This has been talked about for a long time. Some say it can't be done, others say it's easy. But I can never find anything about the ones that have been done. I'm toying with the idea of doing this to my Yukon. I have a set H2s, and a van full float rear. I only want to swap so I have 4.10s, and 8 lug. The bigger brakes are a bonus too I guess. Over on the GMT400 site, there is a right up on swapping GMT800 front brakes on to GMT400s. There are many options, but OP used parts from an 04 I believe Tahoe, had 13" rotor and big twin piston calipers. One of the parts to do the swap was the knuckle. It will fit the upper/lower arms, one needed to be reamed a touch to fit the balljoint. So, in theory could use the knuckles off a 3/4 ton to get the 8 lug, tho I think the stock brakes would be fine on a lighter vehicle. Swapping the 9.25 is relatively simple, have to cut/weld a mount. I can get these parts all day long in one junkyard, cheaper than just regearing the stock 1/2 diff to 4.10s, But then need to get it to 8 lug. Again Im just thinking outloud, not 100% sure Im gonna do it.
CK5
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3/4 suspension in a 1/2 IFS
- Thread starter b454rat
- Start date
I don't know, but I should know soon.
I have all the parts from a 3/4 ton and I just got a 1/2 ton I am parting out.
I can compare and let you know.
That would help. I know the upper arm wont' bolt on. Someone moved the rearward mount on the frame so it would bolt up. The lowers are the same, only difference being stamped or cast. What I'm trying to find out, if I can use the stock upper, with the knuckle from the donor, so I don't have to cut/weld mount for the upper. Read for hours last nite bout donor parts, one mentioned using 99-00 light duty 2500. I have a lift on my Yukon, and don't want to take it off, or having to cut and fab the lift parts just to make it work. This is just to see if I CAN be done with out a shit ton of work. If it's just too much of PITA, I have 95% of the parts to SAS.
I remember researching this and reading tons of posts on various sites years ago. In short, I forget all the specific details but I was never able to find anybody who had completed the task of converting a stock 6 lug IFS over to an 8 lug IFS, either by swapping out the hubs or swapping the complete front diff assembly. There were some that had gotten pretty close but they never got all the way there (i.e. driveable vehicle), and the next step would have been a lot of custom fabrication. Believe somebody had found an 8-lug unit bearing hub that would bolt on but there was some sort of an issue with brakes, thinking along the lines of the backing plate/caliper mount not being correct for bolt on parts.
Granted, I'm sure with enough fabrication and custom parts anything can happen but that kinda' defeats the purpose of this type of swap. If it was all bolt on parts it would be a easy way to have matching 8-lug front wheels to go with a beefy rear axle, but why spends tons of time and money making a 8.25" IFS front end into an 8-lug. The other thing I will say about researching the internet for this type of swap......just because it's not on the internet doesn't mean it hasn't happened. However, if it was easy or common to do this type of conversion, and a very, very common vehicle, you most likely would see tons of write-ups and YouTube videos about it.
Granted, I'm sure with enough fabrication and custom parts anything can happen but that kinda' defeats the purpose of this type of swap. If it was all bolt on parts it would be a easy way to have matching 8-lug front wheels to go with a beefy rear axle, but why spends tons of time and money making a 8.25" IFS front end into an 8-lug. The other thing I will say about researching the internet for this type of swap......just because it's not on the internet doesn't mean it hasn't happened. However, if it was easy or common to do this type of conversion, and a very, very common vehicle, you most likely would see tons of write-ups and YouTube videos about it.
I would swap the diff to, cause it’s cheaper than buying a set of gears to install in the 8.5 diff. I took some pics of the front end trying to find out what it is, and never noticed it has wider a arms on it. Does anybody have dimension of a stock 3/4-1 ton upper a arm?
I will try and get you the dimensions.
I have everything from the 3/4 ton.
I even had the frame from the cab forward but scrapped it when I was running out of room. It might be a few days before I get to it but within a week
just saw a post of a guy that did the exact thing. So it can be done. Im trying to figure what the hell is up with my upper arms. The are wider than stock... pics/measurements would be awesome thank you..
Well did some measuring, went to junkyard n found a 3/4 ton. Same measurements. So either this is a kit or someone built the upper arm/or lift bracket.
Well if didn't get the junkyard pieces and you want to get mine, they are clean, shipping cost and something for my trouble and they are yours.
Gonna hit another hard tomorrow, haven’t been there in awhile, gotta “check inventory”. I might have to put brakes on it now, and would again if I swap the front end over, so gotta make sure have it all....
Did some more digging and found out it is a Rancho. Says it's 4", but can be turned up to 6". Not sure gonna do that, but still wanna try 3/4 ton upper arm. If lowers are the same, and a 3/4t upper will fit, don't see how it couldn't be swapped to 8 lug...
i'll still take those measurements if you have them, maybe my tape measure skills aren't what they used to be lol
So I measured the 3/4 ton pictured here and then measured my 1/2 ton... they don't match.
The outside dimension on the 1/2 ton is 11.5" vs 13.75 on the 3/4 ton.
I didn't go beyond that on the 1/2 ton
That's what I got. Seems some made it work, others say nay. Saying just because it may fit in, it will mess the geometry of the suspension. I get it, but if it don't bind and aligns, whats the problem? Say its wasted effort, either stay 6 lug or SAS it, it's too cost effective to swap. The hardest part it seems is that upper, so don't see how it can be that difficult....Thanks for the measurements....
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Think the only reason you want the upper is for the biggest ball joint, if you can get the bigger ball joint on the 1/2 ton upper you can make it work
I thought I looked up joints both upper n lower n said same. After some reading they aren’t. If I get a chance at parts store I’ll compare em....
Out of curiosity I've been doing some searching on this. Found several posts where people had successfully swapped the 8.25" for the 9.25" IFS front diff, but believe they kept the outers 6 lug. Here are few older threads that talk about this:
Talks about a complete 9.25" diff swap.
https://www.gmfullsize.com/threads/8-25-ifs-swap.284068/
Same thing, 8.25" to 9.25" swap but looking at some pictures they stayed 6 lug.
https://www.gmt400.com/threads/swap-8-5-ifs-for-9-25.38576/
On this thread, if you scroll down to I think post 43 there is a guy who claims he did it. Some details are provided but it requires some custom machining. I did not read the entire thread.
https://www.pirate4x4.com/forum/chevy/924103-gm-ifs-8-lug-conversion-2.html
Talks about a complete 9.25" diff swap.
https://www.gmfullsize.com/threads/8-25-ifs-swap.284068/
Same thing, 8.25" to 9.25" swap but looking at some pictures they stayed 6 lug.
https://www.gmt400.com/threads/swap-8-5-ifs-for-9-25.38576/
On this thread, if you scroll down to I think post 43 there is a guy who claims he did it. Some details are provided but it requires some custom machining. I did not read the entire thread.
https://www.pirate4x4.com/forum/chevy/924103-gm-ifs-8-lug-conversion-2.html
I prolly read those at some point. I’d search for hours looking for whatever I could find. Would join a forum to ask a question. But I’ve given up on it. Be easier just to do the SAS on it and do better all the way around. Also wanted to use the front axle for another project, but that ain’t happening either. Maybe at some point in the future when I have a garage to work I’ll looking into again.
