47-55.1 How to get cab level?

[Dongray]

I am trying to level my cab and it’s been kicking my butt. Everything looks good until I install the the rear mounts(shackles).

I have installed the front mounts and they are slightly thicker than spec but I figure the new rubber spacer will give and get there eventually. The rear cab shackles on the other hand are not working out. I am using the original mounts and they are in good shape with new bushings.

Prior to installing the shackles I had wood between the rear support and frame and the back panel looked nice and even from behind the cab. After installing the rear shackles the passenger side sits about a 1/4 inch higher than the drivers side . I removed all shims between the shackle and floor on the drivers side and it was still uneven. I even moved them all to the drivers side which is about 1/4 inch thick of shims and it was much closer but the cab was now off center.
I released the upper fasteners that go from the shackle to the floor, lifted the cab, re-centered it and installed the blocks again. The blocks give it the correct gap based on what’s in the factory manual. While lifting the cab I noticed that the driver side of the cab there is a lot of weight on the block where as the passenger side is relatively light and easier to lift.

I then tried to line up the holes between the shackle and floor and noticed the driver’s side shackle holes were slightly out board of the cab holes. So if the cab was raised more they should line up. On the passenger side the shackle holes are about 3/8” out board of the cab holes and in order to line them up the cab must be significantly raised on this side which in turn also seems to push the cab over to the driver’s side.
I did look closely at both shackles and they are identical except of course one is left and the other right.



Sorry for the lengthy explanation I tried to get out all the details but if anyone can tell me how to resolve this it would be greatly appreciated. I was thinking perhaps my cab is slightly twisted but nothin appears to be out of place.

Thank you!


Added a few photos of the problem.
The first is the drivers side showing the gap with a piece of wood underneath it. The second is the same piece of wood on the passenger side obviously not underneath it and the third is the shackle with a crap load of shims to get the floor high enough for the holes to line up. There is a piece of ply would in there which is the same thickness of what the gap should be then there is another 3/8" of would on top of it.

Any suggestions would be greatly appreciated.

[mongocanfly]

I hate those shackles..just a little means alot...I did away with mine and made a L shape bracket..the cab stays centered and you can shim up or down...whichever it needs

[Dongray]

Originally Posted by mongocanfly

I hate those shackles..just a little means alot...I did away with mine and made a L shape bracket..the cab stays centered and you can shim up or down...whichever it needs

Hey Mongo,
I was out again tonight and came back with nada to show for it, pain in the @$$!!
Would you be willing to share some pictures or sketches of what you came up with? Im going to try a couple more things in the next day or two but if I can't get it evened out Im gain for just about anything.

Thanks,

Eric

[mongocanfly]

heres what I did..its probably strong enough like it is, but I'm adding a gusset to it..
I used a piece of 6x6 angle 1/2" thick
on mine you could push the cab from side2side...it never would sit level before

[Zippi]

My 49 leans to the passengers side. The distance from the floor to the center wheel opening of the fenders are all pretty much at 26" but yet the cab is leaning. The PO used "L" brackets at the back of the cab and everything looks like it matches from side to side but yet the cab is leaning. I'm just going to leave mine the way it is in fear of getting the cab level then something else being thrown off. These old trucks were not put together very well and we have to do whatever to get everything to come together as best as it will. Tics me off when I look at my truck and see it leaning but a lot of people don't pay any attention to it.

[vintovka]

I like the L brackets instead of shackles. I tried shackles with extension blocks to fit my 84 k10 frame. Big mistake. I yanked them off and went to the simplest system. First i added some cross cab support. Next i raised cab by stacking synthetic decking blocks and thru frame bolting. Was going to use delrin but the decking was handy and very durable and free. Rides fine. Side sway is gone and i see no evidence of stress on the cab. BTW used delrin blocks to raise bed to correct height as well and where i got the idea to use synthetic.

[dsraven]

if you slot the holes that mount the shackles to the frame you should be able to move the bracket up a bit and suck it down tight. the little bit of upward movement of the bracket will possibly fix the issue. you could unbolt it and level the cab, then see how much the holes need to be slotted. could do the cab bracket too bu it bolts to sheet metal so less torque can be added to the bolts. haven's done an AD for a few year so don't remember what holds the cab bracket nut on the inside. if regular style nuts then torquae away, if a stamped steel nut, be careful, maybe just do the frame end.
just an idea, it's all geometry. if you bring the frame bracket closer, the cab MUST raise.