Add a leaf and u-bolt help

[CTcummins24V]

After hauling some concrete manhole risers the other day with the new chevy 1500 long bed 5.3 v8, I decided to install add a leafs and new u-bolts for added pay load capacity, she was squatting pretty bad. Since I'm adding another leaf, thicker u-bolts (9/16" to 5/8"), do I need to torque the u-bolt nuts to the factory specs of 74 ft-lbs, or a higher spec? There were no directions with the add a leafs and the u-bolts I got were universal truck bolts. 

 

http://www.summitracing.com/oh/parts/tfy-81350/overview/

 

http://www.summitracing.com/oh/parts/slf-11004/overview/

[CTcummins24V]

Actually they gave directions for a 4" suspension lift with rear blocks, they said 120 ft-lbs for the u-bolt nuts. Is that 1/2 ton axle beafy enough for that?

[AH64ID]

The axle should be strong enough for what the bolt can handle, and I would suggest using the torque from the u-bolt instructions. Different bolt/nut combo's use different torques.

 

You mentioned you want to add payload capacity, but adding leaf's wont do that. The limit to payload on 1/2 ton's is the axle housing itself, not the suspension. A 1/2 ton axle is generally at it's limit with the OEM RAWR, so I would use caution exceeding that value as a failed semi-float rear axle generally means one tire walks away while driving.

 

Did you go with a full length or short AAL (can't tell in the photo)? Short AAL's can be VERY hard on the OEM springs as they don't move at the same rate and end up forcing the OEM leaves to bend in a W shape which stresses and fatigues them. Long AAL's just make a nice truck ride like crap.

 

Looks like the work truck in your sig has about a 2Klb payload, if you need to haul more than that I would talk the boss into a 2500.

 

BTDT with AAL's, and I wouldn't touch them ever again.

[JAG1]

I kept adding springs once. They just kept loosing their shape letting the truck sag. After many years and a newer truck I convinced myself for a set of airbags. Airbags are a must to help save the springs.

[CTcummins24V]

spec says 1800 lb payload capacity, I think I was just under that with that concrete. 

 

 

 

New spring is between the overload and 2 factory springs

[AH64ID]

That stiff AAL is going to be very hard on the OEM springs, and does nothing to actually help the axle carry the load.

 

Remember everything in the truck takes up payload, you, the toolbox, anything in the tool box, floor mats, nerf bars, etc...

 

I am guessing that it's a fairly common payload, or you wouldn't be putting an AAL in, so be careful when loaded. Semi-Floating axles do not like  being overloaded, and there isn't any real wiggle room on a 1/2 ton.

[CTcummins24V]

Thanks, I don't plan on overloading it past what GM says, but when there's something in the bed or a trailer behind it, I don't want that rear squatting like it did the other day. I probably had 1300-1500 lbs in it, and it was sitting level or just past it.

 

 

 

That would be like a fly in the bed of the Cummins

Edited April 25, 2015 by CTcummins24V

[CTcummins24V]

So they lifted my truck about 1-3/4" to 2". Will those top out my shocks and do I need to get new shocks for the rear? 

[CTcummins24V]

Note to self and others on this forum, 1/2 tons do not like over 1,000lbs of concrete in the bed. Plus a couple hundred pounds of tools...rear differential getting rebuilt now. 

[CSM]

That didn't take long. Hopefully it wasn't too scary. 

[CTcummins24V]

The center pin or some pin was wallowed out. The rear end has been clunking ever since I hauled those concrete risers. Didn't start till after everything was unloaded though. My ride home empty it clunked a few times, then I did add a leafs and it clunked like crazy. Made it 4 hrs out to Indiana though! Thank God for powertrain warranties!

[AH64ID]

That sounds like a u-joint issue if the angle effects it.

[CTcummins24V]

The clunk was coming from the diff housing. The mechanics drove around in the garage pulling a guy on a creeper with his hand on the housing. Truck has 67,000 miles, they said u-joints were tight. I'm guessing the damage was done and the extra lift in the back just exemplified it and driving 4 hrs just made it even worse. 

[AH64ID]

Interesting, lift shouldn't have a bearing on anything but u-joints. The internals shouldn't care about the angle, I wonder if it's just the timing.

[CTcummins24V]

Ya, I don't have an answer that explains all of this. The weight alone shouldn't have done this, the leaf spring install shouldn't have done this. It's suspect...