C30 2wd to 4wd conv,frame height, shackle problem??? - Pirate4x4.Com : 4x4 and Off-Road Forum
 
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Old 10-24-2005, 07:28 PM   #1 (permalink)
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C30 2wd to 4wd conv,frame height, shackle problem???

I am converting an 85 C30 crew cab from 2wd dually to SRW 4wd, The drive train set up is a 6.2,SM465/205, 14FF rear and D44 up front... the 44 came from a 76 suburban and was complete w/ all the front suspension. my problem lies in the C30 frame being taller in height than a regular 3/4 or 1ton as it is throwing my rear shackle mounts for the front axle off... the front suspension was slid under the truck tonite and the front core support mounts and spring hangers where set in place.. but after looking at it for a while we noticed that the leafs where sitting against the frame where the rear shackle bracket would be... and if the rear shackle was set in place then the pinion angle would be out of whack...... we have thought about shimming the axle, and have tossed the idea of lowering( or building a spacer) for the front hangers in order to correct the pinion angle.. there is no lift on this truck and I wasnt planning on putting one in.. as it will see more highway than anything aside from some forest service roads.
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Old 10-24-2005, 08:11 PM   #2 (permalink)
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I don't think the 1-ton frame gets taller until after the shackle mount... double check.
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Old 10-24-2005, 08:24 PM   #3 (permalink)
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I looked back at some picks of a mid 70s 1ton 4wd that I fixed last year and it looks as if the frame has a pronounced slant to it so to not interfere w/ the shackle movement.... Ill have to take some measurements from my frame and ponder it some more... as for the pinion angle what would be the best way to resolve this if the frame forces me to mount the bracket where it looks like it will have to be, thus tossing off the pinion angle.
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Old 10-25-2005, 05:53 AM   #4 (permalink)
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c30 gets thicker starting at axle centerline, k30 is different

what springs are you trying to use? stock negative arc?
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Old 10-25-2005, 12:15 PM   #5 (permalink)
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1 ton frames are only taller under cab and front of bed part,

rear and front ends are same as 1/2 and 3/4 ton

where axles bolt on

height anyways

but there will be minor differences from 2wd to 4x4 to deal with

IMHO its not worth allt he trouble converting a 2wd chassis to 4x4 its so much work and headache and $$$

i would buy a cheap k10 or k20 and then a dana 60 and 14 ff and save headaches

some would agree and some wont,

its all in how you see it

or how much $$ and patience and temper you have

couldnt ever catch me trying convert a 2wd over, there aint no way, i could never put up with all the hassles and cost

screw all that


and a problme with the dually vs single rear lies with the leaf hanger brackets
DRW hanger brackets are narrow and clost to frame rails, the srw ones come out alot farther away from the rails, jut like 1/2 tons and srw 3/4 tons(73up crews, and 68-72 longhorn 20's, etc)


the pinion angle issue i have no idea what has been done wrong ther,e cant tell without seeing pics hmm



but good luck
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Last edited by Fast68; 10-25-2005 at 12:24 PM.
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Old 10-25-2005, 01:55 PM   #6 (permalink)
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Quote:
Originally Posted by Fast68
... DRW hanger brackets are narrow and clost to frame rails, the srw ones come out alot farther away from the rails, jut like 1/2 tons and srw 3/4 tons(73up crews, and 68-72 longhorn 20's, etc)
Not true ... all crew cabs and 1t pickups have the same rear hangers ... 2wd and 4wd differ in the height. They are narrower than 1/2t and 3/4t pickups to compensate for the dually diff.

Update ... this is in regard to the hangers only, not the frames.
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Old 10-25-2005, 04:03 PM   #7 (permalink)
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Quote:
Originally Posted by Fast68
1 ton frames are only taller under cab and front of bed part,
I thought so too... but mj used a C30 frame in his 4x4 shortbox. I trust his findings.

