day i was playing with my shocks and tire pressure and my 670 foots went in the range of 1.38 to 1.42.......our track elevation is 2400 feet and usually corrected in the 3600-4200 range and as bad as 5300 feet

two weeks earlier i took the car to the coast and air was at 1400 corrected the worse and i ran 8 psi in tires and still would load and unload but not as bad with 1.34 60 foots.

So the biggest thing is should i loosen up the front shocks right up and tighten up the backs and go up with tire pressure and try elimanate the load and unload of the tires.....................thanks in advance

[bryanm]

I would try running more pressure, keep going up by a 1/4-1/2 lb until you get it to spin and then back down and see what happens. I had a similar problem and it ended up being the tires, put on a new set and it was cured.

[curtisreed]

Fishman,

If you car has a lot of seperation at launch it might be running out of travel on the rear shocks causing a spin situation as you described. Is there any way you make a shock travel indicator and just make short launches to check it? They are not to tough to make.

Curtis

[fishman1]

Iwas talking to a fellow today that runs a top fueler and he told me a few things, he figures that i am wadding the tires and that i am running my rear shocks to tight as they were set on 8 clicks stiff out of 12 settings, he told me to just play with the rear shocks settings and the tire pressure this weekend and after my first pass give him a shout...........also we were discussing the back end of the car is higher then the front end..........the tire shop has a blow out sale on a set of mickey thompson front tires for $80 a piece and they are 2 inchs taller then mine...that might stabilize the load more or make it worse............front shocks settings are 5 clicks

[fishman1]

I just finished loading the car on the trailer and i noticed that the outside of the slicks are wearing alot more then the inside is that a sign of not enough air...........i would think so but asking anyways

[us7race]

How wide is your rear rims?
I normally run 8.5-9.5psi Seems to like 9.5 better.

[fishman1]

How wide is your rear rims?
I normally run 8.5-9.5psi Seems to like 9.5 better.

The rims are 14 inchs wide

[Bubstr]

The only sure way to tell if your air pressure is right, is with a pyrometer. Taking temp. readings from 3 spots across the tire. When matching up side to side, it can tell you if your getting equal loading. I realize not everyone has one of these, but I have heard that the trigger pull lazier ones for the kitchen work ok, plus they are cheaper. You will want these readings as soon after a launch as possible. Have someone waiting for you at the turn off. You want even temps across the tire and even side to side.

There are several things that can load then unload your rear. Most of the time it has to do with power to traction.

The first situation is not enough power for traction. You will have stored energy in rotating mass of engine and fly wheel/ converter to load it but as soon as stored energy is disapated, your not at high enough RPM to create enough torque to maintain it. (dead hook) The fix for this could be as easy as launch RPM or stall speed or even a rear gear change.

The second situation is too much power for traction. This is basically buzzing the tires. The exact opposite of the first.

The sweet spot is in between these two.

Both cases are a balance between power and traction. Given that you have tires optimized with size and air pressure, the trick is to speed up or slow down wheel speed with gear or launch RPM. The converter plays a big part in this. Getting air pressure right to keep from distorting tire contact patch is first on your priorities. It is true that too much separation can distort tire and can be tamed wit IC settings and shocks, but before you go that way try getting air right first, then if you have to change settings you may have to change tire pressure again, but not much.

[fishman1]

Thanks for the replies guys

I went to a new track this last weekend and my car didn't hook like it does at my track....i figured it was a good idea to play with tire pressure and shock settings

tried loosening the shocks twice in a total of four settings and lowered the tire pressure three times in total 1 1/2 psi..well the sixty foots killed me, so i tightened the shocks up in total 8 settings from the loose setting and played with air pressure and also lowered launch rpm by 200 rpm finally got some of my sixty foots back but was still shy about .04 on 60 foots but the car ran just about the same as my track.......as this is new for me i am guessing the track was not as good as mine so by stiffening up the rear shocks and dropping the launch rpm i was not hitting the tires as hard and the car would hook better........so this is what i am gathering tight rear shocks u can go higher on air pressure and have to drop launch rpm and loose rear shocks u can go down on air pressure and up on launch rpm............let me know if i am on the right path........thanks.also my slicks are just about 3 years old with close to 250 passes on them but there is lots of thread left but outsides are scuffed so i am going to try applying tire bite first to see if it helps before i but new tires

[johnracer]

You really need new tires!! The sidewalls are probably dead after 250 runs.....My 60's will usually start to go away after 100 runs or so.
Johnny

[fishman1]

You really need new tires!! The sidewalls are probably dead after 250 runs.....My 60's will usually start to go away after 100 runs or so.
Johnny

I would have to agree with you as last night i cleaned up the tires real good and used a light to go over them and since the last time i checked them the tires have really took a turn for the worse, time for new tires.........i was wondering with the short wheel base car and light car wieght with me in it is 2600 lbs maybe i should go to a softer compound with a stiff side wall for the new tires.........what u guys think......thanks

[itsabird]

if you are hitting the tires to hard, and it sounds like you are, a stiffer side wall could help the hook and unhook condition.

[fishman1]

if you are hitting the tires to hard, and it sounds like you are, a stiffer side wall could help the hook and unhook condition.

yes i agree am looking at goodyear eagle's d1160 with soft compound with stiff sidewall.......they are for light cars but wear out earlier but will hook up better