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· '03 Disco SE
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573 Posts
Discussion Starter · #1 ·
So you guys know the story - after a suspension lift, the travel of our panhard bar forces the axle sideways so that it is no longer centered under the body. The bigger the lift, the bigger the problem.

Detail:



Because this condition forces the front radius & panhard bushings to be in a constant state of flex it accelerates wear and decreases ride quality. Given enough time, you'll experience vague steering, clunking, death wobbles, tire wear, etc.

The solution is an adjustable panhard rod that enables you to center your axle to offset the additional lift.

I'm currently building my own. My design is based on taking the OEM tube, removing a 4" section, welding in some threaded ends, and using a "jack screw" to attach and adjust the distance between the two halves.

Here's my inspiration:



My design is slightly different because it uses a "jack screw" instead of a threaded rod. A jack screw has opposing threads and acts as a turnbuckle. Therefore it can be tightened or loosened while the bar is installed, unlike the aftermarket versions which force you to remove the bar, spin the head, and reinstall it.

Jack screw:



Here's a quick model of my design:



The threaded ends are 4130 chromoly and the jack screw and jam nuts are Grade-8 5/8"-18 thread. The welding is gas-shielded MIG using ER80S-D2 wire to ensure the highest possible tensile strength. A beveled weld channel between the threaded insert and rod ensures excellent penetration, with two plug welds on each end for added peace of mind. The unit is then finished using automotive primer & paint (catalyzed paint using HVLP - no rattle can). I wish I could powder coat, but I can't.

My question is - are there any forum members out there that would be interesting in buying this piece if I were to build more than one?

Here's what I'm thinking for pricing:

"Base Bar" (Paint & Primer, NO BUSHINGS) - $125 shipped + $50 CORE
Add OEM Bushings - +$35

I'm an engineer by trade, so this is something that I would make in my spare time. I have a couple of spare bars so there would be no downtime. I'm not looking to make a lot of money, I just wanna have fun and maybe help the community a bit. I'm an experienced hobbyist welder and through my job I have the means to do NDE testing to ensure the strength of the welds.

My particular unit should be done by the end of next week and then Ill update this post with more photos.

Let me know what you guys think - you won't be hurting my feelings if you think it's a stupid idea.
 

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Couple of thoughts. I think I would be a little leery of the jack-screw for that application. Just because it's grade 8 does not mean it was designed for the constant compression/tension forces it will be exposed to.
Second, although the idea of easy adjustment is nice, how often do you really have to adjust it? I just installed a Terrafirma bar on my D2 after installing Justin's springs. It took three adjustments and 1/2 hour total. Super easy and I'll never touch it again.
125.00 seems to be good price point, and don't take offense, but I'm not going to install a "untested" critical steering component and put my life, my family's life, and my LR on the line to save a few dollars.
 

· '03 Disco SE
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573 Posts
Discussion Starter · #3 ·
I definitely understand the hesitation, no offense taken. I wanted to test the waters. Just a few of counter-points though, sorry if I go a bit too engineer on you.

1. The "constant compression/tension forces" are pretty much exactly what these bolts are designed for. If your reasoning was accurate (it isn't), wouldn't the OEM bolts that hold the panhard into the brackets also be in danger of failure? What about the bolts holding the track rod and drag link? Wouldn't any of the suspension bolts cause you to be leery?

The OEM panhard bolts are grade 10.9 (metric equivalent of 8) and they're mounted laterally ("weak" axis), and subjected to very strong shear forces because their only contact points are the relatively thin walls of the mounting brackets. Shear forces are typically 60% of the tensile strength (shear for grade 8 is 90,000psi). If grade 8 is "weak" as you say, shouldn't we be popping these bolts left and right?

Grade 8 hardware has a yield strength of 120,000psi and a tensile strength of 150,000psi when mounted longitudinally (like the jack screw). The welds that attach the panhard brackets to the axle and frame are only rated to 70,000psi, which means that they would go well before the bolt was even stressed. Not to mention that the suspension components wouldn't reach anywhere NEAR those forces except in the event of an immensely powerful collision that forced the body one way and the axle another.

You can't even argue that the threads will pull out. Bolt pullout is calculated by multiplying the shear strength of the weaker material by the shear area. Chromoly (weaker material) has a shear strength of ~58,000 psi, and the bolted connection would have a shear area of 1.78in*2 (assuming 1.25" thread engagement). That means the thread pullout force is on the order of 103,000psi. So again, you're breaking welds before you're pulling threads.

Maybe bolt fatigue? Unlikely. The entire D2 suspension uses bushings to isolate the big heavy bits of metal to ensure there is no fatigue. A soft rubber bushing will take up the flex of the suspension before it ever transmits it to the hard bolt in the panhard. If you completely compress the bushing and start transmitting force to the bolt, you have bigger problems.

I'm not discounting the fact that suspension bolts break, but oftentimes these break due to manufacturing flaws (and how can you plan for those?) or incorrect torquing procedures where the bolt is either too tight and has no flex, or too soft and has too much flex. The fact of the matter is that the bolt holding your TF panhard bar together has the same odds of breaking as mine does.

TL;DR - The jack screw is strongest component of the system. Can't argue with science.

2. Adjustment comes down to personal preference. You can set it once and forget it like you did and be happy with that, or you can make alterations depending on your suspension height. When you first get the lift it's at one height, after settling it's another height. Add bumpers, winch, and a rack and you're even lower. Start towing and you're lower yet again. Throw in 5 friends and now the suspension is really low. A fixed panhard has ONE correct position - any alterations in height move the axle. Again it's personal preference, but I'd like to be able to make chances on the fly.

