Will axle wrap cause tire hop?

Hunter44

Hunter44

Well-Known Member
Joined
Feb 26, 2014
Location
Lexington
I've got my rear shocks at an angle and I get bad tire hop around 50mph. Any ideas? Tires are liquid balanced.
 

Attachments

  • image.jpeg
    image.jpeg
    138 KB · Views: 317
Yes. But liquid balanced isn't balanced.

Balance the tires properly and go from there.
 
At that angle, your shocks are doing nothing. You really need to mount them so they are more vertical if you want them to work. A shorter shock looks to be in order.
 
Hunter44 said:
Do I need to take the liquid balance out before I pad balance them?
Click to expand...

Yes, because the liquid is going to interfere with proper balancing (in a rotational speed dependent way) on the spin balancing machine the same way as on the road. If you're going to pad balance them, you shouldn't need the liquid anymore, because the tires will now be... ...balanced.
 
Jody Treadway said:
At that angle, your shocks are doing nothing. You really need to mount them so they are more vertical if you want them to work. A shorter shock looks to be in order.
Click to expand...

That's not entirely true, but they're certainly not going to work the way that they should. The velocity and displacement will just be different for whatever ride frequency, and that's just making things worse if you're already outside of their operating range because there's a shitload more tire and axle weight than they were designed for, or more spring rate, etc.

I agree though, those things should really be remounted in a better position.
 
Hunter44 said:
Should I go back to a factory style shock mount(vertical)?
Click to expand...

Yes. There is so little uptravel there that I am amazed you haven't bottomed out and blown those shocks.

I see so many people mounting shocks like this yet they are very ineffective at that angle and worse do not help at all with roll stability since they are canted so far over. If you can, mount them vertically. Use a bracket that can put the shock in front or or behind the axle and get the thing as straight up and down as possible given the travel you need. If you can outboard them outside the frame rail and position them straight up and down they will work better than any other orientation. They are intended to dampen wheel motions, so the closer you can get them to the wheels the better.
 
OnlyOneDR said:
....and worse do not help at all with roll stability since they are canted so far over.
Click to expand...

That is very true with air struts or coilovers where the springs are oriented along that badly positioned axis, and those springs are what are holding up the chassis/body. Then you have problems with both roll stability and roll damping, both because of the angle and because of the very small distance between the upper mounts. That small distance is actually a much bigger problem than the angle if the springs are mounted along that axis, because that makes a very narrow spot between two pivots that the entire body is rotating about.

But....

This is not the case here because it has leaf springs; in this case the roll stability is mostly a function of the spring rate of the leaf springs, and only the roll damping is affected by the shocks. There's nothing wrong with the leaf spring placement, so bad damping is going to be the problem.
 
Last edited:
Hunter44 said:
So could the way I have my shocks mounted be the cause with my tire hop, causing axle wrap?
Click to expand...

No, the shocks being mounted like that will not cause the tire hop. Having a proper set of shocks mounted properly would possible help hide the tire hop, but your tire hop at 50mph is totally due to wheel/tire imbalance.
 
The shocks mounted like that won't cause the tire hop, they will just make it worse because they're not doing their job properly. The tire imbalance is what is causing the problem, like said above (NC-V).

The shocks are probably not working very well at that angle, because the angle changes the displacement and the velocity that the shocks are designed for at any given amount of axle travel. So they're likely underdamping your axle. But, there's also the matter of maybe a lot more weight from the axle and the tires than what the shocks are designed for, which can also cause damping problems. So you really need shocks that can properly damp the unsprung weight that you have (tires, wheels, axle, etc), and those shocks need to be mounted in an orientation where they can properly do their job.

When you've got large diameter tires that weigh a lot and aren't damped properly, there is a lot of leverage there that could easily cause axle wrap depending on your spring length and rate. Leaf springs really don't do a great job of axle control, but they're simple and easy so we tolerate them anyway.

If you've got one tire that's getting excited and moving a lot up/down, that can feel like axle wrap without being axle wrap. Lots of rapid single-wheel axle motion that's changing the joint and shaft angles still feels weird.

The takeaway is that you need tire balancing, not whether or not you actually have axle wrap.
 
Back
Top