Why you WILL get uneven tire wear with a torsion bar crank
#1
Why you WILL get uneven tire wear with a torsion bar crank
[originally posted in reply to another topic, but it deserves it's own, since t-bars are such a hot topic in general]
I've found that there is no way you DON'T get uneven tire wear from the torsion bar crank. You may not notice it at first, but you will when the tires get more worn.
Know why? We have the "SLA" (short-long-arm) suspension that has a shorter upper arm than the lower arm. As your suspension cycles DOWN, this causes the camber to go negative (bottom of wheel sticking out more than the top). This eventually wears your tires down.
It's takes a cam kit to correct it and most shops charge extra for that. When you get a wheel alignment the only thing they adjust is the toe-in, typically.
So spindles, for example, will allow you to keep your full suspension travel, with near zero camber at rest. An ideal situation if what you want is 3" of lift with the factory ride.
That having been said, I'll be keeping mine cranked WITH the spindles on it and adding cams to get back as close to zero camber as I can.
A torsion bar crank will give you negative camber (no matter what anyone says -- it's impossible for it NOT to) that will cause uneven wear. Only a cam kit for the upper arms will fix that.
I know this because I've been riding with a torsion crank for 30,000 miles plus now, and the wear is very visible on the tire.
Bottom line: no matter what you hear, alignment, by the physics of our suspension, HAS to be affected by the torsion crank. If you want to fix it, put a full cam kit on both sides and adjust the upper arm position. Just the kit is about $40 wholesale, and more in most retail places when you can get it.
That having been said, I'll be keeping mine cranked WITH the spindles on it (when I get them) and adding cams to get back as close to zero camber as I can.
I've found that there is no way you DON'T get uneven tire wear from the torsion bar crank. You may not notice it at first, but you will when the tires get more worn.
Know why? We have the "SLA" (short-long-arm) suspension that has a shorter upper arm than the lower arm. As your suspension cycles DOWN, this causes the camber to go negative (bottom of wheel sticking out more than the top). This eventually wears your tires down.
It's takes a cam kit to correct it and most shops charge extra for that. When you get a wheel alignment the only thing they adjust is the toe-in, typically.
So spindles, for example, will allow you to keep your full suspension travel, with near zero camber at rest. An ideal situation if what you want is 3" of lift with the factory ride.
That having been said, I'll be keeping mine cranked WITH the spindles on it and adding cams to get back as close to zero camber as I can.
A torsion bar crank will give you negative camber (no matter what anyone says -- it's impossible for it NOT to) that will cause uneven wear. Only a cam kit for the upper arms will fix that.
I know this because I've been riding with a torsion crank for 30,000 miles plus now, and the wear is very visible on the tire.
Bottom line: no matter what you hear, alignment, by the physics of our suspension, HAS to be affected by the torsion crank. If you want to fix it, put a full cam kit on both sides and adjust the upper arm position. Just the kit is about $40 wholesale, and more in most retail places when you can get it.
That having been said, I'll be keeping mine cranked WITH the spindles on it (when I get them) and adding cams to get back as close to zero camber as I can.
#3
Yeah, that's about my feeling also. Hey, most of it can be corrected.
The saving grace here is if you do it small, the effect is small. But if you go to 2" or more, it's really severe. Mine is VERY visible just looking at the front of the truck. You can see the tire wear now at 30K, but if you take the tire off and place it perpendicular to the ground, you can really see the "angle" of wear on the tread because it gaps to one side.
The saving grace here is if you do it small, the effect is small. But if you go to 2" or more, it's really severe. Mine is VERY visible just looking at the front of the truck. You can see the tire wear now at 30K, but if you take the tire off and place it perpendicular to the ground, you can really see the "angle" of wear on the tread because it gaps to one side.
#4
#9
Specialty Products sells a nice kit. I have to get it from a local wholesaler or online -- most retail auto parts stores don't sell them over the counter, believe it or not. At least, not out here. I think it's a "racket", lol.
The full kit for all 4 pivot points (2 on each side) lists for well over $50 in most places anyway, so it's not cheap!
And yes the camber kit is the "key" to not having tire wear.
The full kit for all 4 pivot points (2 on each side) lists for well over $50 in most places anyway, so it's not cheap!
And yes the camber kit is the "key" to not having tire wear.
#10
#11
I'm not a big fan of cranked torsion bars myself but I understand why people do it. Just for grins, I tried a 2" crank on mine and I thought the deterioration in ride quality was just not worth it. A crank of 1" is not nearly so bad.
Production SLAs go to negative camber at both extremes of travel, jounce and rebound. At static factory ride height, they generally have neutral or slightly positive camber. Whether your SLA will be in spec after a torsion bar adjustment depends on two things:
1) Where the alignment was within the adjustment range initially; and
2) How far you crank them.
