Will a Rear adjustable Panhard rod Fix Thrust Angle? (1 Viewer)

[k2mantra]

Those measurements for hub to flare looks like 4-3/4” of lift.

Yeah, Slee said that same. Are my calculations correct? - if I'm sitting at .8deg with 3" arm correction (assuming they are 5deg corrections), I'm actually looking for 8degs of correction with a 4.5" lift to set me back up to +3-4degreed. If I move to 5" arms (assuming the @Delta VS 5" arms are providing 8degrees of correction) , that will put me right around +3.8 deg castor.

 

[Delta VS]

Once you get over 3” of lift, you have to start paying close attention to (and decide which is more important) BOTH caster and pinion angle.

 

[landtank]

Yeah, Slee said that same. Are my calculations correct? - if I'm sitting at .8deg with 3" arm correction (assuming they are 5deg corrections), I'm actually looking for 8degs of correction with a 4.5" lift to set me back up to +3-4degreed. If I move to 5" arms (assuming the @Delta VS 5" arms are providing 8degrees of correction) , that will put me right around +3.8 deg castor.

Delta beat me to it as I was walking over to my PC, LOL.

You are limited to how much caster you can introduce before finding your self with uncontrollable drive line vibrations, regardless of what you run for a front drive shaft.
I offer caster plates that were specifically designed to work with a DC shaft which means they introduce the maximum amount of caster and still allow you to have AWD.

And the amount of caster they introduce falls a little short of your 8* calculation, which i think is correct.

This is straight up Geometry, no amount of money or fabrication will change this.

So basically you either correct your caster by introducing 8* of correction and part time your truck and for go having AWD or you lower your truck with additional weight or shorter springs and run less correction, a DC shaft and retain AWD.

 

[k2mantra]

Delta beat me to it as I was walking over to my PC, LOL.

You are limited to how much caster you can introduce before finding your self with uncontrollable drive line vibrations, regardless of what you run for a front drive shaft.
I offer caster plates that were specifically designed to work with a DC shaft which means they introduce the maximum amount of caster and still allow you to have AWD.

And the amount of caster they introduce falls a little short of your 8* calculation, which i think is correct.

This is straight up Geometry, no amount of money or fabrication will change this.

So basically you either correct your caster by introducing 8* of correction and part time your truck and for go having AWD or you lower your truck with additional weight or shorter springs and run less correction, a DC shaft and retain AWD.

Thank you and I really appreciate the insight here. Just so I can wrap my head around this....are you saying that with my current 4.75"ish lift, if I swap arms and go with Delta 5" or another castor correction to introduce the 8* correction, I'm probably going to introduce uncontrollable DL vibes even with a front DC shaft if I want to retain AWD?

 

[gummycarbs]

if I swap arms and go with Delta 5" or another castor correction to introduce the 8* correction, I'm probably going to introduce uncontrollable DL vibes even with a front DC shaft if I want to retain AWD?

I don't think anyone can guarantee that you won't have any vibes. You need the front pinion pointing at the transfer case. In my limited experience, it seems to induce vibes if you're even a tiny bit off.

Custom caster plates or the "washer mod" allow you to dial in exactly the angle you want, but that's going to involve grinding and welding. All of the off -the-shelf stuff will get you close, but there are too many variables to be certain in advance.

 

[k2mantra]

I don't think anyone can guarantee that you won't have any vibes. You need the front pinion pointing at the transfer case. In my limited experience, it seems to induce vibes if you're even a tiny bit off.

Custom caster plates or the "washer mod" allow you to dial in exactly the angle you want, but that's going to involve grinding and welding. All of the off -the-shelf stuff will get you close, but there are too many variables to be certain in advance.

Got it, ok thanks for the clarification. I think i'm finally wrapping my head around this. I really appreciate yall walking me through the details. I thought i was specifically avoiding theses issues by getting 75mm springs

 

[landtank]

Thank you and I really appreciate the insight here. Just so I can wrap my head around this....are you saying that with my current 4.75"ish lift, if I swap arms and go with Delta 5" or another castor correction to introduce the 8* correction, I'm probably going to introduce uncontrollable DL vibes even with a front DC shaft if I want to retain AWD?

