Move Front Axle forward-Leaf Springs - Page 2

boywonder · 10-04-2020, 07:46 AM

Quote:

Originally Posted by TheLetterJ

I also used red loctite on the center pins, cut them flush with the block, then peened the threads... I was paranoid that they'd rattle out and fall out the bottom over time, definitely didn't end up having that problem!

These are 5/8" dowel pins...pressed in....Plan B was to thread and use 7/16" socket head cap screws. The shear strength of these dowel pins is much higher than a 7/16" thread.

.......Hopefully get them installed over the next day or two. I've also fabricated a new panhard rod but I'm a little concerned it's not robust enough. I need the spherical rod ends to allow for the 1" offset of the axle. The existing rod has rubber bushings on the ends.

I'll post pics of the two parts later today.

arctictraveller · 10-04-2020, 10:50 AM

Nice work, it must be so nice to have real metal working equipment. Are the radius'd ends just to prevent stress risers at the contact point of the leaf?

boywonder · 10-04-2020, 05:46 PM

Quote:

Originally Posted by arctictraveller

Are the radius'd ends just to prevent stress risers at the contact point of the leaf?

Yes......Now I need to fabricate a beefy panhard bar......my lathe is limited to 3/4" dia stock...so brainstorming plan B........

Vanimal · 10-12-2020, 07:08 PM

Boywonder, This is a backcountry hillbilly try but it works. I know I will get flack but here goes: My Jeep Cherokee XJ is a rock crawler I built in 1991ish It has been thru the Hammers and just about every other Black Diamond 5 out of 5 or 10 out of 10 trails. When I built the XJ I used Chevy 1/2 ton leaf packs. I re-drilled the main leaf 1" back for clearance. I still have yet to replace the springs, and it's been on the second XJ. The axle extreme articulation that comes with rock crawling is insane so a cheap fix you can re-drill or order a new main leaf with the pin hole at the location you need. If your secondary leaf is too close you can flip it forward or remove some.

boywonder · 10-12-2020, 08:05 PM

I actually drilled the pin hole in my rear springs to try on the front (very similar length) but after a web search decided not to try that...threw them in the trash.......

* I had an extra set of rear springs that were laying in the garage saying "use me".......

Vanimal · 10-15-2020, 06:05 PM

Glad it worked for you.
As far as the re-drill. If it is only an inch and the old hole stays within the u-bolt surface (spring plate) there is literally no, ZERO, nada flex of the spring within this area. When it becomes an issue is if you are out side the supports of the leaf. This is where the flex will ruin the main leaf, keep in mind I said the main leaf and only the main leaf should be drilled. Drilling the pack will cause issues and breakage over time if not the first time out!Lastly, just because I did it does not mean it will work for you but I have close to, and I am not lying to you 28 years with these springs on my XJ.

boywonder · 10-15-2020, 08:49 PM

Well..nothing has actually moved yet...

I have got the materials to fabricate a beefier panhard/track bar..hopefully this weekend.

Vanimal · 10-16-2020, 08:33 AM

I really never understood why Ford used a pan hard bar with leaf spring setup on front axles. Death wobble has nothing to do with the leaf spring type front axle when it comes to preventing it. Although it helps too minimize it by adding stiffness to lateral steering movement of the axle and road forces on the force of the lateral movement, but if your ball joints, or tie rods, or any bushing fitted part are worn, or your Camber Caster are off, the pan hard bar does absolutely nothing to help eliminate the slop in the steering which is the cause of the death wobble in leaf sprung front axles!! Coil front axles are a different bred and the pan hard bar has 70% of the blame because of angle, length and its relation to the drag link and lateral control.

TheLetterJ · 10-16-2020, 12:06 PM

The use of a panhard bar with leaf springs was to prevent bumpsteer, not so much to keep the suspension tight. Even with leaf springs and crossover steering, you would get bumpsteer when the axle moves up and back, but the draglink swings up and to the passenger side during compression. Even though the leaf springs do a good enough job of locating the axle under the vehicle, they don't force it to move in the same arc as the steering without the use of a panhard bar. Now, obviously this induces some binding in the suspension since the leaves don't naturally want to move side to side with the panhard bar, but the rubber bushings in the leaf springs and shackles allow enough movement to accomodate the amount of travel that a FACTORY STOCK leaf suspension has.

GM and Dodge used to use a push/pull type steering linkage to get the steering swinging in a similar arc as their leaf sprung front ends, unfortunately they had much too short draglinks to begin with (less than the length of the front half of the leaf) and even if they were spot on in length, there was no way to allow for the change in length (straight line) as a semi-elliptical spring cycles. That's also part of the reason that their leaf sprung front ends used nearly flat leaves from the factory.

All that said, there are always trade offs when straying from the original design. As you introduce springs and shocks that are capable of more travel, you introduce more potential for binding with the panhard bar. You could remove the bar, but then you will have more bumpsteer, and probably worse yet, you may notice that your steering effort is wasted by moving the body side to side over the axle instead of actually turning the wheels, if you're pushing hard (coming into an asphalt corner too hot, or tire sidewall up against an obstacle when out 'wheelin') There are ways to loosen up a leaf sprung axles side to side movement without affecting their ability to control the fore-aft or up-down, to allow the panhard to take over lateral location duties, but I'm quite certain that it's not a route many people would entertain for their home on wheels. That said, I have a leaf sprung front end (NOT on a van) with a panhard that cycles more than 16" vertically (not articulated) with zero bumpsteer... there's much more to it, but it can be done!

Vanimal · 10-17-2020, 09:06 AM

I was aware of the excelent explanation you provided but as I said maybe I should have been more precise, "I really never understood Why". The issue is that these are trucks trucks handle differently and I know it was an effort to pacify the general public for more sales, the amount of bump steer, or prevention of it is futile and becomes useless once a lift is inserted (speaking on leaf lifts, not coil spring). IMOP in a off road or country road truck the set up actually increases bushing wear on all components, leaf bushing, pan hard bushing, creating shorter life span of the bushings.