GM 10.5" 14 bolt FF rear axle with 4 link installed

[RimoniManu]

Well guys I finally finished another one of my "crazy" ideas. I've been wanting to put a bigger rear axle in my EXT for a while now and today I finished everything. I also installed a 4 link suspension system.

Here it is, along with my new H1 tires and double beadlock wheels.


I cut the small vent behind the tire cause my tires would rub on it. Does anyone know what the vent was for? I looked, reached in the hole, took pics inside but didn't see what it was for.


I need to trim this side as well but want to ask if anyone knows what's behind the small area under the bumper bracket?


Look how huge the diff cover is, the ring gear on 14 bolts is 10.5" vs my 8.6" stock.


Some things to note: Just on the inside of the lower shock mounts are the lower link ends. On top of the differential are the barely visible upper link ends. I raised my spring perches 4.5" up off the axle for a lil extra lift. I also no longer need my panhard bar to locate my axle, my 4 link does that now.


My new drive shaft came off a 1994 Suburban. I had to cut and shorten it to fit. I used a steel drive shaft because I don't have a tig welder to weld aluminum. The other 4 bars are my 4 link rods.




You can see where I welded the drive shaft. After the pic I painted to protect from rust. I also used U bolts instead of U straps.


The spring perch is made from 1/4" high carbon industrial rectangle tubing. Same stuff my rock sliders will be made of. And no the bump stop is not touching the axle. It's actually about 2-3 inches in front of the axle.


This was the hardest part of my axle swap project. Most 14 bolts you'll find use drum brakes but I wanted disc brakes. I used the backing plate and calipers from a 2004 Silverado 2500HD. These calipers are HUGE and HEAVY! The pads are almost twice as big as stock pads. The mounting bracket is made from 3/8" diamond plate steel. I wont go into too much detail but aligning this bracket before welding was very tedious and had to be precise, was a PITA but well worth it.


I raised this crossmember by 3 inches to allow sufficient room for the upper links on their up travel.


I'm not the best welder but did an ok job. The mount that my brake is mounted to is my old sway bar link bracket.


Here's looking forward to show where the 4 links mount to the frame. I removed my gas tank crossmember and welded in this heavy duty tubing in it's place so I could weld my 4 links brackets to. I also positioned the new crossmember so I can still easily remove my t case if needed.




UPDATE:

I re worked the brake lines. I did this because my stock flex lines were rubbing on the tires and also because the brake lines were the limiting factor in wheel travel. I had these custom made from a local shop, they are stainless steel braided covered in some plastic stuff so they can be DOT approved. Our stock brake lines use 1/2" x 20 fittings; out of the three places I went to to get these made none of them had 1/2" x 20 fittings, so I went with 3/8" x 24 fittings. I went to autozone and bought a 25' roll of brake tubing, rented a tube bender and flaring tool, bought the fittings from napa and with some welding and a few hours I was done.

[Mudwheelin]

Wow man, great install! Looks great. Wish I had the time to do that to mine.

[navigator]

as close are you are to the front fender, how much flex can you get before you rub? Could you not have pushed the axle back a couple inches?

[RimoniManu]

I actually have about 2-3 inches between the front of the fender and the tire. I pushed the axle back 2.5 inches from stock. I couldn't go back too far cause of my gas tank in the back. Where it sits right now there is about 2 inches between the tank the the diff cover. My 35's would rub on the front of the wheel well. With these tires the driver side doesnt rub but my passenger side does cause I haven't trimmed the area under the bumper bracket yet.

[chevycrew]

That "vent" is just to let air escape when running the hvac or closing the doors.

I have the same brake setup with e-brake, yet I used the complete disc brake 10.5" axle from a 2004 chevy 2500 non-hd.

[fishsticks]

Those aren't tractor heims are they? Also, what's the bump stop hit now? The control arm?

Watch the frame mounts, it looks like the heims may self clearance them if you flex it out.


Impressive. What's in store for the front?

[mikekey]

Very impressive work.

[bartonmd]

Cool!

Good on the steel drive shaft! They're much more durable in the rocks than aluminum.

The only wincing question I have is, what did you use to weld the links onto the top of the hog head? I hope you used a high nickle stick weld rod, and pre-heated, and post-heated? Even then, there's a reason guys usually attach their upper links to their truss. Even if everything's done right, links welded to the cast iron hog head are prone to popping off.

Mike

[navigator]

Cool!

