Some general leafspring setup questions

[Robprime]

Hello,
Newb here, and especially when it comes to suspensions.

I searched this forum for info about leaf spring setups and was pleased to see that the consensus is that leaf springs can be made to work well if set up properly, which is great as I am on the junkyard budget.

I have an '85 Lwb Ranger Std Cab that has a '78 302/C4 installed. The body was lifted 3" to make more room and it has worked out nicely in that respect. But it didn't do much for the handling.

I'm tackling the rear suspension first.

This truck still has the original 7.5" 3.45 LS rear end with 28 spline axles and drum brakes. It is a spring over axle setup that is 56.5" between the brake drum backing plates. The axle tubes are 3" in diameter and there is 39" of spacing between the spring mounts on the axles. The upper ends of the springs are mounted to brackets riveted to the outside of the frame rails, fixed in the front and shackled in the rear. There is about 2" of space between the outside of the frame and the inside edge of the springs. The shocks are mounted to the inside of the frame rails and are staggered with the drivers side to the rear of the axle and the pass. side to the front, and leaning at a pretty good angle, maybe 30* or so back to front. They look pretty straight up and down in the side to side direction. I run 32" tires on 15" wheels in the back and 31" on the front.

Sorry about this long description. I'll have the bed off early this week and will see about posting some pics. I am in the process of test fitting a 23 gal. Bronco II rear mount fuel tank in place of the 17 gal. side tank there now, and I need the bed in place to check clearances and such.

But anyway, I have a '95 Explorer 8.8" rear end, 3.73 LS with disc brakes that I want to use. Besides the brakes and lower gearing, this rear end is some 30% stronger than the 7.5", with 3 1/4" tubes and 31 spline axles. However, it is an axle over spring setup and is somewhat wider than the 7.5", measuring 59 3/4" between the plates, although the distance between the spring mounts is still 39". I consider that a good thing as I've always felt that the truck was a bit too narrow for its height.

Now for some questions. It's obvious that I'm going to be doing some spring and shock mount relocation and I'm wondering how best to set things up.

I've read that it's best to mount your shocks as far outboard as possible, pretty much straight up and down in the back to front direction, or perhaps with a small angle rearwards at the top of the shock to allow for the rear end moving towards the back of the vehicle as the leaf springs straighten out during hard acceleration or hitting a bump or whatever.
And that it is best to also have the shock mounted straight up and down in the side to side direction also, or perhaps again with a small angle inward at the top to allow for chassis roll during hard cornering or hitting bumps in curves.

Hopefully I am understanding this correctly.

It is really not possible for me to mount the shocks to the outside of the frame rails with the springs as they are now. there is not enough room to get the shock past the springs down to the axles with the axle under spring setup it has now.

And I'd like to change to a axle over spring configuration if I could as I understand that that helps greatly with spring/rearend twist under hard accel and also serves to lower the CG a bit.

I see two ways I might do that. I could mount the springs inboard directly to the bottom of the frame rails (I think that is the normal Explorer setup), which would raise the rear of the truck just about enough that I could switch to an axle over spring setup and the ride height would end up about the same. This looks like it would be very strong and stiff but would narrow the spacing between the springs by about 4" on each side. Maybe not so good in that respect, what with leverage and loading and all. It would let me make free with the shocks outside the frame rails, though.

Or I can fab some brackets for the springs that move them outward that extra 1.5" on each side that the wider rearend gives me. And I could make them so as to move the spring mount points down towards the bottom of the frame rails, maybe allowing me to still go to an axle over config much farther out on the axle tubes. That would open the 2" space between the frame and spring to 3.5", and I might be able to squeeze an extra .5" or so in. That might just be enough room to squeeze in a shock outside the frame rails. Not as solid and strong as the under frame setup, being cantilevered out like that, I wouldn't think. Leverage maybe causing some frame flexing?

Would I have to keep a staggered shock arrangement if I go to an axle over spring setup? And could I get by without traction bars? I found the panhard + leafspring thread interesting also.

If anyone would like to weigh in with some critique, ideas, anything, I would welcome the help. I have read of guys doing this swap before but they mostly just placed the wider rearend back in the stock setup by welding on spring and shock mounts in the normal places. I would like to improve the handling a bit if I can. This truck is capable of moving pretty fast as it is and I even have a 351W I'm thinking of stuffing in.

Rob

[David Pozzi]

Your current shocks are most likely angled to absorb axle torque. The axle below leaf is probably causing a lot of torque issues that need the shocks that way.
Since you are basically converting to Explorer suspension, can you copy the Explorer shock mounting too?
David

[Robprime]

Hello, Dave,

Thanks for replying.

I was busy at the time I bought the rear end and so didn't remove it myself. Just had the yard guys do it. I didn't get the Explorer leaf springs or the shocks with it (or the proportional valve for the brakes, either). I can fix that easily enough though as I have a good relationship with the yard and they let me wander around and find and remove what I need. Just a matter of doing it. It's been raining here for a week.

