I want to ask a question, but could not find away to post it other than this

[Pmac]

I have a '81 C1500 with a J55 brake code, I need new rotors - the parts store(s) are asking what the height of the rotors are - not the diameter, not the width, but the height? This truck was likely used to tote a camper and the J55 has the bigger rear brakes and possibly a different booster - but what is the correct rotor for this application. I know there was a change '80/'81 in rotor width but measuring the height is a new one on me. This truck was built in Oshawa 29 Nov. 1980.

 

[Goldie Driver]

Maybe I am missing something, but wouldn't height be another way of saying diameter ?

 

[75gmck25]

I looked up an '81 C10 in the Rockauto catalog online, and several of the brakes do specify height, while others list a rotor diameter.

Based on the other specs listed on the site for each rotor type, it looks like height might be measured as the distance from the surface of the mounting pad to the back of the rotor, so basically the total thickness of the hub and rotor assembly.

Bruce

 

[Keith Seymore]

I have a '81 C1500 with a J55 brake code, I need new rotors - the parts store(s) are asking what the height of the rotors are - not the diameter, not the width, but the height? This truck was likely used to tote a camper and the J55 has the bigger rear brakes and possibly a different booster - but what is the correct rotor for this application. I know there was a change '80/'81 in rotor width but measuring the height is a new one on me. This truck was built in Oshawa 29 Nov. 1980.

Tell them you have a JB5 brake system and that you need the 1.25" thick rotor (GM part number is 6274216).

That is the information that they are (or should be) looking for.

K

 

[Charlie]

 

[1987 GMC Jimmy]

Yeah, they should be able to cross ref that GM part number. You can do it yourself on the O’Reilly website, and then translate that into their part number, and I think the store system at Autozone has the same function but just not on the website.

 

[75gmck25]

If GM 6274216 is the right parts number, then the parts store catalog should show a total height of approximately 4.95-5.00" and a nominal thickness of 1.280-1.285, and a diameter of 11.86.

6274216 crosses to Bendix PRT1043 and Wagner BD60258.

Bruce

 

[Pmac]

Thanks. Still working my way through posting/reply/etc and the like.

 

[Pmac]

If GM 6274216 is the right parts number, then the parts store catalog should show a total height of approximately 4.95-5.00" and a nominal thickness of 1.280-1.285, and a diameter of 11.86.

6274216 crosses to Bendix PRT1043 and Wagner BD60258.

Bruce

Thanks Bruce - and all those who read my post; the information you provided is precisely what I was looking for. The J5 AND J55 was in the past enough - when this "height" business started - I reckon some time near 2012 - and why is beyond me. Regards, Pete.