[SANDHEAD]

Rear Axle Slamming Up And Down

I have a 01 GMC 2500HD 4x4,4:10 gears with the locking rear diff and from day 1 every time i get some wheel spin and it locks my rear axle slams up & down repeatedly and quickly shacking the truck apart and my teeth out. After getting the run around on reasons Finlay I've been told its the locking diff locking then wheels turning same speed so it unlocks,.001 sec later 1 wheel spins faster so it re-locks,.001 sec later since wheels now turning same speed it will unlock. It does it weather i have a empty bed or our very large 4k lb. cab over camper on it, it doesn't seem to mater ether way. I was told its in the locking part from the factory design and not adjustable. We go to the sand dunes all the time and this really sucks. PLZ advise on how to adjust or fix it other then a new rear dif. And is anyone having the same thing on there trucks or heard of it. THX!

 

[dozerboy]

Its call wheel hop or axle rap has nothing to do with the locker you need traction bars. How anyone that takes their trucks off road doesn't know about this is beyond me.

 

[floriduramax1]

Its call wheel hop or axle rap has nothing to do with the locker you need traction bars. How anyone that takes their trucks off road doesn't know about this is beyond me.

Yeah.. thats why we would rather drive the ol ladys Avalanche to the beach, it dont hop (plus it keeps the sand out of my truck)..):h

 

[SANDHEAD]

Isn't axle rap when its bending the leaf springs back and forth? Because I've had 1 ton leaf springs installed to help hold our 4k lb cab over camper and even with the camper on it still slams up and down. And this is all with the gas peddle held still and never lifting whether at 1/2 or full throttle if i get wheel spin it does it,and has ever since day one when truck brand new.

 

[floriduramax1]

Isn't axle rap when its bending the leaf springs back and forth? Because I've had 1 ton leaf springs installed to help hold our 4k lb cab over camper and even with the camper on it still slams up and down. And this is all with the gas peddle held still and never lifting whether at 1/2 or full throttle if i get wheel spin it does it,and has ever since day one when truck brand new.

Two words.....traction bars

 

[SANDHEAD]

But my axle is going straight up and down and not rotating. i remember in the old days we ran traction bars on our street rods to keep the axle from rotating when you left the line hard, but they didn't do anything for up/down travel did they?

 

[jevanb]

mine did to me pulling in the driveway this weekend,(snow covered) I had to let off the gas and stop then slowely go fwd, I know what you mean it really sucks when it happens shakes your teeth out

 

[woodchuck2]

Sounds like axle rap to me also, my off road truck would do it so bad it would twist out the rear drive shaft and even broke a main leaf once. Custom traction bar cured that problem. I would go with traction bars also on my LBZ if it was a fequent problem. It wouldnt hurt to lower your air pressure either for more ground contact which should take care of some of the hopping.

 

[dozerboy]

But my axle is going straight up and down and not rotating. i remember in the old days we ran traction bars on our street rods to keep the axle from rotating when you left the line hard, but they didn't do anything for up/down travel did they?

It is axle wrap, axle wrap causes the axle to move up and down as the suspension twists and untwists.

 

[SANDHEAD]

Thx,all good advice. Just to make sure i fully understand,axle rap is when the axle it self tries to rotate forward under the truck lowering the rear u-joint then rotating back as if trying to lift the rear u-joint and then back down and so on....? Because when i had the extra heavy duty rear lief springs installed it did NOT change,help,or affect this problem at all. Even running the tire pres anywhere from 15lbs to 65lbs in the rear doesn't effect ether way it at all. I've had the stock tires, BFG A/T, BFG M/T tires on it at diff times and it didn't care ether way. It will do it on the street,dirt,sand,mud,or snow - if i get rear wheel spin the axle goes a slammen....

 

[btfarm]

Bad shocks will make it worse. New ones will help with the slamming motion, but not cure axle wrap.

 

[SANDHEAD]

Ok, I have located a couple diff types of traction bars and they seem to be diff lengths going forward from the rear axle. So my question to you all with traction bars already or knowledge of is when your out four wheeling and you come to a ridge or something 2'+ tall don't the bars hit and if so do they bend? What is the performance diff between shorter or longer traction bars. And is there a performance diff whether the front anchor point is to the leaf springs mounting bolt or to the frame up about where the cab and bed meat? Last question(for now), the shorter pair talked about able to adjust the pre-load on them. Do they all have that option and what diff does that mean/make with or with out pre-load?(ok to that was really 2 questions) THX!

 

[_MJB_]

Tuff Country makes a set of traction bars that attach above the springs instead of below if ground clearance is a problem. They sell them at JC Whitney: link. I bought a set myself but haven't installed them yet.

 

[MaddDogg49]

I know trippin use to sell the caltracs... Give guy a call at SoCal Diesel http://www.socaldiesel.com/

 

[SANDHEAD]

Thx. Only now I'm left with a new question; as far as the performance what is the diff between 'traction bars' & 'ladder bars'?