Does anyone make something, whether it be controle arms or spacers or anyhting to adjust the role center of the z's once lowered?

 

Excellent question! Everyone lowering their Z's should be aware that they are also DRASTICALLY lowering their roll centers. Simply put.......a major change in the moment arm length, necessitating a drastic spring rate increase, which will destroy ride comfort. Been there, done that, learned from it.

Back to your question, no one that I'm aware of offers such a kit. Don't know of anyone else who even considers it an issue.

I do, and I will have a solution soon.

BCR

 

Whats the solution if you dont mind me asking.

Also correct me if im wrong since im still fairly new to the role center and changine it for the better. Cant the improper positioning of the lower controle arm (cause by lowering the vehicle) in relation to the subframe and steering knuckle cause an increase in bumpsteer? Which can also be bad especialy at high speeds.

 

Most people/racers that alter/correct their roll centers do so by raising the inner A arm pivots points. Generally, with unequal length, non parallel A arms, one wants the lower A arm parallel to the ground.

Bump steer can be changed by altering the height of the steering rack, or changing the outer tie rods to rod ends, and using a spacer, or forging a new steering knuckle. Bump steer curves are a PITA to measure. I haven't found a need to change mine, but, I haven't lowered my Z ......YET!

Lowering a car won't always have negative effect on the bump steer, but it will but you in a different starting point on the bump steer curve. You will also be operating from a different point on the camber (negative) gain curve.

Isn't playing with suspensions FUN!

 

I understand the parallel to the gound part with the control arms.

I know that the toyotas have the ability to use a space to aquire the correct angle on the control arms.

I know that SPL parts made control arms front and rear for the old 300zx's and 240sx's that were adjustable for role center and i think they may have ones for the 350z in the works also(dont hold me to that, its just my own speculation from seeing their previous parts)

Also EnthuZ you seem to know a lot about suspension, could you point me in the direction of any good liturature or informative web site.

And playing with supesion is fun when you have knowledgable people and good resources to make sure you it turns out right.

 

For books, a MUST read, are the Carroll Smith books. Start with "Prepare to win", & "Tune to Win". "Engineer to Win" & "Screw to Win" are also Very good.

"Race Car Engineering & Mechanics" by Paul Van Valkenburgh is excellent also, but might be harder to find.

I just bought "Competition Car Suspension" by Allan Staniforth. Looks good but I haven't completed reading it yet.

"How to Make Your Car Handle" is also excellent, can't find my copy, so I'm not sure of the author.

There are many others also, maybe someone else will share their favorites.

 

thanks

 

Update

For anyone lowering their car, I strongly recommend you pick up a copy of Sport Compact Car, August 2005. A very well written article on roll centers, roll couples, camber curves, bump steer, etc. I couldn't find a link on their web site, but I may just be stupid!


...Moderator, could you please correct the spelling in the title?

 

its sad when no one have product such as Roll Center Adjuster for our car.
i'll definitly down for one if its out.