Leaf spring question

[MrGoodpliers]

I have a GMC 3/4 ton truck that I am considering cutting down to a shortbed and converting to 1/2 ton. It has a Dana 60. I was wondering if the brackets on the frame are the same for 1/2 ton and 3/4 ton. And the springs, could I remove some leafs?

[LockDoc]

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I'm not sure I can answer your questions but it will get you back to the top anyway. I think the leaf spring brackets are the same on all the trucks and I can see no reason you couldn't remove a leaf or two. Not being familiar with the leaf spring trucks, I'm not sure how many leafs there are or which ones you would want to take out. You would have to get a new pair of spring bolts (I think they are grade 8) and they would probably have to be shorter. I'm not sure how far down the originals are threaded so they might not tighten back up after you remove a leaf or two. Hopefully someone familiar with leaf springs will chime in here....

LockDoc

[crazy longhorn]

I am running 4 leafs in the stack in me old longhorn(its converted to 1/2 ton ,5lug). I cant say for sure on yours, but I dropped 3 or 4 leafs & the flat helper on my old truck.....the axle is flipped, spring perches moved on the frame, & added slapper bars to help with "wrap up" (wheel hop). I think your C to C will be the same 1/2 or 3/4 ton on the spring perches(longhorn was different), but a 12 bolt axle should bolt under you truckl(42.5" IIRC) CtoC on the spring pins. crazyL

[MrGoodpliers]

Thanks for the responses. Would a 73-87 rear bolt up to those 3/4 ton springs, or do I need to find a 71-72? Or will I be cutting and welding perches either way?

[MrGoodpliers]

Or could I use a 73-87 rear with the springs without moving the frame brackets?

[LockDoc]

I'm not sure about the frame brackets but I think the angle of the spring perches is different on the rear end housing on the later ones. Seems like I read that the perches were out further on the housing too. You can buy new perches, remove the ones from the later housing and weld the new ones on where they should be. You don't say what year your truck is but the later rears are also wider overall than the earlier trucks, like 3/4" on each side. I don't remember for sure when they changed to the wider one but I think it was '71 or '72. If you go with new spring perches I would have an experienced welder weld them on. If you get the axle housing too hot it will warp it and you will have trouble keeping axle bearings in it..... If I'm wrong on any of this someone please correct me.

LockDoc

[crazy longhorn]

The springs are a different lenght on the later trucks, & I dont know about the pinion angles.....but if you are talking 2wd, the later rear should slip in on the same CtoC on the pins. You will need to swap 1 of the shock mounts, as the later rear has them set 1 foward & 1 rearward. 4wd,longhorn,& 1 ton(duallie) are 40" CtoC on the pins.....the other 2wd trucks should be 42.5" CtoC........crazyL

[OldCreek]

Frame brackets can be different from 2wd to 4wd. Most 4wd brackets will have their leaf pins hanging below the frame rail... I believe this is to allow for more lift/clearance. These 4wd brackets will also have mounts to bolt to the under side of the frame rail to prevent warpage/wrap.
There can be varying amounts of 'drop' between the brackets which will alter height/lift.

But you should be able to hang your leafs onto either one.

73-87 have a wider perch/perch width. The frame brackets stick out further from the rail than 67-72.

[crazy longhorn]

Originally Posted by OldCreek

Frame brackets can be different from 2wd to 4wd. Most 4wd brackets will have their leaf pins hanging below the frame rail... I believe this is to allow for more lift/clearance. These 4wd brackets will also have mounts to bolt to the under side of the frame rail to prevent warpage/wrap.
There can be varying amounts of 'drop' between the brackets which will alter height/lift.

But you should be able to hang your leafs onto either one.

73-87 have a wider perch/perch width. The frame brackets stick out further from the rail than 67-72.

67-72 4wd,1 ton, & longhorn have the same width on spring pin spacing(40"), 73 up 1ton (dually) shares that same spacing, where the 2wd & 4wd (73 up) have a wider spacing....42.5" IIRC. That should be the same as the 2wd leaf trucks from 67-72(except the longhorn). note that the spacing is different tween 4wd & 2wd from 67-72, but 73 up have the same spacing 2wd, or 4wd.....crazyL

[MrGoodpliers]

This truck is a 70 GMC 3/4 ton. So it sounds like if I find a 71-72 1/2 ton leaf rear and springs, it should bolt right up to my brackets? And a 73-87 would require some welding on the rearend but the springs will bolt up?

[crazy longhorn]

Thats my take on it......if I missed anything, Im sure somebody will step up with more info....crazyL