ladder bar setup

ok all you chassis guys, need some input. When I set my mud truck up originally, I tried to do what all the other trucks had and I made my ladder bars around 52". I know long as crap. Well, I noticed over the winter that somehow I bent both lower bars (not up like I would think, but pushed about 1.5" toward the passenger side) right in the middle of them. These were 1" chromoly tube. I've got new 1 1/4" chromoly tube coming in that I will make new ones with. The big question is how whould the bars be set? Most drag car setups I've seen have the lower bar parralel to the frame or with the front of the bar a few degrees down. I originally set mine like most truck setups with the upper bar parralel to the frame. Is there a big difference in doing that? I do have housing floaters, monoleaf with spring sliders, and coilovers. The monoleaf is to keep me in class rule, so in reality it should be more like a cadderbar/coilover suspension with the leaf springs there just to keep the axle centered under the truck. So thoughts, input, how do I keep this from happening again?


Edit: looking back at older videos and comparing to new cut down body, it never really launches hard where the front is noticibly coming up. It just used to leave pretty level after a slight roll. I need to fix that too!

Since a ladder bar's lower bars are under compression forces during loading they are more likely to bend/bow if they are real long & the tubing OD is too small. And it's more likely to bend/bow if a real long ladder bar doesn't have enough upright & diagonal braces used between it's top & bottom bars. And it's more likely to bend if the spread/distance between the top & bottom bars isn't increased (more than normal) at the rear housing bracket when a real long ladder bar is used.

Well that explains why a few years ago I found my brackets bent at the axle housing. They have since been straightened and gusseted, so now the stress is on the tube. Measured my wheelbase and it's 129" from axle center to axle center, so looks like the new wet will be 42" long with several braces. Still not sure if I need to lower the front mounts or not.

Never messed with a mud/dirt/pit car, but I'm guessing the general ladder bar basics might sill apply.

(A) Shorter ladder bar (shorter I/C length) should be more violent (hit the tire harder) than a longer bar.
(B) Longer ladder bar (longer I/C length) should be less violent (hit the tire softer) than a shorter bar.
(C) higher ladder bar front rod-end (higher I/C) should be more violent (hit the tire harder) than lower.
(D) Lower ladder bar front rod-end (lower I/C) should be less violent (hit the tire softer) than higher.

So if the basics still apply I can see where if you hit the tire too soft on mud/dirt it might create too much wheel speed (or even flat-out spin). And if you hit the tire too hard (with too much rear suspension separation) & dead hook it it might initially hook, then unload the suspension & spin.

What is desired on mud/dirt when it comes to wheel speed vs trying to dead hook (or as close to D/H as possible)?

I'm guessing that wanting/needing X amount of wheel speed vs trying to dead hook might depend more on which track surface it is (wet mud/clay vs dry dirt, or some mix of both).

Dave, you are asking the million dollar questions! I know that the guys that are fast have very similar setups to drag cars, just with longer bars to make up for the higher center of gravity we deal with. Most cars have a shorter wheelbase than a full size truck, so naturally most places that sell drag race ladder bars make shorter bars for cars. Looking at S&W racecars tonight, they show the typical 32" bars for cars, and surprisingly enough, all the truck applications are still at 32". So looks like the new set will be around 32" with the lower bar pointing slightly downward about 2-4* this time around.

I picked up the 36" S&W ladders for my Bronco Karl.
Would a cross link or a wish bone help the factory leaf springs with the side load?

Double

kjett wrote:...............So looks like the new set will be around 32" with the lower bar pointing slightly downward about 2-4* this time around.

If you use a shorter bar pointed downhill will the ladder bars, LB brackets, or the LB Xmember create a ground clearance problem in a mud/dirt pit?

68formalGT wrote:........Would a cross link or a wish bone help the factory leaf springs with the side load?

Does the higher ride height on these mud/dirt trucks, or even the rough tracks, make it a lot harder for the leafsprings to keep the housing centered?

DILLIGASDAVE wrote:

68formalGT wrote:........Would a cross link or a wish bone help the factory leaf springs with the side load?

Does the higher ride height on these mud/dirt trucks, or even the rough tracks, make it a lot harder for the leafsprings to keep the housing centered?  

Kinda wondering that myself if Karl had a side bend in the lower bar maybe there's not enough support by a single leaf or could it be the frront leaf mounts? Karl don't you have sliders on the rear spring mount?

lower the front of the bar the less the hit on the tires.

Beats me on the side loading. I do know that with these crazy long bars (54" !!) that I made to mimic the old L&L bars for off-road trucks are way past 1/3 of my wheelbase. In fact, they are almost 1/2. Current wheelbase is 129", so 1/3rd would be 42". Was thinking make them even shorter at about 38". Now to figure a new front mounting deal.

kjett wrote:Beats me on the side loading. I do know that with these crazy long bars (54" !!) that I made to mimic the old L&L bars for off-road trucks are way past 1/3 of my wheelbase. In fact, they are almost 1/2. Current wheelbase is 129", so 1/3rd would be 42". Was thinking make them even shorter at about 38". Now to figure a new front mounting deal.

