Stovebolt.com Forums The Shop Area The HiPo Shop Not happy with the front straight axle

In my experience a sway bar will have a positive impact on straightline handline regarding bumps, potholes, etc...anything on the road that causes one wheel to go up or down while the other stays constant (not affected by said bump, hole, etc). The sway bar goes up/down on one side but not on the other. And that causes the bar to flex from the applied torque and that applied torque will pull or push on the other side in a likewise manner. In other words, hit a bump and it pushes one wheel upwards. The sway bar swings up and simultaneously pushes the other wheel up (admittedly not with 100% of the same force, but with not much of it lost). This causes the front end to momentarily assume a more equal posture as both wheels feel the same relative force. Hit a pothole and one wheel goes down but the transmitted force goes against the other wheel simultaneously. Since the force has nowhere to go it actually works to minimize the "drop" in the wheel hitting the pothole by limiting the amount of downward motion. At least this has been my observation.

... also make sure the caster shims are still installed and not turned around backwards.


By the way John M, I never thought I'd hear Arlo Guthrie quoted on this form.

52CARL, I plan on taking my truck in to have what you said, done.
Thank you all for your much needed advice.
Elmo

AA Fuel dragsters run over 330mph in a VERY straight line and they ALL have straight axles. A straight axle and suspension built to factory specs then 7 degree caster shims and p/s added will give a ride that you can let steer itself while you square dance in the bed. Correct shocks and polypropylene plastic between spring leaves can give a living room couch type ride.

Coilover: where do you get your poly to put between the leaves? A buddy here was looking for some a couple months ago and had a reaaly hard time. I don't think he ever found what he wanted.

Check Speedway for Poly.

The last I bought came from Cadillac Plastics in Addison Texas. I bought a roll and it has made spring inserts for 30 years.

I bought mine from Speedway, because they had edges to keep them contained within the leafs. Here is a [LINK] [speedwaymotors.com]

It will go straight real good Evan, but try to parallel park with those 7 degree shims.

As has been said up thread, there's nothing inherently wrong with straight axles. Big trucks use them and roll along at 80 MPH legally in some western states.

They ride rougher in part because the sprung/unsprung weight ratio is somewhat less favorable when one wheel goes over a bump and much less favorable when both wheels do. And as most of them have leaf springs, there is resistance within the spring pack adding to shock being transmitted into the frame. That's a door that swings both ways, enough resistance and there's no need for additional damping. I drove 50s/60s Kenworths and Peterbilts with no shocks anywhere. But the KW torsion-bar rears did have shocks as did the Pete air-leaf rears. Rear shocks on my 1-ton were an option mine didn't have. Loaded it was fine. Unloaded it bounced a lot. It now has rear shocks. My 50 Studebaker had the rear leaves encased in metal jackets with grease fittings. Greasing the springs made a noticeable difference.

Adding a rear swaybar will correct oversteer when loaded as will increased spring rate. Adding a front sway bar will correct understeer, likewise will increasing the spring rate. Adding caster will make the steering return to center quicker but make for heavier steering AND the rig will tend to follow ruts and such in the road. Radial tires will make it much harder to park unless you have power steering.

Changing the wheel offset to more outboard centerline changes the scrub radius and will also cause the rig to follow ruts. Changing the wheel offset also changes the effective spring rate, particularly on independent suspensions but to some degree on a straight axle in a turn or when one wheel hit a bump. Adding wider wheels to accommodate wider tires will change the offset by 1/2 the increase in wheel width.