Build The Truck of Theseus

[The Machinist]

After messing around tonight I'm pretty sure the only way a shackle can invert is if it goes so negative it ends up co-linear with the spring at full droop, which under the right circumstances could allow it to go over center (the wrong way) when the wheel starts to move back up.

You pretty much nailed it here. It can also sometimes happen if the shackle is wedged against an obstacle and the main leaf gets deflected or bent. Its not particularly difficult to fix on the trail if it gets inverted so it shouldn't be too much of a concern. When it happens though it does greatly increase the chances of cracking, breaking or bending the main leaf. (you can see the strain on the inverted leaf in your sample pic)

Your setup looks like it will work very well and will likely take bumping a rock or other obstacle directly on the spring to get it to deflect enough to invert.

 

[littlevulture]

Your setup looks like it will work very well and will likely take bumping a rock or other obstacle directly on the spring to get it to deflect enough to invert.

Great to hear I wasn't overlooking something simple

 

[Manhattan]

You pretty much nailed it here. It can also sometimes happen if the shackle is wedged against an obstacle and the main leaf gets deflected or bent. Its not particularly difficult to fix on the trail if it gets inverted so it shouldn't be too much of a concern.

'Wheeling in Moab years ago, one of the guys, in a mild CJ, i.e. 3" and 35s had a shackle invert twice - which are in the front on CJs (yeah, the wrong end). Both times he got out the high-lift and, click by terrifying click, he "uninverted" it. It was like watching someone slowly crank a (3,500 lb) jack in the box.

 

[littlevulture]

'Wheeling in Moab years ago, one of the guys, in a mild CJ, i.e. 3" and 35s had a shackle invert twice - which are in the front on CJs (yeah, the wrong end). Both times he got out the high-lift and, click by terrifying click, he "uninverted" it. It was like watching someone slowly crank a (3,500 lb) jack in the box.

That sounds super sketchy and it's why I'm trying to understand the system before I commit to a geometry. My shackles are in the front but after reading some of the 60 series stuff I'm not convinced shackle position matters with this because people seem to have problems with the shackles on their rear axle inverting too. Or at a minimum aftermarket companies have convinced people its a problem enough that people keep buying anti-inversion shackles for the front and rear.

 

[Manhattan]

I've been around leaf-sprung trucks for 30+ years and have only seen that one Jeep invert a shackle. I think (statistically) the anti-inversion shackles might be a solution looking for a problem.

 

[littlevulture]

I've been around leaf-sprung trucks for 30+ years and have only seen that one Jeep invert a shackle.

Great to hear, I've got basically no experience so that's a nice data point.

Another question for the masses...when looking down the axle facing the wheel how close to parallel do the tie rod and drag link need to be when the steering is centered? I think I'd like to remake the steering arms and widen the front axle to get more steering angle before the tires hit the frame/leaf packs but I don't wanna mess with that right now since I'm so far behind schedule. If I push the steering box forward in anticipation of longer arms in the future will it cause problems right now since the links won't be parallel when driving straight.

Posts 193 and 199 for reference.

 

[aztoyman]

On a linked front, your drag link and pan hard/track bar have to be parallel to minimize or eliminate bump steer. IDK if the drag link and tie rod has to be perfectly parallel?? It's been so long since I SAS'd these trucks with leaf springs. I do remember having to move my steering box forward on my 88 truck because they hit each other. On my son's 91, same kit and no contact?? Didn't have to move his box.

I just moved the box where it lined everything up and nothing hit when steering and flexed. Never got too picky about it and never noticed anything when driving on the street or interstate. And I daily drove it to work and half of that was on I-10 @ 75MPH. I could take my hands off the wheel and track straight. I never even checked caster. Got lucky I guess.

I just looked at TG IFS eliminator kit instructions and nothing really mentioned but I did see lots of posts about moving the steering box forward and different pitman arm setups on other forums. Run through some old Pirate and Marlin Crawler posts and maybe find some good info.

 

[Mudder]

I know when I did my hi steer setup I went as far forward and tilted the box as far up as I could so I could move the axle forward if I wanted to. I didn’t go through the extent some have of notching the frame and cutting the core support. I haven’t had any steering issues with it and never read about them needing to be parallel.

 

[littlevulture]

On a linked front, your drag link and pan hard/track bar have to be parallel to minimize or eliminate bump steer.

Yeah the track bar and drag link stuff makes sense to me for links.