I can only relate my experience. My off the shelf plates align for a DC shaft and haven't been an issue with vibrations. DC shafts have a pinion alignment tolerance of +/- 1 degree, 8* is outside that tolerance of where my plates point the pinion. So I can only warn you that in my experience introducing 8* of correction is likely going to give you problems.

As far as products from other vendors goes, you need to ask them. I have no information concerning their designs and can't help you with how their products would respond in your particular situation.

 

[landtank]

I don't think anyone can guarantee that you won't have any vibes.

As long as the information provided to the vendor is accurate I don't see why not.

 

[gummycarbs]

As long as the information provided to the vendor is accurate I don't see why not.

Is the customer actually measuring their lift height correctly? What if they add or remove a bumper, winch, etc.? What about the condition (not to mention make) of their suspension bushings? What if one or both radius arms are tweaked? How about if the caster angle is close, but the axle isn't aligned along the transverse axis due to bad radius arms?

I'm glad I'm not in the business of selling these sorts of products. The number of potential customer-caused issues is staggering.

 

[landtank]

Is the customer actually measuring their lift height correctly? What if they add or remove a bumper, winch, etc.? What about the condition (not to mention make) of their suspension bushings? What if one or both radius arms are tweaked? How about if the caster angle is close, but the axle isn't aligned along the transverse axis due to bad radius arms?

I'm glad I'm not in the business of selling these sorts of products. The number of potential customer-caused issues is staggering.

All these concerns should be easily handled by a vendor. That’s the business they are in. I’ve been selling these products for more than 15 years and have been qualifying customer builds for my products and when there is an issue after installing them I work through it with the customer.

And yes I have told customers my stuff isn’t right for them and why.

It’s not that hard.

 

[smritte]

Given the numbers below, will an adjustable rear panhard rod be the ticket to correct my thrust angle (assuming that's the cause for pulling to the left like I was told by the shop that did the alignment) OR do I need adjustable control arms to pull the thrust angle back?

Looking at your printout, your rear diff is pointed to the passenger side / /
That will move the front to the driver side, think forklift turning. Rear goes right, front goes left. Almost like your passenger arms are shorter then your driver side.

When I first saw the printout, I thought the vehicle was put on the alignment rack crooked because, that is a huge issue with improperly trained techs. Then I reread what you wrote and you stated vehicle pulls driver side. Your rear angles say that also.

Considering your post was about the vehicle not tracking straight, I'll comment on your alignment numbers. Nothing I see in the printout will cause your issue except the rear thrust angle. The definition of an alignment is the balancing of angles. Your "front" numbers are balanced well enough to not cause this issue.

You need to measure everything. I would start in the rear. Make sure the distance on the arms are correct, top is shorter than bottom. You mentioned replacing the rear arms. Did you install one in the wrong spot. Make sure your diff is centered. I have 5 inch lift on my 96 and before I did the Delta panhard correction, it was only offset slightly.

Personally, I wouldn't attack the front until the back is straight.
First rule of diagnostics, prove what isn't wrong and look at what you have left.
Prove your arms are correct, prove your axle is straight, prove your axle is centered.......
Don't stop measuring until you checked everything. Don't stop if you find something, prove the rest. Its not uncommon to have more than one issue. People stop looking when they find the first problem, never seeing the second.

 

[gummycarbs]

All these concerns should be easily handled by a vendor.

So you agree that they're issues.

It’s not that hard.

The vast number of posts here by people having problems with lifts, caster, and u-joint angles says otherwise.

 

[landtank]

So you agree that they're issues.

I agree there are solvable issues with old trucks needing maintenance or not properly repaired after an accident.

 

[landtank]

The vast number of posts here by people having problems with lifts, caster, and u-joint angles says otherwise.

Look deeper than the surface. People like to group products and problems together because it’s easy.

“All caster plates have tie rod contact and you need to grind the arms and weeken them”.

Thing is that isn’t true at all.

There are products out there that perform great. The issue is that on MUD you mainly see the ones that don’t perform well and people having a frustrating time dealing with them. That skews everyone perception in that they all don’t perform well.

