71 K-10 Crabbing ?

[54blackhornet]

I moved my K-10 yesterday for the first time, it had sat unused since 2000 when I got it this summer. My wife followed behind me as I drove it to a friends shop to begin removing the cab and bed for a total rebuild. When We arrived at the shop she mentioned that the truck was crabbing sideways down the road ? I did measure the frame in a couple of places, did not see any differences in measurements ? The rear diff has been replaced at some time in the past.
Thanks

[Southcity]

Tough one to nail down but doing some frame measurements to ensure it's square is the best start, once you have verified the frame is square and not damage (or ruled it out so to speak) then you will have to check suspension measurements next. Take your time and triple measure everything to nail down though you might want to first start by having a friend/family member drive the truck while you follow in another vehicle to see if you think it is a "crabbing" issue, good luck!

[turp mcspray]

More than likely, one spring has sagged more than the other. As the springs compress, the rear end housing moves rearward. With one spring sitting lower than the other, that side of the rear end will be further back, causing the truck to "dog track".

[kwmech]

Sometimes driving behind one of these trucks is an illusion, mainly because the rear axle is narrower than the front......about 3-4'' if I remember correctly. Easy to measure rim lip to rim lip, should be within 1/4'' side to side

[Stocker]

Also check for either axle (or both) to be angled sideways slightly relative to the frame.

[swamp rat]

One more often overlooked area is the pin on the bottom of the spring pack, it may be smaller than the hole on the spring mount on the axle, if someone was in a hurry they may not make sure the axle was aligned, axle forward on one side and the other pushed back.

The best way to check is to drive thru a puddle on some concrete and look at the tire patterns on the ground where you left the puddle.

[derotoreut]

I noticed the same issue with mine this summer. My wife drove my '70 K10 home from a show and I followed in my '69 C20. It appeared that the truck was crab walking sideways. I did some measuring and confirmed that the rear axle is 3-1/2" narrower than the front. This places each rear wheel 1-1/2" further inward then the same side front. I have not checked the frame, but I'm in the middle of a spring replacement. Once I complete the Skyjacker 2-1/2" lift I'll be in a better position to confirm. Anyway… you're not alone. Good luck.

[JPBrecheisen]

I think most 4x4 vehicles do this to some degree. I have seen it before as well.

I remember the 88-99 2500s look like they dog track as well, but they also had the wider front track when compared to the rear.

If you don't have any unusual tire wear, pulls, wanders, etc. its probably fine.

If you're curious you can check the track front to rear by making a string box around the vehicle. You'll need to make sure it has good square corners at 90 degrees. Once you have it around the vehicle, you can measure the distance from the string to the wheels at each corner and see how far offset the front and rear are from each other side to side. Any good alignment shop can check this for you as well.

This article kind of explains what I'm talking about if you want to mess with it.

http://www.circletrack.com/chassiste...ring_your_car/

Jonathon

[K10 STEPSIDE]

When I first got my truck on the road I had my father follow me for the first round in case something was wrong. At first he said the same thing but after comparing from one side to the other it was going straight but the narrower axle in the rear can be deceiving if you look at it at a slight angle.

[54blackhornet]

Wanted to update you all on the crabbing issue. I bought the truck this summer for the frame alone, after removing the ft clip, cab and bed I got a good look at what I bought ? O we'll at least the frame is straight. The passenger side of the rear axel was shifted forward about 3 inches on the leaf spring ? PO had overload springs installed at some point and they did a S@ITY job of reinstalling the hardware. I also found out about the wider front axel width while trying to load it on my trailer ? Will be looking for a set of 16in narrow wheels to transport it around during the rebuild.

[61K10]

thanks for the up-date as most threads go un-finished. sounds like an easy fix.

[jasonda]

Maybe I can add something else to this. As being a collision repair speacialist with many years of frame alignment experience I see people deal with this a lot. First and foremost you need to determine that your frame is square. The correct term for this is frame diamond. You can check this by crawling underneath your truck and square measuring between your frame rails at equal points. That measurement should be equal. That is the base that evrything is mounted to including your axles by way of your leaf springs. It's like building a house. You must make sure your footers are right before you start erecting walls. If you need any more assistance on how to do this I will be more than glad to give you direction.

[special-K]

Did you have to correct the steering off center to go straight? I've had people tell me my trucks were crabbing over the years. A driver behind you only sees the driver side and the wider front axle makes it appear to crab. You need to have someone observe the passenger side to really know if it's crabbing. I've seen trucks I thought were crabbing (on multi-lane hiways) and when I looked down the other side it was the same thing.