3/4 ton axles

[HotRodPC]

Making Comparisons on O'Reilly's and Rock Auto, all I see is K10 rotors being 11.86 inches on both sites, and K20 rotors being 12.5 inches on both sites. I didn't see any other options for rotors for either K10 or K20 on either site. The Discard thickness was the same on both though.

Now I was with the understanding that the K10 and K20 spindles were the same too. But... Seems the K10 rotor is actually longer in overal height. I'm assuming by height they mean if the rotor was laying flat on a table. K10 is 7.06 inches overall height, the K20 is 6.72 inches in overall height. So wouldn't this mean the K10 spindle would be longer too?
But then being a 4x4, it doesn't really ride on a spindle anyway does it? Stub shaft isn't it? Are those the same for K10 and K20?

Damn I wish had both to make comparions. But this is exactly why I'd just rather get a complete front K20 axle. Then I know I have the correct ****.

 

[HotRodPC]

Yes, the lighter duty front axle K20 is the EXACTLY same as a standard K10 axle. The only difference being two (2) additional studs on the rotor. The backing plates, calipers, pads, backing plate, disk dia, bearings, seals etc is EXACTLY the same and interchangeable.

There are some higher GVWR rated K20's out there which have a larger dia rotor, which are really cool if you need some heavy duty binders. Hence their pads, backing plate and I believe the caliper is different to fit the larger dia rotor. With that said, the balance of the heavy duty K20 axle assembly is EXACTLY the same as the light duty K10 front axle.

I'm sorry but this is just plain wrong. The 8-lug bolt pattern alone requires a larger diameter rotor. Beyond that, the 8-lug hub has a wider track built into it, requiring different backing plates even IF the rotors were the same diameter.

Nothing like a good debate on GMSB. In this case, it appears bucket is the winner winner chicken dinner according to me comparing rotor sizes on O'Reilly's and Rock Auto. Doesn't that mean jetman owes bucket a chicken dinner?

Dammit, and I so wishing Jetman was right. Maybe he is so we'll give him the chance to find me the 8 lug rotors that are the size of my 6 lug rotors so I can use the same backing plate. I've heard in the past, it's knuckles out that have to be swapped at the ball joints. So maybe that's true. If that's true, then I not only need backing plates and rotors, but I need the whole knuckle assembly. Why can't I just find a damn K20 or even a K30 front axle for cheap? **** !!!

 

[Rusty Nail]

Ya. Loads of great info in this here thread.
How bout them apples OP?

 

[HotRodPC]

Ya. Loads of great info in this here thread.
How bout them apples OP?

Yep, that's how we learn though and get this **** figured out and get to the bottom of it all once in for all. That's why we're so damn good. We dig in deep and get it figured out. If I EVER get a K20 axle, I'll be posting up side by side measurements and side by side pics. Then we'll know 100% what it takes to convert 6 lug K10 to 8 lug K20 without replacing the whole axle. Remember, the axle I'm using is a K10 6 lug axle with 4.10's and an ARB Air Locker. So I'd really rather use the axle I have and convert it to K20 8 lug brakes and hubs.

 

[bucket]

I tell you what, we need a "sticky" of this with definitive info.

Starting in '77, the spindles and bearings are the same between K10-K20. The pads are the same. The calipers while often having different piston sizes, will interchange because they are the same external dimensions. Starting in '79 or '80, the banjo bolts went to metric. The hubs, rotors, backing plates/caliper mounts are different between K10 and K20.

The '73-'76 hubs, bearings and spindles are different between K10 and K20. I do not know which bearings and spindles in those years may or may not interchange with the '77-later stuff. Maybe none of it besides an inner or outer bearing.

The knuckles on '73-'75 trucks are different due to tierod placement and the flat top surface of the passenger side knuckle. When replacing in pairs, they will swap onto any later D44 or 10 bolt axle.

 

[HotRodPC]

Starting in '77, the spindles and bearings are the same between K10-K20. The pads are the same. The calipers while often having different piston sizes, will interchange because they are the same external dimensions. Starting in '79 or '80, the banjo bolts went to metric. The hubs, rotors, backing plates/caliper mounts are different between K10 and K20.

OK, you lost me here. Starting in 77, spindles and bearings are the same between K10 and K20... But starting in 79 or 80...banjo bolts... THE HUBS, ROTORS, BACKING PLATES/CALIPER mounts are different between K10 and K20.

So if the spindles and bearings are the same, but they mount different..?

