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Old 07-07-2019, 07:35 PM   #1
donw1986
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Join Date: Oct 2012
Location: Santa Clarita CA
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Brakes

1986 c10 305 calif emmisions,700r4 1/2 ton

Ok I know this question has been asked a lot and I have read through a lot of posts about this and I'm getting conflicting information my SPID in the glove box says I have J50 Power brakes, a lot of the posts in here are saying that is the same as jb5 brakes and those posts are saying that those are the 11 5/32 x 2 3/4 rear brakes and 12 x 1 1/4 front disks, after measuring i measured 12 x 1 disks and 11x 2 rears, is it possible that the wrong brakes were installed over the years? Would the smaller rotors fit on the same spindles as the larger ones and would the smaller drums and shoes fit on the same rear axle set up ?
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Old 07-08-2019, 07:38 AM   #2
D13
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Re: Brakes

J50 is power brakes. It was possible to have non-power brakes (like my 77).
JB5 is a heavy brake package, often found on diesels. It is not the same as J50.

1986 1/2 ton will have the thin rotors (1") and the small rears (2" wide) unles one of the heavy brake packages was ordered. Your truck is built correctly.

To swap to heavy brakes you will need different front spindles and rear backing plates, plus all the brake components. Unless you are towing or hauling a lot, every day, it's not worth the money. The big gain is resistance to brake fade under heavy load, the current package will stop the truck just fine. If you're racing then you probably are going to lowered spindles and aftermarket brakes anyway, since the big brakes are a lot heavier.
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1987 C10 6.2 oil burner
1987 2 ton
1982 250/TH350 beater in progress
Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping
77 1/2 ton 250, 3OTT, and hokey aftermarket AC SOLD!
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Old 07-08-2019, 07:55 AM   #3
donw1986
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Re: Brakes

Ok thanks for that, there was alot of posts on this forum with conflicting info so i was just wanting to know for sure before i start rebuilding my brakes
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