Dan Wheeler's One-Ton 1.5" Bore Master Cylinder and Hydroboost Thread

[toddz69]

Interesting, I may not have an Astro HB then. I measured the bore, and it looks to be around 1.75-1.8”. This an SD hydroboost?

That's absolutely huge! I'm not sure what that is!

Todd Z.

 

[nvrstuk]

stretch- post a pic

 

[catfan]

Interesting, I may not have an Astro HB then. I measured the bore, and it looks to be around 1.75-1.8”. This an SD hydroboost?

The Astrovan bore is 1 5/8". The SD I have is 1.75.

 

[toddz69]

The Astrovan bore is 1 5/8". The SD I have is 1.75.

What year Astro van has a 1 5/8" bore? All the ones I've seen between 93-05ish are 1.25" bore.

Thanks,
Todd Z.

 

[tripleJs15]

Does anyone know the Wilwood Master cylinder part number for the 199-2004 Mustang hydroboost setup?

This is what I have:
https://shop.advanceautoparts.com/p...8-P?navigationPath=L1*14921|L2*15008|L3*15681

 

[catfan]

What year Astro van has a 1 5/8" bore? All the ones I've seen between 93-05ish are 1.25" bore.

Thanks,
Todd Z.

It's a 94-95 h-boost, the push rod has a 5/8" hole , the 90-93 have a 1/2 hole. I don't have a 90-93 unit to see what the bore is.

 

[gunnibronco]

Sorry to bring this back from the dead, but I was wondering if anyone knows if the 1.5" m/c will fit on the Mustang H-boost?

I'm mostly worried about the diameter of where the m/c fits into the h-booster. I can make an adapter plate to bolt the m/c to the h-boost if the m/c will fit into the h-booster. None of my parts stores/salvage yards has the F-350 m/c in stock for me to look at.

I need to make a big upgrade to my master cylinder for my new axles. I'll be running 96 F350 front brakes and JB6 rear brakes. I'd like to keep my Mustang booster if possible.

 

[DanWheeler]

Sorry to bring this back from the dead, but I was wondering if anyone knows if the 1.5" m/c will fit on the Mustang H-boost?

I'm mostly worried about the diameter of where the m/c fits into the h-booster. I can make an adapter plate to bolt the m/c to the h-boost if the m/c will fit into the h-booster. None of my parts stores/salvage yards has the F-350 m/c in stock for me to look at.

I need to make a big upgrade to my master cylinder for my new axles. I'll be running 96 F350 front brakes and JB6 rear brakes. I'd like to keep my Mustang booster if possible.

If I remember correctly, the 2 bolts/holes that attach the SuperDuty M/C to the booster won't line up - I think the superduty has a wider bolt pattern. Pretty sure the "flange" where the MC inserts into the h-boost is bigger than normal too. I'm not familiar with the Mustang H-boost - what MC are you using? Astro?

 

[gunnibronco]

If I remember correctly, the 2 bolts/holes that attach the SuperDuty M/C to the booster won't line up - I think the superduty has a wider bolt pattern. Pretty sure the "flange" where the MC inserts into the h-boost is bigger than normal too. I'm not familiar with the Mustang H-boost - what MC are you using? Astro?

I'm using the Mustang MC. The Mustang H-boost and MC have the mounting bolt pattern at 11 & 5 oclock instead of 3 & 9 oclock. It can be turned (if it will fit- I'm not sure), or I can build an adapter plate between the HB and MC. An adapter would allow me to bolt the F350 MC on IF the flange fits inside the HB body. Or I could possibly build an adapter long enough to fit the MC flange. I'll just have to figure out an extended push rod.

I actually found that our Napa has the F350 MC in stock with no reservoir so I can go look and take some measurements. I'm going to compare with a 99-04 SD MC that has a 1.375 bore. Both put me close to the "stock" MC bore to caliper piston area ratio (19-21:1). The OBS MCs have a 1.25" bore and put me around 23:1.

