K1500 to 2500 axles/upgrade

[thz71]

If your gonna go through all that work you mise well SAS anyway

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[great white]

I've tried it before.

2500 is a 9.25 front differential and is physically different front a 1500 8.5 front differential.

You either have to cut and grind on the center section and/or install a suspension lift with drop brackets.

The upper A arm mounts are in a different position. You can't just cut them off an move them. Well, you can but you're likely to mess it up more than get it right.

The lower control arms swap over.

Cv axles are different.

Knuckles are different.

Rear stuff bolt in.

If I were to do this, I would find a scrapped 2500 and buy it for the frame.

Then swap the body over from the 1500 to the 2500.

Or, better yet: sell the 1500 and buy a 2500/3500.

Finally: a solid axle conversion.

 

[K15 Blazer]

yeah, cause the SS was a k1500 truck... same thing as a 1970 chevelle SS
you could get a Malibu with a straight 6, or a big block 454 SS... its the same vehicle build differently. that's what used to make chevy successful... options & quality stuck on good frames.

but yeah... I see your point... gotta find a nice K2500 or 3500 burb and frakenstine the frame down to fit my blazer's body... gawd, that's gonna be fun x)

-oh... blazer with a 454.... *Homer Simpson drooooooool*

 

[great white]

yeah, cause the SS was a k1500 truck... same thing as a 1970 chevelle SS
you could get a Malibu with a straight 6, or a big block 454 SS... its the same vehicle build differently. that's what used to make chevy successful... options & quality stuck on good frames.

but yeah... I see your point... gotta find a nice K2500 or 3500 burb and frakenstine the frame down to fit my blazer's body... gawd, that's gonna be fun x)

-oh... blazer with a 454.... *Homer Simpson drooooooool*

If using a blazer, I'm willing to be a 2500 Suburban would be an easier fit....little harder to find though.

454SS was a C1500.

 

[TylerZ281500]

the ss was a c1500 truck, frames on anything 3/4-1 ton is thicker material for the most part. when you get into the 9.25 front diffs like everyone has said youll end up with different mounts.

whats the bigger front diffs gonna do for you and whats your purpose for doing so? you can put a 454 in upgrade your rear and call it a day. a 14 bolt sf or ff swap it easy enough, pretty cut and dry. if your gonna lift it and want one ton or 3/4 ton stuff then a solid axle swap would be your best bet. yea a 9.25 is theoretically cool but its no cooler than any said IFS, if you want something to hold up, lift decently and you can sacrifice a bit of ride quality then solid axle it.

454 in a blazer has been done many times, 454 in anything for that matter, but in stock form there not really anything all that competitive to drool over.

 

[eric.s.t]

Well, actually they made the "454ss" in a "sport edidition truck... 305 or 350 available. Might be that, that he's talking about

 

[great white]

The reality of all this is that you weak link in the front end is the CV axles, not the differential.

The axles are a bit bigger on the 2500, but the CV joints themselves aren't a whole lot bigger and that's what tends to pop with lots of rolling inertia and power. Duramax trucks putting down 1000 hp in sled pulls run a 9.25, so they are plenty strong for most people. But big meats, big HP, deep mud and hitting a root/rock/log when hammer down shock loads things horribly and that's when you get the big "kapow!" Cranking the steering while all this is going on only makes "the walk home" far more likely. Same thing can be done on pavement with big tires, turned wheels and a heavy foot. But even then, it's the CV's that usually go first.

The advantage the 9.25 has over the 8.5 is you can actually buy a locker for the 9.25. There is nothing available for the 8.5 so you're stuck running open diff.

An 8.5 IFS can handle 35's. Not the smartest thing, but it can. It's the CV axles that are the problem and even then it's all in how you intend to use the truck.

Mall crawler?

Chuck your suspension or body lift on there and go impress the chickies (or at least think you are).

Sink it in the mud and start cranking that steering wheel?

Have a recovery method and a spare CV axle at the ready.

Even a D44 would most likely give you less problems....and would likely be easier/more reliable than Frankensteining a 1500/2500/3500 hybrid.

It's no secret I'm not a big solid axle conversion fan. They have their place, just not on my rigs anymore. Just doesn't fit my use anymore.

But if I were planning to run big meats, with big HP and deep mud I would probably pull the IFS off and go solid axle. I'd also probably be building a dedicated buggy of some sort if I were planing serious mudding or crawling, not a full body truck.

 

[TylerZ281500]

The reality of all this is that you weak link in the front end is the CV axles, not the differential.

The axles are a bit bigger on the 2500, but the CV joints themselves aren't a whole lot bigger and that's what tends to pop with lots of rolling inertia and power. Duramax trucks putting down 1000 hp in sled pulls run a 9.25, so they are plenty strong for most people. But big meats, big HP, deep mud and hitting a root/rock/log when hammer down shock loads things horribly and that's when you get the big "kapow!" Cranking the steering while all this is going on only makes "the walk home" far more likely. Same thing can be done on pavement with big tires, turned wheels and a heavy foot. But even then, it's the CV's that usually go first.


The advantage the 9.25 has over the 8.5 is you can actually buy a locker for the 9.25. There is nothing available for the 8.5 so you're stuck running open diff.

i thought lockers were available for the 8.25? im about to check my sales rep at work tomorrow out of curiosity now. they do have those rcx ultimate cvs though, or you can go to a driveline shop and have some custom u joint ones made, thats what im working on since i work at one.

 

[great white]

crap.

Mixed it up again, my oldtimers is getting to me.

It's a GM IFS 9.25 and GM IFS 8.25

I swear, it gets harder every year......

A locker in an 8.25 (even if you could find someone that makes one) raises other issues. The main one is case deflection. See, the problem is the pinion gear acting on the ring gear and what happens when one of the two spinning tires catches a "stopper". All that shock load goes right into the aluminum case since the torque can't go to an open side of the diff. This is what will grenade the aluminum case as opposed to the big cast iron one you have in the rear.

There was once a strong rumor of a E-locker from Eaton for the 8.25, but that was stillborn and never came to be. Probably grenaded enough of them that they decided it wasn't worth the bad publicity.....

RCV axles are also not the all in one solution. People have popped them too. Sometime with no more than normal abuse. Dropping a grand for a couple isn't exactly fun either. You're not getting into any serious strength until you get into custom builds with something like the Porche 930 CV joints and 300M shafts that big power sand rails run. Even then, not really suitable for sinking in the mud....wrong application.

There is an ARB Air Locker, Eaton E-Locker and a Lock-Right Locker for the 9.25. This is because the 9.25 has more strength and is deemed at least capable of handing a locked up front end. Mainly because of the physically bigger case and gear.

But it's still not invincible.

I would say even the+ light D44 could take more abuse in crawling or mudding.

 

[K15 Blazer]

I cracked my rear carrier in half dumping the clutch for a burnout once lol
so pissed I did that