Retaining front and rear track bars with SPOA and shackle flip.

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Nikkormat
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Retaining front and rear track bars with SPOA and shackle flip.

Post by Nikkormat »

Has anyone done a shackle flip and SPOA retaining the track bars? I understand they'll hurt my flex a little but if I'm in a situation where I need every little bit of flex disconnecting them would be easy.

Why would I want to keep them? The way the 91 handles in comparison to my 74 is a night and day difference. I need the extra height for wheeling but the while appeal of the 91 is its great road manners. I want to build a Jeep that rides like a Cadillac, wheels like a Toyota, and embarrasses people at stoplights. And even though I want it to ride like a Cadillac I expect it to still corner as well as it does now.

From what I understand I can just make the axle side mount taller by six inches. Is it that simple? Or would it be more worthwhile to re engineer the whole setup? Has anyone but me been stupid enough to want to keep them yet?
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Stuka »

You don't want to make the axle side taller. The frame side has to be dropped to the same level as the pitman arm. If the track bar and drag link have different angles, you will induce nasty bump steer.

But I would be willing to bet the main difference between the two is the sway bar, not the track bars. Track bars help sure, but are less noticeable than the sway bar, which your 74 did not have from the factory.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Nikkormat »

Stuka wrote:You don't want to make the axle side taller. The frame side has to be dropped to the same level as the pitman arm. If the track bar and drag link have different angles, you will induce nasty bump steer.

But I would be willing to bet the main difference between the two is the sway bar, not the track bars. Track bars help sure, but are less noticeable than the sway bar, which your 74 did not have from the factory.
So I want to mimic the geometry of the drag link? That sounds easy enough. I'll have to take a look at the front fame side mount tomorrow. Going high steer should make the drag link even flatter, maybe the skyjacker track bar brackets will be sufficient up front.

What about the rear?


As for the handling...

The 74 does have a factory sway bar, and it has been upgraded beyond that with a larger one inch sway bar the same as is found on the 91. The sway bar, shackle, and leaf spring bushings are all in good shape. As are the steering components on both vehicles.

Both systems being equal in that regard the 91 has much more responsive steering, is much more predictable hitting an expansion joint or pothole around a corner at speed, and when making sudden direction changes.

In the 74 it feels like the body and suspension are separate, when you steer into a corner you can feel the leafs jack sideways before it turns. Over expansion joints and potholes the suspension jumps violently from side to side. And while executing highspeed maneuvers it feels like you're in a 70's cop drama watching cars sway from side to side. In theory without a rear track bar the 74 should beat the 91 as the post mount has less bushing deflection but in practice that isn't true. So I assume the tight handling can be attributted to the track bar. I'm not talking about body lean either, that doesn't really bother me.

Is my logic flawed?
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Stuka »

Not flawed, but are you taking into account that the body mounts on the '74 are toast if you have not replaced them, spring bushings will definitely be bad if they have not been replaced, and the springs themselves. Then there is TRE wear, steering shaft wear, etc etc.

Lot of things that can all attribute to the differences in driving characteristics between them. Track bars can certainly help it drive better on the HWY, not saying they wont. I am just not sure they were the key difference maker.

Oh and yes, mimic the geometry of the drag link. The reason is that as the suspension cycles, the track bar will push and pull the axle sideways. If the geometry is different from the steering, it means the tires will turn as the axles travels up and down. And typically end up with an oscillation that starts to build as they fight each other.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by derf »

I agree on the body mounts, spring bushings, etc. probably contributing to the disconnected feel.

I also agree that, at least on the front, you really want the geometry of the track bar and drag link to be close to stock to prevent bump steer, etc. And, btw, if you're not planning on doing high steer on your SOA conversion, you absolutely need to start that planning. You want the drag link to be pretty much level to the ground (or as close as you can get it) when the vehicle is sitting level. Raising up the connections at the axle end is mandatory in my (not so) humble opinion when you're doing that much lift. The drop pitman arm only compensates so much. When you factor in the track bar, you need it to match the geometry of the steering or, as was said before, you get bump steer. So look where the bars are sitting on the stock vehicle and try to match that as close as you can. Even if you need to do some raising of the axle side mount and dropping the frame side mount at the same time, do it.

In the rear, the track bar doesn't have any steering to match so you have a lot more flexibility there. (pun intended) Though it would also be a good idea to mix some frame side drop and axle side raise at the same time because flexing the suspension will induce some minor geometry changes.

As far as the swaybar(s), just get longer links. Make sure the arms of the swaybar are parallel to the ground when you're parked on flat ground. Make up the difference with longer links.

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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by AwesomeJ10 »

You will NEVER get a FSJ to 'wheel like a Toyota. Just sayin man. My Honcho can't even begin to keep up with my 'cruiser.

That being said - you might get real close if you ditch the leaves and go with coilovers with good shocks, but that is obviously a whole other story.