Good on the steel drive shaft! They're much more durable in the rocks than aluminum.

The only wincing question I have is, what did you use to weld the links onto the top of the hog head? I hope you used a high nickle stick weld rod, and pre-heated, and post-heated? Even then, there's a reason guys usually attach their upper links to their truss. Even if everything's done right, links welded to the cast iron hog head are prone to popping off.

Mike

brings back memories, I bought a used 4.0 for a jeep and one of the motor mounts was broken off. I had driven like 2hrs to go get it and it was a really good deal. I didn't realize how big of a deal it was to get it welded. I knew dad could weld it. He could have welded it but he called a friend of ours that was better than he was to do it.

We ground the edges a little to get a good bead and heated both pieces up pretty hot and welded it and then covered them with a bunch of rags so it could cool slowly.

If I remember right those nickel rods are really, really pricey.

[The Roadie]

Impressive stuff. The pouch behind the passenger wheel is full of nothing. You can safely slice it off.

[Trail X]

Looks like a monster. Is your rear track width smaller than the front now?

[v7guy]

Were you able to pull the ABS reluctor rings off to mount on the new axle?

I'm a bit curious about the weld to the center section too... has the potential to be bad.

[fishsticks]

Were you able to pull the ABS reluctor rings off to mount on the new axle?

I'm a bit curious about the weld to the center section too... has the potential to be bad.

2002. ABS sensor is on the back of the xfer case.

[snowmirage]

Very interesting project. Something similar to this has crossed my mind more than once.

I would have done focused on doing some type of link suspension for the front first though but that's just me I guess.

We're all very curious how it works out for you and what your future plans are keep us informed and Nice job!

[RimoniManu]

My track width in the back has been narrower than my fronts ever since I out on 35" tires. How it is right now, it has the same width as my stock with my 2" spacers and 35's. Fishsticks I'm not exactly sure what you mean by "self clearance" but when I was building it I made sure I had plenty of room in all directions for flex. On top of the "pig head" I didn't weld the johnny joints themselves to the axle; I made brackets and welded those to the axle for the joints to bolt to. I used 7018 when welding on the cast iron.

[RimoniManu]

For my front you guys will just have to wait.....

[fishsticks]

Fishsticks I'm not exactly sure what you mean by "self clearance" but when I was building it I made sure I had plenty of room in all directions for flex.

The lower link in this picture. In addition to rotating in a vertical arc, that link is going to twist. There are no misalignment spacers in those joints that I can see and the wall of the lower mount doesn't look like it gives the link much room to move in any direction other than vertically. My worry is you may bend the mount or damage the joint.

[bartonmd]

. . . On top of the "pig head" I didn't weld the johnny joints themselves to the axle; I made brackets and welded those to the axle for the joints to bolt to. I used 7018 when welding on the cast iron.

Yeah, I can see the brackets. I know you didn't weld the joints, themselves, directly to the axle. I was referring to welding the joint tabs directly to the diff, rather than welding them onto a truss. 7018 will work, but even with proper preheat, peening, and post-heat with very slow cooling, there will likely be embrittlement of the weld, and it will separate from the bracket under stress. I gather it needs to be some type of nickle rod, and with proper preheat, peening, and post-heat when welding to cast steel. Dana differential housings apparently take welding just fine, but I gather that 14-bolts are known to be a little harder to weld to.

This is what I'm going to use when I SAS/link mine, in the future. It welds to the tubes,and bolts to the pinion retainer.

http://www.undercoverfab.com/truss-syst ... ystem.html

[Trail X]

Mike, I'm guessing the biggest issue when welding a large heat sync like the hog head is that it will force the weld to cool too quickly, resulting in martensite in the heat affected area?

Could the entire axle also be annealed to reduce the internal stresses in the weld? Not sure if that could be done with an axle though, even with an oven big enough.

[bartonmd]

Martensite is a bigger deal in cast iron (like outer knuckles) than in cast steel, like (most newer) differentials, but that's part of it. I'm not a material science guy, but the embrittlement in the weld is apparently from the base metal of the hog head melting into the weld, causing the weld to be too hard, and not join well (or flex well) with the lower carbon steel brackets. So when the brackets flex and work around, the weld doesn't flex with them, and will crack at the joint between the weld and the bracket material. Not such a big deal in a 5-link type system with a panhard, but there's a ton of extra stress on this type of system, using the hypotenuse of a triangle to control forces in the direction of the small side of the triangle.

Mike