 

[DanWheeler]

I'm using the Mustang MC. The Mustang H-boost and MC have the mounting bolt pattern at 11 & 5 oclock instead of 3 & 9 oclock. It can be turned (if it will fit- I'm not sure), or I can build an adapter plate between the HB and MC. An adapter would allow me to bolt the F350 MC on IF the flange fits inside the HB body. Or I could possibly build an adapter long enough to fit the MC flange. I'll just have to figure out an extended push rod.

I actually found that our Napa has the F350 MC in stock with no reservoir so I can go look and take some measurements. I'm going to compare with a 99-04 SD MC that has a 1.375 bore. Both put me close to the "stock" MC bore to caliper piston area ratio (19-21:1). The OBS MCs have a 1.25" bore and put me around 23:1.

got it. Well, FWIF, I really like to see people matching the h-boost to the MC and to avoid using any kind of bracket. It's just such an important function. I don't like seeing those angle brackets. I went to great lengths to flip my 5.0 intake so I could run an unfettered H-boost/MC setup. I'd really recommend the SD h-boost and MC combo I did. If the stock SD reservoir doesn't fit, those Astro reservoirs fit the SD MC great. The SD MC/h-boost combo didn't do anything for my issue of not being able to lock up the fronts but I'm glad to have all Ford parts and a matching H-boost/MC setup with no funny business between them.

 

[gunnibronco]

Agreed on all that. I was able to accomplish that with the Mustang set up (no bracket/matched MC).

At this point my goal is to finish up my axle swap with minimal cash output (budget is already blown as usual), and minimal added "projects". So keeping my Mustang HB accomplishes both those. If adding a different MC gets complicated, I'll resort to swapping the SD HB as well. I haven't read up on what the SD HB swap involves. I'm sure the pedal push rod and hoses will change from what I've got now.

Thanks

 

[DanWheeler]

Agreed on all that. I was able to accomplish that with the Mustang set up (no bracket/matched MC).

At this point my goal is to finish up my axle swap with minimal cash output (budget is already blown as usual), and minimal added "projects". So keeping my Mustang HB accomplishes both those. If adding a different MC gets complicated, I'll resort to swapping the SD HB as well. I haven't read up on what the SD HB swap involves. I'm sure the pedal push rod and hoses will change from what I've got now.

Thanks

yeah, totally get that for sure. It really adds up and goes over planned. I haven't seen the mustang h-boost but yeah could need new hoses/adapters, could snowball messsing with the pedal etc. etc.

Let me know if you're in a jam on that SD MC measurement. It wouldn't be too hard for me to pull mine off the H-boost an inch or so enough to get a calipers in there to measure the flange diameter and bolt spacing.

 

[gunnibronco]

It looks like none of the MCs I'm looking at will fit into the Mustang HB. The bolt spacing is the same, but the flange that fits into the HB won't fit.

The Mustang HB/MC flange is 1-1/2".
The 96/97 flange is 1-5/8".
The 99-04 SD flange is 1-3/4".
I'm betting the 05+ SD flange is the same 1-3/4", I'll be able to measure one later today.

I have an Explorer EFI upper in the "stock" position and no body lift. You said you flipped the upper intake to clear the HB. Did you try to turn the HB 180*? Did it not fit? I could see it interfere with the steering column possibly.

I'm also thinking it could be possible to put the SD HB on the Mustang mounting flange, it has a slight angle to it pointing it away from the EFI manifold.

I found a salvage yard close with 99-05 and 05+ SD HBs and I'm thinking of picking one up.

On another note, the MC reservoir spacing looks the same on all 3 MCs I've measured (we'll see about the 05+ SD). I'm wondering if the shorter 96/97 MC reservoir might work on the 05+ MC. I don't know what the fitting diameters are yet. Just thinking out loud.

