Narrow Independant Differential Options

[spidr]

I havent had an actual wheeler in a while, so my Silverado has been doing offroad duties so I can explore.
In the last few years I've moved to a village that has passed bylaws that that allow anything with an offroad plate to be driven on the street, and the "highway" to town is actually an hour of off highway logging road, and anything that has an offroad plate is legal the length of that as well. From there, there are hundreds of miles of decommisioned logging roads up and over the mountains, along the ocean, some seriously amazing terrain and views.
A while back I started working on a new chassis design specifically with the intent to have it cut on the Tube Dragon, a good friend of mine that I work with bought one, and were finally getting ready to start cutting out some chassis.

If anyone remembers the last buggy I built myself, it was rear engine, IFS, on leaf springs all round, and it was built on a seriously low budget, I put it together for less than most of you pay for a set of tires. My budget is slightly higher this time, but Id just as rather spend the money on my cars, so I'm still building it as if I dont have a penny to spend. I want to build another like my last, that looks better, and seats 2 this time. For the little seat time I got, it blew me away how well it worked. So this time, I'm leaning towards a SD60 in the rear, flipped, because thats easier and cheaper than buying shafts to offset a rear differential, Up front I'll build knuckles again, A arms, but I'm looking at other options for the Differential. Last time I used a TTB50 diff, driveshafft slips from a tank, and TTB50 spindles and hubs, this time I'm thinking SD60 hubs, to match the rear, I'll work on some light brakes all round, but I'm interested in Narrow Differentials.
I've considered narrowing a Chevy 3500 AAM unit, I'm blanking who did it back in the day but I seem to remember it was relatively straight forward once 3" was machined off the long side?
I stumbled onto a 9.75" rear differential from an 03-05 Expedition, which might be the ticket, it looks super narrow, and is bigger than the 8.8 units that come in the Explorers that I just dont think would be big enough.
Anyone think the 8,8 IRS would hold up? Wont see bigger than 40s, rear engine LS, auto, lots of high speed rally driving, a lot of moss covered rock out here, logs, there looks to be some real good technical wheeling if i can get to it, and it will probably get jumped fairly regularly. Will the 9.75 be strong enough?
I'm not spending high dollar 9" money, Id do something stupid and butcher a 14ff and build a narrow pot before I'd do that.

Open to more options though that I might not have seen.
No the portals arent going on this one. Thats something else I'm working on, i just happened to have it modeled and couldnt find a simple SD60 on my laptop

 

[YotaAtieToo]

Anyone know anything about the 2nd generation sequoia rear diffs? They used a massive 10.5" 3rd in the tundra, so I'd think the irs diff would be pretty stout also?

Any idea what happened to the ifs buggy you built? Last I remember the new owner seemed like he wanted to change everything about it

 

[spidr]

I talked to him a few times, he was cool enough to let me have all my hydrodipped panels back since he wasnt using them anyways.
He made it into a 2 seater, and put an LS in. Tried to replace the leaves with some weird air cylinders for manual control, but I dont think they where big enough bore to keep cylinder pressures within what a pump will run. He drove it around some, but last I heard was that he broke the pump on the trans putting the engine in, and had it up for sale, It sat for a while on marketplace and I dont know if it sold, or if he pulled it, but I havent seen anything about it in a couple years now.
I hope someone got to put some seat time in it, it climbed better than anyone ever expected, it was a ton of fun for a garbage car, and I learned a lot building it, so I think this one will be even better.

 

[total newb]

40"s and ls, no the 8.8 or the gm prob wont last long.

The 9.75 would be the only off the shelf option id consider, after that id build one out of a d60 rear cause theyre cheap, easy to build out, and built on.

A 9" outer brg cup welded to the shortest possible tube and a some shafts from dutchman with a convensional cv flange(gm 3/4t for instance) .

 

[arse_sidewards]

The 9.75 would be the only off the shelf option id consider, after that id build one out of a d60 rear cause theyre cheap, easy to build out, and built on.

A 9" outer brg cup welded to the shortest possible tube and a some shafts from dutchman with a convensional cv flange(gm 3/4t for instance) .

I think this is a good ideal. You can already get the 9.75 set up for IRS out of a 2nd gen Expedition (and probably other stuff). If that's too wide maybe get a solid rear and press in aluminum round bar drops to replace the tube and then machine them out for whatever the narrowest bearing you think you can get away with is and a seal to match.

 

[spidr]

I think this is a good ideal. You can already get the 9.75 set up for IRS out of a 2nd gen Expedition (and probably other stuff). If that's too wide maybe get a solid rear and press in aluminum round bar drops to replace the tube and then machine them out for whatever the narrowest bearing you think you can get away with is and a seal to match.

