9.25 IFS Conversion 0-3" lift

[offroadtahoe]

to convert to a 9.25 on a stock or cranked 3" lift truck

I'm sure you can use a diff drop kit and modify it,I tried it but you would have to shave the diff side fins a little bit like they do on the 8.25,and it just hangs too low since its already bigger.i didn't like this route so i went without dropping the diff,on 0-3" inch crank the diff drops kit's drop it 2"

I have a k3500 and k1500 stuffed the 8.25 in the k3500 to check the differences.
The only difference is the driver side top.everything else is the same,tried both,the lower one is the one to use and change the other,for diff cv spindle to not hit frame/ lca bolt

the bolt in passenger side a-arms stay the same for their frame,so you use the 8.25 a-arm bracket for 9.25 diff

to fit the 9.25 in the stock location.
#1 cut the drivers lower side mounting tab,you need to replicate the stock but make a bolt in version,or you wont be able to maneuver the diff in

#2 you need to grind the corner of the drivers motor mount frame,not by much can't even tell,or the top middle of the diff won't clear and you won't be able to get the rear lower driver mount bolt in.

#3 the A-arm bolt's that hold the diff need to be drilled to the next size to be wide enough to use the 9.25 bolts and will bolt up.

#4 the top driver side is going to have to be custom made,check the pics. i will be making poly offset bushings

#5 you will need allen head bolts for the passenger cv,and a little grinding again see pics in post #6

the stock cv's fit without mods,they are not easy to get in though if your cranked you'll have to jack up on the lca/ or remove the top bj


https://www.gmt400.com/threads/swap-8-5-ifs-for-9-25.38576/ has also done this but the diff drop version.driver lower mount was moved straight down im assuming 1-2" you won't have to cut the motor mount edge (see pic) and top might be bolt in,you'd have to figure out dropping the a-arm the same amount.

https://www.gmt400.com/threads/is-my-front-differential-destroyed.46121/ also has done this swap no info on it.but video posted looks like 9.25,same as mine stock location,he's using the stock lower driver mount likely swapped when there was no engine,that would be the only way to get it in otherwise

 

[offroadtahoe]

The top mount bushing,will be a custom offset poly bushing,i will see if i can get a few made if anyone else want's to do this swap

Driver's lower mount will be drilling a hole in center,completely removing the stock mount.then making a stock bracket (unless someone has oem part #) to have it bolt in. (pic for reference)




driveshaft info,if you have this driveshaft it will work without mods,take the clip that holds it off,take off the endcap now you can get move it around enough and use a pry bar to get it in,then put the cap and clip back on

 

[Supercharged111]

So custom offset bushing driver's too, trim near the motor mount, drill for bigger passenger side bolts, cut/weld to raise driver's lower mount, and you have yourself a 9.25" front diff in a half ton? I've seen some of the other conversions as well. Let us know what you find with the custom bushings, I suspect the more you buy the cheaper they get.

 

[offroadtahoe]

So custom offset bushing driver's too, trim near the motor mount, drill for bigger passenger side bolts, cut/weld to raise driver's lower mount, and you have yourself a 9.25" front diff in a half ton? I've seen some of the other conversions as well. Let us know what you find with the custom bushings, I suspect the more you buy the cheaper they get.

the bushings will be expensive,will try to source some or make my own like they do online.just updated,and added driveshaft info.

 

[offroadtahoe]

here are some pics of when i put the 8.25 in a k3500 to simulate whats different.also pics of the 9.25 cv axles cover on the you have to remove they knock right off.
trying to keep everything in detail that you need to do.

 

[offroadtahoe]

a little more work updated in main post

 

[Supercharged111]

a little more work updated in main post

Well that's weird that that hits, they're the same diameter. Or is the 9.25 that much wider of an assembly?

 

[offroadtahoe]

The 9.25 doesn't hit but the axle shaft is little bigger including the bolts,It's the 9.25 cv that contact's a little,just a smidge to remove.

once i get the top bushing made this will be all that need's to be done!!

 

[offroadtahoe]

The 9.25 doesn't hit but the axle shaft is little bigger including the bolts,It's the 9.25 cv that contact's a little,just a smidge to remove.

once i get the top bushing made this will be all that need's to be done!!

sorry the 9.25 cv axle bolt's are not larger they are the same size.

The weakest 9.25" front diff of all G.M. trucks the 88-96 The 97-08 are
better. Lots of extra reinforcement has been added to the aluminum cases and better axle heat treating
processes


The 88-96 9.25 has the least aluminum reinforcement.has a thermal actuator and the tube for it is a hair longer so you have to run a little spacer to upgrade to electric actuator

The 97+ of Gmt400's have this little aluminum reinforcement on two ends.and have upgraded mount bushing's,and they have a smaller tube so no need for spacer for the actuator

The duramax 9.25 both casing sides have alot of extra reinforcement.swap axle tube's and have a strong case? the stock axle tube is at an angle.the duramax is straight?

98-99 silverado gmt800,has the same aluminum casing as duramax,i believe with the axle tube at an angle like stock,and not straight like duramax.

 

[offroadtahoe]

Soon i will finish this install and update this thread.