rear axle alignment

[romiin]

I noticed the rear axle is off centre.can I just loosen the U-bolts on the leaf springs and slide it over, or is there a pin under the leaf spring?. I never really notice it before until I was installing some mud flaps. then realized the tire was closer to the outer fender well on the passenger side than on the drivers side. I'm afraid if I put a wider tire on it will really be noticeable.

 

[Black Dog]

I don't think you can just adjust it as easy as that. On leaf setups there's usually a perch that is welded to the axle housing which the leaf pack sits on (usually with the pin for locating it). For it to be off is probably something else wrong, could be frame or suspension damage, but very much could just be one quarter panel is pushed inward. You want to see if each back wheel is square to the front wheels. I'd mark the ground at each tire in line with the sidewall bulges top and bottom, and cross the line with the axle's dead center. Then measure from X to X diagonally both sides, so it's LF to RR, and RF to LR. Those two line should be close to exactly the same length, assuming your front caster is within spec. If it is as you say then it would be off by a few inches. Or if you made a rectangle out of the marks you should have 4 right angles.

 

[JD Larue]

Not to jack this thread but wow, BlackDog are u a mechanic? How do you know all that stuff?

 

[Thundergod]

What year is your rig? Has it been abused or in a wreck?

 

[Black Dog]

Not to jack this thread but wow, BlackDog are u a mechanic? How do you know all that stuff?

Hey thanks man. Well yeah I was a mechanic for some years when I was younger. I'm not ASE or anything, it started as my father was a Chevy mechanic in the 70s and 80s, he went on to be a Fleet Supervisor for a school district and now a Motor Carrier Specialist for the CHP. Anyway, he had me doing side jobs from age 11. At that age I was doing brake jobs, clutches, pulling trannys, change whatever parts etc. not to mention service fluids and stuff. Within a couple of years I could tune up, rebuild carbs, harder stuff. At 15 I did work as a mechanic in a family friend's shop for a while. I built a 289 for my old Mustang and basically rebuilt the whole car kinda budget street rod style. Then in my 20s I decided that I was tired of all the grease, back aches, and cut fingers. Did car audio for a while (it's way more advanced now than what I ever knew), and some other things. But I've always had a love for the machine, always will, and try to do the shade tree thing as a hobby. Hope to build some muscle cars one day. But I was always math savvy too, like with geometry here, especially where the math is physically applicable. There's a lot I don't know about todays cars, which I try to keep up on, but some things havent changed. Right now I co-own a casino related company, banking the games in card rooms. The math serves me in that I can calculate the frequency of any event, I can tell by watching if something is normal. I'm an expert in strategy and game protection in pretty much any game, yes I can count and shuffle track in Blackjack. I've found thieves hidden in hours of video tape. So anyway that's what I do now and I'm real good at it, but I wanted to emphasize that I always had a greater love for cars, and wish sometimes I never left it. That's why you see me always trying to jump in and crack a problem. Sorry I know you didn't ask for the book version, I get carried away sometimes trying to give a complete picture. Feels like my whole life just flashed before my eyes.

 

[Black Dog]

Anyway so I think either his truck has severe frame damage, or it simply needs a bit of body work on a quarter panel in that that the wheel opening has been pushed in.

 

[johnebgoode]

What year is your rig? Has it been abused or in a wreck?

Excellent question. Did he buy it new or used?

 

[romiin]

axle

the tahoe is a 1999, I bought it used, no vehicle history damage. the truck is mint. the original lady owner traded it in to toyota. there's 60,000 miles on it. the only seat that looks to be sat in is the drivers seat. and the paint is original. I put new shock in and had a good look around under neath I see no repairs?

 

[romiin]

axle

can you guys check your trucks and tell me what you come up with? I just put a straight edge across the fender well and measured the gap, between the straight edge and the tire.

 

[Black Dog]

Or try this- attach any kind of long string or rope to the ground somewhere, or even find a straight line on the ground, as long as it's straight and maybe 30 or 40 feet so you have room to drive alongside it for a while. So drive next to it pretty close to your tire until your sure that your truck is parallel to the line. Then you can measure its distance to each front and back tire. Repeat for the other side. If it is as you say then one back tire will be (+) an inch or so, and the other side will be (-) by the same amount. If the truck is not parallel to the line both times it won't be accurate, but also the measured distances won't cancel each other out correctly, either. But you gotta find out if you are driving a rectangle or a parallelogram!

 

[romiin]

axle

JKmotorsports suggested this:

The panhard bar runs across from the left side of the axle to the frame right above the right side of the axle. This bar prevents lateral movement of the rearend assembly. Because of the geometry of the suspension componenets, when the vehicle is lifted or lowered, the axle moves just a bit either to the right or left, depending on which way you mod the suspension. You can look for an adjustable bar to get the axle centered again or fab a new mounting bracket for the panhard bar to get the axle where you need it.

I did crank up the front about 1"

 

[Black Dog]

He's right, I didn't think about the Panhard thing, but also I thought your year had leaf springs in back, which usually provide their own lateral stability (usually no Panhard bar). If it is so equipped, I think this would only apply if it was the rear suspension that was modified, you only did the front a bit so no. Try the line thing first just to make sure though, you can even use the shadow of a wall if you want.

 

[romiin]

black dog your right!!, it has leaf springs, no panhard bar. I did some major measuring under there, (back of brake drums to frame and both sides are the same, so the axle is sitting true to the frame) no body damage either. the best I can tell by measuring the body to the frame, is the whole body is mounted on the frame more to the drivers side than the passenger side, they had to have done this at the factory.
now having said that, how hard would it be to loosen the body to frame bolts and shift the body over to where it should be? I figure it has to move to the passengers side about 1/2 of an inch. my tire to fenderwell measurement on the drivers side is out about 1", so if I move the body over 1/2" , I'll gain a 1/2" on the passenger side, and lose 1/2" on drivers side. the best I can figure. does that make any sense to you? I have a feeling moving the body over isn't as easy as it might sound, right?

 

[RPMotorsports]

Spring question.

In any multi leaf rear spring, there is what is called a "tie" bolt that holds all the leafs centered. Each leaf has a hole in the middle that the bolt lines up with the head of the bolt going into a hole or slot in the spring pad. It is not uncommon for that bolt to be broken, allowing the rear end to move where it is not supposed to be.

 

[romiin]

the leaf pack is sitting square on the perches that are welded to the axle