Front shackle reversal

[El_Diablo]

when climbing a ledge, the axles in under compression when set up properly, it will not be drooping at that point

[Dirt Wag]

With the SOA your double cardan joint is probably close to binding at full droop - assuming it's a stock driveshaft. A shackle reversal will increase the drveshaft angle even more and you might have to modify the tranny crossmember for driveshaft clearance as well.

[onesunJ10]

I'm no engineer, but I did see that in play as he couldn't climb obstacles that he could clear before the shackle reversal.

I've wheeled both set ups, and, as an engineer, the forces really aren't different. Dynamically, they may act differently initially, but the suspension isn't going to continually move away or towards the obstacles. What i am trying to say is after the initial movement (compression/droop) the suspension is settled and it's not goinig to continually move "away from the rock". It can only move so far. There are so many factors that influence how a truck crawls, and if my shackle reversal made my truck crawl worse, i sure didn't notice.

I love my reversal. Sure, I had to deal with building a custom driveshaft and more significant pinion angle change, but it's worth it, IMO. I mean, look at every single Toyota. Shackles in the backs. And Toyotas are arguably the best vehicles to build into a "budget" hardcore rig (How dare I say that, i know!).

Aside from crawling, the reversal made the biggest difference in the world while mashing thru the desert. My truck likes whoops.

Typically, the hard mounted end of the leaf spring sees about 70% of the load. So, when you hit a rock, you are putting the spring in compression where it is likely to bend. However, when you reverse the shackle, the hard mount is at the front of the truck, and the spring will basically be in tension, where it is less likely to fail.

[Elliott]

I've wheeled both set ups, and, as an engineer, the forces really aren't different. Dynamically, they may act differently initially, but the suspension isn't going to continually move away or towards the obstacles. What i am trying to say is after the initial movement (compression/droop) the suspension is settled and it's not goinig to continually move "away from the rock". It can only move so far. There are so many factors that influence how a truck crawls, and if my shackle reversal made my truck crawl worse, i sure didn't notice.

I love my reversal. Sure, I had to deal with building a custom driveshaft and more significant pinion angle change, but it's worth it, IMO. I mean, look at every single Toyota. Shackles in the backs. And Toyotas are arguably the best vehicles to build into a "budget" hardcore rig (How dare I say that, i know!).

Aside from crawling, the reversal made the biggest difference in the world while mashing thru the desert. My truck likes whoops.

Typically, the hard mounted end of the leaf spring sees about 70% of the load. So, when you hit a rock, you are putting the spring in compression where it is likely to bend. However, when you reverse the shackle, the hard mount is at the front of the truck, and the spring will basically be in tension, where it is less likely to fail.

Thank you, we are talking 2" here folks. If that keeps you from being able to climb obstacles you once could then you have need for some psychoanalysis. 2", get it? Possibly you should simply try driving faster through the obstacles like the shackle reversal will permit. If you think bending your springs is an advantage then by all means don't switch 'em up. Does the nose dive in my F350 make me ill? Not hardly... (don't ask me about the :o:o:o:o:o ABS though)

Someone ask Cappa if HotDot was a POS...



Get ahold of these guys, they have a kit they sell.... and HEY, THEY RACE FSJs Too:

http://www.tandjperformance.com/main.shtml

Now... do make sure your suspension doesn't travel aft more than your driveshaft or you will be sadly disappointed with the results... but heck you can SOLVE THAT WITH FOUR BOLTS.... simply flip your FSJ springs around. The fronts have a 2" offset (and then work in some steering corrections to account for it or you'll be jamming your tie rod into your pitman arm... or maybe not since it all moves aft now).

[billyj7175]

It is quite possible that (mind you, I was referring to Samurai's), he wasn't hitting the obstacle hard enough.

Now that I think about it, his tighter turning was most likely stemmed from running a 2" longer shackle in the original configuration...with the S/R, his caster was probably back in spec, (or possibly beyond).

