Brake rotors

[AzDon]

I just acquired a 68 burb that has had 71 suspension with disc brakes added. The rotors are 5on5 lug pattern, but the rear is still six lug. I'm wondering if rotors are available that are either six lug or 5on4 3/4(?) If so, what would I tell the parts counter guy about make model and year to get the right ones?

[4x4Poet]

Originally Posted by AzDon

I just acquired a 68 burb that has had 71 suspension with disc brakes added. The rotors are 5on5 lug pattern, but the rear is still six lug. I'm wondering if rotors are available that are either six lug or 5on4 3/4(?) If so, what would I tell the parts counter guy about make model and year to get the right ones?

I think we need a little clarity. I gather the truck has 5-lug front hubs with disc brakes and 6-lug rear axle flanges.

So, what are you looking for? I don't get why you seek either 5 or 6 lug rotors when you only have 5-lug disc brake hubs? Or am I missing something?

Are you trying to find matching replacement parts or to make the truck all 5-lug or all 6-lug? If the latter, and the rear axle assy is a 12-bolt, you could swap in 5-lug axles.

[mosesburb]

Originally Posted by AzDon

I just acquired a 68 burb that has had 71 suspension with disc brakes added. The rotors are 5on5 lug pattern, but the rear is still six lug. I'm wondering if rotors are available that are either six lug or 5on4 3/4(?) If so, what would I tell the parts counter guy about make model and year to get the right ones?

It sounds like you might have another issue here. GM never used a 5 on 5 bolt pattern on a 4wd truck. Most everybody else did, but not GM. They used the 6 lug pattern that you have on the rear of your tuck. This leads me to believe that someone used non-GM parts to convert to disc brakes. Now, this may not be a huge issue, but it might be more involved that it appears.

If the spindles are of a type that are the same as GM, you just need a hub and rotor off of pretty much any GM 1/2T 4wd--BUT--GM used two different spindles and splined hubs (what the rotor mounts to). Pre 1977-ish and post 1977-ish. The early hubs and spindles have smaller bearings than the later ones. So, if your spindles are compatible with GM components, you just need to figure out which bearings you have and get the corresponding hub/rotor asm.

Now, if your spindles are not compatible with GM components, or you don't want to have your truck down for a bunch of time figuring out what you have, you can get spindles, hubs/rotors, caliper brackets and calipers out of a wrecking yard pretty cheap and know you have a matched set of goods. If you opt for this route, I recommend the '77-'91 components due to the larger bearings. You can get the goods off of a Dana 44 or GM 10 bolt--they interchange.

[Longhorn Man]

Originally Posted by mosesburb

GM never used a 5 on 5 bolt pattern on a 4wd truck...

Why would you think it's a 4X4?

6 lug rotors are avalible in the aftermarket, no parts stores will have them. They aren't anywhere close to being cheap though.
I am not aware of any car rotors (5on4 3/4) that'll fit.
You can install aftermarket axle shafts in your 68 rear end and get 5 lug drums, or source a 71/72 rear end that already has the 5 on 5 axle shafts if you want to go the 5 lug route.

[mosesburb]

Originally Posted by Longhorn Man

Why would you think it's a 4X4?

Bad assumption on my part. I forgot that these trucks could have six lugs and be a 2wd. I actually went through this with a customer a few years back and the information you give is absolutely correct for a 2x. The six lug rotors are out there and yes, they are not cheap.

[mr48chev]

Don, It's pretty simple. Someone swapped the front end out for a 72 Disk brake front end that has the 5 0n 5 bolt pattern and didn't bother to swap the rear end to one from a 71/72 Half ton to match the front.

Three different possible solutions to solve the issue.

1. buy aftermarket 6 lug disk brake rotors for the front to match the original rear.
2. Swap the whole rear end for one out of a 71 or 72 Two wheel drive half ton.
3. Buy a custom set of five lug axles for the rear end and new drums or have the drums redrilled.
and a fourth possibility. Have the six lug axles redrilled to five lug and get new drums or redrill the drums.

[AzDon]

I wasnt clear-Sorry!
It is a 2 wheel drive that has had later model disc front suspension swapped in.
I don't necessarily have a problem with the six lug/five lug situation if I can get matching wheels. I currently have a nice pair of Ansen Sprint style aluminum slots for the six-lug rear and would like to find matching 5on5x15's. I also have steel truck rallys in 5on5 and could get the matching wide six-lug version for the rear that came on 4x4 blazers and burbs.
Because I'm looking for specific wheels, they seem to be impossible to find.
I was pondering converting all to either six lug or five lug to eliminate the weirdness!

[4x4Poet]

Originally Posted by AzDon

I wasnt clear-Sorry!
It is a 2 wheel drive that has had later model disc front suspension swapped in.I was pondering converting all to either six lug or five lug to eliminate the weirdness!

It's not just weird. Mismatched hubs front to rear means you need two spares to keep a flat from stranding you.