Hydroboost unit/Master cylinder conundrum

[IChaseCoues]

Hey guys I have a 74 that I'm rebuilding (slowly but picking up steam) and am stalled with the hydroboost for the moment. I have searched for days with no success on this one.
The HB unit i purchased was supposed to be from an early 90's Astro but a 93 MC doesn't fit. The "nose" on the MC flange that mates to the HB is 1.925" and the corresponding hole in the HB is 1.63". The HB came with the flat mounting plate attached like a 93 not a 96+ angled plate. In the search for the right MC I ordered one for a 96+ with angled reservoir which had the correct "nose" diameter but will not fit because of the clocking plate and 1/2 inch line threads.
It is so frustrating that no parts stores or sites list full specs or drawings of the parts anymore! It's a guessing game so many times to get parts even for vehicles that I know inside and out.

So the questions are:
1: Is there a MC for a 93 Astro with a "nose" dia of 1.63"-?
2: Would someone be kind enough to measure the dia of the HB mating flange hole?

Thanks in advance for any info!
I don't post here much but have been benefiting from this forums vast knowledge for years. Thank you all for such valuable information.

 

[904Bronco]

This is for 95 parts:

Raybestos master MC-39961 shoulder is a hair over 1.5" dia. that goes into the HB unit.

Cardone #52-7333 reman unit has an opening of just over 1 5/8"

Stud spread center to center is 3 7/16"

I am in the middle of this conversion... 3rd time around... Doug.

 

[garberz]

78’ Camaro MC. Disc/drum.

Mark

 

[Rustytruck]

I have had better luck looking up parts at rock auto then when you get to the part look up the technical page. Sometimes you get lucky. Use to get technical information at napa site but they dumbed down their site too. I guess its too much work to keep up with.

 

[IChaseCoues]

Thanks for the fast response guys!
I looked up the Raybestos MC and it says it fits the early 90's Astro van. Makes me wonder what my local parts store has going wrong. I'll order it from Summit Racing and hope it fits when it gets here!
Will post results when I can.

 

[bronconut73]

78’ Camaro MC. Disc/drum.

Mark

Might should order this one too OP.

 

[904Bronco]

Might should order this one too OP.

Well the one I used (Camero) leaked brake fluid out the top could not get it to stop. So I started using the Astro Van master. Bigger bore, but it stops just fine. And no leaks.
Just my experience.

 

[904Bronco]

Almost done with my conversion...

 

[bronconut73]

Well the one I used (Camero) leaked brake fluid out the top could not get it to stop. So I started using the Astro Van master. Bigger bore, but it stops just fine. And no leaks.
Just my experience.

You have to remove the bail and bend it quite a bit.
Makes it a bitch to remove but it stops the leaks.

More conventional looking alumimum mc with a plastic reservoir is the Dodge Ramcharger or Truck mc from the 80's.

Its popular for us eb owners.

 

[bronco t]

Almost done with my conversion...

Hello 904... Where did you get your PS reservoir from? I like where you positioned the return lines.

 

[904Bronco]

Hello 904... Where did you get your PS reservoir from? I like where you positioned the return lines.

https://classicbroncos.com/forums/showthread.php?t=301374


Guys name is Jaimie, he is on EBay. Took me a few weeks to get this one made as he has had some parts delivery issues (like all of us) and he works full time. He makes Rad overflow bottles as well, located in the Fresno area of CA. He does great work, responsive, asked a lot of questions about your build to make sure it fits. The above thread has contact info...

Doug

FYI... my eBay link is dead on thread above. Contact him via the email link provided....

Here are the spec's for mine:

5.0 V8 Explorer motor
2" from the hood cross brace to the top of the PS mounting bracket (He had me measure this)

4" reservoir diameter
5/8" barbed outlet to the PS pump
6an returns: one HB at 12 o'clock and the other PS box at 5 o'clock

Hope this helps everyone.

 

[Rustytruck]

looks like a really nice set-up.