Alignment spec changes w/ torsion bar adjustment
05-14-2013, 08:15 PM
#1
Alignment spec changes w/ torsion bar adjustment
I just had my project truck aligned. When I took the truck in I had the ride height set exactly where I wanted it, with the front fender height about 1.25" lower than the rear. During the alignment, the shop told me they had to slightly raise the bars to get everything within spec. Now the front is only about 1/2" lower than the rear, and I don't like how it sits. How much am I going to throw off the alignment if I turn the torsion bars back down? It would be about a 1/2-3/4" drop in the front end.
Here's where the shop measured everything after the alignment was done:
Camber: L 0.1, R 0.2
Caster: L 4.8, R 5.5
Toe: L 0.08, R 0.12
SAI: L 10.9, R 11.0
Cross camber: -0.1
Cross caster: -0.6
Cross SAI: -0.1
Total toe: 0.20
Here's where the shop measured everything after the alignment was done:
Camber: L 0.1, R 0.2
Caster: L 4.8, R 5.5
Toe: L 0.08, R 0.12
SAI: L 10.9, R 11.0
Cross camber: -0.1
Cross caster: -0.6
Cross SAI: -0.1
Total toe: 0.20
05-14-2013, 10:28 PM
#5
It'll make your camber move toward the negative. Which wouldn't really be a bad thing. I prefer a little negative camber for handling and overall responsiveness. Make sure your has the half degree split I jumped up and down about... It makes a difference.
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05-14-2013, 11:46 PM
#8
I agree with Ben, you want slightly negative camber, and less toe angle. Lower it back to where you want it, and ask them to try again. Some guys get lazy and crank the torsion bars to get alignment numbers closer. Since your truck front end is stock, not modified or wayyy de-cranked, there really is not a good reason your alignment "can't get into specs without cranking it". Unless the frame is bent.
05-15-2013, 08:12 AM
#9
Ben, can you explain some more about the 1/2 degre split in caster? Does that mean you want it within 1/2 degree of each other, or you want it over 1/2 degree? Also in your other thread you mentioned because of road crown, what does that mean?
Truck seemed like it was pulling to the right on my drive to work this morning. I'm an alignment dummy...is there anything in the numbers I posted above that would indicate a pull in one direction? There's a possibility that it was due to wind, but my gut is telling me it's the alignment...
Truck seemed like it was pulling to the right on my drive to work this morning. I'm an alignment dummy...is there anything in the numbers I posted above that would indicate a pull in one direction? There's a possibility that it was due to wind, but my gut is telling me it's the alignment...
05-15-2013, 09:37 AM
#10
Caster is basically the tilt of the front wheels front to back. I know, most people think "how the hell can it tilt? Its a fawking circle!" lol. It's the difference in the mounting points top and bottom (ball joints) Road crown is exactly what it sounds like. MOST, I won't say all, roads are built higher in the center than the edges by several inches for drainage purposes. By having a half of a degree more caster on the right side (the low side of the road) it will compensate for the crown and track straighter. It doesn't necessarily matter "what the numbers are" as long as you have that split. If its .4 or .6 that's ok depending on the roads you mostly travel, .5 is just usually a good happy medium.
Camber.. I usually shoot for -.03 to -.02 on each side. You don want it straight up and down, and IMO, you don't want them positive. The negative camber helps handling slightly like I said. As the vehicle corners, the tire rolls, and the full contact patch will be more engaged on the leading (outside) tire. Better traction. You'd probably never notice it honestly but it does make a difference as well.
As far as your toe, that seems like a bit much. I wouldn't doubt it if you saw some tread feathering after a few thousand miles. You NEED some toe. If the tires were perfectly parallel going down the road, the truck would wander all over due to the slack in steering components (even new ones) slightly toe'ing them in will "preload" the front steering system if you will. You'll never see any tire wear if it's done properly.
Your alignment numbers aren't horrible, just definitely not how I would have set them up. If everything under the truck is in good shape and no major alterations have been made, you should have no problem getting to the concept I described.
Best way to check (I know this may not be entirely possible where you are geographically) get on the longest, straightest, flattest, and most wind protected road you can find. At 60mph, the truck should drift very very slightly to the right. It's supposed to. Also, previously worn tires can affect how an alignment feels. The numbers may be spot on, but it may pull if the tires are worn on one side more than the other etc. make sure the best two are up front ideally for alignment purposes.
There's a ton more details but that's the meat and tater version of it and should give you a good idea why and how. Sucks to say but you may have to explain some of this to the tech. If they aren't wanting to listen, take it somewhere else. Moving torsion bars should be an extreme last resort to get one in spec if everything else fails. Like atomic said, what would they do if it didn't have torsion bars? Give up?
Camber.. I usually shoot for -.03 to -.02 on each side. You don want it straight up and down, and IMO, you don't want them positive. The negative camber helps handling slightly like I said. As the vehicle corners, the tire rolls, and the full contact patch will be more engaged on the leading (outside) tire. Better traction. You'd probably never notice it honestly but it does make a difference as well.
As far as your toe, that seems like a bit much. I wouldn't doubt it if you saw some tread feathering after a few thousand miles. You NEED some toe. If the tires were perfectly parallel going down the road, the truck would wander all over due to the slack in steering components (even new ones) slightly toe'ing them in will "preload" the front steering system if you will. You'll never see any tire wear if it's done properly.
Your alignment numbers aren't horrible, just definitely not how I would have set them up. If everything under the truck is in good shape and no major alterations have been made, you should have no problem getting to the concept I described.
Best way to check (I know this may not be entirely possible where you are geographically) get on the longest, straightest, flattest, and most wind protected road you can find. At 60mph, the truck should drift very very slightly to the right. It's supposed to. Also, previously worn tires can affect how an alignment feels. The numbers may be spot on, but it may pull if the tires are worn on one side more than the other etc. make sure the best two are up front ideally for alignment purposes.
There's a ton more details but that's the meat and tater version of it and should give you a good idea why and how. Sucks to say but you may have to explain some of this to the tech. If they aren't wanting to listen, take it somewhere else. Moving torsion bars should be an extreme last resort to get one in spec if everything else fails. Like atomic said, what would they do if it didn't have torsion bars? Give up?
Last edited by silver-mod-o; 05-15-2013 at 09:42 AM.