SUA High Steer TRE upgrade lessons

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DomSmith

DomSmith

Joined
Nov 16, 2004
Threads
299
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3,761
Location
Oceanside, CA (Fire Mountain)
So I've been trying a few things on the 40 to improve drivability while strengthening the front steering. I have mini truck discs on a stock 40 axle and 4" spring lift with close to stock shackles (+1/2" maybe). I also have 6 degree shims and have tried every combination in between and these are the ones that track the best. The 40 series TRE's just do not last IMO and I wanted a little less bump steer when accelerating/deccelerating on the freeway. This truck goes off road but is not a crazy rock crawler and I'm not interested in SOA.

The first thing I tried was a dropped pitman arm. This eliminated the bump steer but the shorter arm decreased my turning radius and prevented me from reaching the stops on my axle. I have a 3.5 turn saginaw box. So I pulled that off and ran it for a year or so with the longer flat arm and accepted the bump steer.

I recently started looking into high-steer setups as they claimed to work with SUA w/ 4" of lift. I finally decided on the All Pro setup and installed everything once it arrived. With the 80 series TRE's and the proper angle on my drag link the truck drives like a dream. No bump steer, no tracking issues, nothing. Even my buddies who borrow it once in a while couldn't stop talking about it. The only issue was the tie rod and drag link sat close to the frame and a simple speed bump would provide a solid "Clunk" as they hit the bottom of the frame member.

I drove it cautiously like this for about a month and enjoyed every minute of it but I knew I needed a change as it wouldn't last 5 minutes off road and I hate when things aren't right on the cruiser. So I sent them out to be tapered from the bottom rather than the top as I realized that was the perfect answer. I keep the 80 series TRE's that won't wear out as quickly, resolve the frame issue by lowering the rods, and eliminate bump steer with the proper pitman arm.

In the mean time I put back the mini arms and dropped pitman arm and suffer with difficult u-turns. It drives well but not like the high-steer.

Fortunately these arrived today. Reamed from the bootom for 80 series TRE's and I mounted them up.... only to find that tie rod hits the pumpkin when turned as it sits much lower and the arms are obviously shorter than the mini arms. :mad:

At this point I have about $300 into these paper weight arms (I'm resigned to the fact of eating that) and don't want to go back to the 40 series TRE's and bump steer or bad turning radius. Is another $200+ dollars in a 4 turn box and retaining the 40 TRE's my only solution? Has anyone successfully run a high-steer kit on a SUA rig that has 4" lift? It wasn't even close to working on mine. I don't want frombe, but maybe someone makes longer high-steer arms than AllPro that would clear the pumpkin?

Suggestions?





I'm fried.
 
I don't think you're talking "bump steer" here. Bump steer is the reaction to the arc the relay rod travels when an axle goes through it's upward/downward travel. I think you're having caster related tracking issues. Typical bump steer on a left hand drive vehicle would force the wheels right during compression.
True bump steer would be alleviated by running the relay and tie rods as parallel as possible at ride height.
 
cruiserjunkie said:
The rods were attached below arms. I believe Luke will build standard hysteer arms also
Click to expand...


Thanks for the info. I have an email in to him so we'll see what he has to say.


lcwizard said:
I don't think you're talking "bump steer" here. Bump steer is the reaction to the arc the relay rod travels when an axle goes through it's upward/downward travel. I think you're having caster related tracking issues. Typical bump steer on a left hand drive vehicle would force the wheels right during compression.
True bump steer would be alleviated by running the relay and tie rods as parallel as possible at ride height.
Click to expand...

The All Pro arms just happened to solve my bump steer problem because they bend upward and with the TRE's in from the top they lined up nice and even with my drag link (relay rod) using a straight pitman arm. With the TRE's from the bottom the angle would have been well within limits to reduce the bump steer to almost nothing as well but it hits the pumpkin. The tracking is pretty good with the stock TRE's but even tighter when I dropped the passenger side TRE not needed in the high steer kit. Bump steer is solved now with an extreme dropped pitman, I just don't like the turning radius or the 40 series TRE's if I can prevent it.

:beer:
 
I'm not sure if it is the perfect option, but maybe worth looking at. GM 1-TON offset TRE's at ruff stuff.


 
DomSmith said:
Thanks for the info. I have an email in to him so we'll see what he has to say.




The All Pro arms just happened to solve my bump steer problem because they bend upward and with the TRE's in from the top they lined up nice and even with my drag link (relay rod) using a straight pitman arm. With the TRE's from the bottom the angle would have been well within limits to reduce the bump steer to almost nothing as well but it hits the pumpkin. The tracking is pretty good with the stock TRE's but even tighter when I dropped the passenger side TRE not needed in the high steer kit. Bump steer is solved now with an extreme dropped pitman, I just don't like the turning radius or the 40 series TRE's if I can prevent it.

:beer:
Click to expand...

I just thought it odd. I don't remember any discernible bump steer from a 40
with 4" lift. I like running this setup. FJ60 tie rod ends, with lower FJ60 relay rod end and GM 1 ton high angle relay rod end at the pitman arm. Pitman arm is early wagoneer reamed to fit the GM. This is a 4~5 inch lift

IMG_3351.jpg
 
lcwizard said:
I just thought it odd. I don't remember any discernible bump steer from a 40
with 4" lift. I like running this setup. FJ60 tie rod ends, with lower FJ60 relay rod end and GM 1 ton high angle relay rod end at the pitman arm. Pitman arm is early wagoneer reamed to fit the GM. This is a 4~5 inch lift

IMG_3351.jpg
Click to expand...

