How to measure 14 bolt drum?

[boltbrain]

How are drums measured? I thought inside. But the ID on my 14 bolt is only 11” and when I got rotors for the front they gave me 13” because they said my rear brakes were 13”. Trying to order from Rick Auto, which has no phone help. They have 11 and 13” drums. Mine are 13 1/2 OD
Thanks

 

[Blue Ox]

It's ID.

There's two 20 series, standard and C6P heavy duty. It has the 13" drums and uses bigger calipers and D153 pads.

Standard uses 11" drums and D52 pads.

They all use the same rotors, so I have no idea WTF they're talking about.

 

[boltbrain]

THANKS

 

[boltbrain]

The 13” rotors fit on my Dana 44

 

[Blue Ox]

AFAIK the only difference in the front brakes was the calipers and pads.

The specifics of the JB6 and JB7 brakes thing may be from the '81 redesign. I'd have to check a book that I don't have in front of me now. But I'm pretty sure the idea carried through the whole line.

 

[Craig 85]

The 11" drum on a 14 bolt looks similar to the first photo. Photo 2 is the 13x 3.5" on my K30. On a 16" wheel, the 13" drum will look like photo 3. Fit is fairly tight. You would have a really noticeable gap with the 11" drum.

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[boltbrain]

Thanks very much. All I know is my Dana 44 had 13” (12.5) rotors when I got it, and when I replaced the rotors and calipers Napa gave me 13” rotors (12.5 actually) but the calipers they gave me wouldn’t fit over them and when I returned the calipers they said they should have asked me which size drums were on the 14 bolt. I didn’t know right off, but they assumed I had 13” drums so exchanged my calipers for 13” ones which did fit. All of which convinced me the rear drums were 13”. So when they measured 11” I. D. I was surprised. After much consideration ordered disc conversion parts from lugnut. Not a kit, just what I needed. I got rotors that match my front, but calipers with the E brake. I could have used front calipers on the rear but wanted the E brake. Just ordered what I needed not a kit. Now I’m shopping for a new master cylinder that’s heavy duty and will get a new manual proportioning valve also. I almost got new drums instead but didn’t want to go to bigger ones, with the weight, and I’ll have more stopping power with the 13” discs going down passes with loads.

 

[boltbrain]

Thanks very much. All I know is my Dana 44 had 13” (12.5) rotors when I got it, and when I replaced the rotors and calipers Napa gave me 13” rotors (12.5 actually) but the calipers they gave me wouldn’t fit over them and when I returned the calipers they said they should have asked me which size drums were on the 14 bolt. I didn’t know right off, but they assumed I had 13” drums so exchanged my calipers for 13” ones which did fit. All of which convinced me the rear drums were 13”. So when they measured 11” I. D. I was surprised. After much consideration ordered disc conversion parts from lugnut. Not a kit, just what I needed. I got rotors that match my front, but calipers with the E brake. I could have used front calipers on the rear but wanted the E brake. Just ordered what I needed not a kit. Now I’m shopping for a new master cylinder that’s heavy duty and will get a new manual proportioning valve also. I almost got new drums instead but didn’t want to go to bigger ones, with the weight, and I’ll have more stopping power with the 13” discs going down passes with loads.

BTW I’m replacing my rear lines without hoses too, not that difficult.

 

[bucket]

Thanks very much. All I know is my Dana 44 had 13” (12.5) rotors when I got it, and when I replaced the rotors and calipers Napa gave me 13” rotors (12.5 actually) but the calipers they gave me wouldn’t fit over them and when I returned the calipers they said they should have asked me which size drums were on the 14 bolt. I didn’t know right off, but they assumed I had 13” drums so exchanged my calipers for 13” ones which did fit. All of which convinced me the rear drums were 13”. So when they measured 11” I. D. I was surprised. After much consideration ordered disc conversion parts from lugnut. Not a kit, just what I needed. I got rotors that match my front, but calipers with the E brake. I could have used front calipers on the rear but wanted the E brake. Just ordered what I needed not a kit. Now I’m shopping for a new master cylinder that’s heavy duty and will get a new manual proportioning valve also. I almost got new drums instead but didn’t want to go to bigger ones, with the weight, and I’ll have more stopping power with the 13” discs going down passes with loads.

Sounds like they simply sold you the wrong calipers and used the rear brakes as an excuse. Did the calipers not fit because the rotor was too thick? If so, those calipers they first sold you were for a light duty C10.

 

[Radiohead]

Besides, I remember drums having their max diameter spec stamped or cast in. Was none of that apparent or did I miss something?

Bucket is spot on about the caliper issue.

 

[boltbrain]

Sounds like they simply sold you the wrong calipers and used the rear brakes as an excuse. Did the calipers not fit because the rotor was too thick? If so, those calipers they first sold you were for a light duty C10.

If the Dana 44 only came with one rotor diameter ( 12.5”) then that’s likely what happened. I told them I had a K20 and that I had a Dana 44

 

[boltbrain]

Besides, I remember drums having their max diameter spec stamped or cast in. Was none of that apparent or did I miss something?

Bucket is spot on about the caliper issue.

Thanks, not sure what a max diameter spec is. I do recall you saying yours was a one ton and I’m pretty sure those didn’t come with 11” ID drums. I just meant to say, since my 11” drums, shoes, cylinders were all toast, I figured I’d go bigger, and that I may as well go disc since it was about the same price. I can appreciate the original drum setup too.

 

[boltbrain]

Sounds like they simply sold you the wrong calipers and used the rear brakes as an excuse. Did the calipers not fit because the rotor was too thick? If so, those calipers they first sold you were for a light duty C10.

Yes, the calipers they gave me wouldn’t go over the rotors, so I kept their rotors, exchanged the calipers.