Metric Super Stock Front End Geometry et al.

  
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Metric Super Stock Front End Geometry et al.

 
Scotty B Scotty B
New User | Posts: 1 | Joined: 07/15
Posted: 07/19/15
03:44 PM

Hi guys.

I decided to get into racing two years ago and spent the past year and a half putting together a super stock from a bare chassis.  The only things on it that I could use aside from the frame, roll cage, and body were the upper and lower control arms.

So you can imagine the work researching which parts to buy to build a solid car.  I got a lot of advice which was nice.

I'm halfway through the season and we've gotten the car drivable and semi-raceable.  The issue I have at this point is getting the front end geometry right.

The upper control arm on the LF has some downward angle but the RF is level.  This puts the moment center god knows where and I know it's wrong.  I've worked the caster and cambers in really well and I'm getting great temps but that's with the jacked geometry.

Now a lot of guys said to run the 2" drop spindles.  So I got those.  My question is would a standard spindle from a Camaro or something get those upper control arms at a more downward angle where they need to be if I installed them and reset the ride heights?

Also, should the lower control arms be level?  I've hears "yes" and "it doesn't matter."

Lastly: I'm running a Ford 9" rear end with the GM mounts and I'm wondering if the rear ride heights need to be set so the lower control arms are level.

Thanks in advance.

Scott  

Just Try It1 Just Try It1
New User | Posts: 5 | Joined: 04/15
Posted: 10/18/15
10:11 AM

just curious.. are your team members measuring the tire temps across the face of the tire as soon as you come into the pit..

left center right of each of the tires..  

on a friends street car... where he was worried about wheel alignment and suspension angles.  we did some bizar stuff..  we measured the camber of all 4 wheels and the ride height..  measured the caster of the front wheels..

we rigged up 2 chunks of acme all thread to install where the shocks were..

this allowed him to crank down on the suspension by tightening the nut on the all thread to duplicate the suspension and body movement. during suspension compression.  he remeasured the wheel alignment change every time he screwed down one corner a 1/4" of ride height..  he was able to play with his settings to get closer to what he wanted..

i wondered about using a hydraulic cylinder and a hand pump to do it also..  but the acme all thread was easier.  we just double nutted some big flat washers on the bottom where the shock would normally fit..  we did use a water pipe flange and a short nipple threaded into it.. sitting on the top of double nuts but under the washers to avoid damage to the acme threads, there was a drilled bar bolted between the double nuts to prevent the all thread from rotating while he turned the upper nut.  there was also a pipe flange and short nipple up there also. but with a GM you may not have room for that one.

this allows you to measure the body roll also.. something that is hard to do with just a wheel alignment gauge on turn tables.


i told him we should have used springs and ratcheting straps to pull on the right then left side of the car to duplicate cornering forces on the tires and suspension..  since it was a street car he was not interested in that.


is your track smooth.. no dips or bumps in it that causes you to loose rear traction..

i learned a secret watching the corvette racers they have lots of damping on their rear shocks on compression.. but almost none on extension..  this allows the rear wheels to maintain the most contact patch with the track..


don't forget to measure your Ackerman angles.  so you can get the wheels going the proper direction when steering.. no use scrubbing off speed in the corners..

you can adjust this with different lengths of pitman arms and idler arms.  since its hard to change the steering knuckles..  

be sure to place a video camera in the car.. looking at the steering wheel you have wrapped with different colors of tapes..  so you can see how many fractions of a turn you are actually making with the steering wheel during a corner.  you may not be turning hard enough to need to change anything..

if you are only turning 1/2 to 3/4 turn.. you may not need to do anything other than measure.