Elliott: That's some good info on the spring center difference.

[Elliott]

The 2" offset... that would probably not be a problem on spring reversal with shackle reversal. If you flip the springs around on a normal rig you will have trouble on compression but with the reversal... seems like you'd be clear.

On another note, I guess if you found the braking conditions to be undersireable (although 900Lbs over my front >flat< as in no arch springs isn't a problem for me on the F350<) I would think that installing an adjustable proportioning valve would help you dial it in to your liking better.

[Dirt Wag]

I have BJ's 6" lift with the drop pitman arm on my 85 GW. Can I just flip the springs around and do a shackle reversal without other mods?

[J20 project]

I mean, look at every single Toyota. Shackles in the backs. And Toyotas are arguably the best vehicles to build into a "budget" hardcore rig (How dare I say that, i know!).

and, as an engineer,

Man, these are just begging to be hammered..LOL

This question is just like the, "Do I switch to a SBC question"....The bottom line is,, knock yourself out. It's your money and time.
J20

[Elliott]

I have BJ's 6" lift with the drop pitman arm on my 85 GW. Can I just flip the springs around and do a shackle reversal without other mods?

No, like Stuka pointed out you need to rotate the pinion up to compensate for how it will now drop when you apply the brakes (where it didn't before). How much it's actually going to drop is going to depend on the springs you have and the weight on them. Certainly a flat spring will let it drop more than your high arch 6" lift springs... you may actually be ok if you have a high angle driveline and maybe a high angle pinion yoke (like Parts Mike sells). Also take into consideration that the front hangers are going to give probably another 2" of lift and that will have it's own variables depending on the setup you have now.

[rocklaurence]

No, not without centering the axle in the well. So, the front hanger will have to be dropped approximately 4" and the rear shackle mount will have to be moved as it will now attach to the long end of the spring. Im going to be doing this soon on my J15 and will have a square cross tube with the hangers welded unto it. This tube will provided lateral support to the hangers and more area to attach the hangers to the frame.

[onesunJ10]

Man, these are just begging to be hammered..LOL

Shackles in the back. My bad. Unless you weren't pointing that out. I do believe that I could build a more capable Toyota for less $ than my J10. Plain and simple. Everything on those cookie cutters has been done so many times that it's just a simple science now. I've had a lot of trial and error with my J10, and that's not cheap.

[rocklaurence]

I stand corrected, the steering box sets bellow the frame rail preventing a cross bar unless it sets infront of the mount. Hmm? Im still going to need a 4" drop in front to correct the caster. Or use wedges??? Buy at www.rocklaurencevintageautoparts.com

I now have a bolt in kit: RockLaurence vintage auto parts and I have a store on Ebay

[rocklaurence]

OK, this is the Universal Heavy Duty Slider Boxes that I have listed on my store. The one for the FSJs will be the same with the addition of a side plate to locate the brackets via the two lower transmission crossmember bolts. Ill be putting that together soon. https://rocklaurencevintageautoparts.co ... de-springs

https://imgur.com/NR9hl4k

https://imgur.com/AK97jBv

https://imgur.com/8JjIDp5

https://imgur.com/L1l6K1H

[rang-a-stang]

I have the Rocklaurence FSSR kit on mine and I love it. (probably close to 5k miles with it). I originally had it with stock springs, now have Rancho lift springs.

Some notes for anyone considering it:
1) You will need to have your front driveshaft lengthened and/or have a long travel yoke added.
2) I was able to keep my stock brake lines but moved the bracket that holds the fitting where the soft lines meet the hard lines down a notch.
3) When you brake, the truck does nose down a bit more than it used to. It feels like the front brakes are doing all the work but they are not; it's just the physics on how the springs work now. Again, not really a problem.
4) the centering of the axle does not really end up being a thing. At least I don't think so. You would be hard pressed to tell the difference before and after install. If you REALLLLLY look at before/after pics, you can see it moved but it's not enough to really be an issue.