TBuskey

So i tried the search function and was just confused by multiple answers about measuring locations and proper tolerances.

If i am measuring directly in front of the front jack puck slot and directly behind the rear jack puck slot.. what should the difference between the two measure?? I know factory is 1/4"....but i have read about people running 1" which almost has to be total from front axle to rear.

Car is mainly used for Autox..

93Rubie

How is it going Tom? Shawn Bauman here. I know you recognize the car.

Anyhow, IDK, the answer but I know who does.
Call Sam Strano, he has only setup more than a few winning C5's. 814-849-3450.

TBuskey

Yea...Sam was next on my list if this didn't work. He was very helpful with my Camaro.

93Rubie

CF is a great resource but Sam is as well and his experience is hard to match, as you well know.

Scooter70

This is from the Pfadt coilover installation manual but it gives you an idea of their recommendation. The last two columns are the measurements from the shipping tie-down holes to the ground.

TBuskey

Great info, Thanks

duegatti

I have a thread going in C5 tech, and I thought that this forum might be able to help. I need clarification of what Pfadt means exactly, with respect to the J/K measurements, by "rocker panel" and "frame".

The only true piece of frame that I can see in the vicinity of the J/K spots is a narrow band surrounding the indented, dimpled jacking point - but it is the frame, and it is flat. Confusing the matter is another sheet of metal in between the body plastic and the frame - I think this is involved in supporting the floor boards.

At the J/K locations (35" behind the front center; 31" in front of the rear center), I am clear of the jacking points, and it seems there is just plastic bodywork, which I am assuming is the "rocker panel". What bothers me is that the body plastic does not seem very flat, and so the J/K positions are not well defined.

My front J measurements are 3.78" and 3.90" - way below the Pfadt recommendation of 5.04", for deltas of -1.26" and -1.14". The front wheel arches are 26.18" and 26.26", below the recommended 27.0", for deltas of -0.82" and -0.74".

It bothers me that the wheel arch and J discrepancies don't match, when the Pfadt data shows that both positions should move by the same amount.

My rear K measurements are 4.25" and 4.41", below Pfadt's 5.24" with deltas of -0.99" and -0.83". The rear wheel arches are 27.60" and 27.52", below Pfadt's 28.3", with deltas of -0.70" and -0.78". The discrepancies between the two measuring points are much less in the rear.

I began to take "frame" measurements, for which Pfadt recommends adding 10 mm, but I stopped when I was confused over what surface and what location I should be measuring at.

I really don't want this car to be too low, and I've also read on these forums a suggestion that the C5 suspension geometry has a "sweet spot" precisely at the Pfadt recommendation to lower 1" from stock. And now I'm pretty confused about where I am, and about the measuring process.

I'd really appreciate any clarification you folks could provide. The car is due in for ride height adjustment and re-alignment on Friday.

Many thanks,

Joe

duegatti

Is there no one who races with Pfadt products and has set their ride height according to Pfadt instructions?

weekendracer

Bump The topic. I just picked up a Z and am looking for Rake settings to go along with my autocross alignment as well.

Or is the answer call Sam?

It would be nice if one person calls him and posts his response so Sam doesn't get a call every time someone comes to the thread.

I am on stock suspension currently setting up for the new street class.

argonaut

I've had my C5 professionally aligned and set-up twice - by two of the most acknowledged Corvette setup guys in the northeast. Both guys said the same thing - ride height and rake should be measured off the angle of the control arms...not the height of the frame from the ground.

Just throwing it out here. For the guy trying to do a home alignment this may not be very helpful as I don't know the exact process nor the optimum angles.

Miguel S

I have been thinking about this as I am about to do a home alignment on the car. I am going to run the car square on 18" wheels and this will by itself change the rake. My question really is, what is the rake actually for, is the rake for aero stability, proper suspension arm placement, or really a combination of both. I would think by setting the ball joint locations (or suspension arm angle) you are hitting the sweet spot in the suspension, but do you loose aero stability by reducing the rake with the square setup. If anyone has insight I would like to learn, thanks!

argonaut

I can tell you this: I run 18" square and my setup guy did add rake to the car. I believe, in part, the rake is for aero stability purposes. Not sure if it serves any other purpose.

Gordy M

Rake must be set correctly or at 130+mph your car can become a wing set for takeoff. While the control arm angle is the best, most DIY try to measure at the Jack points. 5-9mm seems to be where most recommend at the jacking points. Even with 2.5" race ramp and scales it is extremely hard to measure at the control arms.

Miguel S

Thank you gents, I will set the front control arm angle the best I can and add rake to set the rear.