PDA

View Full Version : Ride Height



BCR
08-22-2011, 10:11 AM
OK tunning in a new frame and gonna hit practice. The frame is a old asphault converted to dirt so even if I knew the maker. I am sure it wouldnt matter anymore.
Impala front clip 3 link with rear coil overs RR in front LR in rear
My question is simple.
Whats a good ride height starting point ?
What does increasing the ride heights actually do as far as handling ?
like higher = more side bite or tightens and so on. NOT SURE what it actually affects to help tune in at track with practice.

Bcollins82
08-22-2011, 10:00 PM
OK tunning in a new frame and gonna hit practice. The frame is a old asphault converted to dirt so even if I knew the maker. I am sure it wouldnt matter anymore.
Impala front clip 3 link with rear coil overs RR in front LR in rear
My question is simple.
Whats a good ride height starting point ?
What does increasing the ride heights actually do as far as handling ?
like higher = more side bite or tightens and so on. NOT SURE what it actually affects to help tune in at track with practice.

Ok, lots of questions here, but not a ton of info... For starters, the springs are in the opposite spots they should be. LR in front, RR preferably on top, but if your on a coilover and you must choose, it should be in back.

On ride heights there isn't a lot to go by, but a general rule of thumb would be to map your balljoint, find the center of the pivot, measure to the ground with the tire pressure set. Then raise the car to where the center of the inner pivot on the lower is the same height. Set the LF inner pivot about 1/4 higher than the RF, and set the rear ride height by putting about 1 to 1.5" of rake from front to rear with the rear being higher.

As far as what raising or lowering the car will do, you can write an entire book on it. As far as weight transfer, obviously it will transfer more, giving the car more sidebite, but there's also a huge can of worms geometry wise that you open up by changing ride heights. This is why it's always better to start with a car that is modern from a chassis builder that can give you this info. Good luck!

1Blacksheep
08-23-2011, 06:32 PM
The front end Geometry will likly suffer severe changes that need to be addressed to run dirt (raising it). I would raise the back a little and try an leave the front alone to start. On a slick smooth track it will possibly be close where it sits, in the tack and (Rough)its going to struggle.However the pickup points on the chassis were likely installed to run at low ground clearance which will start to add crazy things into the equation when you raise the car. I would start where it sits, and add ballast high to get the sidebite it wants while at least maintaining the original ride ht while doing so .

Bcollins82
08-23-2011, 09:32 PM
If I'm understanding correctly you have no ride heights to go from at all? Do you have any scale numbers your going to start at? What type of pullbar does it have? Where are you starting as far as spring rates? Is the rearend super wide and offset in either direction? If you want some help getting it close before you hit the track post some specs and pics of the front and rear suspension. There are a lot of experienced guys here that would much rather help you get it close before you hit the track instead of showing up to the track and being out of control in a car that's out in left field and possibly tearing other cars up. Just sayin...

LM14
08-24-2011, 03:43 PM
The above recommendation to set the ball joint pivot points 1/4" lower that the inner pivots of the lower a-frames and use 1 to 1.5" of rake in the chassis front to back is a good recommendation. That's exactly what we do with our Jet on a Metric Impala and have done this with Chevelle stubs, too. I think it's a good rule of thumb.

How heavy is the driver, what tires, springs and everything else can you tell us about the car. What shocks do you have, style and rate? Do your left side or right side tires line up with each other when you stand behind the car and look at it?

The more you let us in on the more we can help. Also, is it a full size Impala (pre '77) or the later metric Impalas?

SPark

1Blacksheep
08-24-2011, 04:55 PM
LM 14 ,didn't you mean to say A frame inner pivot points lower than lower balljoint ? Thats what I would set it at anyway. 1/4 " lower to start. Then check for pos caster both atleast 2deg,pos camber left 1-3 deg,neg camber rt 3-5 deg. Set rear trail arms level at the same plane as the frame rails for ride ht setting. Then raise both sides to 5deg uphill from axle. Hard to say without seeing it but that should be close to a neutral start point. Being asphalt ,car will likly be low and components (battery ,motor and such)offset to the left for high left %. Raising it up will help produce sidebite but change alot of geometry front and back. 6" ground clearance at frame S maybe with rake up toward rear as mentioned.

LM14
08-24-2011, 09:20 PM
You are correct. The inner pivot points are lower than the ball joint rotation pionts.

Thanks for catching that!
SPark

BCR
08-25-2011, 10:44 PM
I got it all set up, pretty much did the front the way you guys said and set the rear about 3/4 inch higher.
Now my only question is .... Raising the rear higher would do what to the handling of the car ???
TY