Torsion Bar Adjustment

[a990dna]

The suspension is definitely asymmetric. In the FSM (Thanks CDan - I'll never go back to a Haynes) [SA-64] it advises different "anchor arm bolt" depth specifications for the right and left hand sides. The spec also has an acceptable range of around 2/3 of an inch (17mm) so it should not suprise that we see so much difference from truck to truck. Looks like there can be quite a bit of torsion bar variation (Jim's "statistical variation" in spring rate) that has to be compensated for by anchor arm adjustment.

Measuring proper vehicle height is covered in the front wheel alignment procedure [SA-5] and involves measuring the difference between the height of the "spindle center" (basically the wheel center) and the lower suspension arm as measured from the center of the the front bolt. For stock the spec'ed difference should be 2.795 inches.

Now I need to go get under my truck and see why my driver's side sits 1/2 inch lower than my passenger side up front.

I realize this is an old thread, but I also noticed my new 2005 LC driver's side is 1/2 inch lower than the passenger side. I looked underneath and the passenger side T-bar anchor arm bolt is adusted slightly deeper, appearing it has more preload.

I've adjusted T-bars before on my '65 Plymouth. My question is can I even out the front driver/passenger side 1/2" on an LC without creating any problems? It appears the FSM indicates an uneven adjustment is required and I'm within spec.

Thanks,
Bob

 

[NMuzj100]

My question is can I even out the front driver/passenger side 1/2" on an LC without creating any problems? It appears the FSM indicates an uneven adjustment is required and I'm within spec.

Although the adjustment bolts may end up uneven( adjusting for T-Bar strength/, I am quite sure that the truck should appear symetrical on the exterior (i.e. tire to fender measures). I still haven't fixed mine and wonder if the shocks need replaced

 

[spressomon]

I can't imagine why Toyota would recommend more T-bar torque/lift on one side than the other...but that is the way mine was. I fixed that...for better or worse I guess...mine are now (and have been since I put the OME lift on several months ago) even left/right...seems fine to me.

 

[a990dna]

I can't imagine why Toyota would recommend more T-bar torque/lift on one side than the other...but that is the way mine was. I fixed that...for better or worse I guess...mine are now (and have been since I put the OME lift on several months ago) even left/right...seems fine to me.

I also don't understand why that would be expressed in the FSM---I'll need to buy a set for a 2005. The only thing I can figure is they experience and anticipate that each LC suspension will settle differently after assembly?... or maybe its an adjustment detail they don't spend too much time on during assembly due to the same. I'm guessing they torque the bolts down to a certain spec and then perform the alignment.

Also being ancord down for that long trip from Japan may cause uneven settling due to T-bar strength variation.

It drives arrow straight so the alignment is dead on. I have a 30mm socket so I'm going to spend the time with the preload and see what I get.

Thanks

 

[a990dna]

Although the adjustment bolts may end up uneven( adjusting for T-Bar strength/, I am quite sure that the truck should appear symetrical on the exterior (i.e. tire to fender measures). I still haven't fixed mine and wonder if the shocks need replaced

My bars are already adjusted uneven... there's currently more preload on the passenger side contributing to the 1/2" height difference. If anything the R/L anchor bolts may wind up at the same depth.

I haven't looked at everything on my LC... unless they have coilovers I don't think changing the shocks will help resolve the uneven suspension.

 

[hoser]

I doubt this is the reason but you guys might find it interesting.

I am also a sports/track car enthusiast. With track cars, we have adjustable spring perches on 4 wheels that allow for adjustable ride height. After setting up the suspension height/rake to near of what we want it. We'll take it to a suspension shop and they put the car on 4 scales, one on each corner and with weight in the drivers seat. They adjust each side so that the front Left and front Right side get near equal proportion and do the same in the rear. To get more weight on one tire, they usually increase the height on the diagonal tire. It's a tedious process and usually costs a couple hundred dollars each time.

Anyway, in the end, the car is usually NOT level at all. But handles much better. This is called "corner-balancing."

