9.25 ifs suburban swap

[Lscobra]

Hey guys first post here, hope its in the right section. I have a 94 suburban k1500, and a free 14 bolt ff axle out of a 94 3/4 ton diesel suburban. Ive read threads about the 3/4 ton swaps on our trucks. Some say the 9.25 wont fit because of the arm locations, some say that there was no difference in mounting locations between 1/2 and 3/4 ton on the suburbans so im confused. I was at the junk yard last week looking for front axles and found an obs tahoe right next to a nbs 2500 suburban and was starting to think that a nbs knuckle swap with obs control arms might work and allow the use of the 9.25 with the 3/4 ton cvs to end up with a 3/4 ton axle swap front and rear. Anyone know anything about this or know someone that has tried it? Im mainly looking to take advantage of a free axle that’s already geared lower since im about to add lift blocks in the rear.

 

[ddaxe]

never tried nbs-obs conversion .. but I have done 15-25 swap.. uca's is what needs to be modded.. the mounts need to be spread 2" also.. the 25's upper 9.25 diff bracket is a bit longer than a 15's.. which causes a bolt interference between lca and cv shaft drivers side.. nothing a cut off wheel can't fix.. it's more than doable ... just take your time.. and think it out.. you'll get there.. heres mine... now 93 step side 2500 HD 14bff 454 NV4500 6" w/ 35x12.5... was a 93 1500 350 auto

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[XJPhoenix]

I've been so curious about something like this. I used to be a die-hard Jeep lover, but the thought of wheeling a full-size chevy is awesome. A solid-axle swap is pretty intense, and part of the appeal of these big rolling sofa-beds is the sweet ride, thanks to the IFS.

When approaching these swaps, are the stock 1500 torsion bars retained?

LSCobra: Please keep us in the loop as to what you come up with, and what you do with your rig. A lot of us wrench vicariously through folks like you and DDaxe!

 

[ddaxe]

I used the bars from a donor HD 2500 that had the 454.. 9.25 diff uca's... etc ... having a donor vehicle will save you hunting for parts ... not only that.. but you can compare each the way they came from the factory...


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[Lscobra]

DDaxe: awesome info and rig. Its good to hear some real first hand info from someone thats done it, thats a nice truck. XJphoenix: thanks for the kind words i will keep you all in the loop even if progress is slow. I believe the 1500 torsion bars can be kept depending on what parts i can make work together. The goal here is to use this 14 bolt ff with 3.73 gears and open diff that a friend told me to come get out of his yard. Im doing lift blocks anyway so why not swap a free axle is how i look at it. My truck is geared 3.42 with a 285/70/17 tire so id like the 3.73. Which brings me to the front axle. Needs to be swapped with probly a junk yard 3.73 9.25 ifs. Plan for the front already was a diff drop and to get as much crank as safely possible out of an upper ball joint flip with spacers. Ive heard and read that 1500/2500 suburban front ends are the same dimensionally with respect to mounting points of upper and lower lca but nothing concrete.

 

[ddaxe]

I can't say for sure about the 'burb's configuration... I haven't seen one... but yes.. you can reuse your lca's from a 1500.. as 15 or 25.. they are all the same.. it's only the upper where you will need to mod the mounting in order to get 25's uca's to fit.. iirc.. the front mount needs to be moved ahead 2 inches...
no prob sharing my experience .. as many had told me it couldn't be done.. or why not just buy a 2500... not easy to do as the never built a short frame step side 2500....



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[Lscobra]

Definitely appreciated. Ive also wondered about the possibility of using 3/4 ton knuckles and cv shafts with the 8.25 axle if the other route doesnt work out.

 

[ddaxe]

unless you can change where the cv bolts to the diff.. it would be a tough task.. not totally impossible.. especially if you have a lathe and or a milling machine...


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[Lscobra]

When you did your swap, did you use the stock location of the rear mount for the uca and just weld up the front mount in the new location?

 

[ddaxe]

When you did your swap, did you use the stock location of the rear mount for the uca and just weld up the front mount in the new location?

not exactly.. but that is certainly one way to get there... (and most common) I actually used a 1500 RC 6" lift and spread the drop bracket .. sorta kinda.. lol.. if I were to do it again.. I would move the front bracket.. the way I did it was pretty involved..


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