it seems to me that lowering blocks would reduce axle windup, by virtue of the center of rotation being further from the spring, and also from the forward vector of the axle having more leverage to flatten the spring as it moves forward. what do you guys think?

I'm not a mechanical engineer but I do work closely with one...I believe you are missing the fact that a lowering block will act as a lever increasing the torque effect...

If you have an object that has torque, a longer lever will decrease force made by that torque. Torque is force x displacement (distance from the axis of rotation), thus force= torque/displacement. The main issue I would see is rigidity.

Guess I should have asked Rich.. The lever is actually an advantage...

Dont sweat it. I'm reminded why I'm taking all these hard azz classes instead of being an arts major or something. It's something I can actually apply to my life.

Not a engineer, just an auto instructor. Put lowering blocks on and try to control the axle rap. I grew up when everyone did this to their 56 ford and chevy. Wrap so bad that now we repair the rear end. Don't worry about why , just don't do it.

TO put it in perspective, think of a 4WD truck with really big lift blocks in the back. Say like 8 or 10 inch blocks. Without a control device on the rear, those axles will move ALOT.

Seen people driving on the road, with a lifted truck and big blocks, and I can actually watch the spring wrap. Especially if its a stick truck.

If the springs still arent strong enough to control the wrap, by increasing the distance you have now increased the magnitude of the wrap, which will also cause the axle itself to move around.

lowering block and axle above the spring. also the traction input has additional leverage on the system. my guess is it cancels out the rotational moment. i'm seriously considering mounting a camera under my car and documenting the shenanegans. thanks for your input.

If you decide to do it post the video..

Not a mechanical engineer, but a mechanical designer... what I get for dropping out!

Here's a thought experiment:

Imagine you have your park brake on real tight.

Your car's on a lift.

You grab that rear wheel and try to turn it - you go grab a socket, breaker bar, and six foot 'cheater' pipe; try to turn that wheel with a lug nut (let's pretend you don't twist that lug off!)

You know that you'd feel that leaf spring move around, right? Of course, with that much bar, you could probably knock the car off the lift, too... pretend it's welded on.

Now, imagine you had a foot of spacer between the spring and the axle; doesn't it make sense how the rotational forces applied to the axle would tend to grab that long block and twist the spring?

Hope this helps.

-bill

I think you will find that with the lowering blocks the hit is a lot harder. Here is a photo of my car with 2" lowering blocks and a 1/2 leaf added on top of the front of the spring allso clamped at every section in the front. That is the rear section of the spring allmost hitting the ground.

The farther out you go from centerline the greater
the torque lever

In mud racing the first thing new racers do is install lift blocks to fit larger tires , Big mistake , leeds to major axle wrap & bent or broken leaf springs.

I`ve gotta call bs on this one. I`m running 2" lowering blocks on my dart and have no damage or issues and although my car runs good, a buddy of mine was in the low 8`s with the same blocks(he makes em). His chassis guy uses em all of the time and his cars fly. Calvert has no issues w/using em eighter.

I am a Mechanical Engineer and my feeling is that lowering blocks won't improve axle wrap. The overall stiffness needs to be increased. Which is why getting the axle closer to the front of the leaf works. Ever notice how Mopar's didn't have the same wheel hop problem back in the day compared to other makes? But obviously if traction bars are used that changes things.

we all know real race cars don't have leaf springs so whats all the fuss

That`s interesting because the mopar guy at calvert I talked to(forgot his name)said he saw no problem w/lowering blocks.