Developing a Proper Suspension Model

[Racecomp Engineering]

- Andy

[RBbugBITme]

Originally Posted by cdrazic93

What would that translate to on the graph? When you say all areas im assuming you mean a quadruple adjustable shock.

I simply mean that we have the ability to build a shock with almost any damping rate required at pretty much any sector of the shock dyno graph. We simply have to incorporate different technologies to do it such as cut bands, high flow/velocity dependent/linear/digressive/regressive pistons, various adjusters, remote flow control devices, interconnected suspensions, and active damping if necessary.

[Racecomp Engineering]

Originally Posted by cdrazic93

What would that translate to on the graph? When you say all areas im assuming you mean a quadruple adjustable shock.

Basically, you can close your eyes and draw a line that goes up and down and they can build it for you, with or without adjusters.

If you build the shock exactly the way you want, you don't need adjusters at all. They do help with quickly fine-tuning for different situations.

- Andy

[gramicci101]

What I would love to see is something similar to PASM for these cars. I can't even imagine how much something like that would cost though. You'd need a control module with at least two accelerometers, preferably mounted somewhere near the CG of the vehicle. You'd need struts and shocks that could be electronically adjusted on the fly to compensate for road surfaces and driving styles, and springs that would work well with the entire range of adjustment. And you'd need some inspired programming to get it all to work properly.

[DeaconRoc]

I'm doing my best to get as good an understanding of suspension and dampers as possible as I really do think a good suspension set up is make or break on a car.

However, obviously it's a really complex topic.

What would you expect a damper that produced a graph like this to be like:-



It uses this piston:-

[cdrazic93]

Ill take a crack at that;

My guess is that it looks like a digressive/linear piston from what Shankenstein posted.

Basically a shock that would be pretty predictable on the street while giving you a decent amount of damping. (Then again i could be impossibly wrong).

[RBbugBITme]

Originally Posted by DeaconRoc

I'm doing my best to get as good an understanding of suspension and dampers as possible as I really do think a good suspension set up is make or break on a car.

However, obviously it's a really complex topic.

Meister seems to make a nice piston and that looks more like a high flow linear piston. I'm used to force/velocity graphs and maintaining uniform units of measure but the compression side is the high flow/lots of bleed side and the side we're looking at in the picture. Basically it dumps a ton of pressure when the shims open with the huge ports.

The smaller ports are the inlet for the rebound flow. Smaller ports allow for higher pressures/forces and greater adjustability range. The adjustable range is excessive. You could run any spring you ever want and never have to change the shim stack on the rebound side but I'd hope it has a lot of clicks that allow you to take smaller adjustment steps or you'll never be able to dial the car in correctly.

I have a piston similar to this in my Corvette and I love it on the street. With so much compression bleed it feels pretty good on pothole ridden streets. I barely notice running over train track crossings.

[DeaconRoc]

Originally Posted by RBbugBITme

You could run any spring you ever want and never have to change the shim stack on the rebound side but I'd hope it has a lot of clicks that allow you to take smaller adjustment steps or you'll never be able to dial the car in correctly.

I have a piston similar to this in my Corvette and I love it on the street. With so much compression bleed it feels pretty good on pothole ridden streets. I barely notice running over train track crossings.

Thank you for your thoughts on these.

They are single way 36 point adjustable - dialing them in is definitely proving a challenge!

You're 100% right about the potholes though - they soakthem up like no suspension I've ever tried. The internals are made by a company who specialise in rally car suspension which might explain it.

[7thgear]

asked this in a separate thread but got a hypothetical answer.

Does toe change in the rear with ride height changes?


And if it does even a little bit, which way does it change when the car goes up or down?

[fika84]

Someone with a model will have to check the amounts, but it absolutely changes with ride height! It just depends on the radius of curvature of the tie rod. Usually it will toe in under compression AND rebound, but it depends at the point the tie rod is at it's maximum extension. Someone with a model will need to tell us at what chassis height this maximum extension is at. Maybe @RBbugBITme has this info, or @Racecomp Engineering

[7thgear]

Originally Posted by fika84

Someone with a model will have to check the amounts, but it absolutely changes with ride height! It just depends on the radius of curvature of the tie rod. Usually it will toe in under compression AND rebound, but it depends at the point the tie rod is at it's maximum extension. Someone with a model will need to tell us at what chassis height this maximum extension is at. Maybe @RBbugBITme has this info, or @Racecomp Engineering

just to make sure, I'm interested in the rear of the car.


I'm particularly interested because I just had my alignment (a very aggressive, for testing) done with 1/4 tank and spare removed. I'm curious which way it will go once I put everything back in + an extra 50/60 pounds of cargo.

becase if it will go back towards centerline that's fine, but if it will increase my settings then I'd be worried. :o

[fika84]

Originally Posted by 7thgear

just to make sure, I'm interested in the rear of the car.


I'm particularly interested because I just had my alignment (a very aggressive, for testing) done with 1/4 tank and spare removed. I'm curious which way it will go once I put everything back in + an extra 50/60 pounds of cargo.

becase if it will go back towards centerline that's fine, but if it will increase my settings then I'd be worried. :o

Yes, the rear.. I use the term tie rod for both front and rear, even though in the rear it's a toe arm I guess.. same stuff to me.

Hopefully someone can chime in, I think I remember seeing a chart of someone that posted this kind of information.. I'll hunt around for it.
@7thgear - Here is a good link with someone saying they've measured it and it toes in under rebound and toes out almost the entire amount of travel under compression... I'd want a second look.

[7thgear]

Originally Posted by fika84

Yes, the rear.. I use the term tie rod for both front and rear, even though in the rear it's a toe arm I guess.. same stuff to me.

Hopefully someone can chime in, I think I remember seeing a chart of someone that posted this kind of information.. I'll hunt around for it.
@7thgear - Here is a good link with someone saying they've measured it and it toes in under rebound and toes out almost the entire amount of travel under compression... I'd want a second look.

no link!

[fika84]

Originally Posted by 7thgear

no link!

I'm retarded... http://www.ft86club.com/forums/showthread.php?t=56488