Easy way to determine front caliper size?

[SUX2BU99]

My passenger side brake likes to drag. When I touch the brakes I get a pull to the left side as the driver side caliper seems to grab quicker, and release quicker. The passenger side seems slow to react to anything and also occasionally sticks on.  I presume this is a caliper issue? What do I need to know when I'm shopping for a new one as far as what size of brakes I have? My truck is a mutt so I can't rely on what was originally put on.

Thanks.

[zieg85]

Also could be a collapsed brake hose.  Measure the rotor thickness, that will tell you what you need

[Irish_Alley]

just had this problem on my 94. slam on the brakes the driver side would dive then the passengers side would work. it got to the point that when i came to a stop and pressed the brakes, i could release the brakes and the truck still wouldn't move cause the brakes where dragging. so i lifted the front up pressed the brakes then tried to turn the front tires. the driver side spun while the passengers side wouldn't move. so i already got brake hoses. so i replaced the passenger side and bled the brakes, fixed the problem. then despite what most people say as the hose "collapsed" this is true to a point. i examined the hose and noticed where the metal bracket that holds the hose in place was rusty. so i put it in a vise and pried it open to release the hose. and what happened was the rust expanded in between the bracket and hose causing it to "collapse" the hose. i then cut the hose open and didn't see any problem with it besides where it was squeezed by rust. but yeah i would bet it was the hose also

[SUX2BU99]

^ Interesting. Amazing what rust will do, eh?

I measured my rotor and it's 1-5/16" thick. So what does that tell me for what caliper I need? In looking at a parts vendor catalogue I see there is a multitude of calipers available for 2wd trucks, depending on year and rear brake size. Well my truck is a mutt so I can't rely on what was stock for it. I know I have a pre-1981 frame even though my truck by VIN is a 1981. I do have the the larger rear brakes (2 3/4" shoes and the beefier drums). So if I'm ordering parts, what year of truck should I use to search for? Also, my caliper has these 4 digits on it: 4149.

[Irish_Alley]

that 4149 number will cross to a brake caliper for a 79-86 chevy c10
c527
i wouldnt worry about what size rotor you have for a caliper i would always take in my old parts so i can do a visual

[SUX2BU99]

Thanks, that helps get me going in the right direction. I'm wanting to order some parts online so I want to get it right the first time. Same with a hose.

When I go parts hunting online I see that a Raybestos FRC4139 will fit a 1979 1/2 ton and a 1981 1/2 ton but when I look at a FRC4123 it wont work on the 1979 but will for the 1981. The 4123 appears to be for the standard brake system and the 4139 was used on the more heavy duty. Would one be for the 12.5" rotor and one for the 11.86" or are both for the 11.86"? I'd love to see a cross-reference chart!