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I figured before I reinvent the wheel and adapt a larger dual diaphragm brake booster for my 70 j2500 I’d ask y’all what you’re thoughts or recommendations are before I order parts and fab up linkage to adapt something. I’m even up for hydro boost, just seeing what has been done and possibly save some work.

Thanks in advance
Steve

I did a Hydroboost with this guys help on my 69 Wagoneer and I love it.

http://www.custompowerbrake.com/

Thanks for the info

I recall the later booster for a Grand Wagoneer or J20 is dual diaphragm? Before you think about adapting something, I suggest you search old posts. There may be a factory equipment dual diaphragm that bolts in. Even if it's a little different, get friendly with your local old-time parts store and ask them to order one for you to look at. They may have a "20% restocking blah blah blah" policy, but if you are a good customer, they should do that for you. They do it all the time for their repair trade customers, and it does not cost them anything to send stuff back.

tgreese wrote: ↑Thu May 06, 2021 5:25 am I recall the later booster for a Grand Wagoneer or J20 is dual diaphragm? Before you think about adapting something, I suggest you search old posts. There may be a factory equipment dual diaphragm that bolts in. Even if it's a little different, get friendly with your local old-time parts store and ask them to order one for you to look at. They may have a "20% restocking blah blah blah" policy, but if you are a good customer, they should do that for you. They do it all the time for their repair trade customers, and it does not cost them anything to send stuff back.

Yes, go this route. Ive never had issues with the Daul booster, Disc brake setups.

My 89 came with the dual diaphragm booster. I converted to hydroboost. Hydroboost is loads better IMO. Brakes require far less input. But, more $ and complexity.

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Really looking at hydro boost. Need to go to the picknpull and get a booster off a later model truck and see what I can do. I’ve installed it on customer vehicles but we bought them a kit that basically bolts on. I’m too cheap and doing it myself with a used unit it’s about the same cost as buying a vacuum booster. I’ll be sure to document what I come up with. Currently with the old single diaphragm booster it stops really good with little effort just cruising around but when you really need it to stop in a hurry it needs more boost, both feet aren’t enough lol

The Chevy Calipers and JB7 pads are also a nice improvement.

Are those drop in with stock rotors?

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I would point out that the 11"x2" drum brakes may be the weak link here, not the booster. They will fade. Drilling the drums was race-car tech from the day.

Never mind - read your old posts and apparently you have a front disk conversion of some type. Disks are not self-energizing like drums, and the existing booster may be inadequate. CJ owners with through-the-floor pedals often go front disk with manual brakes. In that case, soft organic pads make the braking effort less.

An Astro Van is a common source for junkyard hydroboost.

I also did the Hydroboost along with rear disc conversion using Cadillac Eldorado calipers...'76 I think...On my '78 J20. Fantastic braking.

Personally, I would go dual diaphragm over hydroboost mostly for the reliability and simplicity. Its not quite bolt in for a 1970, but its pretty close. You would also need the master cylinder matched for it. Plus the rod going from the brake pedal would need to be different. And I know you converted to disc, but make sure you also have the correct proportioning valve for front disc brakes.

89_Wagon wrote: ↑Fri May 07, 2021 6:02 am Are those drop in with stock rotors?

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Yes, the caliper is the same with the exception of the piston. Its approx 20% larger and the JB7 pads have approx' 25% more surface area. Theres plenty of writeups on the upgrade.

Thank you everyone. I appreciate your responses. for myself I normally do a dual diaphragm booster but typically I’m also running a assist on the steering and have witnessed flow issues with that and hydro boost. No assist going on this truck, no front locker and smallish (for me anyway) 33” tires so really no need for it

As part of my disc swap I did install a tuff stuff proportioning valve for disc/drum. I did use the large Chevy calipers. Also used Ford F-150 hubs/rotors to keep 5x5.5 wheels. The disc set up doesn’t work with axles shafts on the closed knuckle front but it’s going to get replaced with a later j10 front housing that I picked up this week and it will all direct carry over to that without any issues. I knew that was the plan and I why I didn’t mess with adding the cj style discs. I also installed a 1-1/8” bore master cylinder to properly supply those big calipers with the correct amount of fluid volume to keep the pedal high and tight instead of low and scary. I’ll put all of this info in one thread soon.

I got hydroboost added today. Picked up a booster off of a 2005 Chevy diesel, was a very simple conversion. It comes with a plate that booted it to the firewall. Drilled holes in that plate and original booster bracket, lengthened the push rod 1/2” and bolted it up. Brakes are fantastic.

I got hydroboost added today. Picked up a booster off of a 2005 Chevy diesel, was a very simple conversion. It comes with a plate that booted it to the firewall. Drilled holes in that plate and original booster bracket, lengthened the push rod 1/2” and bolted it up. Brakes are fantastic.

I got hydroboost added today. Picked up a booster off of a 2005 Chevy diesel, was a very simple conversion. It comes with a plate that booted it to the firewall. Drilled holes in that plate and original booster bracket, lengthened the push rod 1/2” and bolted it up. Brakes are fantastic.

Double post is weird, only clicked submit once

Yeller wrote:I got hydroboost added today. Picked up a booster off of a 2005 Chevy diesel, was a very simple conversion. It comes with a plate that booted it to the firewall. Drilled holes in that plate and original booster bracket, lengthened the push rod 1/2” and bolted it up. Brakes are fantastic.

What master cylinder did you use?

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Since I wrote this I developed a leaky booster and replaced it with another that I had and used the master cylinder that was with it, it works very nicely. The current unit is off of a 2003 3500 express van. I still had to lengthen the push rod 1/2" and used the flat adapter plate that came from the pick up unit instead of the formed one that came with the van unit. but it all interchanged and bolted up. Hope that all makes sense....LOL