REAR SUSPENSION IDEAS

[anwat]

I'm looking for some advice/input/ideas for how to get my rear suspension under the truck. I currently have shocks that extend into the bed area and I'd like to get it all under the truck if at all possible. If I can't do that, at least make the intrusion into the passenger's compartment minimal, because having it like it is makes the bed useless for pretty much anything.
It would also appear the shocks I have are too short, since there's only 3" of shaft showing at ride height. The other 13" is droop. Since both shocks have blown seals and are leaking all over the place, I'm hoping I can tackle both issues at once. The only way I can think to address this is to put a false floor in covering the shock towers. Which isn't really a good idea, and it results in a ton of wasted space. So, I'm opening the door to whatever anyone may want to suggest to get the shocks back under the truck without giving up too much travel.
I'm not doing any high speed desert racing with this, it's a bit of highway and mostly washboards and big rocks in the desert. Maybe I don't need so much travel, but since I have it, I hate to give it up. Any way to do it without giving up the entire bed to the shocks?

 

[Hogback Fabrication]

What springs are those?

 

[anwat]

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.

 

[rampage]

I know I’ve mentioned this a few times but look into cantilever shocks. Depending on how long/short you design your lever arm you can use either stiffer or softer shocks and longer/shorter travel shocks to give the same rebound/compression that you currently have. Or if you use a lever arm that is 1:1 so it simply changes the direction of the shock then you could use your current shocks ... if any of that makes sense.

Here’s an example:

 

[bmxbryant9]

Streched wheel tubs then notched around that cross bar. Similar to this but just the cross bar coming out the side of the wheel well tub

 

[Hogback Fabrication]

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 was guessing 64's.

Flat is actually pretty ok with leaves. Leaves don't really care what shape they are, both positive and negative arch are perfectly fine. What matters is how far they can be flexed before they take a permanent set (i.e. stay bent).

The amount they can move without permanent damage depends mostly on the length of the leaves and the thickness of the leaves. It's very common for soft and long travel leaves to go inverted and if they're designed to take it, is perfectly fine.

Also, with the steep shackle angle you have, the spring rate will go through the roof as soon as that spring goes flat. If you want any travel beyond that, you'll need less shackle angle.

To answer your direct question, the shock is ideally mounted as vertical as possible and as close to the tire as possible. If you want to stay under the bed, you need to drop the axle side mount a bunch.

 

[JoshHefnerX]

I welded some tabs onto the axle front/rear to get enough travel out of my shocks. You can gain several inches of shock travel that way.

 

[anwat]

The cantilever idea does make sense. I actually started to look into it, and once I started reading, I sounds like there's a lot of calculation that has to be done to get that type of system to work correctly. Way more than I'd be comfortable doing. Couple the math with my mediocre fabrication skills, and it sounds like a recipe for disaster. Even if there was a prefab kit available, it's probably not going to fit the oddball configuration I have. From what I read, it's not as easy as picking pivot point and working from there. I like the idea, it's ideal, I just don't think I can do it right. And it sounds like it would be prohibitively expensive to have someone else do. Any off for Covid-19 fabricators out there looking for some extra cash?

 

[rampage]

The cantilever idea does make sense. I actually started to look into it, and once I started reading, I sounds like there's a lot of calculation that has to be done to get that type of system to work correctly. Way more than I'd be comfortable doing. Couple the math with my mediocre fabrication skills, and it sounds like a recipe for disaster. Even if there was a prefab kit available, it's probably not going to fit the oddball configuration I have. From what I read, it's not as easy as picking pivot point and working from there. I like the idea, it's ideal, I just don't think I can do it right. And it sounds like it would be prohibitively expensive to have someone else do. Any off for Covid-19 fabricators out there looking for some extra cash?

True, it would take some fiddling around with but I imagine (I haven’t actually looked into it) if the two lever arms are the same length then the you can use the same shock since you’re just changing the direction of travel. The thing I’d change with the pic I posted is the pivot point being a larger diameter tube that goes from frame rail to frame rail instead of the bolt they’re using. Of course then you’d need to mount the shock on the front side of the axle since the gas tank would be in the way. I don’t know why one of our vendors haven’t designed this setup yet.

 

[anwat]

The wheel tub idea is great, but I would still have to tie the two towers together with a bar across the bed, correct? I guess it could be two bars right at the floor of the bed , which would free up some space, but It's still going to be hard to slide stuff in and out over the bars, and come bedtime, I'll be sleeping over them, which isn't going to work. Maybe I can brace the hoops up off the frame or something since I have the wider wheel wells....never would have thought of that one...

