Hitch-pin wheeling conclusions.

[alkaline747trio]

Well, I've had the hitchpin mod done for several months, and over that time I have done some extensive off-road testing.

The mod worked great, the front end flexes atleast as well as the back and the "squishy factor" is awesome.

Here's that flex

This mod is great, but it needs a little improving. The axle mount of the side you pull the pin from endures great stress and all kinds of movement that mishapes it.

Conclusion. With a little beefing of the axle mounts and better shock placement, this mod is great for improving off-road ride and flex. I'm gonna be running 4 axle bolts for a while and hope that the mount straightens its self out, and then add some 1/4" plate to both sides and have another go.

 

[landtank]

that doesn't look like stock arms. Are those Slee's gen 1 arms?

 

[alkaline747trio]

Yup, gen 1 (technically gen 2 if you count the adjustable ones as gen 1 arms).

 

[landtank]

Yup, gen 1 (technically gen 2 if you count the adjustable ones as gen 1 arms).

Those arms are thicker than the stock ones and might deform the brackets more as there is less room for movement.

The Gen 3s are back to stock thickness.

 

[alkaline747trio]

FJBen is running the same arms, and claims of no issues. Maybe I wheel too hard Three-link is in my future, so I reckon beefing things up a little bit will have to do the trick for me.

I do believe you are right about the thicker arm being another factor, but with less than 10k on those bushings, I'd imagine they deflect pretty good.

 

[alkaline747trio]

Well, got things beefed up. Used some 1/4" rectangular steel to sturdy it up. I'll let the pics do the talking.

 

[sleeoffroad]

Just a FYI on this. You have now re-inforced the mount, so when it twist you are putting all that stress on the arms. Make sure you check them regularly. There is a reason the mounts get bent out when you pull the pin.

 

[alkaline747trio]

This will be a good test on your product now, wont it I do a once over on my truck after every wheeling trip, but I'll double check the arms.

 

[-Spike-]

And on that note, in preparation for trying the poor-man's 3 link- AKA hitchpin mod, I also modified the frame-end of the Slee arms I'm running. As noted earlier, the Slee arms are wider than stock at the bushing sleeves. I took a grinder to the frame end bushing sleeve, reducing the width at the top and bottom so that the arm can twist in the mount more before the sleeve hits the mount. I also replaced the bushings on the assumption that the old rubber was hard and would not flex as well as new rubber. I'm putting more stress on the bushings now, but that's where I'd like the stress to be. If a bushing somehow fails, the truck will not become uncontrollable. At worst, it will be uncomfortable to drive at high speeds, but it will get me home. The idea behind modding the frame end was that I'd like most of the twist to be taken up at that end, where there's only one mount, hopefully that will lessen the twist at the axle end and allow it to flex easier.

I ran a familiar trail after the mod, but forgot to pull the hitch pin. Even so, it seemed to improve the front axle articulation, but that was only a seat-of-the-pants observation.

Thoughts? I will try to remember to take some pics when I remove the arms again- I need to orient the bushings correctly. I was in a hurry and forgot the holes in the rubber are there for a reason.

-Spike

 

[concretejungle]

I need to orient the bushings correctly. I was in a hurry and forgot the holes in the rubber are there for a reason.

-Spike

What's the deal on that? I know it's been said before, even by Cdan that the holes should be oriented correctly. I also did what you did and i have no idea what the orientation of the holes are. So is it really that big of a deal? Should i leave them or remove them and reset correctly oriented?

 

[-Spike-]

Alky, why did you choose to pin the driver's side? I went back and forth trying to decide which side would be best, and finally decided to pin the passenger's side. The Slee arms are different, as you know, with the passenger side having a cut-out area due to the axle tube being larger on that side. Although it is reinforced there, I figured it might be slightly weaker than the driver's side, so I figured the driver's side arm would be the better choice to take the extra forces involved in holding the caster angle with only one arm. Also, on my truck at least, there's more room between the arm and the axle on the passenger side, in fact the driver's side arm almost touches the axle between the bushing sleeves leaving very little room for movement upwards. Did you have some reason I'm not considering for pinning the driver's side?

-Spike

 

[-Spike-]

What's the deal on that? I know it's been said before, even by Cdan that the holes should be oriented correctly. I also did what you did and i have no idea what the orientation of the holes are. So is it really that big of a deal? Should i leave them or remove them and reset correctly oriented?

I don't have an FSM, but common sense says the holes are the weak point in the rubber, probably so that the bushing can flex easier. The bushings have to take the twist when the suspension flexes. Orienting the holes in line with that twisting direction should allow the bushing to flex easier. It's a lot easier to compress a hole than to compress solid rubber. I'm thinking that a line drawn through the two holes in the bushing should be essentially perpendicular to the arm. To be technical, the holes should be perpendicular to a line drawn from the frame end bushing center to a point between the axle end bushing centers. I guess that's about as clear as mud.

