how do i know what size rotors i have?

[cheap]

So, I'm planning on ordering new drop spindles. Aside from measuring, how can i know what size rotor i have? It's a 1977 C10 Custom Deluxe

[cheap]

no option for heavy duty brakes, vin says Base: 1315. any help?

[raggedjim]

Honestly, measuring is the only way to be sure.

Rg

[cheap]

Originally Posted by raggedjim

Honestly, measuring is the only way to be sure.

Rg

Alright, i suppose I will. Its obviously not a big deal to measure them, but i was just hoping someone might know.

[pistonbroke800]

I just ordered drop spindles for mine. I pulled a front wheel off and measured the rotor with my calipers. they were like .987'' so I am guessing they started at 1'' then wore down a bit with regular wear. I ordered stuff for 1'' rotors so hopefully everything works.

[f.monroe]

Originally Posted by cheap

Alright, i suppose I will. Its obviously not a big deal to measure them, but i was just hoping someone might know.

Most early trucks were 1 1/4 so that would be my guess but you could have either. Its always best to measure to be sure. Even if it came from the factory with one size a previous owner may have changed them at some point. Best to be sure before ordering parts. It saves you time and frustration.

[enaberif]

Originally Posted by f.monroe

Most early trucks were 1 1/4 so that would be my guess but you could have either. Its always best to measure to be sure. Even if it came from the factory with one size a previous owner may have changed them at some point. Best to be sure before ordering parts. It saves you time and frustration.

Actually depending on the GVWR of your truck you could have 1" or 1.25" in the front and 11" x 2" or 11 5/32"x2.75"

On my truck I have 1.25" front and 11"x2" rear

[f.monroe]

Originally Posted by enaberif

Actually depending on the GVWR of your truck you could have 1" or 1.25" in the front and 11" x 2" or 11 5/32"x2.75"

On my truck I have 1.25" front and 11"x2" rear

That's sort of my point. You have light duty rear brakes but 1 1/4 front rotors. I personally have never seen 1" rotors on anything older than 1977. That's why I said he could have either but checking is the best thing to do.

[Keith Seymore]

The 1" rotors are only used on the manual brake system and the lightest power system, so without even seeing your truck I would guess 1.25".

I have the brake system release chart for '74 scanned (I also have the '77 system in the book but not scanned) but it does not give a specific measurement.



I also have the '87 system scanned, which is a bit easier to read. You can see how the rotors are released here, based on GVW and brake system RPO (JB1 vs JB3 vs JB5).



K

[bigblock73]

If you are going to go thru the effort of installing drop spindles, you can easily twist off 5 lug nuts and measure the rotor thickness. Now isn't the time to be lazy, especially when it can cost you $$