Axle hop explaination and a cheap cure

[Humvee21]

The lift block also acts as the bump stop right?

 

[bstoner59]

The lift block also acts as the bump stop right?

The lift blocks have the strike pad for the bumpstop built into it. If you remove the block and keep the original bumps you need to Fab a new strike pad that is the same height as the original. If you don't the shock will get too much bump travel and act as the bumpstop...not good.

 

[GRT4DRT]

Subscribed.... xclnt thread!

 

[AlbertaRaptor]

Went top perch today. Now I just need to budget time and money for the rear. I also installed the SDHQ rear frame kit:

My dilemma now is that the rear is actually very close in height to where I want it in relation to the front. If I measure front to rear wheel opening distance to ground they are only 1/4 of an inch difference.

The front is still lower than the rear even on top perch and I'm thinking my N-Fab front Bumper is a tad heavy compared to stock:

Anyways, just checking in and I'm hoping to get some pics of the rear spring work when it goes down.

( and some real pics of my truck lol )

Jeff

 

[LVdezertdawg]

The bumper is awesome!!!

 

[BigJ]

Subscribed. Very cool stuff, well explained and thought out.

My only concern is your cold setting approach. I know this is commonly done in neighborhood shops, but in my experience its used as a temporary fix, not a permanent solution. And usually aren't the springs re-arched to their original state? Not further beyond it?

I suppose my concern is that spring steel has a memory, and unless you use heat to erase that memory and reset it, its going to try and return to its relaxed (sagged) state, no? But if you've braced it so that it cannot relax, now all the stress has moved from the no-longer-springy steel to the clamps/mounts/etc keeping it from relaxing.

Is re-heat treating cost prohibitive?

 

[RPG]

Here is some food for thought.

Rearching Services - Eaton Detroit Spring

 

[AlbertaRaptor]

You are both right and if we were dealing with a 1997 F150 the cold re-arch would be useless.

I will explain it the way my shop told me:

Jeff, you have basically a new truck. We don't re-arch the springs to do anything other than to set the proper arch so that both sides are equal today and fit the arch of the add a leaf better

Not re-arching to achieve the lift 100%, but making sure the right fit of the parts is achieved so the add a leaf can do it's job.

Now if we were trying to lift an old truck or trying to get the lift block removed by re-arching or trying to achieve 3-4 inches of lift this would never work.

I'm talking an inch or so guys

Jeff

 

[BigJ]

I hear ya. And I might be being too knit-picky here but...

1) what is it about age that has them saying 'no' to an older truck, and 'yes' to a newer? I understand leafs fatigue, but that's from use right? Not necessarily from them sitting around for 100 years on the shelf (assuming no rust).

If its from use, I'd still be a bit concerned and inspect them carefully before deciding to cold work them. I had just under 40k miles on my stockers when they came off, and already you can see they were starting to sag


2) Again, cold working spring steel does nothing to reset its memory. Just changing them only up an inch from where they were set when last worked with heat is going to put the spring in a state of stress even with no load on it. Its going to fight hard to return to where it was last set (or where it has last fatigued to).

So... a) those main springs are doing less to support the load and work as part of your suspension because they're stressed in the wrong direction to begin with, b) that extra spring you're adding ends up holding your main springs in place to some extent and c) that extra spring ends up working far more than it should because now its doing the suspension work the main leafpack isnt.

Like I said, I'm probably being picky. But there are reasons cold working isn't considered a good option for long term use. I'm just letting my engineering brain sort of wander from there, trying to maybe think about why that would be so. I definitely look forward to learning more about this, and seeing maybe where my thinking has gone wrong

 

[AlbertaRaptor]

I hear ya. And I might be being too knit-picky here but...

1) what is it about age that has them saying 'no' to an older truck, and 'yes' to a newer? I understand leafs fatigue, but that's from use right? Not necessarily from them sitting around for 100 years on the shelf (assuming no rust).

If its from use, I'd still be a bit concerned and inspect them carefully before deciding to cold work them. I had just under 40k miles on my stockers when they came off, and already you can see they were starting to sag


2) Again, cold working spring steel does nothing to reset its memory. Just changing them only up an inch from where they were set when last worked with heat is going to put the spring in a state of stress even with no load on it. Its going to fight hard to return to where it was last set (or where it has last fatigued to).

So... a) those main springs are doing less to support the load and work as part of your suspension because they're stressed in the wrong direction to begin with, b) that extra spring you're adding ends up holding your main springs in place to some extent and c) that extra spring ends up working far more than it should because now its doing the suspension work the main leafpack isnt.

Like I said, I'm probably being picky. But there are reasons cold working isn't considered a good option for long term use. I'm just letting my engineering brain sort of wander from there, trying to maybe think about why that would be so. I definitely look forward to learning more about this, and seeing maybe where my thinking has gone wrong

No disagreement here with your reasoning. I honestly cannot find a flaw in what you state.


So I speculate:

Maybe because I have less than 15,000 miles?

Maybe because I am at near factory spec ride height already?

Maybe because the add a leaf is the same thickness of the main leaf and between the two you end up with greater than 100% of the original factory strength when all is said and done?

I dunno?

But I'm gonna find out



Cheers