I just looked at TG IFS eliminator kit instructions and nothing really mentioned but I did see lots of posts about moving the steering box forward and different pitman arm setups on other forums. Run through some old Pirate and Marlin Crawler posts and maybe find some good info.

I haven't been able to find any really good technical info on steering box placement, side note but it seems like every day it gets a little harder to find what I'm looking for on google...

I know when I did my hi steer setup I went as far forward and tilted the box as far up as I could so I could move the axle forward if I wanted to. I didn’t go through the extent some have of notching the frame and cutting the core support. I haven’t had any steering issues with it and never read about them needing to be parallel.

That's good to hear, matches what I came up with when I went inside...turns out I was overthinking this too (no surprise there). I sketched it out in CAD and decided it won't have any meaningful effect if I push the box forward. Looks like gibberish without the dimensions and relationships but this is a top down view of the steering, one location has parallel links when the steering box is centered and the other one is 2" forward of that.

 

[littlevulture]

Got a lot done in the last 10 days, long weekend for Presidents day helped.

- Cleaned up some old steering links I forgot I had, 1.25"x0.25" wall DOM. I think they're old Budbuilt parts but I could be wrong, got them for free with some other parts years ago.
- Moved the rear spring mount for the front axle forward 1cm to get the tire away from the firewall, lengthened the shackles by 1cm as well to match.
- Got a cheap Bauer portaband from Hazard Fraught and made a quick knockoff of the SWAG stand. Faster, more accurate, and less messy than a cutoff wheel...feels like cheating.
- Located the steering box (went as far forward as I could), cleaned the frame up some more, and got the frame plates tacked on. Found a pinhole in the frame hiding under a weld for an original bracket, definitely wasn't a rust hole so I'm guessing someone at the factory got a little too hot welding the bracket on.
- Made a bracket to mount a 5VZ AC compressor and power steering pump to the VW TDI, power steering pump also serves as the tensioner. These are using the 4-rib 5VZ alternator pulley I mounted to the crank in post #143 although the power steering pump is in a different place than I was expecting.
- Replaced the power steering reservoir that was attached to the pump with a homemade adapter for a remote reservoir. I had a 22RE reservoir in my parts stash but I can't find it anymore. I'll need to track one down cause it seems like it'll fit really nicely where I'm thinking.
- Filled the worst of the pitting on the knuckle balls with JB weld and knocked down all the other high spots with some fancy mesh fabric sandpaper I found.
- Started making new shock towers out of 4"x4"x0.25" square tube.

Zinc primer between the plates and frame. Figure its cheap insurance since water can get between the frame and plates through the frame holes.

Accessory bracket in-progress. Power steering pump pivots about the right hole and is locked by a bolt on the backside that clamps to the slot on the left. I don't think it'll be too bad to swap to a different pump in the future if I ever need to upgrade.

Power steering remote reservoir adapter. This was surprisingly difficult to make, especially the tube. Scrapped the first attempt on the lathe and nearly scrapped the second when I was pressing it into the block.

Toyota accessories mounted with remote reservoir adapter installed.

Fancy Diablo "SandNET" brand sandpaper I found, wasn't really any more expensive than the normal stuff and its definitely more flexible, also seems more durable so far.

 

[aztoyman]

Nicely done.

 

[littlevulture]

Decided I didn't actually like any off the shelf power steering reservoir solutions I chopped up the 5VZ one last night. The body is the same diameter and thickness as a 2.75" exhaust coupler. Not sure if I want to reinstall the factory reservoir screen before I weld it up or just run a small oil filter inline with the return somewhere. The way its designed there's really no good way to ever clean that screen.

Also got the shock towers done last weekend and located with the axle side mounts. Not perfect but I think they'll be functional. In hindsight 4"x4" box tube probably wasn't the best choice of material, lots of residual stress in the material when I started cutting it up.

 

[Mudder]

I’d bypass the screen and install an inline after going through the hassle to clean the one on my 3rz. I don’t think I got the top to recrimp properly on mine and now I had a minor leak from it.

 

[littlevulture]

Reservoir is done and mounted, capacity works out to about 0.4L if it's full to the brim. Decided to delete the internal screen, after some more staring I noticed it only strained fluid as it's added and didn't actually have any flow through it during operation. I'll stick a small filter somewhere on the return line from the box. Threw an old "TOYODA" cap I had on it for some extra style, it's a direct replacement for the original plastic 5VZ cap.

Also built a new engine hoist point into the mount, this was the only corner without a nice robust lift point from VW.