axle movemnt (wrap)?

[scottiebe]

picked up a 90 k5 all original, about 130k, only "mod" I can tell is some worn out 31's. so finally gathered enough cash to put some new tires on, and actually start driving this thing!! I notice when I come to a stop and then let off the brake, the azz end "drops"! I cant say I notice any noises (at least that would go with that issue). I crawled under the truck, all looks "normal" but I grabbed the rear tire and "rocked" the truck, and it seems like the axle rotates a fair amount when it hits the park pawl. so how much movement is ok, and where do I start to try and fix?
thanks in advance

 

[rampage]

Only way I know of to check for axle wrap is to follow the truck while driving/braking.
Other than that I'd check for worn spring bushings (3 per spring), worn shocks (push down on bumper and it should settle quickly) and make sure your u-bolts are very tight.

 

[pblaze725]

Welcome to CK5.

From what I understand normal axle wrap is about 2-5 degrees going upward under load.
I learned this from a driveshaft expert that was teaching me how to properly measure my driveline angles.

In my opinion if you can grab the tire with your hand and make the axle wrap then something is loose. I suggest you inspect your U bolts and make sure they aren't coming loose.

If they have been loose for a while you may have damaged the center pin or reamed out the hole it drops into on the spring perch.
Another thing that comes to mind is if the bushings are worn out in your leaf spring it could allow the axle to move like you describe.

Disclaimer: 60% of the time I'm wrong all the time.

I hope this helps. Good luck.

 

[ryoken]

Disclaimer: 60% of the time I'm wrong all the time.

.

I think this applies in general, unless your Fordum of course...


OP, my axle wrap test is to floor it, if the tires want to jump into the bed, you've got axle wrap and need to look at new springs, antiwrap setups or less hp......

 

[scottiebe]

yeah thanks for the input fellas, after more thinking, and driving around the block, although I still haven't taken a socket to the u bolts, im kinda leaning towards the bushings and or springs, as I am planning to do a small 2-3 inch lift, so I guess I will just do new spring packs and go from there! thanks again

 

[scottiebe]

I think this applies in general, unless your Fordum of course...


OP, my axle wrap test is to floor it, if the tires want to jump into the bed, you've got axle wrap and need to look at new springs, antiwrap setups or less hp......

yep! that's just what I need!! LOL

 

[ryoken]

I suggest ton's of searches in the forum and reading.. we've answered EVERY possible question eleventy times about these rigs. the answers are out there...

oh, and welcome to our madness...

 

[scottiebe]

thanks ryoken, I did search, but after a fair amount of reading, and not knowing exactly what to search, I gave up and said screw it!

 

[ryoken]

just start new threads and ask anything... we have enough guys here to answer just about anything you can think of..

 

[Fordum]

When you let off the brakes, do you hear a loud clunk, and maybe the truck jumps a little?
If you have a spline on the rear driveshaft instead of a slip yoke in the transfer case, it may be worn.
Running many miles without much in and out movement will cause the splines to wear a step in themselves.
As you come to a stop, the splines twist slightly and the step keeps the shaft from compressing as it wants to due to normal or slightly abnormal spring wrap.

This causes the suspension to be loaded up and in a bind. When you let off the brake, the spline untwists and slips like its supposed to.
That causes everything to jump back.

Usually greasing the spline will stop it for a short time, and is often a good test. But the only fix is to replace it.

 

[scottiebe]

When you let off the brakes, do you hear a loud clunk, and maybe the truck jumps a little?
If you have a spline on the rear driveshaft instead of a slip yoke in the transfer case, it may be worn.
Running many miles without much in and out movement will cause the splines to wear a step in themselves.
As you come to a stop, the splines twist slightly and the step keeps the shaft from compressing as it wants to due to normal or slightly abnormal spring wrap.

This causes the suspension to be loaded up and in a bind. When you let off the brake, the spline untwists and slips like its supposed to.
That causes everything to jump back.

Usually greasing the spline will stop it for a short time, and is often a good test. But the only fix is to replace it.

huh!! I get what you are saying, I will have to look into this. thanks!!

 

[6872xtc]

What i found on my old '79 short bed truck AND my '90 K5 is that the rear shocks were worn out. They both had a feeling of the rear dropping with a mild thud. Both trucks quit doing it when I replaced the shocks. The shocks had gotten low on oil and had a zone of "slack" in their travel. But make sure you check everything for problems.
Your '90 has a slip in the tail of the t-case for the rear drive shaft.

 

[rebelgregory]

When you let off the brakes, do you hear a loud clunk, and maybe the truck jumps a little?
If you have a spline on the rear driveshaft instead of a slip yoke in the transfer case, it may be worn.
Running many miles without much in and out movement will cause the splines to wear a step in themselves.
As you come to a stop, the splines twist slightly and the step keeps the shaft from compressing as it wants to due to normal or slightly abnormal spring wrap.

This causes the suspension to be loaded up and in a bind. When you let off the brake, the spline untwists and slips like its supposed to.
That causes everything to jump back.

Usually greasing the spline will stop it for a short time, and is often a good test. But the only fix is to replace it.

^X2. Mine had this exact problem. Sometimes the tension would relieve while just sitting at a red light and sometimes right when I let off the brakes. Grease does help. Sounds exactly like what you describe...except for the 'getting the axle to wrap by hand' part. That ain't right.

 

[blazinzuk]

The spline problem can happen with a slip yoke style as well.

First thing is to check all your suspension components. Simple as that.

 

[Stomis]

^X2. Mine had this exact problem. Sometimes the tension would relieve while just sitting at a red light and sometimes right when I let off the brakes. Grease does help. Sounds exactly like what you describe...except for the 'getting the axle to wrap by hand' part. That ain't right.

Lol Im no help but I couldnt help but share how much this reminds me of when I had a lockrite in the flatbed and the thing would randomly BANG and unlock 10 mins after I parked it and it cooled off. Scared the **** out of some people walking by lol. It fell off a curb once from that too. lol

 

[6872xtc]

The spline problem can happen with a slip yoke style as well.

First thing is to check all your suspension components. Simple as that.

I completely agree, I just wanted to point out that it may be simple. My '90 has 274,000 on it and doesn't have that problem after changing shocks. Whatever it is CK5 can help fix it!

 

[jekquistk5]

Welcome to Ck5! If everything is all original and its a MI truck you are defiantly going to have issues. We have a pretty big group of MI guys on here and we meet up to wheel a couple times a year.

Hope you get it figured out!

 

[Blue85]

I notice when I come to a stop and then let off the brake, the azz end "drops"! I cant say I notice any noises (at least that would go with that issue).

This sounds just like sticking driveshaft splines as Fordum suggested. The slip yoke could be worn or maybe the bushing in the transfer case tail. Yes, stock springs do wrap a lot, but it's typically only a problem on hard acceleration. You might notice s pulsing to the acceleration or a vibration that only comes in when you're on the gas (because the U-joint angle is changing). Then in severe cases stuff binds, breaks a yoke and either drops a driveshaft in the ditch (if you're lucky), thrashes the floor with it (if you're unlucky) or tries to pole-vault the truck (if karma owes you for voting for Obama).

EDIT: I think I missed the whole second page of posts before I responded.

 

[scottiebe]

thanks all, still haven't had a chance to get back under truck, but after driving a little bit today, and really paying attention, I think its the driveshaft sticking, but of course I will check all rear suspension components.