Shock mounting tabs will be moved to the bottom of the axle, at least. That will get me about 3"...if I end up tearing a mount off on the rocks, it can be fixed. They say life is full of compromise, and I'm willing to risk it to get the comfort and convenience of being able to sleep out of the weather. The guy who built the truck was clearly more interested in performance and mounted the shocks at the best location, I'm willing to trade a little of that away for convenience. What about just a shorter shock and some sort of limiting straps similar to the front suspension setup I see a lot. Maybe a 14" shock with three additional inches added to the mount would work. I've never seen limiting straps on the rear, is that something that isn't a good idea?

 

[anwat]

True, it would take some fiddling around with but I imagine (I haven’t actually looked into it) if the two lever arms are the same length then the you can use the same shock since you’re just changing the direction of travel. The thing I’d change with the pic I posted is the pivot point being a larger diameter tube that goes from frame rail to frame rail instead of the bolt they’re using. Of course then you’d need to mount the shock on the front side of the axle since the gas tank would be in the way. I don’t know why one of our vendors haven’t designed this setup yet.

It almost sounds like you're describing an anti-rock swaybar setup for the rear. Except instead of using a torsion bar, you're using a shock absorber...I don't know if I would have room to mount a shock that long anywhere else under the truck, either. I know that with too much angle they will loose their dampening ability, I'm assuming that goes for forward and rear angles, too?

 

[rampage]

It almost sounds like you're describing an anti-rock swaybar setup for the rear. Except instead of using a torsion bar, you're using a shock absorber...I don't know if I would have room to mount a shock that long anywhere else under the truck, either. I know that with too much angle they will loose their dampening ability, I'm assuming that goes for forward and rear angles, too?

No, I just don’t like the way that the cantilever is mounted with that bolt going through the frame. Seems like a lot of stress on it and it could break. It does look like the frame is reinforced. I was just thinking of a way to make that pivot point a little more stout and that’s the first thing that popped to mind. I haven’t looked into the design enough to tell you, but if it does in fact loose it dampening ability then you can always step up to a stiffer shock.

 

[jkroberts]

I squeeze 14" of travel from a 12" travel shock mounted under the bed. On a 52" spring as well. For your application, you can probably get more. Shoot, bronco guys are swinging 18" for the same setup! Not sure you could do it with a shackle flip like that, but its worth a shot.

 

[folkenheath]

Link it and mount the shocks to the lower arms so you can ratio it. It would be easy to get 15" travel from a 10" shock at a little bit of an angle. The shock will need to be firmed the moment you give the tires a lever against it no matter which method you use.

 

[jake 03]

No more space than you need I would just mount the shock off of the bottom of the axle. Just by doing that you could move the shock down 3-6 inches no problem.

 

[anwat]

I squeeze 14" of travel from a 12" travel shock mounted under the bed. On a 52" spring as well. For your application, you can probably get more. Shoot, bronco guys are swinging 18" for the same setup! Not sure you could do it with a shackle flip like that, but its worth a shot.

View attachment 354708

OK, that's what I'm looking for. I notice you do have the limit straps on there, so if I drop the mount to the bottom of the axle, and go to a 14" shock, I might be able to swing it. Tell me more...what am I missing? How are you getting more travel out of a shorter shock? I'm going out to measure, but I can tell already this seems like the best option...I'm happy with 14" of travel...but how do you get it from a 12" shock?

I like that swaybar setup on the rear, do you have a photo that shows how you've got it attached to the axle?

 

[muddybuddy]

If you angle the shocks in (in-board) they lose their effectiveness/dampening but you can get more travel out of a shorter shock.

 

[anwat]

Since I clearly don't understand shocks, lets start with what I'm assuming. You take a shock and extend it all the way until it mechanically stops, like the piston is hitting the top of the tube, that's as long as it gets...You measure it from eye to eye, and that's your extended length. Let's say 36". Now take that shock and compress it all the way until it stops, as in there's no more shaft showing, and measure it eye to eye, that's your compressed length. Let's say it's 26". Am I wrong that that would be sold as a shock with 10" of travel? And if the shortest distance between two points is a straight line, how are you going to get more travel by mounting the shock at an angle? Now you have to make up the distance lost by lateral movement, and you only had 10" to start, so you would have less. What am I missing here?
As far as losing effectiveness, I believe that's sort of a sliding scale, right? The further from vertical you go, the more effectiveness you loose, correct?

 

[folkenheath]

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.

 

[jkroberts]

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.