Yeah I'm a fan of any time I can scavenge junkyard parts to get the job done.
The expeditions are getting old enough I can likely grab the diff, shafts and some rear bearings for pretty cheap, likely machine the CVs down to make a stub on the cheap. If there's nothing else out there really then that's what I'll start chasing

 

['84 Bronco II]

There was a guy building a 6.0L Trail Blazer for the 4600 class using the Ford 9.75 center and shafts out of an Expedition. He said the 33 spline outers went right into a GM hub and it gave him a centered diff. I'd say the 9.75 is every bit as strong as a Dana 60.

EDIT: To clarify, he was using 3/4-1 ton GM hubs, not Trail Blazer hubs.

 

[spidr]

There was a guy building a 6.0L Trail Blazer for the 4600 class using the Ford 9.75 center and shafts out of an Expedition. He said the 33 spline outers went right into a GM hub and it gave him a centered diff. I'd say the 9.75 is every bit as strong as a Dana 60.

Thanks for the link.
I think the decision is pretty easy, looks like they arent even that expensive.
Turns out someones played with them before and even modeled a chunk and shafts, isnt much else to do now but lay out some control arms.

 

['84 Bronco II]

No idea if this is helpful to you, but some more info:

Expedition driver side shaft:

Passenger side:

 

[spidr]

No idea if this is helpful to you, but some more info:

Expedition driver side shaft:


Passenger side:

That is actualy. Thank you.
I've got a cad file, but its just labeled CV axle, didnt tell me sides and I assumed they where differant since the diff is offset. I'm going to run it centered, working on A arm layout right now that fills in some blanks

 

[YotaAtieToo]

There was a guy building a 6.0L Trail Blazer for the 4600 class using the Ford 9.75 center and shafts out of an Expedition. He said the 33 spline outers went right into a GM hub and it gave him a centered diff. I'd say the 9.75 is every bit as strong as a Dana 60.

EDIT: To clarify, he was using 3/4-1 ton GM hubs, not Trail Blazer hubs.

That's pretty awesome.

Nice to not have to drop a shit ton of money on custom shafts right away, or have to cobble some shit up. I'd imagine being full-size the wms would work out well.

 

[spidr]

That's pretty awesome.

Nice to not have to drop a shit ton of money on custom shafts right away, or have to cobble some shit up. I'd imagine being full-size the wms would work out well.

I've got it modeled in CAD right now, Basing it off the shaft dimensions and models I have, If I use both short side shafts its around 66" WMS Just over 3" wider if I use both long sides, which is my plan. Travel numbers look good, If it was a rear with how i have the arms laid out I could get around 24" not having to worry about steering. It'll be more than enough for what I want out of this thing.

 

[pennsylvaniaboy]

What are the chances that the 33 spline outers are the same a dodge 33 spline outers? no idea if that would even be helpful. Just stuck out as a shared spline count part.

 

[crazybluerider]

I've got it modeled in CAD right now, Basing it off the shaft dimensions and models I have, If I use both short side shafts its around 66" WMS Just over 3" wider if I use both long sides, which is my plan. Travel numbers look good, If it was a rear with how i have the arms laid out I could get around 24" not having to worry about steering. It'll be more than enough for what I want out of this thing.

People were cycling a lot of travel on those axles and diffs at one time. These diffs were popular in the low rider truck scene for a while because they could lay out air suspension and have enough travel to get it up to ride and still have some left for ride quality once they got there.

 

[mobil1syn]

spending the money on portals really opens the options up for lighter duty differentials, just saying

 

[spidr]

spending the money on portals really opens the options up for lighter duty differentials, just saying

The next buggy is getting portals. It's even designed already, inner Cs, custom housings, all of it. This one I'm doing on the cheap, I'd rather give up travel to have a beater that i can finish quick.
I'm not giving up this one when I build the other chassis, we need 2 buggies up here so I can take the kids out when they visit.

 

[spidr]

What are the chances that the 33 spline outers are the same a dodge 33 spline outers? no idea if that would even be helpful. Just stuck out as a shared spline count part.

Someone said they're the same as the Chevy, so I'm thinking that they're pretty universal. Next time im in town I'm going to try to get my hands on a few bearings and a shaft, and see what fits. The more I play with the parts in Cad, the happier I am with it all.

People were cycling a lot of travel on those axles and diffs at one time. These diffs were popular in the low rider truck scene for a while because they could lay out air suspension and have enough travel to get it up to ride and still have some left for ride quality once they got there.

I can see why. I need to get ahold of a shaft and see what the max operating angle is. so that I can finalize the drawings.. I've already put out some feelers to get ahold of a differential, I was thinking I'd find more options with a post but It only made the decision easier.

 

[spidr]

I'll start a thread for it whenever I start cutting parts, but I think I've got a pretty good handle on the plan now. Advantage of sitting home with the wife and dogs so much is Ive had a mountain of time to invest in designing.

