Upgrade 1/2 ton suburban to 3/4 ton

[BR@NDON]

Can anyone detail what would be involved in converting an 88' 1/2 ton 4x4 burb to 3/4 ton? Are the frames the same in ways of mounts etc.. Trying to figure out if I'm better off just getting a 3/4 ton or modifying my current rig since the suspension has had it's day and needs to be replaced.

 

[CSFJ]

As far as I know, the 1/2 and 3/4 used the same frame. At least on the pick-ups. You may only need to change the axles and springs.

 

[BR@NDON]

That makes things easier. Any idea of the brake part interchangeability?

 

[CSFJ]

I want to say that the front calipers are the same. The front axle is actually the same, the outer spindles are the difference for the 8 lug set-up. Rear drums will be whatever is on the axle you use. 14 bolt semi float (light duty), or 14 bolt full float (heavy duty)

 

[yevgenievich]

Frames are same except for thickness. 3/4 got a heavier frame. As mentioned, front axle is same, but i believe most steering components are heavier duty in 3/4 as well. Rear spring pack was larger in the 3/4 and is 56", while some 1/2 have 52" springs(not sure on a 4x4)

 

[bucket]

My '88 V10 Burb came with rear 52's.

Mine came with crappy 3.42 gears, so I didn't bother converting the front axle... I just swapped it out with an axle from a '91 3/4 ton Burb. My axle didn't come with calipers, so I reused my originals even though they are technically different (piston is like 1/8 smaller). It does have the hefty tierod, but other 3/4 ton trucks sometimes have the smaller one.

The rear is a very easy swap too. The holes are already punched in the frame to move the rear spring hangers back for the longer 56" springs (which ride better despite having more leaves-8). Everything I installed in the rear was actually from a 1-ton, with the giant brakes. The 1-ton stuff requires a little more parts swappin. I also used a conversion u-joint for a while (NAPA #447) but eventually had a shaft made with 1350 joints at both ends.

3/4 ton trucks also used a different master cylinder, but I found the 1/2 ton unit works great. It has a better pedal feel, the only downside is the smaller piston makes it more sensitive to proper rear brake adjustment.

 

[bucket]

The only big thing left is the 700r4 trans. I had mine built when it started to fail, it has lasted for around 80K though. A th400/208 or an sm465/208 will go right in it's place though, using the same shafts.

 

[BR@NDON]

Thank you for the replies guys