Which brakes are right

[MikeB]

on my 81 the parts store sold me the wrong calipers, I didnt research enough to know there were 2 different brake set ups for a 2wd. The first calipers were bigger and were like a 1/4 inch away from fitting.

Yes, base trucks got JB1 (manual) or JB3 (power) with 1.04" thick rotors.

A step up was JD3 with 1.29" rotors.

Calipers and inner wheel bearings were also different. Pads were the same.

Did I get this right, Keith?

 

[MikeB]

454 cubic inch = 7.4 liters, 6.0 liters = 6.0 liters. "There is no replacement for displacement." Exceptions; turbo or blower.

Another exception: Cylinder heads

 

[SeanV]

So the truck does have CPP drop spindles installed. AND, the calipers/pads they sent for what we thought was “stock C20 Suburban brakes” bolted right up and work fine.

 

[shiftpro]

Except a twin turbo 624.

Better fuel economy with the little 496 lol..

 

[bucket]

It does have a GM 12 bolt Truck axle under it. Correct me if I’m wrong, but were these square body C20/C30’s “supposed” to be equipped with the Corporate 14 bolt?

Not supposed to, they simply were. Depending on the year and if a dually, there were 3 different axle types used. All were 8-lug.

So the truck does have CPP drop spindles installed. AND, the calipers/pads they sent for what we thought was “stock C20 Suburban brakes” bolted right up and work fine.

Other than the JB1 "light duty" calipers that Keith mentioned, C10 and C20 calipers interchange. Sometimes a C20 caliper will have a larger piston, but the caliper fits the same.

What I find interesting is the rear. C20 shoes should not fit on any of the K10 axles that I'm aware of. And yes, K10 is what that rear axle came from because of the 6 lugs.

 

[SeanV]

Not supposed to, they simply were. Depending on the year and if a dually, there were 3 different axle types used. All were 8-lug.



Other than the JB1 "light duty" calipers that Keith mentioned, C10 and C20 calipers interchange. Sometimes a C20 caliper will have a larger piston, but the caliper fits the same.

What I find interesting is the rear. C20 shoes should not fit on any of the K10 axles that I'm aware of. And yes, K10 is what that rear axle came from because of the 6 lugs.

Ok, from the sound of things, it looks like someone has been in there and changed suspension parts around. Being that it’s the lighter 7100 GVWR, it may or may not have had a 14-bolt rear? Is that correct? I know those axles are popular for the rock crawler crowd. Also, getting drums for a 12-bolt truck rear isn’t that hard to find, but the next question remaining is what to ask for with front rotors? They’re hub-in-rotor castings with the 6-lugs. What year trucks would be best that I quote at the parts counter/online?

 

[bucket]

Ok, from the sound of things, it looks like someone has been in there and changed suspension parts around. Being that it’s the lighter 7100 GVWR, it may or may not have had a 14-bolt rear? Is that correct? I know those axles are popular for the rock crawler crowd. Also, getting drums for a 12-bolt truck rear isn’t that hard to find, but the next question remaining is what to ask for with front rotors? They’re hub-in-rotor castings with the 6-lugs. What year trucks would be best that I quote at the parts counter/online?

Lighter gvw or not, it had the 14bolt full floater originally, with the 10.5" ring gear. The 14bolt semi-floater did not come around until '81 I believe.

The front rotors, you will have to match up. Being that you have CPP drop spindles, my hunch (and purely a hunch) is that you have a complete disc brake swap, with drop spindles, for a '67-'70 truck.

Do your front control arms have rubber type bushings, or threaded steel inserts with the big hex on them?

 

[SeanV]

I’ll have to take a look at the A-arms tomorrow in the light.

 

[George LaFave]

I have never seen a 6 lug 3/4 ton... if you have 6 bolt pattern it is more than likely a corporate 12 Bolt with 8-7/8" Ring Gear and 30 Spline Pinion. 3/4 ton would have 8 bolts and prob be a corp 14 bolt.

1/2 ton has fewer leaf springs in the back... 3/4 and 1 ton are thick stacked. ( my V30 has 12 springs in the rear) I would order the disk conversion for the rear and then get a 1980 vette master cylinder with an adjustable proportion valve. An old timer reccently told me that if you use older Riviera calipers they have a ratchet type piston that you can pretty easily hook up the e brake;

 

[SeanV]

George, thanks for the additional information.

I think we’ve determined the truck has undergone a suspension swap in the recent past. Either something happened to the original rear end, or it was pirated for some reason. It was replaced with a 12-bolt truck rear. Not a bad rear end, just not what I thought I was buying. That likely left the front end sitting very high so they installed CPP lowering spindle and bolted up 6 lug rotors so a match set of wheels could be used. Again, not a bad set up, just not what I thought I was buying.

 

[Keith Seymore]

George, thanks for the additional information.

I think we’ve determined the truck has undergone a suspension swap in the recent past. Either something happened to the original rear end, or it was pirated for some reason. It was replaced with a 12-bolt truck rear. Not a bad rear end, just not what I thought I was buying. That likely left the front end sitting very high so they installed CPP lowering spindle and bolted up 6 lug rotors so a match set of wheels could be used. Again, not a bad set up, just not what I thought I was buying.

I'd guess the other way round.

Somebody wanted to lower their 3/4 ton suburban, so they purchased spindles and bolted up the 6 lug rotors. Then - changed the rear axle to a 1/2 ton 4wd squarebody axle in order to match the 6 lug.

K

 

[Keith Seymore]

Yes, base trucks got JB1 (manual) or JB3 (power) with 1.04" thick rotors.

A step up was JD3 with 1.29" rotors.

Calipers and inner wheel bearings were also different. Pads were the same.

Did I get this right, Keith?

Other than the JB1 "light duty" calipers that Keith mentioned, C10 and C20 calipers interchange. Sometimes a C20 caliper will have a larger piston, but the caliper fits the same.

What I find interesting is the rear. C20 shoes should not fit on any of the K10 axles that I'm aware of. And yes, K10 is what that rear axle came from because of the 6 lugs.

Yes that's correct.

K

You must be registered for see images attach