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preferred hydroboost options

Bronchole

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Mar 24, 2004
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Chatsworth, Ca (LA)
Been a while since I have been on here. I am helping a friend improve his brake system on his 67 Bronco and wanted to know what the current "best" hydroboost and master cylinder setup is to achieve the best braking he can get. I recommended that he stick with the 11x2.25" drum brakes on the rear mainly because I have never been impressed with any of the disc conversions. We are replacing the wheel cylinders with some new 15/16" diameter ones and putting new shoes on. In the front I have him going with the Thunderbird calipers. Replacing all the hoses and lines. Looks like adapting a saganaw pump on to his engine should be pretty easy, just need to find one with the dual returns on it somewhere.

He already has a bracket that kicks his current vacuum boost and master off at a 45° angle. I figured I would make some sort of adapting plate to mount a Astro van hydroboost unit. If I go that way, what master cylinder should I use? I have seen the couple threads talking about adjusting the length of the push rod to correctly engage the master. I think I can handle that pretty easily.

I have seen the kits now available from all the Bronco vendors, but wow that looks like quite a bit of markup. I am a cheap bastard and can't see spending $1k+ on the hydroboost and master.
 

RODRIG3911

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Jul 9, 2007
Messages
970
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Tucson
I'm running the Astro-Hydroboost setup with a 70's Corvette MC. I have the Big drum brakes on the rear and T-bird calipers up front... It stops on a dime! I bought my Astro-HB on here for like 40 bucks. The hoses I had made locally at Hosepower USA for $70. The Corvette master cylinder was about $80 on ebay brand new. I've been running the hydroboost for about 6 years now with zero complaints. I am running a dual return Saginaw
 
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Bronchole

Bronchole

Bronco Guru
Joined
Mar 24, 2004
Messages
1,611
Loc.
Chatsworth, Ca (LA)
I'm running the Astro-Hydroboost setup with a 70's Corvette MC. I have the Big drum brakes on the rear and T-bird calipers up front... It stops on a dime! I bought my Astro-HB on here for like 40 bucks. The hoses I had made locally at Hosepower USA for $70. The Corvette master cylinder was about $80 on ebay brand new. I've been running the hydroboost for about 6 years now with zero complaints. I am running a dual return Saginaw
Is this the master cylinder?

1975 Corvet power master cylinder from Rock Auto
 

RODRIG3911

Sr. Member
Joined
Jul 9, 2007
Messages
970
Loc.
Tucson
What is "the year" for the Astrovan hydroboost I should be looking for?
Here's a couple links that helped me. There was another useful write up I used using a newer truck Hydroboost. That first one by Dan Wheeler is really nice and has all the part numbers he used on his. As for the year Vette MC, I BELIEVE I used a 1979 Corvette master but it's probably the same part number you posted... This was one of by best upgrades I've done man. It was pretty cheap to do DIY, but there was alot of reading and tinkering to get it just right. Good luck
https://classicbroncos.com/forums/threads/dan-wheelers-astro-hydroboost-thread.175818/
https://classicbroncos.com/tech/hydroboost-brakes
 
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Bronchole

Bronchole

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Joined
Mar 24, 2004
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Loc.
Chatsworth, Ca (LA)
Where do I get the push rod that goes between the master cylinder and the hydroboost? I am going with the 1992 hydroboost (1/2" push rod hole) and the 1976 Corvette 1.125" bore master cylinder.

I'll read thru the couple threads recommended above tonight.
 

toddz69

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Where do I get the push rod that goes between the master cylinder and the hydroboost? I am going with the 1992 hydroboost (1/2" push rod hole) and the 1976 Corvette 1.125" bore master cylinder.

I'll read thru the couple threads recommended above tonight.
I probably have one that will work. I think the Corvette master has a shallow hole in the back.

Todd Z.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,614
We have used Astro HB and M/C as a unit. They work better than GREAT. I don't understand the reasoning to try to adapt different mc's onto the Asto HB unless it's for appearance or ??

