Jb5 brake interchange and donors

[Ricko1966]

Looking to upgrade the brakes on my 1986 C10 to JB5 brakes. Wondering if anyone knows which vehicles I can mix and match parts from. Like I'm assuming I could use spindles and calipers from a C20, rear backing plates I would assume could come off of any 10 bolt . Rotors and Drums I'll buy new. Does anyone know the easiest vehicles to source my JB5 stuff? Also want to go Big 10 springs I assume I just buy new and move my rear spring shackles. Basically I want build a 1986 Big 10.

 

[Grit dog]

No idea on parts interchangeability for the brakes and spindles.
You can buy about any combo of rear spring length and capacity or any other of a host of ways to beef up the rear suspension capacity without finding a set of 40+ year old springs to replace the existing ones. With shops like Atlas and General Spring in KS, you could get what you want brand new and local and maybe save the $100+ shipping.
If I had time to lower my 77 in the near future and you were closer, I’ll be removing a good set of BIG10 springs and a new set of airbags off the 77.

Unless you have broken or sacked out springs or some other viable reason to swap them, maybe investigate all the options to give you more suspension capacity without having to remove springs.
Add a leaf top mount, airbags, aux coil springs (like little bags if they still make them), coil over shocks, air shocks, Timbren type bump stops all come to mind for easy solutions.

 

[Ricko1966]

I was planning new springs,thought I wrote that in there? Anyways question was can I just relocate my existing shackle and go with new springs and ubolts.

 

[Grit dog]

^Yes you did. My mistake.

 

[legopnuematic]

Things changed slightly with brake codes in the 80s versus 70s, I know the 70s stuff much better than 80s.

1973-1980 JB1 was 1” non ventilated rotors, 11x2” rear drums, manual brakes, JB3 was 1.25 ventilated rotors, 11x2” rears, power brake, JB5 was 1.25 ventilated rotors, 11 5/32x2 3/4 rears, power brake, different booster but same masters between power brakes.

In the 80s I believe JB3 became a 1” ventilated rotor, JD3 I guess replaced the old JB3. Sort of but not entirely. @Keith Seymore has posted a chart before that shows what each code would get you. Keith or any others, feel free to correct what I wrote above, if needed. The 80s stuff gets confusing.

If your truck has 1.25 rotors up front, it should be the same a JB5, just the rears. I know that the backing plates will interchange from a 12 to 10 bolt as my 79’s 12 bolt I put backing plates from an 85 C10 (2 3/4” wide shoe for both) and everything fit like it’s supposed to.

 

[legopnuematic]

I found the 85 chart Keith had posted before:

 

[legopnuematic]

The holes for 56” springs should already be punched in the frame too.

 

[Ricko1966]

I found the 85 chart Keith had posted before:

This rocks!!!! There a pedal ratio change that would have crept up as a surprise. Didn't see that coming. Thanks. Never mind was looking at the wrong column. But still super cool info.

 

[Keith Seymore]

Things changed slightly with brake codes in the 80s versus 70s, I know the 70s stuff much better than 80s.

1973-1980 JB1 was 1” non ventilated rotors, 11x2” rear drums, manual brakes, JB3 was 1.25 ventilated rotors, 11x2” rears, power brake, JB5 was 1.25 ventilated rotors, 11 5/32x2 3/4 rears, power brake, different booster but same masters between power brakes.

In the 80s I believe JB3 became a 1” ventilated rotor, JD3 I guess replaced the old JB3. Sort of but not entirely. @Keith Seymore has posted a chart before that shows what each code would get you. Keith or any others, feel free to correct what I wrote above, if needed. The 80s stuff gets confusing.

If your truck has 1.25 rotors up front, it should be the same a JB5, just the rears. I know that the backing plates will interchange from a 12 to 10 bolt as my 79’s 12 bolt I put backing plates from an 85 C10 (2 3/4” wide shoe for both) and everything fit like it’s supposed to.

JDx is hydraboost; JBx is vacuum.

K

 

[Keith Seymore]

This rocks!!!! There a pedal ratio change that would have crept up as a surprise. Didn't see that coming. Thanks. Never mind was looking at the wrong column. But still super cool info.

I have those starting in 1969 up through 2008 maybe.

The oldest ones are hand written.

K

 

[Scruffy49]

Are you staying with a plastic and aluminum master cylinder? My 85 C10 swb has the lightest duty springs offered, but HD brakes/cooling. Per the spid.
You can do the HD brake swap with off the shelf parts, just need to order new front spindles to go with the rotors/calipers.
Note, if you run F/R Gabriel load assist shocks, and like your stock ride height, plan on a lowering kit…

 

[xm20k]

I was planning new springs,thought I wrote that in there? Anyways question was can I just relocate my existing shackle and go with new springs and ubolts.

Both rear mount locations are drilled in the frame. I swapped to regular half ton 4 leaf springs out of my Big Ten and moved my brackets forward to the shorter position. The forward point only had the four outer holes, and the brackets had 6 rivets on mine, maybe due to the heavier capacity they added the extra rivets for strength. At some point I should probably drill the inner 2 and bolt them up. Your going the other way so look to see if your brackets have 4 or 6 holes when you slide them back you may have to bolt them up and use the frame as a guide to drill the other 2 in the bracket.

The pedal angle depends on where/who made the hydro boost mine sits angled up as it was built specifically for a C10 by CPP and uses the stock power brake pedal. Also fits a 1.125 diameter stock master or an aftermarket like Willwood.

Street Beast HydraStop Booster Assembly for 1973-87 Chevy Truck

1973-87 Chevy Truck Street Beast HydraStop booster assembly with direct mount bracket

classicperform.com