3. I completely understand the "untested" comment. And I wouldn't dream of sending one of these out without putting it through some serious abuse and scanning the welds before and after. But wouldn't your reasoning apply to any component we put on our cars? Did you look at the mill test report of the TF bar to make sure that the metal in it isn't laminated Chinese garbage? Did you ask for NDE (non-destructive examination) paperwork to make sure that the welds have adequate penetration? Are you confident that the bolt they used is the correct grade?

I'm exaggerating, obviously. The point is that we take the quality of a lot of components for granted without doing any first hand research. I'm not saying that makes my product better or worse, but it's a point to consider.

At any rate, thanks for letting me know your thoughts. I'm open to all comments.
 

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It'd be easier to just cut one bushing off and replace it with a ballistic fabrications adjustable bushing. The middle seems like too much work.

Also, the LR panhard will bend if you hit something while off road. I've bent one, but I'm out here in the rocks, so I bend stuff frequently if I make one mistake. There is no field repair for that, your just sol, I had to get a tow. That's why they offer HD versions, imo.

For someone who moderately goes off road, then this should be fine.
 

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Maybe your right, maybe your wrong, but I'll let others take your word for the engineering. I've already got my bar. A little clarification on the ease of use you are touting. Making an adjustment after a lift is one thing, but how many lifts are you going to put on it? Second, the amount of shift in the front axle is going to be minimal if you already have decent springs when adding equipment. Towing? That's the rear-end. Lastly, the adjustments I talked about were to the drag link, not the pan-hard bar. The pan-hard bar was set the one time. What that does is throw your steering wheel off, so you have to adjust the drag link to bring the steering wheel back to center.
I have to agree with Dane that I would be concerned about the comparable weakness of the adjustment point vs. a HD bar with adjustable ends when it gets slammed on a rock or hung up on a stump.
Lastly, besides the adjustment feature, people buy aftermarket bars because they are HD. You are offering adjustment, but not any more strength than stock and possibly weakness at the jack-screw.
I just don't think there's the market here to re-invent the wheel.
 

· disco biscuit
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1,062 Posts
I think its a good idea. If for nothing else to save you money. I would offer constructive criticism...I would think the nuts could use a stopper to keep things in place. Besides that. I like that you put the nut assy close to the edge up out of line of fire. Maybe enough to keep the modification alone from causing bending weaknesses. I think you should consider the weakening of metal and whether or not the base metal(OE rod) doesn't require controlled temps. Meaning pre and post heating to bring it up to temp and back down to cool correctly. In the plant you can pass xrays all day long but that says nothing for what the welding process can do to the molecular structure of a metal. It could look great now under a microscope then later crack under stress or bend. I wouldn't go into just welding on something blind. Too much liability. That being said I would consider one of these during my lift depending on the savings over others of course. And also depending on whether I steal your idea and chop one up myself....no pun intended at all. I have thought of modifying parts for my own vehicle and bravo to you for that...!
 

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Here's really the bottom line for me. I can get an OE adjustable bar from you for 160.00 shipped with OE bushings or a HD adjustable bar from Justin with urethane bushings for 220.00 shipped. I'll gladly spend the extra 60.00.
In the end, I don't think your offering enough of an upgrade that most will not just pop for the extra for a HD bar.
As for the "market", have you received any interest or orders for your bar? Looks like you've had 143 views and only 3 of us have responded with our "constructive" criticism. PM's for orders?
Also, If your really trying to gauge the market, I would post over at dweb. I think you'll really get a feel for your idea, if you know what I mean.
 

· '03 Disco SE
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573 Posts
Discussion Starter · #9 ·
Managed to wrap up the bar - no paint yet as there's still some detail work to be done.



Ended up taking 3-1/4" out of the bar. At the stock length I still have 1-3/4" of thread insertion on either end.

The inserts are held in with 4 rosettes and a 3-pass bead around the circumference to ensure I filled the bevels.



Ended up grinding the welds to give it a more "stock" appearance - Once again I made sure to prep the tube ends with a nice bevel so that I didn't sacrifice the weld strength by grinding. I did end up pre & post heating the unit (thanks disco biscuit). I don't think it was necessary, but it's a bit of extra insurance.



@Dane - I'd be happy to tell you what parts I used when it comes time to build your own. You really only need 3 components that are fairly inexpensive.

@helievac - This is just a hobby of mine - I'm certainly not concerned if I don't sell anything. As for the "constructive" criticism, I don't recall asking for any. I asked if there was any interest if I had extras to sell since I already have the extra components. I'm an engineer and I do this for a living- do you really think I'd risk my ass and offer a product that wasn't properly thought out? For criticism to be constructive it has to come from someone who has experience in engineering analysis or fabrication, and you clearly don't know **** about either.
 

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I'm going to do mine differently. I'm cutting my frame mount off and using a different axle entirely. I'm going with 1.5' .25" wall dom tubing and probably heims. Thanks though.

It does look pretty sweet. I'm sure there will be people interested. I bent mine along with other things, before you'd bend your panhard you'd also do damage to your TRE's or the steering rod itself like I did.

Also, this forum is dead, you wont really get sales here. I'd post up in the LRF classifieds or something.
 

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"Let me know what you guys think - you won't be hurting my feelings if you think it's a stupid idea."
That quote sound familiar? If your memory's that bad, I REALLY think it's a bad idea. Also heard the quote, "You don't have to be a chicken to smell a rotten egg?
What you really meant to say was: "Please love my idea, trust everything I say because I'm a genius engineer and if you don't agree with me I'll throw a tantrum."
I love it when people go on an open forum, ask for opinions and get their panties in a wad when someone actually gives it to them.
Hike your skirt up and go over to mommies for that hug you so desperately need.
 
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