Looking at the 8.8" rearend, there ar no obvious shock mount brackets on the thing that I can see, nor any burn marks where they might have been cut off. There are certainly none that hang down below the axle 3" like the ones on the 7.5". I plan to crawl under an Explorer at the yard and see what's up with that when I get a chance. Maybe I can find something online. Glad you mentioned it. I don't know if the Explorer shocks are staggered, either. Maybe not if it is an axle over spring setup.

I won't be able to replicate the Explorer setup. I read that the Explorer springs mount directly under the frame and if that's so then the Eplorer frame must be about 40" wide where the springs mount, because the mounting pads on the axles are 39" c-c. The Ranger pads are also 39" c-c but mount well outside the frame rails on brackets, as the Ranger frame is only about 33" out-out in that area.

I did a lot of research over the weekend on rear suspensions in general and I think that I will use some ladder bars to control the axle wrap. They seem to be the simplest effective solution. Doing that will release me from having to use the shocks to try to control axle wrap and wheel hop, so basically I can mount the shocks where they will do the most good, handling wise.

I found this link to be most instructve, in a general sort of way.

http://www.4x4wire.com/jeep/tech/susp/axlewrap/

I could, I suppose, simply build some longer rear spring brackets to lower the shackles about to 4" below the frame rails, from the 1/2" below that they're at now. And do the same to the front brackets also to lower them a bit more, from the 1 1/2" below the frame that they are at now.

I wouldn't even need to redo the Explorer axle pads, as they are already at the right width and located for axle over spring. Just put my axle on top, weld on some ladder bars, and some shock mounts in the stock locations, and be done with it. It probably wouldn't handle any worse than it does now, maybe a tad better with the ladder bars and wider axles and axle over spring.

Would the handling be very much improved if I went with the thoughts I outlined in my first post? Moving the springs as far out as possible on the wider axle tubes, getting the shocks mounted outside the frame rails (and standing straight up), and using ladder bars under the frame to control axle wrap? Removing the mid fuel tank opens up that area for some bracing between the rails at the front spring mount location. And adding the rear fuel tank requires some bracing between the rails in the rear area of the frame in order to have something to mount the tank to. Amazingly the brace needed to catch the back of the tank and its straps falls very close to the rear spring mounts, and, even more amzingly, the brace to catch the front of the tank falls almost exactly where the shock mounts would be. The tank and skid plate are actually notched on one side to accomodate the rearward leaning drivers side shock. A little triangulation here and there and this frame could be very stiff. One of the benefits of working with a full-frame vehicle, I guess.

Would all this be worth the trouble in terms of handling and safety? Would it actually do any good? It's not really that much extra effort, being as how I'm going to do the rearend and fuel tank anyway.

And I thank you in advance for wading through these posts. I hope my powers of description have been adequate.

Rob

[David Pozzi]

Your frame rails may be more narrow than the Explorer, so you may be able to make some brackets off the side of the frame to mount the spring. The spring angle, relative height of front and rear spring eyes, should be copied off the Explorer. I doubt you will need to add any extra links, try the springs alone. Ladder bars can easily cause binding so I'd only consider one torque arm if you need anything at all. Shocks should be close to straight up and down, you can place one in front and one behind the axle to reduce the chances of wheel hop problems. The shock angle can vary 10˚ or so inward at the top. without much harm.

Extra bracing would help frame rigidity a lot. Pickups usually need help in this area. I'd probably only add minimum crossmembers and bracing, and develop the spring and shock setup, then once that is all working, add some diagonal bracing to stiffen the frame.
David

[Nate K]

I dont know if this will help but I had a 86 ranger with a 302 that I did some similar things to. I fipped the rear with the stock springs and installed lowered I-beams. I moved the shocks behind the rear and mounted them almost vertical. I used an explorer rear and needed to use wheels for a probe so they wouldnt rub. I also installed swaybars front and rear. It handled way better after the changes and didnt wheel hop.

[Robprime]

Thanks for the replies, guys.

I haven't posted for a couple days but I have been busy. Got the bed off and cleaned the frame prior to painting. I test fitted the tank using wooden crossmembers (being a carpenter, I find wood easy to work with, got all the tools I need). Made all my fitment mistakes with that, then bought some 2" wall heavy sq. tubing and have fabbed my crossmembers and brackets for the tank. Just got stuff bolted together now and probably won't weld any crossmembers until I've driven the truck a bit, which will be a while yet.

Took some pics with my crappy camera.

24739


This is the rear end I'm going to use and I've been looking at the control links, wondering if I should try to make them work. It has what Ford calls anti-wrap members in the front and a small gauge way bar in the rear, with an additional pair of short bars attached to it. There is also a bracket attached to the pinion bart of the rearend that looks like some sort of panhard bar was fitted also.

As I said earlier, the Explorer frame must be about 40" wide because that is about the spacing of the anchor ends of these bars. But the rear ones look like I'd be able to re-arrange and make fit under the Rangers narrower frame. The front ones I'd have to remove the welded brackets on the rear end and move them inboard. There is room to do that, though.

