The Stovebolt Site Forums The Shop Area The HiPo Shop Lowering Springs. Interference?

No, I'm not lowering Ol' Roy. I just have a general question about installing springs to lower ride height.

When the body is lowered to sit closer to the ground via weaker(?) leaf springs or shorter coil springs, doesn't the drive shaft angle become closer to horizontal? As such, can the drive shaft or U joint contact the floor boards or other components when hitting bumps or pot holes?

Maybe this is more likely to happen in a car with a driveshaft tunnel than a truck?

What happens when the rear end extends to full travel on vehicles with coil springs in the rear instead of leaf springs? Could the coils get loose or fall out?

The springs are almost never the limit of travel.

The axle itself will hit the frame before the driveshaft collides with the body. The lowering springs reduce the total travel, rather than just moving the frame (and thus body) down.

That said, if you channel the frame, then this does become a concern.

Coil springs are typically attached at both ends to prevent them from being able to come out.

I’ve seen people notch or remove the rubber bump stops while lowering. That might put you close to things hitting other things when full compression happens. But the closer to 0* pinion angle can cause vibrations. Most small lowering jobs don’t cause any other issues.

When the body is lowered your pinion angle will always change. Yes, the further you lower it, the closer to horizontal the driveshaft will be. You always have to check your pinion angle and correct it...the angles being equal but opposite. And please do not overlook the extra 1 degree down at the differential to compensate for torque wrap-up of leaf springs. You'll be surprised how easily 1 degree is gained.

One problem with changing ride height is that there needs to be at least a small angle of a U joint to assure that the needle bearings in the caps move a little. As the angle approaches zero, the grease in the caps quits circulating, and the needle bearings wear out quickly from lack of lubrication. There are a lot of unintended consequences to any changes to ride height, track width, steering geometry, or other angles built in by the vehicle designers. The laws of physics are not "suggestions"- - - - -something that shade tree engineers often tend to ignore!
Jerry

Lowering will change the pinion angle. If you get too close to zero you will need to change the diff angle and the transmission angle to get back closer to 3-4 degrees. The more power you are running the more this matters. There are several ways to handle axel wrap. JMHO.

Being lowered is no different than being over weighted and bottomed out, the driveline will still clear. As far as springs falling out, maybe but it would be one heck of a bump and suspect you would have other things to worry about at that point.

"Proper" lowering (if such a thing even exists) would include installing shock absorbers that would limit the downward travel of suspension components sufficiently to keep springs from falling out of position at full extension. Operating at or near the maximum travel of any suspension component will induce a lot of unintended consequences- - - - -most of them pretty unpleasant, or possibly deadly dangerous.
Jerry

Suspension limiting straps are not expensive. https://www.summitracing.com/search...&keyword=suspension%20limit%20straps