Upgrading a k1500 to 2500/3500 questions?

[RBurman]

All right here goes nothing, I just bought an 88 k1500 Shortbed for $320. It's going to see daily driver duty and mud lots of mud. The guy was running 38s on this with nothing more than a 3 inch body lift. I plan on swapping between 38s for play and smaller tire for daily use. I really don't plan on keeping the body and eventually swapping to a 40s-60s chevy truck cab,clip, and bed and having a cool yet tbi injected cruiser and mudder that will run and not bog going over ruts/hard bouncing.

But my questions concerns what parts are really an upgrade using mostly stock GM parts that I can get off the shelf anywhere or guys parting out 2500/3500 series trucks(this happens a lot in my area)? I know there has to be some strength gained with going to the 8 lug axles of the 3500/1 ton series. I would prefer the truck to be 8 lug anyways.

The truck has a really good running 305 and I'm not sure on the current gear ratio yet but I'm getting around to it. I realize the work and time this will take but I believe that the clearance gained from not having a front pig trying to plow through the mud like sas trucks would be an advantage if I can make it hold together. Thanks for any help.

 

[dirtyhick42]

You're not gonna stand up to 38s in thick mud especially not if the truck has already been abused... no way around it without going to SFA.

 

[RBurman]

I refuse the SAS swap might as well just junk the truck and get a 73-91 fullsize box chevy. I believe it will hold up to 38s. It has for a while now and I really don't see why it wouldn't keep doing it. Like I said it's not rollin on 38s on the street.

 

[dirtyhick42]

Is there a certain reason you refuse to do a SAS? Pushing the axle through the mud is not a good enough reason in my book since in reality you are already dragging one and pushing the ifs front end through the mud isn't gonna be much different.

The guy telling you that it has held up on 38s and personally having it up to 38s are 2 completely different things. To some people swapping balljoints, tie rods and cv's every few months is considered regular maintenance.. with 38s especially. That 38s isn't doing the drivetrain any favors either.

 

[great white]

The issue with the big tires and mud running is going to be the CV joints.

That's your weak link.

The rear axle will swap a 14 bolt Semi or Full floating axle with little more than spinning wrenches. Good luck popping a 14 bolt full floater. I've seen it done, but it takes some serious abuse. Nothing a TBI 350 can put out....

The larger 2500/3500 front diff (9.25 vs the 8.5) will not go into a 1500 frame without modifications. You will need front diff/suspension drop brackets or some serious grinding and cutting on the bigger diff. Sometimes both. Then there's the rest of the suspension to deal with: track width, mount points, etc. The 2500 front suspension won't just bolt on either. The lower arms will go in, but the upper mount geometry and the bracket placement is different. Mixing 1500 uppers and 2500 lower won't work either. You either have to do something with custom length cv axles or cut and weld the upper A arm brackets.

You do not want to cut and weld the upper A arm brackets. Trust me, you don't.....

The big plus of the bigger from diff is you can run the bigger 2500 CV's. They're not a lot stronger than the 1500's, but stronger. As long as you keep the lifts low and the shafts fairly flat, CV axles hold up fairly decent.

The other big plus for the 9.25 front diff is you can actually buy a locker for it. Nothing available for the 8.5. locking up the front in deep mud is a must IMHO. If you are talking serious mud it is, if you're talking splashing around in puddles then don't worry about locking it. Problem is; when you lock it up, you're putting more stress on the diff. If the axles don't pop first, you might pop the 9.25. That takes serious abuse, but it can be done. Eh, the CV's usually "go on vacation" first....

There was a thread (on pirate 4x4 I think) about modifying 2500 CV axles to fit a 1500. You might want to see if you can dig that up. Word of caution: don't say you're building a GM IFS over on teh pirate board. You will get flames 6 different ways to Sunday.....

There are custom front CV axles, but they are uber bucks. As in: take your purchase price and multiply by 3....If I remember, that will buy you one axle....and guys even pop those mud running.

38's are little big for any CV axle though, no matter how you slice it. The IFS is not designed to handle it either.

Take away points:

keep the CV axles flat as possible.
Minimize turning when hammering it
Be ready to replace CV axles/parts with big wheel speed and hitting buried stumps/rocks/solid ground.

Cheers

 

[dirtyhick42]

keep the CV axles flat as possible.
Minimize turning when hammering it
Be ready to replace CV axles/parts with big wheel speed and hitting buried stumps/rocks/solid ground.

Cheers

With a body lift and 38s flat angles are never going to be possible.

 

[great white]

With a body lift and 38s flat angles are never going to be possible.

Suspension lift: no.

Body lift only: stock angles are possible.

Will require lots of cutting I would think though.

I would say if he's got 38's on a GMT400, there's more than a just body lift going on.

 

[SCOTTYINWV]

I would like to see pics of said truck with 38s

 

[RBurman]

To fit 38s with nothing more than a 3 in body lift it requires some serious cutting of the rear and rear of the front fenders. I'm pretty sure the bars are not cranked either. I don't have pics of the truck on 38s because I don't in fact own a set yet. Sold my last set of 38s 3 months before I got this truck. You really don't want to see this ugly pile anyways as its rusty and the fiberglass stepside bed is all beat. I did see this truck in action and with the super swamper tsl boggers he had on it did really well for a damn near stock truck.

As for snapping CVs and whatnot I figured on that ahead of time and will buy a few of them to keep in the toolbox. Hell my buddies still have problems snapping axles in front 10 bolts and dana44s.

Greatwhite.. sounds like I need to get the complete frontend and brackets from a larger series truck. What is the track width difference between the two?

I know I sound dumb to most but I just think there is an advantage to the ifs in mud. Call me crazy but I just want to make it work.

 

[great white]

Greatwhite.. sounds like I need to get the complete frontend and brackets from a larger series truck. What is the track width difference between the two?

You're better off finding a trashed K2500/3500 and swapping over whatever good parts you can use off your K1500 to it.

They're not "brackets", they're welded in integral/structural parts of the frame. The geometry is easy to frig up when you start cutting and hacking. You'd be better off trying to separate the front frame halves and welding them to the 1500 rear section. That would also be one heck of an abortion.

If you want 2500 components, get a 2500. Use your $320 beater as a parts bin....heck, at 320 bucks if you even get a decent running engine out of it you're already on the "win" side.

If you don't want to do any of that, I recommend you just live with the 1500 components.

Seriously, what you are suggesting is a bad idea. Financially, structurally and safety. Bad idea.