I should look in my carport... I have a C30 and a K30 frame to compare
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Old 10-25-2005, 05:12 PM   #8 (permalink)
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the dually that I'm working w/ is a narrow 14FF.... this truck was originally a PA D.O.T. truck w/ a factory flat bed... thus the dually rear didnt stick out like most do... it and the dual rear wheels only came out as far as a fleet side bed, which is what is on it now. to answer MJ's ? I have the stock springs from the 76 3/4 burb, which is a 2 pack, those trucks usually sat w/ a negative arch even w/ a small block,,, I am contemplating how to trade off for a set of heavy duty 3 packs from a fella here locally, and if I can I will track down a set of 5/4 springs since Im dealing w/ a diesel. yes the 2wd to 4wd conversion is some trouble, but heck we did this more to see if it could be done, than to really do it out of desperation,,, build to date cost is $700, thats tranny/t-case change, flywheel, clutch, front axle and all hardware springs, steering etc, and rear and front wheels.
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Old 11-19-2005, 06:47 PM   #9 (permalink)
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Quote:
Originally Posted by u2slow
I thought so too... but mj used a C30 frame in his 4x4 shortbox. I trust his findings.

I should look in my carport... I have a C30 and a K30 frame to compare
so?
the c30 gets thicker between the front and rear axle centerlines doesn't it?
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Old 11-19-2005, 06:52 PM   #10 (permalink)
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Quote:
Originally Posted by Fast68
1 ton frames are only taller under cab and front of bed part,

rear and front ends are same as 1/2 and 3/4 ton

where axles bolt on

height anyways

but there will be minor differences from 2wd to 4x4 to deal with

IMHO its not worth allt he trouble converting a 2wd chassis to 4x4 its so much work and headache and $$$

i would buy a cheap k10 or k20 and then a dana 60 and 14 ff and save headaches

some would agree and some wont,

its all in how you see it

or how much $$ and patience and temper you have

couldnt ever catch me trying convert a 2wd over, there aint no way, i could never put up with all the hassles and cost

screw all that


and a problme with the dually vs single rear lies with the leaf hanger brackets
DRW hanger brackets are narrow and clost to frame rails, the srw ones come out alot farther away from the rails, jut like 1/2 tons and srw 3/4 tons(73up crews, and 68-72 longhorn 20's, etc)


the pinion angle issue i have no idea what has been done wrong ther,e cant tell without seeing pics hmm



but good luck
I guess I am on the "some will disagree" camp on most of your post.
it is a very easy swap. how many times have you done it?
most 4x4 frames are cracked in several spots where the 2wd are usually pristine.
I bought a c30 frame and every 4wdr crossmember and bracket I wanted for $300cdn to replace my shattered k10 sb frame.
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Old 11-20-2005, 03:31 PM   #11 (permalink)
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the frames are relitively the same w/ only a couple differances... the problem I ran into,(bear in mind my donor for brackets and axle was a 76 3/4 ton suburban 4wd) One problem I ran into is that the engine mounts from the 4wd frame were taller than the 2wd frame thus we had to cut the top off of them in order to place them in the correct spot. ok that took about a couple hours and 4 other trucks to referance and come up w/ the final fabrication. next the rear shackle hangers have to be placed correctly... no big deal just some minuete measureing off the body mount while keeping in mind that the C30 fram is taller than the 3/4 ton donor. ok got thourgh that one fine,.... however the frame angle at which the frame rises up to meet the engine mount area is differant than a 4wd... the 4wd has a more pronounced slant rather than a curve. as for the previous statement by a reader that all the frames are the same,,, this is not true. the thickness of the 3/4 and light 1 tons are the same, the blazer and half tons are the same... I know this because I took two K30s last year, one was a 76 the other an 85, cut the front off the 76 under the cab and grafted the 85 back into its place. the thickness played a major role in what frame to use. another thing about the frames... the frames from the seventys are the same but somewhere in the late seventys or early 80s GM moved the rise for the bed forward to just under the back of the cab.
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