Adjustable suspension for the street

[mn_vette]

I was reading the write up on the racing of the 818R and they said that the suspension was messed up from the wind tunnel testing and once they fixed it the car handled much better. From what I've read the 818S will also have adjustable suspension. My question is, how idiot proof is the suspension adjustment for the street car? The race team didn't know the suspension was out of adjustment until they got it on the scales and these guys know what they are doing. How am I supposed to adjust mine to get the proper handling withing killing myself in the process?

[Gordon Levy]

Generally you find a baseline and then do adjustments from there. It really isn't hard to do. Once it's set for your likes you really never need to mess with it.

[mn_vette]

That sounds good, but how do you find a baseline safely. You can't really find out how it performs without finding its limits.

[68GT500MAN]

Basically you just follow the instructions, set the ride height and get the front end aligned. The race team was trying to set the cross weights and balance set for track performance.
Doug

[Evan78]

Are you familiar with corner balancing? If you find a local alignment shop that will do corner balancing and set the alignment to FFR's recommended specs (do we have those yet?), then you can make changes from there. Autocross and track regulars will often do their own alignments, so you could probably find people to help do it yourself even. The scales are expensive and not something you'd want to buy, but maybe renting/borrowing them would be possible.

[Bob_n_Cincy]

Are you familiar with corner balancing? If you find a local alignment shop that will do corner balancing and set the alignment to FFR's recommended specs (do we have those yet?), then you can make changes from there. Autocross and track regulars will often do their own alignments, so you could probably find people to help do it yourself even. The scales are expensive and not something you'd want to buy, but maybe renting/borrowing them would be possible.


Here are the alignment specs 21114

[Frank818]

@Bob, got that from the manual?

[Evan78]

@Bob, got that from the manual?Yep. Appendix D: Alignment and Ride Height.

[skullandbones]

Here's my take on "idiot proofing" suspension. It's kind of like EFI. When you set it up stock for the street, adjust it and forget it. But if you decide you want more there is a very steep learning curve to make it good for racing. Suspension is the same way. Set it up like in the numbers given above and cruise. When you take that first step into weighing the corners (anything beyond camber, castor, and toe), you have started down a very slippery slope!! $$$, scales, computer programs, components............... There's no easing into it. IMO, WEK.

[CHOTIS BILL]

If you want your own scales with out spending lot of money check out Ruggles Scales. https://www.pegasusautoracing.com/pdfs/098.pdf. The are less than $500 and work well but do take longer to use and you have to do all the math. I used these for many years with good results. I marked each piece of mine as to which wheel position they go to so that I could set them up the same each time. As a matter of fact I think I may still have mine but one of the scaled needs to be replaced I think.

Bill Lomenick

[Bob_n_Cincy]

If you measure your 4 spring lengths. Know you spring rate and suspension geometry.
Can you calculate each corner weight?

[CHOTIS BILL]

Measuring the spring length to check corner weight is an interesting idea which I never thought about but should get you close. If you start by fallowing the FFR manual at set each spring collars to where each spring is just snug and adjust front and rear pairs the same from there it should be close but there are some variables. There is a tolerance on spring length so four 8 inch long springs may not all be exactly 8 inches long. Springs rates for any given rate will vary. A spring marked as 250 pound spring may check out to be 237 pounds or 265 pounds. Some springs come with the actual test rate etched into the end of the last coil but you don’t know what method was used to check the rate. Eibach rates there springs between two points and some rate the spring on how much pressure it takes to compress the spring the first inch. This link gives some good info. http://performance-suspension.eibach.com/motorsport/products/suspension_worksheet . But for the average street driven car this method should be close enough. The next time I set a car up I will definitely check to see how close the springs length is to each other.

Bill Lomenick