Shackle reversal woes.

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pbgbottle

pbgbottle

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Found an old pic of one of my my oops. Won’t be doing that again.
Old pic from years gone past. I was cruising down the logging road heading for home probably a bit quicker that I should be ,when all of a sudden I came upon this small washout. Hit the brakes most likely nosediving the crusier then the suspension dropped as I flew and dropped into the shallow washout . Cycling my driveshaft to far and it separated,dang. Flopped around under the rig and went bang. Jammed into the leaf spring Shock area. Bent the leaf spring and snapped the bottom shock mount off. I got out to access the damage and found my shaft laying on the road.
Not fun. Unlocked the hubs tossed the shaft into the rig and limped it home. Fun day it was.
Or it happened when I launched out of the washout. I can’t remember. Twisted off the pinion dented the drive shaft tubing.

Note to self build a front driveshaft with a longer slip joint when running a shackle reversal.
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IMG_9120.webp
 
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I just used that kit on a dline. Nice pieces. With that u-joint & yoke the dline will travel beyond what the coilovers will so no binding issues & thats with 14" travel. It says " Early" fj40, however I had a 1970 and the dline had the smaller, not square pattern so I had to have a custom e-brake drum made with the 60 x 60 pattern, thanks Georg.
 
I never understood the reason for shackle reversal. Is it for lift? Better off-road approach? I mean leaving the shackles at the extreme ends (stock location) dials in a bit of ‘oversteer’, wouldn’t that work better in off-road conditions?
 
Mark Jennings said:
I never understood the reason for shackle reversal. Is it for lift? Better off-road approach? I mean leaving the shackles at the extreme ends (stock location) dials in a bit of ‘oversteer’, wouldn’t that work better in off-road conditions?
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Keep the vehicle lower when sprung over is the main reason most people do it.

Cheers
 
Mark Jennings said:
I never understood the reason for shackle reversal. Is it for lift? Better off-road approach?
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If you’re climbing vertical rock ledges head-on (Elephant Hill Trail in Canyonlands NP as an example), the SR would give you a slightly better approach angle - but I still wouldn’t do it even for that myself.
 
Mark Jennings said:
I never understood the reason for shackle reversal.
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I remember the ads for those SR kits back in the day, something about the axle moving rearwards when encountering an obstacle was supposed to help something. Seemed weak at the time
 
No doubt reverse shackle has a smoother ride. Braking on the other hand it removes the ying yany of the original shackle location. Shackle in the original location as you brake pressure on the front wants to flatten the springs. To do that shackle has to move forward against the movement but while the axle is pushing back against the momentum of the vehicle. Probably why I've never seen a production vehicle with leaf springs with shackles on the back of both front and back springs.
 
Living in the Past said:
No doubt reverse shackle has a smoother ride. Braking on the other hand it removes the ying yany of the original shackle location. Shackle in the original location as you brake pressure on the front wants to flatten the springs. To do that shackle has to move forward against the movement but while the axle is pushing back against the momentum of the vehicle. Probably why I've never seen a production vehicle with leaf springs with shackles on the back of both front and back springs.
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I agree with most of what you said in the beginning of your statement, but GM and other manufacturers did a shackle reversal on the front end of their trucks. On the rear end the shackle was inverted, so the end of the spring was over the frame mount.
 
Decades of domestic trucks had front leaves with the shackles at the back, but they had flat or inverted leaf packs.

The push to do the mod on 40s was for supposed improved ride and handling. When I had my 40 on the road with the spring bushings able to flex I never felt like a shackle reversal could improve functionality.

As I wait to work on building my truck, I struggle with using longer fj60 rear leaves up front vs going to links and coils.
 
Way back when I did my spring over shackle reversal. I did it that way because that’s how Warden’s off-road did I it and that’s how I saw it done in an off-road magazine a write up on it. I followed the pics in the magazine when I did mine. lol. Did the cut n turn from pics in a magazine also. SOA wardens way. Solid axle mini truck also had the solid mount up front. Crazy how long ago it was when I did my SOA after seeing pics in a magazine. lol.
4WD & Sport Utility 1997. I think. Call SPRING FLOP.
 
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Toyota Mini trucks and 4runners have the front shackle in the back as well, so Toyota thought something when doing this. Shackle in the front helps push the axle forward and over an obsticle. Jeep kept their shackles in front on the CJ's and YJ's. Maybe better for shorter wheel base vehicles??
 
matzell said:
Toyota Mini trucks and 4runners have the front shackle in the back as well, so Toyota thought something when doing this. Shackle in the front helps push the axle forward and over an obsticle. Jeep kept their shackles in front on the CJ's and YJ's. Maybe better for shorter wheel base vehicles??
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or maybe fj40 were designed after WW2 jeeps. Both Jeeps and 40 were based on 1940 designs. The shackle placement on both makes driveshaft design simple and cheap as long as you maintain stock parts. The 40 gets by with a 2 3/4" slip as long as you're stock. Anytime you move away from stock you should consider any and all the repercussions. Same goes for motor transplants, tire size and ride height changes. If your thing is nasty rock crawling, the shackles up front are definitely more vulnerable. If your favorite wheeling spots involve nasty side hills with scary drops, stay away from SOAs with 4" lift springs
 
So, from the answers above to my Question, Trying to Understand Shackle Reversal….it actually comes dow to personal preference. And improvement’s to your rigs to enjoy ultimate off-road capability.

The reason for GM and Toyota Mini-truck shackles at the rear IMO, was to keep drivers from falling off freeway ‘off ramps’. Shackles to the rear dial in ‘under steer’ so as you take a turn, you have to include more steering input, kind of a natural reaction….not counter steer, which our lizard brains find counterintuitive….🤣🤣🤣
 
Mark Jennings said:
So, from the answers above to my Question, Trying to Understand Shackle Reversal….it actually comes dow to personal preference. And improvement’s to your rigs to enjoy ultimate off-road capability.

The reason for GM and Toyota Mini-truck shackles at the rear IMO, was to keep drivers from falling off freeway ‘off ramps’. Shackles to the rear dial in ‘under steer’ so as you take a turn, you have to include more steering input, kind of a natural reaction….not counter steer, which our lizard brains find counterintuitive….🤣🤣🤣
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I also think reverse shackle and flat springs offers a slightly smoother ride by rolling over bumps and collapsing/swinging the shackle rearward. .
 
That was my understand of how it was supposed to work. On the other hand how much not like a buckboard can stiff axles ride? Its a tractor.
 
charliemeyer007 said:
That was my understand of how it was supposed to work. On the other hand how much not like a buckboard can stiff axles ride? Its a tractor.
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That's all about the leaf design. It's more expensive to make a leaf that rides well but there are tricks to making a soft leaf spring with lift.
Spring rate has to be matched with free arch and small tricks to speed up the frequency of the leaf pack have to be looked at. The recent fascination
with the parabolics has merit. The gaps between leaves reduce leaf to leaf friction and speed up the frequency or time to react both under compression and
rebound. This can be done to all leaf packs using 16~14 gauge 2 x 4 shims between each leaf at the center pin and the pucks at the end of each leaf.
For a production spring like OME, Skyjacker, etc, it adds cost and higher costs affect sales. The other issue is that springs are wear items. Spring steel has a
lifespan of only so many cycles. The less full cycles they go through, the longer they last. A super flexy spring won't last as long as a very stiff spring and
manufacturers don't want the reputation of short lived springs. I build the springs I want to have on my truck because I'm old and like a nice ride.
I'm Ok with spending 3~400 a leaf. I just eat more ramen and less steak
 
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