Looks beefy! What tie rod is that? FJ60? Sorry for the hijack!

Cheers!
 
lcwizard said:
I just thought it odd. I don't remember any discernible bump steer from a 40
with 4" lift. I like running this setup. FJ60 tie rod ends, with lower FJ60 relay rod end and GM 1 ton high angle relay rod end at the pitman arm. Pitman arm is early wagoneer reamed to fit the GM. This is a 4~5 inch lift
Click to expand...

Dave-

Thanks for the info and the pic. I think the sag box on mine sits higher than the one you show but it seems like there's lots of spread on my setup. I'm not really sure why??

I snapped a quick phone pic on my way out the door at 4am this morning. I know this drop arm is a bit excessive but it's one I had on the shelf and I don't have a pic of the flat one installed here at work. I really want to be sure I come up with a better plan before throwing more money at parts I'm not going to use.... again.
image-2577464549.webp
 
I'm assuming you're using a Jeep CJ rod end at the pitman arm. That's the one Advance adapters sell .
The pitman arm is probably the standard Jeep CJ drop arm. If I'm right then the center to center length is too short and you won't get your best turning circle. I, as well as many shops like Luke at 4x4Labs are using the Wagoneer arm. It has a 1" drop and a lot of material to allow reaming to larger rod ends and is 6 3/4" center to center and easily travels through the turning radius.
Unfortunately the CJ and FJ40 rod ends are too small to use this arm so if you stay with your relay rod setup you'll have too find an alternate pitman setup. Like cruiserjunkie suggested a cut and turn will allow better caster without sacrificing u-joint angles. Combined with softer front spring rates a 2~3 degree positive caster setting you'll find your front end will become more controllable. The fronts look like Rough Country springs. A spring shop could rework them by replacing the bottom three leaves with a lighter gauge leaves and compensate with more arch to achieve the same ride height. With the V-8 you're running less weight up front than the springs are rated for. They were rated high even for a straight six
 
lcwizard said:
I'm assuming you're using a Jeep CJ rod end at the pitman arm. That's the one Advance adapters sell .
The pitman arm is probably the standard Jeep CJ drop arm. If I'm right then the center to center length is too short and you won't get your best turning circle. I, as well as many shops like Luke at 4x4Labs are using the Wagoneer arm. It has a 1" drop and a lot of material to allow reaming to larger rod ends and is 6 3/4" center to center and easily travels through the turning radius.
Unfortunately the CJ and FJ40 rod ends are too small to use this arm so if you stay with your relay rod setup you'll have too find an alternate pitman setup. Like cruiserjunkie suggested a cut and turn will allow better caster without sacrificing u-joint angles. Combined with softer front spring rates a 2~3 degree positive caster setting you'll find your front end will become more controllable. The fronts look like Rough Country springs. A spring shop could rework them by replacing the bottom three leaves with a lighter gauge leaves and compensate with more arch to achieve the same ride height. With the V-8 you're running less weight up front than the springs are rated for. They were rated high even for a straight six
Click to expand...

Thanks for all the info, I appreciate the time you're taking to help me sort this out. Yes the CJ arm is what I have. Ordered it 8+ years ago and ditched it because of the turning radius. I'll look into the Wagoneer arm as I want to lose the small TRE's anyway. I'm sitting on 80 series TRE's and rods so if I can use those that would be great but if I need to start over its not going to kill me. Can I ream the mini arms to accept 80 TRE's or are they short on meat? Not sure the mini arms and a 1" drop pitman would eliminate my bump steer though.

I'm happy with the tracking I accomplished with the new TRE's in the high steer so I think I'll wait on cut and turn but I am going to measure the caster angle when I get home tomorrow. I suppose my options for steering at this point are:


1- Keep it the way it is (no thank you).

2- Put the straight pitman arm back on and deal with the bump steer from the sharp angle of my setup.

3- Re-ream the All Pro arms to GM 1 ton and use the offset TRE's pictured above with new rods to clear the pumpkin and add the Wagoneer pitman arm. I'm not sure the two GM TRE's (one offset) would fit on the arm that accepts the relay and tie rod?

4- Have Luke make me longer high steer arms for the 80 TRE's and rods I already have and add a Wagoneer pitman arm reamed to 80 series TRE.



The springs are 8 year old 4" Skyjacker Softrides that have softened up a bunch over the years so not sure changes there will do me much good.

Here's a pic of how close the high steer setup was to the frame when installed. (it's all I've got on my phone).
image-1868912607.webp
 
I may have more going on than I originally thought. I used a flat piece of 1/8" narrow sheet to extend from the axle perch so I could measure caster with an angle finder and it looks like I have about 1 degree negative caster (front pointing towards the ground). My garage is pretty much flat but I suppose it may not be perfect. Either way I don't think it's that far off. Is there a better way to measure?

I'm already using 6 degree caster shims which I think is a lot, especially considering I only have a little bit longer shackles. I suppose it could have something to do with stuffing my front end on a razorback at SnT 4 years ago?

IMG_2701.jpg
 
lcwizard said:
buy a digital level from sears. They're pretty cheap there now. Lay it across the 4 studs on the steering knuckle. It will get you close. Do both sides and take the average
Click to expand...

I'll grab one Monday and use the studs. I was afraid that maybe the studs wouldn't be seated all the way and could give me a false reading.
 
Is the thick end of your caster shims at the front or rear?

Edit: I see you have them installed correctly. I'm surprised you need shims at all with just 4" leafs.
 
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