rear end axle spring perch set up

[alwaysFlOoReD]

I wanted to get some opinions of my proposed axle re-rigging. This is for my low buck short course off road race truck. I feel that my build thread doesn't get as much traffic as here would, so i copied and pasted my last entry.In particular I'm worried about spring perch angle, in general about my rear end set up.

"I've finally got my spring frame mounts removed. Only one of six bolts decided to take it easy on me. I used the method that gwaii mentions; cut the head of the bolt off, then turn the nut in, add washers behind the nut as needed to pull the bolt through. Also used a zip tool to cut the bolt inside of the shackle or mount in two cases where the thread in the nut stripped out. Gotta love the smell of burning rubber, reminds me of drag racing.

So now I'm at the point where I need to decide how I'm going to put it back together. I've decided to move the front mount forward 6", keep the shackle mount pointing in the stock direction, and use 2" belltech lift/drop shackles. At the same time I'm adding spring perches to the axle so I can run spring under axle. From the research I've done, that'll negate the need for anti wrap bars. So I'm hoping that the ~4" drop from the s.u.a. will be countered by the 2" lift and the 64" chevy main + assorted ranger and b-II springs.

If I'm lucky I'll be able to get some frame mounts from a '97 and up ford from Bulldog Scrap Metals and then do a shackle mount flip, though I don't know as if I'll need one as I'm allowed maximum 12" of movement front and/or rear. I guess I'll see when I'm done.

I got a piece of 2.5" x .180" x 24" tube to make spring perchs from, cost C$5.00. I'm thinking that I'll set the axle on top of the perch on top of the spring and tighten down just enough that things don't move, then make sure the center line of the pinion and tail shaft are parallel at ride height. Then I'll weld in the perches to the axle tube. If this method is not a good way of doing the perches, please let me know.

I've also installed an after market steering wheel that is a smaller diameter thinking that will give me quicker steering response. I'll just have to remember to bring the old one in case it's too small when racing.

I have to find some of the plastic that goes at the ends of the springs. Does anyone have a name and a source for these thingys."

Thanks,

Richard

 

[4x4junkie]

Not quite sure I see the question... You asking about what your pinion angle should be? (which would depend on whether you have a double-cardan driveshaft or not)

Your description of bolting everything together to find your pinion angle prior to welding is normally how it's done, so no issue there.
Flipping between SUA and SOA will usually net you a difference closer to 5.5" however. Remember the height of the axle tube, leaf perch, the thickness of the leaf spring itself, and any shims that might've been present will all factor into the change in height.

 

[alwaysFlOoReD]

Not quite sure I see the question... You asking about what your pinion angle should be? (which would depend on whether you have a double-cardan driveshaft or not)

Your description of bolting everything together to find your pinion angle prior to welding is normally how it's done, so no issue there.
Flipping between SUA and SOA will usually net you a difference closer to 5.5" however. Remember the height of the axle tube, leaf perch, the thickness of the leaf spring itself, and any shims that might've been present will all factor into the change in height.

I didn't express my thoughts very clearly in my original post and probably won't yet again, but here goes;
Yes, I'm asking what my pinion angle should be. My thoughts are that the u-joints should be in phase and parallel to each other [trans/crank center-line and pinion center-line] at ride height when on the gas. Maybe I'm over thinking this but when I'm racing I'm either on the gas or braking, very seldom am I at part throttle. That being the case should I try to emulate the on throttle position of the pinion angle? I don't have a double cardan shaft if that is the double u-joint at one end. This is on a '91 ranger reg cab long box with a 4.0l and 5-speed.

I'm not to worried about the soa and sua. I'll adjust that later by lowering the spring frame perchs, if need be.
Thanks for responding.

Richard

 

[4x4junkie]

Correct, if you have a single-cardan shaft (single u-joints at each end), you want both joints close to the same operating angle (both shaft centerlines being parallel would accomplish that). One thing I would do though is add about 1-2° more downward angle at the pinion to account for windup of the rear leaf springs (this of course unless you have a traction bar mounted on the rear). This way when you're on the throttle it'll actually be parallel with your t-case during that time (during braking it's not all that important).

 

[alwaysFlOoReD]

Thanks,

Richard