With ANY HB conversion you want to make sure you install a mechanical brake bias valve so you can dial in the correct bias to those rear drum brakes (which take LESS pressure to operate than discs do).

The Astro MC reservoirs do not leak, weep or rust :). They are low profile.

We have had excellent resutls with the Astro HB & MC when running this combo with the T-bird calipers up front.

Good luck
 

RODRIG3911

Sr. Member
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Jul 9, 2007
Messages
970
Loc.
Tucson
To add some more experience with the Astro master cylinder, It worked awesome for me too just like nvrstuk. For me it was WAY too touchy though. I didn't have much brake peddle feel at at. It would just stop extremely hard, almost too good! Mine had an angled brake fluid tank that I didn't like either, but they aren't all like that. In the end it'd probably personal preference, but the Corvette MC does have a really nice peddle feel in my opinion
 

nvrstuk

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Just a Bronco driver for over 50 yrs!
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8,614
I wrenched at a GM dealership for years with "touchy" pedals on GM cruisers. I know what those are like! ;)

Rodrig3911, were you running the Tbird calipers or stock? Maybe that bore dia difference is all it was.. That much bore dia can be enough to make that difference. Also , what size tire?

Just wondering.
 

RODRIG3911

Sr. Member
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Messages
970
Loc.
Tucson
I wrenched at a GM dealership for years with "touchy" pedals on GM cruisers. I know what those are like! ;)

Rodrig3911, were you running the Tbird calipers or stock? Maybe that bore dia difference is all it was.. That much bore dia can be enough to make that difference. Also , what size tire?

Just wondering.
At the time I upgraded to Hydroboost I still had the K5 Chevy calipers on the front with BB 11" drums. I recently upgraded to F150 Knuckles with T-bird calipers.. You make a good point about bore size possibly being different. As for tires, I'm running 33x12.5r15
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
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8,614
Yup, bore, tire size/tire rotating weight make big differences.

I literally "hate" rusty or paint peeling mc's. Rest of my rig can look ugly and I'll fix that first! LOL (correctiin- second to any oil leak). ;)
 

toddz69

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There are at least 2 different bore sizes with the Astro master cylinders too. The earlier ones were 1.125" bore units with some appearing to be the quick take-up stepped bore models. Later units (late '90s, etc.) were 1.25" bore. You'll definitely have a different pedal feel with those two bores, with the smaller one being 'touchy'.

I recently changed to a 1.25" bore master on my truck (used a Dodge one) and I really like the pedal feel. Pedal is a lot more solid, has less travel, is a lot less 'touchy' but still has good braking power. I've recommended 1.125" bore masters for our rigs for the last 20+ years of using hydroboost but if you're using the T-Bird calipers or other similar large bore piston calipers (I happen to have some Dodges on the front of mine) - I'd encourage you to try the 1.25" bore as well.

Todd Z.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
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Messages
8,614
Most don't understand all the ratios and how as little as .125" bore can make so much difference when dealing with discs-makes a big difference.

I have since bumped to 1.33" bore with my JD6 calipers on all 4 corners.

Great pedal feel & good stroke distance-great combo for my tons frt & rear.

Thx for posting up Todd.
 

toddz69

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Most don't understand all the ratios and how as little as .125" bore can make so much difference when dealing with discs-makes a big difference.

I have since bumped to 1.33" bore with my JD6 calipers on all 4 corners.

Great pedal feel & good stroke distance-great combo for my tons frt & rear.

Thx for posting up Todd.
You and Yeller were two of my inspirations for trying a larger one, Brian!

Todd Z.
 
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Bronchole

Bronchole

Bronco Guru
Joined
Mar 24, 2004
Messages
1,611
Loc.
Chatsworth, Ca (LA)
I also been looking for the dual; return power steering pump. I was going to use the 1974 Lincoln Mark IV one, but they are not very available. Looks like the 2003 Chevy 2500 has the dual return and is very available. Any reason not to go that rout?
 
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