REAR SUSPENSION IDEAS

[anwat]

It's about wheel travel vs shock travel. If you mount the shock at an angle (inward for articulation or forward/backward for go fast travel), then the shock will still be the same travel, but the as the wheel moves up, since the shock is at an angle it only moves part of that. So what happens is the wheel can travel more straight up and down than the shock travels at an angle. In doing this it puts more force on the shock so in order for the shock to have the same effectiveness it needs to be tuned stiffer.

I was saying to mount the shock partway up a lower link arm. If the link arm is 4 ft and you mount the shock at 2 ft for example, every time the shock moved 1" the wheel would move ~2" . That's a little extreme and not exact because its an arc, not linear. One would probably do more like 3 ft on a 4 ft arm, so the wheel travel would move 4/3 or ~1.33 x the shock travel. Then if you angle the shock forward you can get even more wheel travel from the same shock travel. But then you get more and more angle as the wheel gets closer to full bump, which is not good. You'd rather have it more straight(or perpendicular to the arm) at full bump. That's a whole different subject.

OK, that makes sense, you're putting the shock on the link arms rather than the axle. I've seen that done a lot on the race trucks, and it even works for me with the limited geometry knowledge I have...I missed those two words at the beginning of the post...which seems to be the right way to do it, although by far the most expensive. I may end up heading that way eventually, and the PO of this truck told me he had originally intended to link the rear, so he had set things up with that in mind as he built the rear. It's a big step, though, and I'm not sure I really need all that travel...but I don't need most things I have. Thanks for the explanation, though. It's kind of along the lines of me thinking maybe I could put a shock on the anti wrap bar up closer to the middle of the truck. Problem is, I would only have one.

 

[anwat]

So when you have the leaf soring mounted with a tension shackle, like from the factory, as the suspension compresses the axle move towards the back of the truck. As it drops, it moves forward. By tilting the top of the shock towards the forward part of the truck, you get a digressive rate the closer to get to bump. These are mounted at 70* at full bump (assuming 90* is vertical) and at droop, it gets closer to 90*. Bronco guys are laying them down to 45* at bump. However, at that point to have to have a bypass shock. Even with how I did this setup, a bypass would make it work even better.

The limit strap is there so the shackle doesn't go to far and flip back. It also saves the shock. At full droop I like to have zero leaf spring separation, but a tiny bit won't kill ya. At bump, the main leaf is flat. Zero negative arch. This should let this leaf pack live for a long time.

OK, I get it. Thus the comment about the shackle flip being an issue. I'm also assuming the arch of the spring is going to play a big part in how far the axle will move forward/back. I noticed the spring in the photo has a very noticeable arch compared to mine, which is almost flat because it's so long.
I'm going to go do some measuring and see if maybe I angle the shock at 70* and drop the lower mounting tab to the bottom how much room that will buy me. Most of the high quality shocks seem to have about the same dimensions in overall length to travel length. Are both the shocks angled forward, or is one forward and one back?

 

[jkroberts]

OK, I get it. Thus the comment about the shackle flip being an issue. I'm also assuming the arch of the spring is going to play a big part in how far the axle will move forward/back. I noticed the spring in the photo has a very noticeable arch compared to mine, which is almost flat because it's so long.
I'm going to go do some measuring and see if maybe I angle the shock at 70* and drop the lower mounting tab to the bottom how much room that will buy me. Most of the high quality shocks seem to have about the same dimensions in overall length to travel length. Are both the shocks angled forward, or is one forward and one back?

Yeah the way the spring is designed makes a big difference. Shackle flips and stock springs are a great budget option, but if your looking for more performance, you will need to switch it up. And yes both shocks are forward. I am in the process of developing a 64" spring kit for these that will do 18" of travel.

 

[anwat]

Yeah the way the spring is designed makes a big difference. Shackle flips and stock springs are a great budget option, but if your looking for more performance, you will need to switch it up. And yes both shocks are forward. I am in the process of developing a 64" spring kit for these that will do 18" of travel.

New springs are a lot cheaper than linking the rear. Looking forward to meeting you next week and will post up the final decision next week if anyone wants to know how this turned out.

 

[Magikal]

Your setup looks identical to mine except i got 18in coilovers in. Sitting on 5" lift

 

[anwat]

Funny you should say that, I was just thinking yesterday about coilovers in the rear. For what I'm looking to do, which is get the bed back, it's not a good option. But I was wondering why the PO didn't set up the rear on coilovers since he did the front that way. For all the work it took to get the 64" spring and shock towers in, he could have just welded some tabs on the axle and used coilovers. I'd imagine there's some pretty good lateral movement on those when it gets twisted up all the way, I know my tire almost touches the frame when it's stuffed all the way up. If you can, post a photo of your setup, maybe I can steal something from it. How are you keeping the axle where it belongs? I'm going in to talk to Jkroberts next week about all this, so the more ideas I have to bounce off him the better.

 

[chulisohombre]

64" on your hangers. They seem to be a little flat, I've always thought a leaf spring should have a substantial arch to it, but these are almost flat. But then again, the stock k5 fronts come with a reverse arch, so maybe I'm wrong.

I inviardef mine with a new cross member under the bed of my blazer. You still get all the articulation but just need a slightly stiffer shock because of the slight angle to let the shock rotate better with the axle. I bought mine off a member that built mine but they aren’t here anymore. But diy4x has a similar kit. Just another idea to look into.i also have mine in the inside edge of the spring not outside like yours.