 

[mobil1syn]

I'll start a thread for it whenever I start cutting parts, but I think I've got a pretty good handle on the plan now. Advantage of sitting home with the wife and dogs so much is Ive had a mountain of time to invest in designing.

you will get longer life out of your pivot joints if you swap the orientations ... lower bolt horizontal to the ground, upper perpendicular

 

[spidr]

you will get longer life out of your pivot joints if you swap the orientations ... lower bolt horizontal to the ground, upper perpendicular

Thats the way I built the last one, and I cant remember why I wanted to do it differant this time. Its been a few years and I didnt keep notes
I'm messing with a few differant options right now, the rest of the chassis has been finished for a while I just need to plug all this in over the next month or two

 

[TRINDU]

Narrow you say?

Sequoia IRS diff. I believe its 9.5", but don't what parts its shares with a conventional third.

This ebay link with a bunch of pics:

2008-2021 TOYOTA SEQUOIA REAR LOWER AXLE DIFF DIFFERENTIAL CARRIER CASE 139K | eBay

Find many great new & used options and get the best deals for 2008-2021 TOYOTA SEQUOIA REAR LOWER AXLE DIFF DIFFERENTIAL CARRIER CASE 139K at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Ghetto Fab.]

Do these rear IRS options still use tripod style cv joints for the inner joints? Those always seemed like a weak link.

 

[bdkw1]

Thats the way I built the last one, and I cant remember why I wanted to do it differant this time. Its been a few years and I didnt keep notes
I'm messing with a few differant options right now, the rest of the chassis has been finished for a while I just need to plug all this in over the next month or two

It also allows you to get the bottom pivot closer to the CV too. This can help get your scrub inline without special inset wheels.

 

[Wilson]

Mosebilt was the guy narrowing and working with the GM stuff

 

[spidr]

Mosebilt was the guy narrowing and working with the GM stuff

I found it after i posted, it was my original idea, but i always hated the clamshell for serviceablility, I think with the other large options available, its a better fit since I'm starting from scratch

 

[spidr]

It also allows you to get the bottom pivot closer to the CV too. This can help get your scrub inline without special inset wheels.

I've got scrub at zero, using a 17x9 with 4.5" of backspace. My camber change is comfortable throughout the travel, and according to the computer the model only uses 0.04" of shaft plunge. I'm just messing with the upper arm angle and caster gain right now,.

 

[spidr]

Do these rear IRS options still use tripod style cv joints for the inner joints? Those always seemed like a weak link.

Yeah, it looks like it. But if I want to go aftermarket I could build a stub and buy RCV. Having production shafts available at the parts store, that where designed for the rear of an 8000lb truck makes me happy for now. I'm not planning to thrash this thing right away, as long as I can bolt something in its a cheap step in the right direction.

 

[Wilson]

Narrow you say?

Sequoia IRS diff. I believe its 9.5", but don't what parts its shares with a conventional third.

This ebay link with a bunch of pics:

2008-2021 TOYOTA SEQUOIA REAR LOWER AXLE DIFF DIFFERENTIAL CARRIER CASE 139K | eBay

Find many great new & used options and get the best deals for 2008-2021 TOYOTA SEQUOIA REAR LOWER AXLE DIFF DIFFERENTIAL CARRIER CASE 139K at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Those look great

 

[Motiracer38]

I didn't realize Spidr was over here, I love your take fabwork on the other site. The last IFS build was great to watch, even if it was a bit zany. I collected an Explorer 8.8 rear with 930s, F150 stubs, and Dodge unit bearings to use on the front of a truck build but got concerned it wasn't beefy enough. The 9.75 sounds promising and the 33 spline axles should work with 1 ton Chevy unit bearings for the 8x6.5 lug. What is the overall width between inner joints? I'm curious if I can fit it in my chassis. In fact, where did you get the CAD file? I can't seem to find it.

 

[spidr]

I didn't realize Spidr was over here, I love your take fabwork on the other site. The last IFS build was great to watch, even if it was a bit zany. I collected an Explorer 8.8 rear with 930s, F150 stubs, and Dodge unit bearings to use on the front of a truck build but got concerned it wasn't beefy enough. The 9.75 sounds promising and the 33 spline axles should work with 1 ton Chevy unit bearings for the 8x6.5 lug. What is the overall width between inner joints? I'm curious if I can fit it in my chassis. In fact, where did you get the CAD file? I can't seem to find it.

The last one I misscalculated some stuff, life kicked me pretty hard back then, and I couldnt focus. This one is much cooler, I'm far happier with it already than I ever was with the other one.
The model came from a facebook group, it was started by chris Roes, and for the life of me I cant recall his user name on here.
Offroad CNC CAD File Sharing
They had the Differential, as well as the shafts on there. Most of my models I find on Grabcad, but its lacking for a lot of what we do, or theyre just not trustworthy dimensionally. This one looks good, But I wont exactly be making mounts without having one in my hand.
According to the model, the diff is 12.64" wide overall, CVs would obviously be outside of that, and the upper joint in factory application is a plunge, honestly tonight I'm not sure what point I would pick for center of the upper joint. For my math I chose the half way point of the plunge give or take.