 

[k2mantra]

Looking at your printout, your rear diff is pointed to the passenger side / /
That will move the front to the driver side, think forklift turning. Rear goes right, front goes left. Almost like your passenger arms are shorter then your driver side.

When I first saw the printout, I thought the vehicle was put on the alignment rack crooked because, that is a huge issue with improperly trained techs. Then I reread what you wrote and you stated vehicle pulls driver side. Your rear angles say that also.

Considering your post was about the vehicle not tracking straight, I'll comment on your alignment numbers. Nothing I see in the printout will cause your issue except the rear thrust angle. The definition of an alignment is the balancing of angles. Your "front" numbers are balanced well enough to not cause this issue.

You need to measure everything. I would start in the rear. Make sure the distance on the arms are correct, top is shorter than bottom. You mentioned replacing the rear arms. Did you install one in the wrong spot. Make sure your diff is centered. I have 5 inch lift on my 96 and before I did the Delta panhard correction, it was only offset slightly.

Personally, I wouldn't attack the front until the back is straight.
First rule of diagnostics, prove what isn't wrong and look at what you have left.
Prove your arms are correct, prove your axle is straight, prove your axle is centered.......
Don't stop measuring until you checked everything. Don't stop if you find something, prove the rest. Its not uncommon to have more than one issue. People stop looking when they find the first problem, never seeing the second.

This is increadablly useful advice. Thank you for laying it out like that.

The arms are absolutely beautiful and new from @landtank, so im pretty confident thats not it. I also had the same issue before replacing the arms (old ones bushings were shot so i took the opportunity to beef up on my heavy rig).

Time to get surgical with the measuring tape.

 

[k2mantra]

Look deeper than the surface. People like to group products and problems together because it’s easy.

“All caster plates have tie rod contact and you need to grind the arms and weeken them”.

Thing is that isn’t true at all.

There are products out there that perform great. The issue is that on MUD you mainly see the ones that don’t perform well and people having a frustrating time dealing with them. That skews everyone perception in that they all don’t perform well.

All really good points, and i really appreciate all the time and advice you have provided here. I've certainly learned quite a bit since going into this which is part of the fun, and definitely not done. Its definitely a bit if work to take a holistic approach and aggregate everyone's opinions and unique experiences that shape them. But damn, what an awesome community y'all are to take the time and try to help a guy out. Sure beats shooting from the hip with no direction

 

[gummycarbs]

There are products out there that perform great. The issue is that on MUD you mainly see the ones that don’t perform well and people having a frustrating time dealing with them. That skews everyone perception in that they all don’t perform well.

Cool, I look forward to seeing you solve this guy's problems on the first pass.

 

[landtank]

Cool, I look forward to seeing you solve this guy's problems on the first pass.

Already posted what he had to do. Did you miss that?

Lifts between 3”- 4” and over 4” ( give or take a little) are not AWD friendly with caster with in factory specs.

So if he wants proper caster and no vibs he has to change his ride height.

 

[gummycarbs]

Already posted what he had to do. Did you miss that?

I missed the part where it's done.

 

[ScribeForce3FE]

Hey k2mantra, I've got a 92 FJ80 with a stage 1 Slinky 75mm intermediate lift, Black Hawk HD extended rear LCA, Black Hawk rear adjustable UCA, Black Hawk from adjustable panhard bar, Slee castor correction plates, Delta rear 3" panhard bracket, and 35x17 tires. The Slee caster correction plates gave me 2.0 degrees which puts me at the minimum end of caster per FSM and zero toe. My truck tracks and steers great but I've also replaced a lot of stuff. The rear alignment numbers are Left Rear 0.11 degrees toe and Right Rear 0.01 degrees toe with Thrust Angle at 0.05 degrees. I'm not sure how the rear toe on my truck is off like so. Despite the Delta 3" bracket the rear end still pokes a little more on the rear passenger side and I'm thinking about adding a Slee adjustable link into the equation. Also, I found an interesting link on rear alignment on a 100 series so I don't know how much different both platforms are.

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