Rear axle alignment

[Logan2500]

Hey guys I have a 77 k20 that I'm just about done restoring and I noticed that when I drove it up to get painted that the rear tires don't follow the front very well. It has a suspension lift that was on it when I bought it is there any suggestions on how to get it to track better?

 

[MrMarty51]

I see a lot of these Square Body pickups that are Dog Tracking,there has to be something that is not setting right,some I follow are severly dog tracking and I do`nt know how the person driving the pickup can`t notice it.
Might be spring bushings,shackle bushings,or,possibly a bent spring center bolt or two.

 

[tanz45]

Check bushings.

Examine the angles of the shackles, are they the same/close side to side?

Are the leaf spring pack pins the right size for the pad? A 1/2 pin in a 5/8 will be off.

If there is any major weight difference from side to side, then that can cause it too. As a rear leaf goes up, the wheel moves back. As a front leaf goes up, the wheels moves back too.

Just some suggestions.

 

[HotRodPC]

Dammit !!! It happened again. I tell people all the frggin time... Don't be putting mismatched heads on your damn truck. If you do, one side is faster than the other then you end up with dog tracking problems.

So here's what you do. Whichever side is out forward, you tighten up the rear brake a little bit on that side. That should slow that side down just enough to even it out. Problem solved.
If you by chance have converted to rear disks, well then sorry buddy. Don't know what to tellya. You just might be fuct !!!

 

[Logan2500]

Yea ill take a look at the leafs and the pins when it get back from paint. And no hottie I didn't put different head on lol but good one.

 

[HotRodPC]

Yea ill take a look at the leafs and the pins when it get back from paint. And no hottie I didn't put different head on lol but good one.

hmmm, well then.... Yeah, I'd check those shackles and bushings. Is this still the OEM rear end? Noone has done a spring perch relocation or flat rate springs that might relocate the centering pin or anything dumb like that? Sometimes, you will see some guys do some ironic crap when doing lifts and spring work.

 

[MrMarty51]

Dammit !!! It happened again. I tell people all the frggin time... Don't be putting mismatched heads on your damn truck. If you do, one side is faster than the other then you end up with dog tracking problems.

So here's what you do. Whichever side is out forward, you tighten up the rear brake a little bit on that side. That should slow that side down just enough to even it out. Problem solved.
If you by chance have converted to rear disks, well then sorry buddy. Don't know what to tellya. You just might be fuct !!!

 

[GreaseDog]

It's not hard at all to track a frame out of square, might not be a bad idea to get it on a rack just to be sure if you're restoring it.

 

[HotRodPC]

It's not hard at all to track a frame out of square, might not be a bad idea to get it on a rack just to be sure if you're restoring it.

Kinda what I was thinking. Even if just to take it to a tire shop for a good 4 Wheel alignment. They should be able to tell you if something is not right, and then you can take it for there.

DO NOT fall for a Thrust Angle alignment. And many times, when you go in for a 4 wheel alignment, and something is not quite right, they'll do a Thrust Angle alignment instead, and that's exactly how you end up seeing cars that are 4 wheel adjustable, going down the highway dog tracking.

All a Thrust Angle alignment does, is ensure that all 4 wheels are point straight ahead equally. It DOES NOT ensure the rear wheels are directly behind the front wheels. So in a Thrust Angle Alignment, you may very well have all 4 wheels pointing straight ahead equally, but possibly have your rear wheels 2-6 inches off center or to the left or right of the front wheels, then you have a dog tracker.

 

[MrMarty51]

So in a Thrust Angle Alignment, you may very well have all 4 wheels pointing straight ahead equally, but possibly have your rear wheels 2-6 inches off center or to the left or right of the front wheels, then you have a dog tracker.

So,if the front weelz is off 2-6 inches would that be a 'AntiThruster"?

 

[HotRodPC]

Call it what you want, but a Thrust Angle alignment is pretty much just to make sure all 4 wheels are pointed in the same direction. It's supposed to be to align the rear axle parallel to the front wheels based off the centerline, but it doesn't ALWAYS work that way.

So if you get a 4 Wheel Alignment on a non adjustable rear axle, it should be able to tell if here is a problem.

 

[HotRodPC]

I found a decent video to esplain it a little better than my lingo could. This kid seems to know his what he's talking about.

In theory, the Thrust Angle SHOULD and is supposed to fix Dog Tracking, but.....

[yt]BLRqEU8xrWM[/yt]

 

[MrMarty51]

YUP,I unnerstood whut You was saying,I jus had to throw in some of My fugged upo humor.thats all.good video by the way.
I come into posession of a very badly wrecked Harley,FXDWG,the frame was badly bent,I mean BAAAAAADDDDDdd,it took Me a couple of months,using string lines,levels,straight edges and anything else I could get My hands on,tilt indicators too,and I did get that frame straightened.bad thing about the FXDWG is the swing arm is mounted to the engine,rubber mounts to boot,I did have to replace those,they was tore up real bad.
That Harley tracks straqight and true,no bad death wobbles,no nothing but straight down the road.
That was an experience,would I ever straighten another motorcicle frame ??? not if I could help it.
After I got a real good swtart on that project,I callled the Harley dealer,new frame,1400 bucks,I continued working on My frame for about a week or so,called back,of course this was when sscrap steel was going sky high on prices,and that same frame went from 1400 to 3600 bucks,fugg that,I finished Mine and glad I did,just for the experience of it all.
OH YEAH,nice motorcicle too by the ways.

Call it what you want, but a Thrust Angle alignment is pretty much just to make sure all 4 wheels are pointed in the same direction. It's supposed to be to align the rear axle parallel to the front wheels based off the centerline, but it doesn't ALWAYS work that way.

So if you get a 4 Wheel Alignment on a non adjustable rear axle, it should be able to tell if here is a problem.