Axle wrap

[ALLIMAX]

I have read that some of the Ford aftermarket chip makers reccomend not going over 80hp on upgrades unless suspension changes are made to prevent the rear axle from wrapping during hard acceleration. Would the duramax need similar upgrades when using the current power upgrades that are availible? I have never noticed it in my truck but was wondering.

[madmax7]

I don't think so. The truck lauches hard with the Juice, and if anything it will spin the wheels, but no axle wrap.

I don't know what the Ford guys are saying about axle wrap. I had an Excursion and my only axle wrap problem was in deep sand. Not uncommon for any leaf suspension.

[R Waller]

lift also is a factor in axle wrap, most fords 4x4's have 4" blocks in the rear, I dont believe the gm' do...

[7mmSTW]

If Ford still runs their shocks both trailing back towards the axle instead of staggered, one in front and one behind, this will cause axle wrap also.

[R Waller]

7mm,good point...

on the pre-superduty's, the shocks are both on the front, on the SD's the shocks are both on the rear of the axle...

[jawmail]

OK I feel dumb, what's axle wrap ?

[dmaxstu]

That is when your driveshaft is no longer aligned with the differential,the third member either tilts up or down and will destroy your universal joints. Stu

[Idle_Chatter]

Stu nailed it, jawmail. When the torque applied to the wheels is fed back into the rear axle assembly, the whole axle "wraps" or rotates in the opposite direction that the wheels are turning - the springs give in an "S" shape with the spring in front of the axle bowed upward and the spring in the rear bowed downward. The front of the diff moves up and the driveshaft follows, causing the front universal and spline shaft to slide out of the tranny/transfer case to make up the additional length required. Reverse happens in reverse, when the diff rotates downward, once again pulling the spine shaft out. This spline shaft sliding in and out is a possible cause of many driveline "clunks" if it binds going in either direction. This is why serious race vehicles have traction bars bolted to the bottom of the axles, either levering up against the front spring mount on heavy acceleration or actually mounted to the frame at the front spring mount in a shackle and bushing.

[dmaxstu]

And for any of you who are interested I had a situation were I was trying to tow with an older vehicle. One day my universal joints went out and I contributed it to age, but I replaced them with hardened ones.Soon afterward my hardened joints had gone the way of the first ones. It turned out that the springs had weakened over the years and were unable to keep my differential aligned when I was climbing a long grade while towing a trailer. I remedied the situation by adding another leaf to the springs.
The moral of this story is if you ever tow with an old truck or van expect axle wrap unless you beef up the springs first. Stu