how long is your

[slngsht]

rear suspension link (what did you think I was going to ask?)

 

particularly interested in 4 link suspension setups.

 

Rotus came with 9" links, which seem really short to me.

 

I have the opportunity of going to 14" by changing the chassis pickup points.

 

Seems like most locosts are 11.5 - 12".

[JohnK]

Yes, size does matter.

 

The setup on my ultralite is 5-link, so your 4-link is what, solid axle? Continuing on anyway in case its still relevant, the configuration on my car is that of pairs of parallel, unequal length A arms- which puts the roll center on the ground. A fifth link runs fore and aft, positioning the hub and angle of the hub in the wheel well space. These links run from 14" to 22" eye to eye. Long links make the instant center of the wheel swing through a smaller arc, making changes in camber less, which is good (ref the length of the links on the front of F1 cars).

If you're really interested in understanding and modifying your suspension to make it better, check out Wm C. Mitchell's WinGeo3 (http://www.mitchellsoftware.com/). Being able to take advantage of this pkg takes more than a little work, BUT once learned, you will be able to see and test all kinds of things re your suspension's behaviour from the comfort of your desktop, and to a degree that will amaze you. Of course you'll probably lose all your friends 'cause you'll have actual factual data to show what's happening as your car works - rather than participating in the time-honored tradition of arm-chair hand-waving :-) . (If you get serious about buying this software, I can give you a description of what you'll face getting up to speed on it, before you spend the money).

[11Budlite]

I just went out to the parking lot and measured the Birkin trailing arms at approximately 13-3/8". Measured with a tape measure lying on the ground so not too accurate...

 

Check out these:

 

http://www.usa7s.com/aspnetforum/upload/906989896_image002-607x289.jpg

 

Bruce :7drive:

[slngsht]

I just went out to the parking lot and measured the Birkin trailing arms at approximately 13-3/8". Measured with a tape measure lying on the ground so not too accurate...

 

Check out these:

 

http://www.usa7s.com/aspnetforum/upload/906989896_image002-607x289.jpg

 

Bruce :7drive:

 

I can go from 9" to 14" and be pretty conventional.

 

I think the longer the better.

[MHKflyer52]

Mazda,

 

The trailing links on my car are 12 inches from center to center and mounte 9inches apart. the important thing to get correct is the mount on the rear end needs to be centered on the axle tube for both top and bottom otherwise your axle will tourque twist more on acceleration also you need to set them for you max upward droup with out having the rear contacting any structure and that includes keeping your shocks from bottoming out to their stops. If you put adjustable rodend in you can adjust them for better control of alignment and wheel hop if you find that you have that problem. Make sure your panhard rod is also level with the centerline of your axle when the car is sitting on the ground to keep the float even when taking bumps and turning.

Hope this helps.

 

 

[slngsht]

Yup. I'm good on the rest of the things you mentioned. I think I'm just going to try increasing my arm lengths to 14" from 9".