OK, so bottom line. On my 85 front 6 lug axle, or my 87 front axle in this case that has the 4.10's and ARB Air Locker, what do I have to change to go 8 lug K20? Just the backing plates, hubs and rotors ONLY? Spindle, Stub Shafts, knuckles, ball joints and all that will be the same right?
So if I was to buy new rotors with the hubs as 1 unit, then I just need to find backing plates? I'd just hate to buy all that, then find out it won't work and will have wished I just waited and bought a whole front axle like I thought I was going to buy today.

 

[bucket]

I just was mentioning the banjo bolts because of the required brake hoses. If you have a setup from say, a '78 and you want to use it on your '85, you will need the hoses to match the calipers with the SAE banjo bolt.

So HRPC, if you finally can locate the parts for your swap and it's from a '77 or newer... you will need the hub, rotor, and caliper mount (AKA "backing plate) for your 8-lug swap.

If you get parts from a '73-'76, you will need to also use the spindles and matching bearings. Those earlier hubs will also require the external style lockouts and likely the matching stub axles too.

 

[bucket]

If you notice, the '77 and later K10 hubs/lockouts stick through the wheel more than a K20 does. This is simply because the K20's wheel mounting surface is moved outwards on the hub. The overall width of the axle (lockout to lockout) is the same, which is how the spindles and bearing placement is the same between the two.

 

[HotRodPC]

Yes, I did notice that on the K20. It's as if they have a captive rotor and maybe the K10 does not.

No, I'll be keeping this as simple as possible. I prefer to just get parts off of another 10 bolt and I'm hoping not to late model so I don't have to worry about the 28 and 30 spline issue. I've got 3 bolt fronts now and will probably keep the 2 spares for parts just cuz they're 10 bolts and I do expect to break a few parts. I can see selling a complete 10 bolt hub to hub for $100, then when I break an axle have to pay over $100 or a new one. Someday when I get rich and can afford a Dana 60 vehicle, then I'll sell the spare 10 bolt axles.

So, I can buy new rotors with hubs at the auto parts store. So if I can find K20 backing plates from any 10 bolt front axle, which is going to be 77 and later, then I'm good to go right? Those shouldn't be to expensive to have shipped if I can find someone with some used ones. I can't seem to find anyone that sells new ones. Backing plates won't matter on the spline count of the axles, so any K20 10 bolt backing plate should be good.

 

[bucket]

All styles have the rotors pinned to the hubs with the wheel studs. Aren't new rotor/hub combos expensive? I haven't priced them myself. I don't remember what I last paid for K20 Rotors.

I "think" you can use the '73-'76 caliper mounts, as they should be the same as the later stuff. Rotors are the same. It's just the hub/bearing/spindle
/lockout stuff that's different from the later years.

 

[HotRodPC]

Rotor and Hub at O'Reilly's is $73.99, and rotor only is $39.99. At RockAuto, rotor and hub combo for AC Delco Brand is $134.99 and rotor only is $24 for AC Delco Brand. See, rotor and hub combo even at $74+ tax, I'd be better off finding a complete K20 axle for $100-$150, then I'd have the backing plates too. Of course that's used rotors and used hubs that may or may not be any good. Backing plates aren't wear items, so if I found those then bought new aftermarket rotors and hubs with 2yr warranty then I'd at least know they're good to go for 2 years.

 

[jetman]

How about the burban 3/4 axles? Wonder what they use..

 

[Honky Kong jr]

How about the burban 3/4 axles? Wonder what they use..

Same as the trucks until 89 then they got 30 spline axles as did the Blazers. 89 was a half year for them hit or miss. I have a 91 burban front axle in my V10 with a 30 spline 8.6 Eaton carrier.

 

[bucket]

Rotor and Hub at O'Reilly's is $73.99, and rotor only is $39.99. At RockAuto, rotor and hub combo for AC Delco Brand is $134.99 and rotor only is $24 for AC Delco Brand. See, rotor and hub combo even at $74+ tax, I'd be better off finding a complete K20 axle for $100-$150, then I'd have the backing plates too. Of course that's used rotors and used hubs that may or may not be any good. Backing plates aren't wear items, so if I found those then bought new aftermarket rotors and hubs with 2yr warranty then I'd at least know they're good to go for 2 years.

Hubs really aren't a wear item either unless someone keeps driving with a toasted bearing. So if you can manage to get your hands on an axle, you really only might need rotors.

But if you do happen across a pair of backing plates, getting everything else new really isn't a bad way of doing it either.

 

[HotRodPC]

True, that's a good point. Replace bearing races and bearings, should be good as new again unless like you said, someone flat out ignored maintenance and drove on some bad bearing tearing up the hub to where it doesn't hold a race anymore.