I gotta go for a bit. Later

[Robprime]

Black Betty,

I gather from your post that you wanted to lower your truck. Did you have the leaves recurved for more travel or did you stay with the stock curve? My truck has 5 3/4" space between the top of the 7.5" axle and the bottom of the snubber on the frame. If I simply place the axle tubes on top of the leaves then that travel will be reduced by 3 1/4", the diameter of the larger tubes. That would only leave 2 1/2" of travel. Not good for me. I like a bit of ride height and I occasionally put weighty objects in the back of my truck. I am glad to hear that you had no wheel-hop problems after moving both shocks to behind the axle as I want to do that also. And stand them straight up as you did. I understand that a lot of wheel hop can be eliminated by moving the rearend to an over spring configuration.

[Robprime]

So, back to generalities. This thread is becoming too Ford Ranger specific.

If I have the leaves recurved to allow more travel, it would have to be a pretty good curve in order to make up the 3 1/4" and get the travel back to stock. And the more I have the springs curved, the closer together the leaf eyes will become, possibly to the point where they will no longer hit the frame mounting points. Which are riveted to the frame and not easily moved.

After some searching I did find a resource for leaf spring specs that was pretty informative.

http://www.stengelbros.com/HeavyDutyLeafSprings.htm

They give the lengths of the spring stacks from the axle centerline to the eye centers at each end, width of the leaves, the number of leaves in each stack, and the strength in pounds that each leaf supports. Pretty handy.

So I noticed that the 97-03 2wd std cab F-150 has a length of 26 3/8 front and 32 1/8 rear, is 2 1/2" wide, and is rated at 332 lbs. That's the top spring of the stack, I'm pretty sure.

This sounds almost perfect. My Ranger is listed as 25 5/8" front, 31" rear, 2 1/2" wide, and rated at 307 lbs. That's an added 3/4" front length, 1 1/8" rear, and 16 lbs stronger, which would help to make up for the added weight of the larger rear end. This added 1 7/8" in length would seem to be just about right to make up for the length lost by recurving. Should hit the stock mounting points nearly perfectly after recurving. They don't give any arch specs on the site though.

The whole stacks might be good to get instead of just the top leaves. F-150 = 1415 lbs, Ranger = 1250. Maybe better to do that.

I'll be off to the junkyard again this weekend, I guess.

[Robprime]

About those suspension bars that are pointing forward on the new rearend. Ford calls them anti-wrap bars and I assume that they perform the function of preventing pinion rise during acceleration. They are pretty short, though, only 19" eye to eye.

I understand that one of the problems with arms like this, and ladderbars, is that the bars and the leaf springs move in seperate arcs and bind because of that. As to why Ford would put arms this short on the Explorer is a mystery to me if that's the case.

How about if I made some new arms that were longer. I could make them the exact length of the leaf front half distance (25 5/8") and could set their front mount positon to be exactly the same as the leaf springs. That would give both the leaves and the bars a common origin centerline and eliminate the seperate arc business. A single stout bar on each side along with an axle over spring setup should control any wheel hop, I would think. This is a street truck and if I can get by without a bunch of ladder bar or 4-link stuff hanging down below the axles and springs, the better, I guess.

[David Pozzi]

About those suspension bars that are pointing forward on the new rearend. Ford calls them anti-wrap bars and I assume that they perform the function of preventing pinion rise during acceleration. They are pretty short, though, only 19" eye to eye.

I understand that one of the problems with arms like this, and ladderbars, is that the bars and the leaf springs move in seperate arcs and bind because of that. As to why Ford would put arms this short on the Explorer is a mystery to me if that's the case.

How about if I made some new arms that were longer. I could make them the exact length of the leaf front half distance (25 5/8") and could set their front mount positon to be exactly the same as the leaf springs. That would give both the leaves and the bars a common origin centerline and eliminate the seperate arc business. A single stout bar on each side along with an axle over spring setup should control any wheel hop, I would think. This is a street truck and if I can get by without a bunch of ladder bar or 4-link stuff hanging down below the axles and springs, the better, I guess.

If those links run parallel to the leaf, then there won't be any bind. I think it's called a Link/Leaf system. The rubber bushings in the links can handle some convergence towards the front. If you made them pivot off the front leaf bolt as you suggest, you would be making a huge anti-roll bar out of your rear axle housing, because you would have a triangulated link/leaf arrangement on each side.

David

[Robprime]

If those links run parallel to the leaf, then there won't be any bind. I think it's called a Link/Leaf system. The rubber bushings in the links can handle some convergence towards the front. If you made them pivot off the front leaf bolt as you suggest, you would be making a huge anti-roll bar out of your rear axle housing, because you would have a triangulated link/leaf arrangement on each side.


That's an interesting idea, Dave. Would that be good to do?

I really hadn't been thinking about the horizontal plane when I was considering what to do with those front links. I had only thought to try to control any axle wrap and binding in the vertical plane.