Thanks

 

[DanWheeler]

It looks like none of the MCs I'm looking at will fit into the Mustang HB. The bolt spacing is the same, but the flange that fits into the HB won't fit.

The Mustang HB/MC flange is 1-1/2".
The 96/97 flange is 1-5/8".
The 99-04 SD flange is 1-3/4".
I'm betting the 05+ SD flange is the same 1-3/4", I'll be able to measure one later today.

I have an Explorer EFI upper in the "stock" position and no body lift. You said you flipped the upper intake to clear the HB. Did you try to turn the HB 180*? Did it not fit? I could see it interfere with the steering column possibly.

I'm also thinking it could be possible to put the SD HB on the Mustang mounting flange, it has a slight angle to it pointing it away from the EFI manifold.

I found a salvage yard close with 99-05 and 05+ SD HBs and I'm thinking of picking one up.

On another note, the MC reservoir spacing looks the same on all 3 MCs I've measured (we'll see about the 05+ SD). I'm wondering if the shorter 96/97 MC reservoir might work on the 05+ MC. I don't know what the fitting diameters are yet. Just thinking out loud.

Thanks

Bummer it doesn't fit. Were you heading down this route of sizing up the MC just to get the MC bore to brake piston ratio in the right range? Reason I ask is because when I moved from the 1.25" Astro MC to the 1.5" SD MC, I didn't gain any braking improvement. I know the bigger MC is better on paper but after upgrading, I still question what I actually gained and I'm on one-tons with 41" tires. My 1.25" Astro MC had zero issues locking up the rears when I still had the huge Chevy JB7 calipers. In fact, I sized the rears down to the eldorado calipers and I could still lock up the rears with the 1.25" Astro MC. It's always been the fronts I can't get to lock up on dry pavement and that's why I tried the super duty MC but it didn't make any difference. I barely felt a different in the pedal firmness with the bigger MC bore.

 

[gunnibronco]

Interesting.

I am changing from front T-bird calipers and 79 F150 drum rears to 96 F350 front brakes and JB6 Chevy rears. The Mustang MC is only 1" bore.

When I changed from the 79 F150 calipers to the T-bird calipers, it pulled my brake bias forward as planned, but the pedal became noticeably longer/softer. Performance is fine- 33's then and 37's now.

I'm expecting totally unacceptable performance from the small MC bore with the new brakes.

I've used the page below that gives a pedal ratio/MC bore/front caliper size relationship. Using it, my new set up comes out slightly below 1.25" MC bore.

Effects of Master Cylinder Bore Size on Your Brake System

Follow this guide to learn how the change of bore size on a master cylinder affects a four-wheel disc brake system. View the conversion chart to figure the total bore area for your brake setup.

www.speedwaymotors.com

The MC bore/total caliper ratio looks ok for me with MCs from 1.25" - 1.5". My guess is any of these sizes will perform adequately. But with the relatively huge calipers and the assistance of Hboost, I'm leaning towards bigger is better.

I just want to land on something that works the first time. I'm also weighing the time/cost of fabrication to make mismatched stuff work together against buying something like a complete SD set up. I do have an old vacuum angle bracket that could make an Astro van set up work easily, I didn't know the MC was 1.25" and might work. There are so many options, and it takes so much time to read up on how to make each one work. My head is swimming in all the options.

 

[DanWheeler]

ohhh, yeah 1" is a little small for those big brakes. Well, hard to go wrong with the SD HB/MC combo. Just more $$$ and screwing around with hoses, mounting, pedal etc.

To answer your question about my flipped intake, I think with my 3" body lift, the intake in it's stock position would have been in the way of either the h-boost and/oor the master cylinder, I don't remember but I think that's why most people have the angle bracket but I wanted nothing to do with that so I flipped my intake and had the Explorer elbow machined down just a bit shorter so it would clear the hydroboost and master cylinder. That was all back in 2009 and to this day, I've never heard of anyone else doing that, it's one of my favorite mods.

