The Stupid Axle Questions Thread

[Erik the Awful]

Ok, thanks for the info. I was worried at first when I saw 10 bolts but I knew it wasn’t a 1/2 ton rear. Any recommendations on lube? I know it’s pre-synthetic but??

Gear oil. I don't think it's limited slip, and it's old enough that anything reasonably thick will probably work. Get some 75/90 and throw it in.

 

[Schurkey]

Whatever the service manual for that vehicle specifies.

But, yeah, generic gear lube is probably fine.

 

[DerekTheGreat]

Someone here just went through that. If it's not terrible it could be repaired. I've lost track, is this a 9.5" 14 bolt SF you've found? If so, it's very likely worth repairing. If it's an 8.5" 10 bolt, ehhhh, tough call.

Richard

Yessir, it's one of them thar magical & rare 6 lug 14 bolt SF's with the ratio I need and a G80. Brake drums, shoes and hardware look damn decent on it too. Can't even feel a wear ridge in the drums.

I called the shop that would be doing the swap and yeah, he didn't seem deterred by the axle tube rot. Says they do repair axles from time to time. Also called the place I got the axle from, they'd refund my dough. Trouble is, I also called around on the other axles that popped up during my search for one. Cheapest I found was for $650, and they don't know if that's a G80 and it could be just as rotten as the one I have and the brakes could be junk.. For what it's worth, I got the one I have for $175.

 

[someotherguy]

Yessir, it's one of them thar magical & rare 6 lug 14 bolt SF's with the ratio I need and a G80. Brake drums, shoes and hardware look damn decent on it too. Can't even feel a wear ridge in the drums.

I called the shop that would be doing the swap and yeah, he didn't seem deterred by the axle tube rot. Says they do repair axles from time to time. Also called the place I got the axle from, they'd refund my dough. Trouble is, I also called around on the other axles that popped up during my search for one. Cheapest I found was for $650, and they don't know if that's a G80 and it could be just as rotten as the one I have and the brakes could be junk.. For what it's worth, I got the one I have for $175.

Man.. as distasteful as it may seem, I'd repair it!! At that price, you have some room for repair cost. Years ago, I'd have sold that one for $300 or so depending on condition plus core (mostly just the junk axle in return so I could prop the donor truck up) - so $650 sounds like robbery to me, but it's a different market.

Richard

 

[DerekTheGreat]

Sounds like robbery to me too, but I've never gotten anywhere trying to haggle/argue with strangers so I'd end the call and contact the next outfit on the list.

Looks like I'm having this thing repaired! Perhaps I'll post back once I get the truck back.

 

[1998_K1500_Sub]

I picked up a 6-lug 9.5" rear w/11.2" drums the other day, 4x4 width. This will replace the 8.5" w/ 11.2" drums on my Suburban.

I'm looking at the brakes on the 9.5" rear... yeah, they're 11.2" diameter, but the drum is a LOT (2x?) heavier than the 11.2" drums on an 8.5", in part due to the extra iron in the drum to accommodate the OFFSET from the axle's flange to the backing plate (see picture).

The JB6 brakes use a 2-3/4" wide shoe (I measured them).

Look at that flange offset on the 9.5". It could, with a different drum, accommodate a 4" wide shoe.

Now I'm wondering: Was this same 9.5" rear used in another application, like a van, where it was given a much wider drum?

Otherwise: Why did GM stick that 9.5" axle flange so far from the backing plate, when they didn't do so on the 8.5"?

Observation: The heavy 11.2" drum used on the 9.5" rear likely has much better performance as a brake vs. it's 8.5" counterpart, not in terms of braking force but it's much greater mass can sink much more heat, as might occur on a long downhill grade or a heavier load.

Below: 9.5" axle flange, 11.2" shoes and backing plate

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Below: 9.5" drum next to 8.5" drum, both 11.2" JB6

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Below: 8.5" axle flange, 11.2" shoes and backing plate

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Below: Treasureyard 9.5" 6-lug 4x4 rear w/ 11.2" drums

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[Schurkey]

I picked up a 6-lug 9.5" rear w/11.2" drums the other day, 4x4 width. This will replace the 8.5" w/ 11.2" drums on my Suburban.

Does that 'burban have a rear sway bar? Lotsa SUVs have the rear bar, pickups don't.

So the SUV axles should have the sway-bar mounts that the pickup axles don't.

 

[1998_K1500_Sub]

Does that 'burban have a rear sway bar? Lotsa SUVs have the rear bar, pickups don't.

So the SUV axles should have the sway-bar mounts that the pickup axles don't.

I heard a rumor that only the 8.5” rears got sway bars on the utility GMT400.

The OE sway bar mounts are integral to the shock mounts. See picture of an 8.5” below.

I’ll graft the sway bar mounts from the 8.5” onto the 9.5”, after a little cutting, as it has none.

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[1998_K1500_Sub]

These guys have u-bolt kits, you just need to figure out the length of the u-bolts. If that’s not what you’re looking for, I probably have a set of saddles, you would need u-bolts.

https://www.autoandtrucksprings.com/chevy-leaf-spring-upper-and-lower-saddle-ubolt-kit-9/16-x-10-1/2-uboltsfree-shipping-bt5-218ck/

The 8.5" axle tube OD is 3.125" and the 9.5" OD is 3.375" (at least on the two that I have, pictured).

Do they require different saddles to conform to the OD?
I would expect they do, but I don't see that mentioned on autoandtrucksprings.com (see the link from @SNCTMPL).

hillbillywizard.com specifically mentions the axle OD:

GM 14 bolt U-bolt plate set

Hillbilly Wizard sells the hard-to-find parts you need to build your project vehicle!

www.hillbillywizard.com

(edit) This seems like an alternative solution, it puts the U-bolts' nuts on top, eliminating the saddle on the bottom...

3/4T or 1T (14B) U-Bolt Reverse Kit for 3-3/8" and 3-1/2" Axle Tube, 11" U-Bolts

3/4T (14B) U-Bolt Reverse Kit for 3-3/8" and 3-1/2" Axle Tube, 11" U-Bolts. Includes u-bolts and u-bolt plates for one axle.

www.offroaddesign.com

Clearance on top, between the spring and the frame, may or may not be a concern. I'm not impressed that they don't differentiate between 3.375" and 3.5" axle tubes; they spec the same U-bolts for both sizes

 

[SNCTMPL]

The 8.5" axle tube OD is 3.125" and the 9.5" OD is 3.375" (at least on the two that I have, pictured).

Do they require different saddles to conform to the OD?
I would expect they do, but I don't see that mentioned on autoandtrucksprings.com (see the link from @SNCTMPL).

hillbillywizard.com specifically mentions the axle OD:

GM 14 bolt U-bolt plate set

Hillbilly Wizard sells the hard-to-find parts you need to build your project vehicle!

www.hillbillywizard.com

(edit) This seems like an alternative solution, it puts the U-bolts' nuts on top, eliminating the saddle on the bottom...

3/4T or 1T (14B) U-Bolt Reverse Kit for 3-3/8" and 3-1/2" Axle Tube, 11" U-Bolts

3/4T (14B) U-Bolt Reverse Kit for 3-3/8" and 3-1/2" Axle Tube, 11" U-Bolts. Includes u-bolts and u-bolt plates for one axle.

www.offroaddesign.com

Clearance on top, between the spring and the frame, may or may not be a concern. I'm not impressed that they don't differentiate between 3.375" and 3.5" axle tubes; they spec the same U-bolts for both sizes

I used the Off Road Designs on my son’s truck and I really like it. I don’t think the 1/8” makes a big difference.

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