Critters mounts look like they set lower maybe 8"-10" below the frame.

His are and I think he uses the shorter 36" bars. Going to start with doing a little more with getting pinion angles better. When it was set up originally, pinion angle was factory where a leaf spring perches was. And on most late 70's 4x4 trucks, that's about 4* up, so going to move that down to 2-3* down, make some 38" adjustable bars with the bottoms are the bars parallel to the ground

kjett wrote:His are and I think he uses the shorter 36" bars. Going to start with doing a little more with getting pinion angles better. When it was set up originally, pinion angle was factory where a leaf spring perches was. And on most late 70's 4x4 trucks, that's about 4* up, so going to move that down to 2-3* down, make some 38" adjustable bars with the bottoms are the bars parallel to the ground

I set up my 8.8 in my Jeep 2* down and I never had any vibration or drive shaft problems, will the flex in everything allow your truck to get back to 0*? I think in the install instructions for my ladder bars it said to put the pinion/drive shaft at 0*, what would be the best way to go?

I guess I need to see what angle is coming out of the transfer case 1st to make them match. Fixing the cracked case on the trans, then will drop that back in and measure from there. Im concerned that the 2-3* down combined with a potential 0* angle coming from the transfer case output will be too much, but it could be perfect. This whole deal is a mystery to me.

On a good note, think I figured how to mount the front of the new bars. Currently, everything is mounted about 2 1/2" inside the frame rails, so the plan is to cut some 2x3 box that will be welded inside the frame channel at the lowest point sticking inside the frame about 5". The frame will then be boxed over to give support to the new stubs. From there the good folks at S&W racecars are making me new 3/8" plate elongated notch style front ladder bar brackets that will hang down about 11" from the notch with the standard holes at the lowest portion. They are also including some strips to be welded in on the front and rear of the new brackets for support. I'm thinking I'll also weld in a tube brace from the lowest portion of the bracket and angle back up to the frame to help handle the stress of the longer brackets. What y'all think? will it hold up or am i doomed?

I was thinking for the front mount on mine notching the bottom of the channel then putting some square tubing in the notched area butted up to the top part on the channel. Weld it all the way down on the inside of the frame then it could be covered and boxed in. Those front mounts s&w is making sound like they would work perfectly. How soon till you get them and could you post a picture? I'm putting my Bronco in the shop on the 11th so I have a week and a half to get it all figured out.

Ordered them yesterday and the sales guy said it would take a few days to cut them, so hopefully sometime next week I'll have them

After re reading your plan Karl it seems like you and I have the same thoughts for the front mount.

kjett wrote:ok all you chassis guys, need some input. When I set my mud truck up originally, I tried to do what all the other trucks had and I made my ladder bars around 52". I know long as crap. Well, I noticed over the winter that somehow I bent both lower bars (not up like I would think, but pushed about 1.5" toward the passenger side) right in the middle of them. These were 1" chromoly tube. I've got new 1 1/4" chromoly tube coming in that I will make new ones with. The big question is how whould the bars be set? Most drag car setups I've seen have the lower bar parralel to the frame or with the front of the bar a few degrees down. I originally set mine like most truck setups with the upper bar parralel to the frame. Is there a big difference in doing that? I do have housing floaters, monoleaf with spring sliders, and coilovers. The monoleaf is to keep me in class rule, so in reality it should be more like a cadderbar/coilover suspension with the leaf springs there just to keep the axle centered under the truck. So thoughts, input, how do I keep this from happening again?


Edit: looking back at older videos and comparing to new cut down body, it never really launches hard where the front is noticibly coming up. It just used to leave pretty level after a slight roll. I need to fix that too!

disregard post

Karl, I was looking at my Bronco and the front control arms set close to level with the ground, the end rod for the arm is about 10" down from the top part of the frame channel, would you think that is low enough? If you put the lower bar level it seems like it would set real low and the mount would be in the mud.

That's the plan. I already had a new set of drop brackets made by S&W racecars. They will be about 10.5" below my frame and hang in the mud. Hopefully, I can hook up enough that I'll get up on top and not have to worry about them. Rear end is already out and being cleaned up/repainted, New bars and brackets will be welded in by the end of the weekend as long as the honeydoo list doesn't get in the way.

Karl did you get the brackets yet? Can you post a picture and who did you talk to?

Yep. they look great. Here is a quick pic of them when I opened the box:

Those look good. Did you have to get a new cross member to?

Can't run a full crossmember due to the driveshaft, so I'm welding some 2x3" box stubs in the frame. The frame will get boxed around the stubs to keep from twisting up. This will be helped by keeping the original tubular crossmember that is about 6" away. The new brackets will get an angular brace on the front side going back up to the original front brackets to triangulate everything and keep it strong.