Shock mount angle for ladder bar suspension

[RFE]

I have a 57 chevy hot rod project which is equipped with a ladder bar suspension system. It is in the mock up stage and I am trying to route exhaust pipes over the axle. Limited room has prompted me to investigate other shock mounting angle alternatives. The system has a provision to move the top shock mounts towards the centerline of the vehicle. The range of positions is approximately vertical to about 45 degrees

What is the effect on the handling of moving the shock angle inboard? Obvious effects are reduced spring rate and damping based on angle, but are there any limits or problems that can be encountered?
THX Any help would be appreciated.
RFE

 

[patdaly]

I would say that is the most imporant criteria, though you must understand, and the effective rate decreases, of which you must increase spring rate to compensate, the stresses imposed upon the coil over will increase, causing the possibility of failure of either the shock or mounting point. I am curious though, the 57 is pretty wide,and on my 70 Nova, narrowed for 17.5x 33's with ladder bars and coil overs, there is enough room to snake dual 4" pipes over the axle and out the rear at a 45 exit. It is close, but it fits. Do you have something else in the way?

 

[RFE]

Pat,
The distance between the cross member for mounting the suspension and the thick section of the ford 9 inch only provides a small amount of clearance. This isn't enough to provide the entire suspension travel.
RFE

 

[carnage]

how about modify your floorboards and run the exhaust over the cross member through a heat shield?

 

[SWB]

If possible, you would be best to keep them no more than about 20 degrees inboard. The rate will change as they compress and the more you angle them the more the rate decreases as they compress, which is undesireable.

Sean

 

[RFE]

Carnage, SWB & Pat,
Thanks to all for the input.

Carnage; thought of that already but I have quite a lot of gear just above that area of the floor. Booster, vacuum pump, battery, etc.

SWB; I'm looking at moving the shocks out the other way, i.e. more vertical. And then trying to squeeze a little room here and a little there. Lifting shock by 3/4 inch, notching crossmember by 1/4 inch, flattening exhaust tube by 1/4 inch, etc.

RFE

 

[SWB]

OK, Vertical is fine. Ideally the rate would be maximum at full bump and that is something you can check easily as you build the car. The more the shocks compress for each inch of axle travel, the greater the rate. They usually angle the shocks inward at the top to give an increasing rate (as determined above) as the car rolls. So there is a trade off between vertial movement and body roll. You'll notice most drag cars have shocks in a verical position with road course vehicles being a compromise as stated.