Anyone have any 18P calipers to sell?

[260Alpine]

Series II used 3.5" mounting pattern. Series III should too. Series IV and V used 3.25" mounting pattern. You will have to use the Series IV calipers.

 

[Barry]

OK, interesting discussion here. At what serial number did the spacing change? I bought series II spindles which included the calipers rotors and steel wheel hubs. Going to use the hubs on my early series IV to replace the wire wheel hub. Not using the series 2 spindles at all. If the Calipers are the same, then I will rebuild these S-II on the bench before swapping parts. But if they won't fit, then I have to rebuild the Series IV calipers that are on the car now. When did this change take place? Serial numbers if you have them.
Thanks

It's not about serial numbers, it's about the front suspension stub axle carriers (aka, uprights or spindles).

The early (S-I / II / 3) "kingpin spindles" work with 3.5" mounting center calipers and 9.5" brake rotors; the later (S-IV / V) "ball joint spindles" work with 3.25" mounting center calipers and 9.85" brake rotors.

Your S-IV should have the later front suspension with ball joint spindles, 3.25" mounting center calipers and 9.85" brake rotors, but your post mentions "... bought series II spindles which included the calipers rotors and steel wheel hubs."

I vaguely recall that early hubs are not a bolt-on with later spindles; something about the combination of the early inner wheel bearing seal and the "distance piece" on the later stub axle.

 

[Gumby]

According to Rick at Sunbeam Specialties, the bearings and hubs are the same, but the inner grease seal is different. Not because of a change to the hub, but because of a change to the inner edge of the spindle. So the series II hubs with new bearings and the later "cupped" grease seal will work find. I will need to swap the brake rotors, and use my existing calipers.

This means of course I will have a set of series II spindles, wire wheel hubs, brake rotors steering arms and calipers (stuck, 125 psi would not budge the pistons even through they had brake fluid in them.) for sale soon, and a rear end with matching wire wheel hubs too.

 

[Barry]

According to Rick at Sunbeam Specialties, the bearings and hubs are the same, but the inner grease seal is different. Not because of a change to the hub, but because of a change to the inner edge of the spindle. So the series II hubs with new bearings and the later "cupped" grease seal will work find. I will need to swap the brake rotors, and use my existing calipers.

This means of course I will have a set of series II spindles, wire wheel hubs, brake rotors steering arms and calipers (stuck, 125 psi would not budge the pistons even through they had brake fluid in them.) for sale soon, and a rear end with matching wire wheel hubs too.

Typical operating pressure in a hydraulic brake system is about 400-800 PSI, so 125 PSI from an air compressor is often not enough to move stuck pistons. Try a Zerk fitting and hand grease gun which can easily get up to a thousand PSI and is safer than compressed air.