 

[a990dna]

Thanks Hoser, yes I'm familiar with that process. Uneven spring rates are typically used on the passenger side rear leafs on our Hemi cars.... mostly to compensate for torque, weight distribution and chassis dynamics.

I don't think I want to take it that far though... as soon as my girlfriend sat shotgun it would change my setup. I would need to stagger my girlfriend in the back seat... I don't think she'd understand. LOL

 

[NMuzj100]

I doubt this is the reason but you guys might find it interesting.

We'll take it to a suspension shop and they put the car on 4 scales, one on each corner and with weight in the drivers seat. They adjust each side so that the front Left and front Right side get near equal proportion and do the same in the rear. To get more weight on one tire, they usually increase the height on the diagonal tire.

This is called "corner-balancing."

Sounds cool but, Like you I doubt that that is why my drivers side is low.

The asymmetry of the suspension more likely is designed to compensate for the varying stresses caused by different average speeds in left and right hand turns. The same thing that causes wheel bearings and tires to experiance more wear on one side than another.

That makes me think that since we drive on the right-side but the truck may have been designed to drive on the left that our suspension set-up may be opposite of the ideal.

Are the suspensions of RHD and LHD trucks different? (mirrors?)

 

[NMuzj100]

Uneven spring rates are typically used on the passenger side rear leafs on our Hemi cars.... mostly to compensate for torque,

I hadn't thought about the need to compensate for front driveshaft torque in the full-time 4WD.

 

[dclee]

I've adjusted T-bars before on my '65 Plymouth. My question is can I even out the front driver/passenger side 1/2" on an LC without creating any problems? It appears the FSM indicates an uneven adjustment is required and I'm within spec.

Coincidentally I just did this last night. This is a factory bone stock 2004. I did have the slight lean toward the driver's side that others mentioned. After putting on the ARB bumper, it dropped about an inch, so I decided to raise it back up to about stock height and also try to even it out side to side.

It's actually a fairly easy process. Just jacked up one side at a time until the tire was off the ground, supported on jackstands, and then cranked the adjuster bolt (tightened - clockwise). The bolt turns fairly easily once unloaded like that. Then dropped it, bounced on it, checked height, and repeated if necessary. I got it back up fairly easily, but also went an extra two turns on the driver side adjuster bolt to try to even it up. Didn't quite get there as the rear also seems to have a bias and I didn't want the front adjustment overpowering the rear, but got close. But the unintended consequence was steering alignment. Now when driving straight, the wheel is cocked ever so slightly to one side. Not sure how else it affected alignment, so will likely have it realigned soon.

 

[a990dna]

Coincidentally I just did this last night. This is a factory bone stock 2004. I did have the slight lean toward the driver's side that others mentioned. After putting on the ARB bumper, it dropped about an inch, so I decided to raise it back up to about stock height and also try to even it out side to side.

It's actually a fairly easy process. Just jacked up one side at a time until the tire was off the ground, supported on jackstands, and then cranked the adjuster bolt (tightened - clockwise). The bolt turns fairly easily once unloaded like that. Then dropped it, bounced on it, checked height, and repeated if necessary. I got it back up fairly easily, but also went an extra two turns on the driver side adjuster bolt to try to even it up. Didn't quite get there as the rear also seems to have a bias and I didn't want the front adjustment overpowering the rear, but got close. But the unintended consequence was steering alignment. Now when driving straight, the wheel is cocked ever so slightly to one side. Not sure how else it affected alignment, so will likely have it realigned soon.

Derek, I did mine around noon today. You really only need a couple strokes on the floor jack to take the pressure off the T-bar, no need to place it on stands. It took about 5 minutes and 2.5 turns on the driver side to get close to equal preload. I think I may also take 1 turn off the passenger side. It didn't affect my steering center.... I don't why that would happen.

Yea, I agree..... need to be aware that uneven rear spring rates may also play a part in the front sag. I was told by Deaver that coils have less variation than other spring types, but its possible.