I can tell you that with my most recent FSJ build (the '88GW that I sold) was SOA on tons and was too tall/heavy. I think sway bars would have helped a bunch...

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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Nikkormat »

Blake wrote:You will NEVER get a FSJ to 'wheel like a Toyota. Just sayin man. My Honcho can't even begin to keep up with my 'cruiser.

That being said - you might get real close if you ditch the leaves and go with coilovers with good shocks, but that is obviously a whole other story.

I can tell you that with my most recent FSJ build (the '88GW that I sold) was SOA on tons and was too tall/heavy. I think sway bars would have helped a bunch...
I'm gunning for leaf sprung land cruisers, not 80 series and newer.

I typed an hour long response about why a wagoneer is better than an FJ60 in every regard for expedition wheeling in most of the world, but my session timed out and it did not save upon login. :x :banghead:

Basically wagoneers are cheaper with better parts availability. And are cheaper to build. Can be built with greater range. And don't rust nearly as bad. And come stock with a flat belly. And look way better. And we have a friendlier online community. :fsj:
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Nikkormat »

derf wrote:I agree on the body mounts, spring bushings, etc. probably contributing to the disconnected feel.

I also agree that, at least on the front, you really want the geometry of the track bar and drag link to be close to stock to prevent bump steer, etc. And, btw, if you're not planning on doing high steer on your SOA conversion, you absolutely need to start that planning. You want the drag link to be pretty much level to the ground (or as close as you can get it) when the vehicle is sitting level. Raising up the connections at the axle end is mandatory in my (not so) humble opinion when you're doing that much lift. The drop pitman arm only compensates so much. When you factor in the track bar, you need it to match the geometry of the steering or, as was said before, you get bump steer. So look where the bars are sitting on the stock vehicle and try to match that as close as you can. Even if you need to do some raising of the axle side mount and dropping the frame side mount at the same time, do it.

In the rear, the track bar doesn't have any steering to match so you have a lot more flexibility there. (pun intended) Though it would also be a good idea to mix some frame side drop and axle side raise at the same time because flexing the suspension will induce some minor geometry changes.

As far as the swaybar(s), just get longer links. Make sure the arms of the swaybar are parallel to the ground when you're parked on flat ground. Make up the difference with longer links.
Perfect, and yes high steer is already part of the plan. I'll have the flat top knuckles off of the 74.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by FSJ Guy »

Stuka is correct. The front track bar must mimic the drag link to your pitman arm.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by AwesomeJ10 »

Nikkormat wrote:
Blake wrote:You will NEVER get a FSJ to 'wheel like a Toyota. Just sayin man. My Honcho can't even begin to keep up with my 'cruiser.

That being said - you might get real close if you ditch the leaves and go with coilovers with good shocks, but that is obviously a whole other story.

I can tell you that with my most recent FSJ build (the '88GW that I sold) was SOA on tons and was too tall/heavy. I think sway bars would have helped a bunch...
I'm gunning for leaf sprung land cruisers, not 80 series and newer.

I typed an hour long response about why a wagoneer is better than an FJ60 in every regard for expedition wheeling in most of the world, but my session timed out and it did not save upon login. :x :banghead:

Basically wagoneers are cheaper with better parts availability. And are cheaper to build. Can be built with greater range. And don't rust nearly as bad. And come stock with a flat belly. And look way better. And we have a friendlier online community. :fsj:
haha cool man

BTW I know a guy who mills/drills D44 flat top knuckles for $50 each here in longmont. He's done mine for years. I have a bunch of new D44 high steer components that I will sell you for cheap too. Arms, studs, ball joints, TRE's, weldable inserts, etc. Text me if interested.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Tad »

Nikkormat wrote:...The 74 does have a factory sway bar...
Gabe, can you post a picture of this 74 factory sway bar please?

I have parted put a lot of FSJ's over the past 16 years and have never seen a factory sway bar on a pre 76 FSJ frame (except for the one I removed from an 85 and added to my rig and that was not a simple cut it off and weld it on deal) and I'm pretty sure they were just options for 76-77.
The 75 and older frames are vastly different up front.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Nikkormat »

Tad wrote:
Nikkormat wrote:...The 74 does have a factory sway bar...
Gabe, can you post a picture of this 74 factory sway bar please?

I have parted put a lot of FSJ's over the past 16 years and have never seen a factory sway bar on a pre 76 FSJ frame (except for the one I removed from an 85 and added to my rig and that was not a simple cut it off and weld it on deal) and I'm pretty sure they were just options for 76-77.
The 75 and older frames are vastly different up front.
Sure thing, I'll see if it's in the TSM too.
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Re: Retaining front and rear track bars with SPOA and shackle flip.

Post by Tad »

I see it in the TSM, section 12-5 but only for the 8000lb GVWR trucks.
I supposed that could be transplanted easy enough.
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