sport mod rear suspension

[newguy]

Our rear suspension rules are similar to the northern sport mods and im wondering if there are any good resources out there?

[kwagner]

http://www.thedirtforum.com/toolbox.htm

[newguy]

thanx for the link, anything on length of pullbar in relation to length of lowers? or location and height of pullbar mount on rear end etc. i bought a steve smith book, but holy cow i think the technology is 20+ years old. in it it says the pull bar should be 70% of the length of the lowers, but im wondering if this is still practiced, and does it relate to a solid pullbar?

[MM90]

REAR SUSPENSION: All components must be steel. No covers allowed. All mounts and brackets must be welded or bolted solid. Coil springs must remain
vertical and over center line of rear-end housing. No coil-over eliminators allowed. No chains, cables or tethers. Rear shocks cannot be mounted on control
arms. All rear control arms and panhard bars must be straight. Must utilize one of the following designs:
(A) Aftermarket three link design requirements: Must use 16 inch minimum, 24 inch maximum lower control arms. Must use one upper control arm, solid
tube only, located at top center of rear end housing and remain centered (one inch tolerance) on housing over drive shaft. Must use minimum 23 inch panhard
bar located behind rear end housing. Lower spring perch must be welded to rear-end housing. Bottom of rear spring must remain within 0.75 inch of the axle
tube. Must use steel upper weight jack. No floating or bearing rear spring perches/cups allowed, top or bottom.
(B) Multi-leaf spring design requirements: Must use steel multi-leaf springs with no additional suspension components besides one shock per wheel. Adjustable
aluminum lowering blocks allowed.
(C) OEM stock design requirements: Rear crossmember, control arm mounts and bolt holes on frame must be in stock location. All components must be
unaltered, approved OEM, and match frame. Control arms cannot be altered in any way. Steel, rubber or nylon control arm bushings only. Springs must remain
in stock location. Lower spring perch must be welded to rear-end housing. Must use steel upper weight jack.


If these are your rules, then your panhard bar can be no shorter than 23 inches.

[newguy]

I dont think im haveing an issue with my panhard bar, my lower control arms are 20" long, and my solid upper is as well, im wondering if i need to shorten my bar, if im right 70% of a 20" bar is 14" also i notice mounts that locate the pullbar a few inches behind the rear end, im trying to figure out if there is some kind of equation for all of this,

[racinjj]

Shorten your left trailing arm to 16" and get a longer pullbar, I dont use anything shorter than 30".

[newguy]

here are the rules for 3 link rear suspension,
Top bar maximum length of 20 inches.
Panhard bar minimum length of 20 inches. Must be mounted behind rear end.
Lower Bars minimum length of 20 inches, maximum length of 22 inches. max 1" differance from side to side

[Salvin49]

I dont think hes asking what the rules are, I think he is asking what length of bars will perform the best...

[newguy]

I guess my question is if i have the same length trailing arms, pull bar, and panhard bar, am i creating any kind of mechanicle drive? is there something i can do given the limitations to increase this.