I'm going to take mine to Accurate Alignment in Orange.... they specialize in off-road race trucks and other similar performance setups.

 

[dclee]

Derek, I did mine around noon today. You really only need a couple strokes on the floor jack to take the pressure off the T-bar, no need to place it on stands. It took about 5 minutes and 2.5 turns on the driver side to get close to equal preload. I think I may also take 1 turn off the passenger side. It didn't affect my steering center.... I don't why that would happen.

I did it more for safety purposes. I actually kept it on the jack, but put two stands under the frame, both in front and behind the jack, "just in case." I wouldn't have worried so much on my 80, but the 100 is so low to the ground that I could see getting crunched by the frame or slider if it dropped while I was under there fiddling around with the adjuster (or at least having it bounce off my chest...).

Yeah not sure about the steering thing. Maybe something to do with the way the variable rack works. Don't enough about the 100 front suspension yet to say for sure.

Glad to know my truck isn't the only one with the Land Cruiser "lean."

 

[pfran42]

Sorry to revive an old thread but I thought this would be the appropriate place to post rather than starting a new thread.

Quick question. I tightened my torsion bars today because my fender to ground measurements were off by more the 3/4". I also didn't like the stink bug look. From reading other threads on the subject I gathered that 3 X 360 degree turns = about 1/2'. I was in the 33.5" range from center of front fenders to level ground. My tires are 275 70 r 16 with about 70% tread on them.

I compensated for the 3/4" pre-adjustment difference in FL and FR and ended up at 35.75" and 35.65". My rear center fenders to ground are both about 35". Do I need to loosen them up a little to get the front height back down?

Running a level along the bottom of the side windows I can see that the posture of the vehicle is slightly sloped down to the front (as it should be). I guess what I am asking is if I exceeded the (Mud members recommended) adjustment threshold for T-bars on a bone stock 02 LC. Am I going to have to worry about CV boots and shocks b/c I went from a 9 year old setting that had settled in? The front is roughly 2" higher than it was before I started.

The reason I am asking is b/c I was planing on getting an alignment tomorrow and I don't want to waste the money if I need to bring the front back down a little first.

 

[2000UZJ]

Sorry to revive an old thread but I thought this would be the appropriate place to post rather than starting a new thread.

Quick question. I tightened my torsion bars today because my fender to ground measurements were off by more the 3/4". I also didn't like the stink bug look. From reading other threads on the subject I gathered that 3 X 360 degree turns = about 1/2'. I was in the 33.5" range from center of front fenders to level ground. My tires are 275 70 r 16 with about 70% tread on them.

I compensated for the 3/4" pre-adjustment difference in FL and FR and ended up at 35.75" and 35.65". My rear center fenders to ground are both about 35". Do I need to loosen them to get the front height back down?

Running a level along the bottom of the side windows I can see that the posture of the vehicle is slightly sloped down to the front (as it should be). I guess what I am asking is if I exceeded the (Mud members recommended) adjustment threshold for T-bars on a bone stock 02 LC. Am I going to have to worry about CV boots and shocks b/c I went from a 9 year old setting that had settled in. The front is roughly 2" higher than it was before I started.

The reason I am asking is b/c I was planing on getting an alignment tomorrow and I don't want to waste the money if I need to bring the front back down a little first.

If you CV's leak, reclamp. You shocks will be fine, no added stress. Just different start position in the stroke.

 

[OregonLC]

Depends on who you ask. I'm a diff drop believer, some say not needed. With your lift I don't think it would be necessary, but that's my opinion.

If you do put the drop on later, you shouldn't have to re-align as it doesn't alter any of the hard points for the suspension mounts.

 

[re_guderian]

I wasn't in a hurry to align the front end, and ended up tweaking the torsion bars a little. Let it settle in for a week or so, and see what you think...

 

[1loudLX]

ALSO, dont measure from fender to ground. Measure from fender to center of hub(s). That takes out any variances of the tire when measuring and makes it much easier to compare to everyone elses. Kind of creates a standard in which we can all talk about the lift height.