Swap K3500 Front on K1500 Suburban?

[GoreMaker]

I've got a 99 K1500 Suburban in pretty decent shape that I recently acquired. In my back yard, I've got a rotting 98 K2500 pickup with F-code 6.5TD (so it came from the factory with a K3500 full-float 8-lug setup). I'd love to convert the Suburban to 8-lug with my pickup's components. Do the front control arms and spindles bolt in? Are there any changes required with the torsion bars? Does steering linkage need to change? Or are none of the components interchangeable?

 

[b454rat]

Be easier to find an 8 lug frame, swap ur motor/trans/t-case over. I guess it can be done, but if Im gonna go thru all that BS, I'd SAS if want 8 lug....

 

[boy&hisdogs]

From everything I've read, it's not (reasonably) possible. It's more work than just going SAS.

 

[Schurkey]

The upper control arms are not going to interchange without frame modification. The 8-lug upper arms are wider. And you can about give up the idea of using the 9.25 front differential. There's a thread about swapping a 9.25 where an 8.25 was, but it's a LOT of work. So the pickup rear axle better be the same ratio as the suburban.

www.gmt400.com/threads/k1500-8-25-to-9-25-swap.56989/

K1500 8.25 to 9.25 swap

Hey all! So as far as i know i only seen a couple of threads (like one or two) about completing a 9.25 front diff swap. Well i just completed my swap and its equipped with front ARB lockers. i will try to answer as many questions as i can since there isnt to many threads about this. okay if...

www.gmt400.com

IF the ball joint tapers are similar--and I think they are, but don't have confirmation--then I'd think this is a fairly easy swap up front. "I" would leave the torsion bars alone; I don't think the TurboDiesel torsion bars are suitable.

Lower arms are optional. Most folks seem to prefer the forged arms over the stamped-steel, or stamped-steel with forged ends. I'm not sure it makes an actual difference.

What would matter are the steering knuckles/hubs; brake rotors/calipers, and the master cylinder/booster.

Measure the spring pads and overall width of the rear axle to assure it's gonna fit. I'd expect the driveshaft will have to be shortened, and a bigger U-joint yoke welded-on. Maybe it's easier to start with the pickup shaft as a core. I don't know. I'd use the Suburban leaf springs so you don't screw-up the balance front/rear.

What are you gaining? Better brakes all around; heavier wheels and tires. The Highway Patrol won't care about the bigger axle and brakes as far as towing- or load-limits.

 

[HotWheelsBurban]

Burb rear leaf springs are different length than pickup ones IIRC....

 

[GoreMaker]

Burb rear leaf springs are different length than pickup ones IIRC....

That's not a concern, leaf spring pads can be cut and re-welded easily.

I'm not going solid axle with this vehicle, it's not for off-roading or lifting or big tires. If anything, I might drop it a couple inches. I'm planning to use it as my family winter road vehicle, preferably with an NP149 transfer case behind the 4L80E that's currently in my K2500. I have no intention of swapping out the front diff for a 9.25", it'll only ever be used to compensate for rear slip in winter conditions. I mostly just want the 14-bolt FF because it's sitting in my back yard, it's in excellent shape, it's reliable, it has bigger brakes, and it has 3.73 gears in it (and I'd switch the front gears to 3.73 to match). From what I've seen, switching a 14-bolt FF to 6-lug is a pain and requires disc brakes, and switching the front to 8-lug with adapters requires adding 2" thick adapters Those are crappy options.

Is the lever length of K1500 and K3500 control arms the same? If it is, could I use a K1500 upper control arm with a K3500 upper ball joint, and the K3500 lower control arm and steering knuckle? Seems like both the K1500 and K3500 use the same 33 spline interface for the CV joint, and even the same 55-tooth ABS reluctor ring, which implies I could plug K1500 CV axles into K3500 hubs. The axle nut looks to be the same, too. Then I could even use K3500 brakes, which I like much better than these wimpy K1500 brakes.

 

[stutaeng]

14 bolt 6 lug rear swap is difficult? Not from the same generation of trucks. The 2500 6 lug 9.5" SF axle is what you want. It's a direct swap. It has drum brakes.

But if you have the 8 lug version in 10.5", I see you wanting to run that one.

 

[GoreMaker]

14 bolt 6 lug rear swap is difficult? Not from the same generation of trucks. The 2500 6 lug 9.5" SF axle is what you want. It's a direct swap. It has drum brakes.

But if you have the 8 lug version in 10.5", I see you wanting to run that one.

I have a 14-bolt already that I want to use. It's a FF, and it's 8-lug. You're correct, I don't want to buy another rear end.

I just checked and K1500 uppers are 13" long compared to 13.75" for K3500 uppers. I haven't been able to confirm what the lower control arm lengths are for each, but if it's a similar difference (3/4"), that means I'd be running uppers that are 3/4" shorter than intended. That actually sounds like a GOOD thing, because it would add a moderate amount of camber gain in turns that would be beneficial for handling, especially if I lower the suspension a couple inches.

 

[boy&hisdogs]

14 bolt 6 lug rear swap is difficult? Not from the same generation of trucks. The 2500 6 lug 9.5" SF axle is what you want. It's a direct swap. It has drum brakes.

But if you have the 8 lug version in 10.5", I see you wanting to run that one.

This is the way to go IMO. I went back and forth on it for years, spent countless hours digging through a decade of forum posts all over the internet, hours in the junkyards searching and figuring. In the end I just did the 14bSF swap. There's no good way to change the front to 8 lug or the FF to six lug without spending a whole bunch of time and money and trouble.

 

[GoreMaker]

In retrospect, this is probably the wrong category for this thread, since I'm neither planning to lift the vehicle nor drive it offroad, but I couldn't find an appropriate category in the Street section