 

[gunnibronco]

Have you ever installed a prop valve to turn the rears down, to prevent them from locking up? I know that it doesn't make the fronts "stronger", but it would move the bias forward and balance the performance.

I'd 100% do the SD HBoost/MC if I knew it would clear the EFI (stock or clocked 180*). Most the pics I've seen use the smaller Dodge MC with a spacer and the HB is clocked 90*.

I see 3 possible routes forward right now-
SD HB - clocked 180*
SD HB - mounted to the Mustang firewall bracket- the booster reservoir location of the SD and Mustang HB are very similar, but my Mustang set up needed turned very slightly off vertical to clear the upper intake- a little weird looking but works great
Astro MC on my Mustang HB- it looks like an adapter plate could be used for the bolt pattern and the pushrod from the HB trimmed- not ideal (adapter plate) and smaller bore than the SD

 

[DanWheeler]

Another option would be Astro HB and MC matched pair. Might be cheaper and easier to find and the reservoirs sit lower than superduty. You'd also be in good company with lots of other Broncos and I think 1.25" bore would be plenty with your 33s even if not perfect on paper. I ran this for years with the JB7 rear calipers and Ford Dana 60 front calipers on 41s.

How are people doing a 90 degree clocking on the HB? Wouldn't that put your MC sideways and all the fluid would run out?

I do have a prop valve on my setup. The rears are turned way down but the rears still lock up while the fronts won't. I think if I get on some wet pavement the fronts will lock up. I have a lot of dive from my link setup so I think there's just a ton of weight transfer pushing down on those big 41s that keep them from locking up. The stock Ford Dana 60 calipers aren't gigantic - two pistons each, I forget the size. You'd think they would be huge on a 1-ton truck that tows but maybe they don't upsize front brakes on tow rigs because a lockup in the front hauling a trailer might send you into a jackknife.

 

[gunnibronco]

I'm running 37s now and will be going bigger in the future, I'm sure. That's why I'm moving to 1 ton axles.

I *think* a 1.25" MC might be enough, but I'd rather overkill it than come up short. Good to know you ran that with D60/JD7s. I'll be running the D60 with smaller JD6s. The OBS D60s have 2 x 2.2" pistons/caliper.

Most the SD HB are installed turned 90* with a spacer/adapter to the Dodge MC. The HB bolts are at 12 & 6 oclock, and the spacer/adapter bolt holes are at 3 & 9 for the MC. Something like this would let me install the Astro MC on my Mustang HB, or really any MC. I'd just have to adjust the push rod length. You can see the spacer in this pic. But I'd like have a matched system, and if I'm going to rework for a whole new HB then I'd rather install the larger SD option.

 

[DanWheeler]

I'm running 37s now and will be going bigger in the future, I'm sure. That's why I'm moving to 1 ton axles.

I *think* a 1.25" MC might be enough, but I'd rather overkill it than come up short. Good to know you ran that with D60/JD7s. I'll be running the D60 with smaller JD6s. The OBS D60s have 2 x 2.2" pistons/caliper.

Most the SD HB are installed turned 90* with a spacer/adapter to the Dodge MC. The HB bolts are at 12 & 6 oclock, and the spacer/adapter bolt holes are at 3 & 9 for the MC. Something like this would let me install the Astro MC on my Mustang HB, or really any MC. I'd just have to adjust the push rod length. You can see the spacer in this pic. But I'd like have a matched system, and if I'm going to rework for a whole new HB then I'd rather install the larger SD option.

oh OK I thought you said 33s but yeah if 37s or more then by all means step on up to super duty.

Oh man, I don't know about that clocking adapter plate. I know there's a million things an insurance adjuster would use to exempt themselves from a payout if one of our heavily modified Broncos got in an accident but that in particular does not seem safe. That looks like a good 1/2" being taken away from the total pushrod throw distance on the hydroboost. Are the h-boost push rods adjustable?