I've freed up my schedule and am planning to hit the project truck hard this weekend. The spring problem has brought things to a halt, but I had an idea recently and did a bit of work on things today. Here's what I have in mind:

In order to get the lift we need, we really should do it all with springs. Lifting the front with blocks and/or extended shackles isn't really a good idea. I've tried bending the sprrings we have and had very little success, I've only managed to bend one leaf by about 1/2". It's going to take more like 4-5" more arch to get what we need.

I've been driving past the rear axle I took out of the '85 I built last year almost every day, and really got to looking at the arch of those rear springs...so I finally took a tape measure to it. The length of the springs is exactly the same as the front springs in the project truck when measured eye-to-eye, but while the axle mounting point is centered on the front springs, it's offset towards the front 2-1/4" on the rear springs. I took them off the axle today and bolted one of them to our front axle, and it really looks promising. The stiffness of them seems comparable to our two-leaf fronts, and being multi-leaf they're more adjustable. Since the mounting points haven't been put into the truck yet I can move them 2-1/4" rearward from where they would have been for our springs. And it appears the ride height will be where we need it.

My chief concern is the unequal length, with the axle not being centered in the springs and what this might do to the handling. I'm no suspension expert, but here's what little I do know in this regard:

Understeer, or push, is built into most vehicles purposely as it's a handling characteristic that's more instinctively handled by the average driver; as the vehicle pegins to push in a turn, the driver just steers more sharply as opposed to oversteer (or loose) where the driver must steer in the opposite direction to regain control which is not an instinctive reaction in most folks.
The way this built-in understeer is often acheived with leaf spring suspension is to cant the springs so that the front of the spring is closer to the ground than the rear, which induces rear axle steer when cornering.

I don't know if the unequal distance between the axle and the spring mounting points on rear springs has anything to do with this, or if it's more to give the springs a progressive stiffening effect as the spring is compressed. Or if it's for an entirely different reason...I'm hoping someone will have more insight to this than I and can advise me accordingly. I suppose I could drill a new hole (maybe...?!) in the main leaf and move the mounting point back towards center, moving the rest of the leaves into the new position. I don't believe that the extra hole would weaken the spring by a noticeable amount, but I could be wrong...have been before, will be again.

Any input, folks? I've got to make something happen with this beast soon, running out of time. We'll be losing the shop space soon, he wants the truck gone so he can get his '57 Chevy in there.

 

Dan,

What I can tell you it's tough to drill those springs (in my experience). Have to be done on a drill press with real slow speed and lots of cooling oil or you'll be smoking bit's quickly...kinda like drilling stainless steel.

Can't help with the suspension/handling characteristics other than to say it may not be a big an issue for our purposes, straight line running and slow trail riding, but I really don't know.

 

I've drilled them before too, and my experience was the same as yours.

I got the springs bolted up to the axle today, stuck the whole mess under the truck after jacking it up a bit more and got some better measurements. It seems I was in error; the original springs do not have the center equidistant from the eyes after all, the front is shorter than the rear but not by as much as the rear springs that I want to use. With the axle centered in the truck the mounting points for these springs will be 2-1/2" further to the rear than the original mounting points. I like it, the stance seems to be just right and it will be easy to stiffen them for the weight of the 460 if needs be. If nobody comes on here tonight and tels me something like, "No you idiot, don't do that, you'll screw the suspension geometry all up" then I'm going to go for it tomorrow...

 

Dan, please post this question in the 4wd forum also - - - could save us a hell of a bunch of rework!

 

I just want to say you're an idiot...

But I've no opinion,

Hey, just think it over and do it dammit!

Just like me and these heads, I'm grinding here and there "by feel", they'll work and make power...your suspension will hold us up in the air and get us there.

 

My only .02 is:

Maybe you want to arc the rear spring a little less for weight tranfer to the back.
Are Air Shocks / Bags allowed in the class and is it a good idea so that we could adjust the rake of the truck for the mud drags?

Just a thought..... Sorry, I can't make it this weekend. Next weekend look much better.

Guys, is there anything I should look for at the Goodguys swap meet tomorrow. Just that of this. I should have put it out there earlier today. What I can do is get numbers and we can call them later and see if they have the parts we need. Anything in particular that we need for the project truck? Any nice things to look for that might bring us an advantage dragging it?

BTW - Are you going to use some sort of adjustable ladderbar set up?

 

Okay, Clint arrived this morning and we beat up on the truck a bit. Clint worked on the rear end, pulling the axles, brake drums and brakes complete with the backing plates (all pretty new stuff). The plan is to swap it all onto the rear end that Tim donated, however, the 4.10 rear end from Tim takes fine spline axles and the project truck's rear has coarse spline axles. I know from a recent wheel cylinder replacement that my '68 also has the coarse spline axles, so we're quickly running low on options. In the moring we'll pull an axle on my '72 and if it also has the coarse spline axles then I'll have to look at changing to the coarse spline side gears in the Tim rear end. Since it's a Trac-Loc rear, that'll mean waiting till I can change the rear end in my '68 so I can use the side gears out of it, since it's the only Trac-Loc D60 I have. (I'm planning to change it anyway and use the 3.54 that I have out of the '85 once I relocate the spring perches.)

And while Clint was engaged in all that, I started torching and drilling holes in the frame and mounted both the rear spring mounts (for the front springs.) The truck's weight is now resting on the front axle (front spring mounts are clamped in place, I'll work on mounting them tomorrow.)

I'll also put my bigger jack stands under the rear end and bring it up to the height of the front so it sits level agian and grab some pics so ya'll can see the new ride height. By end of day tomorrow I hope to have the truck sitting at height on all fours, although possibly without the rear axles in place. Not too sure about the rear lift blocks though...I have some to try that will most likely be too short but I also plan to modify the rear mpunts on the back springs and do away with the overloads which will gain us some additional height there.

I also have to figure out how much the front will drop when the 460 is dropped in and the front clip bolted back in place. I may not spend too much time on the rear and leave the final adustments back there till the truck is all together and I can see where it needs to be to sit level...

 

Hey Dan,

I do have the full floating 4.10's out back under the one chassis...

 

I'll bet that thing's not a straight bolt-in for our rig though...probably a bit wider, doncha think?

 

I don't know, should be pretty close in size, I'll go out and try to get a hub to hub width for you.

 

Just in case I can't get to the phone, the rear out back is about 56 1/2" from backing plate to backing plate, tough to get rea accurate, but should be close enough to work without any issues if we want to.