-Spike

 

[alkaline747trio]

Spike, after reading that, I wish I would have picked the PS. But really, there was no reasoning at all...I just left that bolt out when I was installing the new arms. Please do post some pics of your frame end modification, it sounds like something that could be worthwhile in this situation.

To all the forseen issues, I'm doing with the "if it ain't broke, don't fix it" mindset, I only beefed up the axle mount because it bent and flared, if the frame end does that also, I will fix it; if not, more money in my pocket.

 

[-Spike-]

The frame end is already somewhat reinforced by the factory. However, as Christo said, something has to give. Removing one bolt allows the axle to twist more, and all that force is transferred through the arms. If something breaks, it's probably going to be one of the bushing sleeves breaking at the welds, and with only 3 bolts, that could be catastrophic depending on when it breaks. It would most likely break on the trail, while you're moving very slowly over a rock, but it may do a lot of collateral damage to other suspension components when it goes. If it cracked, and let go at speed somewhere, it could get considerably ugly. That was my motivation for the frame-end mod, thanks to Tools R Us for pointing out the limitations of the wider bushing sleeves.

-Spike

 

[alkaline747trio]

I think I'm gonna look at machining the bushing sleeves slightly to help with that. I'm just gonna stay under the assumption that fresh bushings will take most of the stress and things will just bottom out when they reach a limit.

 

[Tools R Us]

According to my '96 FSM the bushings are installed with the holes top and bottom, have heard that they may have changed that recommendation, CDan? Holes top and bottom would net the best flex.

On my junk the acceleration, braking, twisting loads are carried by the right arm, the left only has one axle end bushing. The bushings are narrowed, softened, the first set (used, 35K miles, 10 yr old) was installed with the holes top and bottom. That proved to be too soft, they only lasted a couple of months before they cracked, then the axle could oscillate, shake when hitting bumps at high speed. Ordered new ones from Dan, narrowed and installed with the holes front and back, so far so good.

With the narrow arms and bushings (1.3" wide) there is no contact at full flex and it flexes much easier. Thinking about making a set of narrow, 4 bushing arms to see how that would work.

 

[-Spike-]

the first set (used, 35K miles, 10 yr old) was installed with the holes top and bottom. That proved to be too soft, they only lasted a couple of months before they cracked...

I'd theorize that the old bushings were just not flexible due to age, which caused them to crack under the increased stress that more suspension travel put on them. I don't think mileage- low or high- is a factor, I think it's simple time that kills rubber. I'd further theorize that not having the holes in the proper alignment might put more stress on the bushings, as the solid rubber has to be compressed rather than the relief hole. Pure speculation on my part.

-Spike

 

[jmaddocks]

I've been wheeling over the last year or so since I originally posted the hitch pin mod. I've got the passenger side pinned -- I seem to recall that I had better clearance between the control arm and steering tie rod on that side. I beefed up the driver's side forward control arm mount with 3/16" steel plate. No problems so far, but I know it's been really hard on the rubber bushings.

 

[Tools R Us]

...I don't think mileage- low or high- is a factor, I think it's simple time that kills rubber...
-Spike

Agreed, 10 years in AZ is hard on any rubber, the new bushings felt softer. With only 3 bushings they work differently, the right arm controls axle roll, the left arm only locates the axle. With 4 bushings both arms fight to control axle roll, when flexed the low arm is trying to turn the axle forward and the high arm turning it backwards, causing the bushing crush and flex bind. The main forces on my right bushings are controlling axle twist from acceleration and braking, so they work well installed with the holes front and back.

I would bet that offroad there is less stress on the bushings, arms, brackets than stock, due to the reduced bind, bushing crush. ect. Compare this pic of Juan's flexed to mine in the pic above.

 

[-Spike-]

Oh, absolutely- the axle bind, or twist, as I prefer to think of it, scares the hell out of me. I'm sure it works fine in the situations it was intended- cross-country driving- but for constant flexing and with the other mods we do to increase that flex, the thought of the forces trying to twist the axle housing makes me cringe. Your bushings are definitely seeing less stress with only three of them, as strange as that sounds. I'm contemplating cutting the front bushing eye off one of my stock arms and only running three, depending on how the truck drives with the pin pulled. I need to measure the Slee arms and see if they're any longer than stock- I suspect they're not, but I can't remember Christo saying one way or the other. The thing that scares me is having the one arm bearing the caster load breaking at highway speed. To address that, I'm also contemplating a hybrid 3-link/radius arm setup, with a link coming off the passenger arm to the top of the pumpkin, but I'm not sure that would be any easier than just doing a traditional 3-link. I'm not even sure I need to go much further- the truck does what I want it to do the way it sits for the most part. I can't take an 80 on much harder trails than some of the ones I run now. I guess it might make the ones I run now easier, or it just might be the relentless persuit of a better mouse trap making me want to mod more stuff under there.

-Spike