Check my work!!! Suspension.

[Knucklehead97]

Spent the whole day adjusting my front end/tightening everything up. Bilsteins are mounted, have about 4"-4 1/2" of up travel with them. Gotta bumpstop accordingly but I don't plan to be flexing it so that will come a little later. Got my Trac bar adjusted and tightened up, tires are sticking out the same amount on both sides. I got my caster set to 6* positive on both sides with my LCA's centered in the wheel wells. And finally... The toe-in. I'm running 1.25" spacers in the back to push out the rear tires some. So realistically to correctly toe in I should subtract 2.5" from the number, right? I did that and it still had the tires in a reverse-toe (angled out on both sides) not sure how else to measure it to get the right number. I've got brand new 265/75/15 Cooper AT3's sitting in my room waiting to go on. Just gotta finish up the brake bleeding and get the toe-in right. How would y'all go about doing the toe in considering my situation?

[Eagle]

2 hours ago, Knucklehead97 said:

And finally... The toe-in. I'm running 1.25" spacers in the back to push out the rear tires some. So realistically to correctly toe in I should subtract 2.5" from the number, right? I did that and it still had the tires in a reverse-toe (angled out on both sides) not sure how else to measure it to get the right number.

 

  Spacers in the rear have nothing to do with front toe-in, and you don't add or subtract anything based on the rear. You measure the distance between the centerline of the front tires at the front, and again at the rear of the front tires. If the number from the front of the tires is larger, you have toe-out; if the number at the rear of the tires is larger, you have toe-in. The theortical ideal is zero, but in the real world you should aim for about 1/16" with 1/8" being the max.

 

You do NOT want toe-out.

[DirtyComanche]

1 hour ago, Eagle said:

The theortical ideal is zero, but in the real world you should aim for about 1/16" with 1/8" being the max.

 

It depends on tire size.  And yeah, you don't want zero for anything that goes faster than about 15mph.  1/16" is a minimum, 1/8" is great.  On larger tires (37"+) 1/4" is a better number to go for, especially if you have minimal caster and can't add any; you're sacrificing some tread life for actually being able to keep it on the road.

 

He's got lots of caster...  So anywhere between 1/16" and 1/8" will be fine.

[Eagle]

47 minutes ago, DirtyComanche said:

 

It depends on tire size.  And yeah, you don't want zero for anything that goes faster than about 15mph.  1/16" is a minimum, 1/8" is great.  On larger tires (37"+) 1/4" is a better number to go for, especially if you have minimal caster and can't add any; you're sacrificing some tread life for actually being able to keep it on the road.

 

He's got lots of caster...  So anywhere between 1/16" and 1/8" will be fine.

 

Not true. We want zero toe-in -- when the vehicle is rolling down the road. We set it for slightly more because once the tires start rolling and encounter road resistance, that resistance takes up all the slop in every tie rod and joint in the steering mechanism. Way back when I was in my teens (around the time they signed the Magna Carta), the good front end shop in town used a spring loaded spreader bar that fit between the leading edges of the two front tires to force them out, simulating the real-world rolling condition. Otherwise, if we set it for zero in the driveway, on the road that built-in slop will allow the tires to splay out, and then we have toe-out -- which is what we DON'T want.

 

Yes, tire size affects toe-in, because what we're really looking for is an angular measurement. In the old days, it was just easier to express and measure it in inches. IIRC, the 1988 factory service manual for the XJ and MJ give the alignment specs in inches (fractions). The FSM for my 2000 XJ gives the specs in degrees, which are independent of tire size. But if we're doing it at home, we're not set up to measure angles so we use a tape measure. And if we're doing it with a tape measure, the larger the tires, the greater difference between the front and rear sides of the tires for the same angle. I've never rolled on anything larger than 31x10.50s and I still regard 1/8" of toe-in as the maximum I want to see. When I'm doing a shade tree alignment, each time I make an adjustment to the toe I roll the vehicle back a car length, then roll it forward again. This allows the tires to "sqirm" into the new alignment, so my measurement isn't fighting sidewall tension created by making an adjustment while the tread contact patch is firmly planted on Terra firma.

[Knucklehead97]

5 hours ago, Eagle said:

 

  Spacers in the rear have nothing to do with front toe-in, and you don't add or subtract anything based on the rear. You measure the distance between the centerline of the front tires at the front, and again at the rear of the front tires. If the number from the front of the tires is larger, you have toe-out; if the number at the rear of the tires is larger, you have toe-in. The theortical ideal is zero, but in the real world you should aim for about 1/16" with 1/8" being the max.

 

You do NOT want toe-out.

That's where I was confused. The tutorial I read just said REAR tires. Not rear of FRONT tires. So I was measuring the rear tires thinking I needed it to be 1/16"-1/8" toe-in in comparison to the rear tires. That makes a lot more sense and should turn out much better than before!

[Knucklehead97]

Got it all fixed thanks to y'all. After over a year off the road, she is finally drivable. Just took her 65 down the road with NO issues. Still got small electrical and cosmetic stuff, and gotta work on my vacuum leaks, but she did fantastic driving.

[Eagle]