I believe that some trucks will still be in spec after a 1" crank but that none will be in spec after a 2+" crank. Installing a camber kit on a jacked up SLA suspension can bring the static camber adjustment back and improve tire life. It will also make for very weird geometry as the suspension cycles. The alignment will go very positive in midstroke and then return close to neutral when bottomed. This is not the hot ticket for street use.
Still, if you crank your torsion bars a bunch, you don't have much choice - unless you choose to live with the tire wear caused by the camber change.
Production SLAs go to negative camber at both extremes of travel, jounce and rebound. At static factory ride height, they generally have neutral or slightly positive camber. Whether your SLA will be in spec after a torsion bar adjustment depends on two things:
1) Where the alignment was within the adjustment range initially; and
2) How far you crank them.
I believe that some trucks will still be in spec after a 1" crank but that none will be in spec after a 2+" crank. Installing a camber kit on a jacked up SLA suspension can bring the static camber adjustment back and improve tire life. It will also make for very weird geometry as the suspension cycles. The alignment will go very positive in midstroke and then return close to neutral when bottomed. This is not the hot ticket for street use.
Still, if you crank your torsion bars a bunch, you don't have much choice - unless you choose to live with the tire wear caused by the camber change.
#12
Originally Posted by rwenzing
Still, if you crank your torsion bars a bunch, you don't have much choice - unless you choose to live with the tire wear caused by the camber change.
i am fine... 45k out of bfg mud terrains already is outstanding, and they have been on since the day of the tbar crank...
#13
#15
Originally Posted by rwenzing
Because you had the camber kits installed.
I can't make up my mind if you're arguing with the point or not, Christian? It WILL wear your tires if you don't adjust the camber -- which you did. So what are you saying exactly? Are you confirming the worth of the camber adjustment or what? It seems like you're disagreeing but it's hard to tell because you're not saying much, lol!
#17
What did they do when the "aligned" it is the question. Also, how many miles on the thornbirds?
That's been my point all along. I'll say it again for those who aren't getting it. No one is saying you can't crank them and get even wear IF YOU DO THE ALIGNMENT. Only if YOU DON'T DO THE ALIGNMENT will you have issues.
If you want your tires to wear evenly after a torsion bar crank, with our SLA suspension, you must get a FULL alignment paying attention to camber.
There you go.
This post was meant to settle, once and for all, the alignment question on getting a torsion bar crank. It does, but some of the posts here are sure clouding the issue.
That's been my point all along. I'll say it again for those who aren't getting it. No one is saying you can't crank them and get even wear IF YOU DO THE ALIGNMENT. Only if YOU DON'T DO THE ALIGNMENT will you have issues.
If you want your tires to wear evenly after a torsion bar crank, with our SLA suspension, you must get a FULL alignment paying attention to camber.
There you go.
This post was meant to settle, once and for all, the alignment question on getting a torsion bar crank. It does, but some of the posts here are sure clouding the issue.
#20
Originally Posted by Johawk
I cranked the t-bars on my truck on the alignment rack at work. The camber is right on where it should be. -.5 degrees. And I just about maxed out the torsion bars.
What was it BEFORE you cranked it? You cannot tell me it didn't change because that's not possible unless you were right on the other side of center the same amount and went from -5, through zero to -5 again after the crank. Not likely for most people. You got lucky.
The geometry doesn't lie. Your experience doesn't prove an alignment isn't needed for everyone else: one data point does not make a trend.
#21
#22
Yes, that's the problem, Christian. Too many of you read the titles and then POST without actually reading the text. I see it all the time. Very frustrating. My first post makes it clear if one were to actually read it thoughtfully.
Well, you guys have fun. I can't believe you all either don't read or don't get it. The geometry makes it obvious -- but apparently some of you just want to argue for something you can't prove, and flies in the face of the science. I won't waste my time any further.
Well, you guys have fun. I can't believe you all either don't read or don't get it. The geometry makes it obvious -- but apparently some of you just want to argue for something you can't prove, and flies in the face of the science. I won't waste my time any further.
#25
Originally Posted by n3elz
Yes, that's the problem, Christian. Too many of you read the titles and then POST without actually reading the text. I see it all the time. Very frustrating. My first post makes it clear if one were to actually read it thoughtfully.
and my reply was actually, looking back, to rwenzing:
Still, if you crank your torsion bars a bunch, you don't have much choice - unless you choose to live with the tire wear caused by the camber change.
i just adjusted my above posts to make more sense... i just added in the "quote" so you could see what i was replying to...
you crazy old man...