73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: Captain Swampy on October 27, 2016, 09:59:52 pm
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A stock 1/2 ton has a 15/16" wheel cylinder. I read about using wheel cylinders from a 1 ton on a 1/2 ton on a dodge forum. Yes I own a dodge, a Ford, and a KW besides our Chevys. Anyhow, I bought 1 1/16" wheel cylinders for a 1 ton and put them on our 95 dodge. It stops awesome now. My next thought was doing this to Bedazzled. The 1 1/16" cylinders look the same as the 15/16" cylinders as far as the mounting. I think they have the same part # as the dodge. I think they are using the same cylinders. Does any one know for sure if the mounting is the same? Sure should be. It's cheap and very effective.
Some guys were using 1 3/16" cylinders, but they could lock up the rear brakes. I'd guess that would increase stopping distance. Maybe it would be OK if you always hauled stuff , towed a trailer with some tongue weight, or upgraded the front brakes to match. I like the 1 1/16" cylinders. You can feel the whole truck slowing now. It used to nose dive, but now feels nice and even.
So I'm almost positive it will work. I always thought the square bodies could use more rear brake. I'll probably switch them for Brooke after we drive the dodge a little more. My wife thinks it's a huge improvement too. :D
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In 1996 I upgraded the rear brake shoes and drums on my 1987 R10 from JB1 (11" x 2") to JB5 (11.15" x 2.75") and installed 1 3/16" wheel cylinders from a 1-ton dually. I upgraded to a dual diaphragm vacuum booster at the same time. The improvement in braking effectiveness and front-to-rear brake balance was nothing short of remarkable. The vehicle stops on a dime and never experiences brake fade.
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In 1996 I upgraded the rear brake shoes and drums on my 1987 R10 from JB1 (11" x 2") to JB5 (11.15" x 2.75") and installed 1 3/16" wheel cylinders from a 1-ton dually. I upgraded to a dual diaphragm vacuum booster at the same time. The improvement in braking effectiveness and front-to-rear brake balance was nothing short of remarkable. The vehicle stops on a dime and never experiences brake fade.
Did you have to change the backing plates also? I tries this on my 83 and the JB1 backing plates were different than the JB5 plates........
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The backing plates are necessary for the upgrade.
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In 1996 I upgraded the rear brake shoes and drums on my 1987 R10 from JB1 (11" x 2") to JB5 (11.15" x 2.75") and installed 1 3/16" wheel cylinders from a 1-ton dually. I upgraded to a dual diaphragm vacuum booster at the same time. The improvement in braking effectiveness and front-to-rear brake balance was nothing short of remarkable. The vehicle stops on a dime and never experiences brake fade.
Thank you for the info. What would the JB5 brakes be on, so we could find them? I'm guessing the backing plates would be a wrecking yard trip. I'll try the wheel cylinders first, The brakes and drums are only a year old. That would give me time to find the other parts. What is the dual diaphragm booster sourced from? Maybe there's some info in the Technical pages, I'll check there.
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JB5 - VACUUM POWER BRAKE DISC/DRUM - 6,400 LBS
When scrounging for parts at the wrecking yard, look for "JB5" or "JD5" on the glovebox SPID label...
Non-consumables:
JB5/JD5 backing plates: 85-86 C/K10 and 87-91 R/V10 (GM #14055279 left; 14055280 right)
JB5/JD5 park brake struts: 85-86 C/K10 and 87-91 R/V10 (GM #468661 - left and right sides are the same)
JB5/JB6 dual-diaphragm power booster: 85-86 C/K10/20 and 87-91 R/V10/20 (GM #18010581)
Consumables:
JB5/JD5 11.15" x 2.75" shoes: 85-86 C/K10 and 87-89 R/V10 (GM #1155445)
JB8 1-3/16" wheel cylinders: 85-86 C/K30 and 87-89 R/V30 with dual rear wheels rated 10,000 lbs (GM #18004609)
JB5/JD5 11.15" x 2.75" rear drums:
- 5-lug: 85-86 C10 and 87-89 R10 (GM #14070351)
- 6-lug: 85-86 K10 and 87-89 V10 (GM #14070352)
IIRC, with the exception of the park brake struts, all springs, links, levers, adjusters, anchors and miscellaneous hardware are interchangeable between JB1/JB3/JB5.
Initially, I stated that I upgraded from JB1 rear brakes. In fact, I upgraded from JB3. The JB3 and JB5 RPOs (both vacuum power brakes) share the same master cylinder (GM #18013435), whereas JB1 (manual brakes) is different. I don't know the differences or similarities in bore, stroke and fitting sizes between the two, so it's possible that a JB1 M/C will need to be upgraded along with the other parts.
See RPO Codes (http://forum.73-87chevytrucks.com/smforum/index.php?topic=32316.msg273202#msg273202) for specific details on what GM RPO code numbers represent.
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BD, thanks for all the information. I'll have to look at Brooke's truck and see what is in it. The rear axle has to be swapped in, it's a 12 bolt. Being an 87 it might have the JB5 brake booster.
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BD, would you mind explaining what is different about the two backing plates? I currently have the jb5 plates on my 79 12 bolt that need replacing, I pulled a set of 11x2" backing plates from a 77 c10 on Friday thinking they were the same compatibility. Or were they the same on the 12 bolt rear? Thanks for the information
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BD, would you mind explaining what is different about the two backing plates? I currently have the jb5 plates on my 79 12 bolt that need replacing, I pulled a set of 11x2" backing plates from a 77 c10 on Friday thinking they were the same compatibility. Or were they the same on the 12 bolt rear? Thanks for the information
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JB5 shoes are 2.75" wide. JB1/JB3 shoes are 2" wide. The JB5 backing plates re-position the mounting height of the wheel cylinders to center the pins on the wider shoes.
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Thank you for getting back with me so quickly, so if I were to pull jb5 plates off of a 10 bolt rear axle would they work on a 12 bolt? I'm having a hard time finding the proper parts in the salt belt.
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Couldn't say.
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Bookmark!
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JB5 Plates also locate the wheel cylinder deeper into the plate to make up for the difference in width of the brake shoes.......what was the JD5 brake system? Hydraulic booster only?
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Well I may have to pull a jb5 set from a 10 bolt at a yard and see whether or not they fit a 12 bolt, if I go that route I will be sure to follow up with information about fitment.
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.......what was the JD5 brake system? Hydraulic booster only?
JD5 is similar to JB5, but substitutes a Hydro-boost hydraulic power booster.
Well I may have to pull a jb5 set from a 10 bolt at a yard and see whether or not they fit a 12 bolt, if I go that route I will be sure to follow up with information about fitment.
That would be great information to add to this thread!
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Well as I said I would I pulled a set of 10 bolt jb5 plates and they were a direct match and proper fitment to my 12 bolt jb5 plates I don't have any pictures to add at the moment but I will try to later on
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