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Old 10-04-2012, 01:31 PM   #1
i8tokyo
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Brake help? 1978 C-20

Hi all, trying to gather parts for a needed brake job but have a question concerning the size of my rear shoes/drums. The build sheet shows I have a JB7 Power brake option and the J55 HD brakes. Would that be the 11X2.75 or the 13X2 shoes/drums. If it wasn't for having a 14bolt 10.5 rearend I'd just yank the drum off and check. But given I have to pull the axle to get the drum off, not as simple. Any guidance on this? Thanks in advance!
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1982 C-20, 454, TH-400, PS, A/C, 71,000 miles
1978 C-20, 350, TH-400, PS, Non-A/C, 112,000 miles

If it ain't broke, there is still probably room for improvement.

Speed costs money, how fast do you want to go?
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Old 10-04-2012, 01:39 PM   #2
Keith Seymore
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Re: Brake help? 1978 C-20

Here are the actual brake system release charts that we used to select the parts for production; for a '74 and for an '87.

Scan through those and see if they answer your question (let me know if you need some help navigating)

http://67-72chevytrucks.com/vboard/s...d.php?t=510519

Looking at the '87 chart, for a R20 JB7 (page 4) rear shoes look like 13x2.5 to me.

K
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Old 10-04-2012, 02:09 PM   #3
i8tokyo
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Re: Brake help? 1978 C-20

Quote:
Originally Posted by Keith Seymore View Post
Here are the actual brake system release charts that we used to select the parts for production; for a '74 and for an '87.

Scan through those and see if they answer your question (let me know if you need some help navigating)

http://67-72chevytrucks.com/vboard/s...d.php?t=510519

Looking at the '87 chart, for a R20 JB7 (page 4) rear shoes look like 13x2.5 to me.

K
It's looks that way to me as well. Thank you for the guidance and info. That's just one of the things that makes this place a pleasure to hang out in. Best, Don
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1982 C-20, 454, TH-400, PS, A/C, 71,000 miles
1978 C-20, 350, TH-400, PS, Non-A/C, 112,000 miles

If it ain't broke, there is still probably room for improvement.

Speed costs money, how fast do you want to go?
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Old 10-04-2012, 07:53 PM   #4
Billy81
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Re: Brake help? 1978 C-20

I just took my rear wheel off and looked at the outside of the drum if it says 13.09 max dia you have 13" brakes.
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Old 10-07-2012, 03:20 AM   #5
85chevy383
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Re: Brake help? 1978 C-20

That axle should be 13'' brakes
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