Hydroboost brake conversion

[Blacktop]

Oh. Ok. I didn't read the writeups.

But if you are at a salvage getting the parts, then get the pedal as well so it'll be a bolt-in. (Or, if you have a good friend pulling the parts, have him get it. ) And the later pedal will work in a Bullnose bracket. I've tried.

I'm hoping to source all the parts on rockauto and ship them over to me here in the UK.

I will read all the info on the link and get myself educated fully on the conversion first though.

Thanks again for all your help guys👍

[Ford F834]

I'm hoping to source all the parts on rockauto and ship them over to me here in the UK.

I will read all the info on the link and get myself educated fully on the conversion first though.

Thanks again for all your help guys👍

Hello, once again I am late to the party but hopefully I can still add value to the discussion.

The very basic parts that you need are the booster, pump-to-booster pressure hose, booster-to-steering-gear pressure hose, and booster to reservoir low pressure return line. All of these are available at RockAuto.

The return line on the factory trucks went into a second bung on a hydroboost specific reservoir for the C2 steering pump. It used to be you could order this, and swap the plastic reservoir, but they are obsolete. Most people simply use a brass T to join it with the return from the steering gear. This is what I did and it works fine. It’s not as “clean” of an install but it works.

As far as the master cylinder, I used the F450 unit because it came with the booster. It has larger a piston diameter because of the larger wheel cylinder volume and rear disc brakes on the F-Superduty. The side effect of the larger piston is less pedal travel. This may or may not bother you, but my pedal stays way up there. Hydroboost does not have much pedal travel anyway. If you do order the F450 master cylinder and reservoir, select “without cruise/speed control” since you don’t need that electric cancel switch.

Many F250/350 owners opt to use their existing master cylinder which is fine if you have the HD vacuum booster. The stud spacing is the same and they will bolt to the hydroboost. It looks like you are working with a F150. Your master cylinder should therefore be the one for the light duty vacuum booster. The mounting stud spacing is closer together and it will not fit. If you want you can buy and use a F250 HD or F350 master cylinder as they are cheaper and easier to find. I would recommend the 87-96 style with the aluminum body and plastic reservoir vs. the old cast iron type.

The next issue that you are going to run into with your F150 is the master cylinder brake line fittings are different (than either the F250/350 master cylinder ports or the F450 F-Superduty ports). I could not find an adapter to reduce the large diameter plug on the forward port. I ended up taking the brake line off of my project F350 and buying step fitting to fit it to the master cylinder. You can, of course, cut the line, replace the fitting and re-flare the line, but for brakes I prefer the factory tooling.

The hydroboost brake pedal is the hard part to find. A lot of F250/350 owners use their existing pedal with no complaints. If they later upgrade to the right pedal, the usual comment is that it has improved pedal feel. However, note that the F250 HD F350 vacuum pedal is different than the light duty vacuum pedal. The pin is higher. I do not know of anyone who has tried to use a half ton vacuum pedal with hydroboost, but I don’t think it would work well. I think the geometry with the rod is too different. The leverage would be even less, resulting in (probably) unacceptable pedal feel. If you can’t find a hydroboost pedal, I would at the very least try to find a HD vacuum pedal, or better yet find a machinist to move the pin. There is a guy on one of the diesel Facebook pages that offers that service. Below is a photo showing the light duty vacuum pedal (left) HD vacuum (two in the center) and hydroboost (right).

Here is the correct pin location for hydroboost:

Here is a thread on modifying the pin:

https://www.powerstrokenation.com/forums/17-1994-1997-power-stroke-technical-info/196241-converted-vacuum-brake-pedal-into-hydroboost-pedal.html?amp=1

Last comment... hydroboost brake conversion is TOTALLY worth it. It’s not that big of a job, it can be done in a few hours and puts your braking power in a whole different class. Minus modern Anti-Lock capabilities, the brakes on my ‘81 F150 are the best of any vehicle I’ve ever owned.

 

[Ford F834]

Hello, once again I am late to the party but hopefully I can still add value to the discussion.

The very basic parts that you need are the booster, pump-to-booster pressure hose, booster-to-steering-gear pressure hose, and booster to reservoir low pressure return line. All of these are available at RockAuto.

The return line on the factory trucks went into a second bung on a hydroboost specific reservoir for the C2 steering pump. It used to be you could order this, and swap the plastic reservoir, but they are obsolete. Most people simply use a brass T to join it with the return from the steering gear. This is what I did and it works fine. It’s not as “clean” of an install but it works.

As far as the master cylinder, I used the F450 unit because it came with the booster. It has larger a piston diameter because of the larger wheel cylinder volume and rear disc brakes on the F-Superduty. The side effect of the larger piston is less pedal travel. This may or may not bother you, but my pedal stays way up there. Hydroboost does not have much pedal travel anyway. If you do order the F450 master cylinder and reservoir, select “without cruise/speed control” since you don’t need that electric cancel switch.

Many F250/350 owners opt to use their existing master cylinder which is fine if you have the HD vacuum booster. The stud spacing is the same and they will bolt to the hydroboost. It looks like you are working with a F150. Your master cylinder should therefore be the one for the light duty vacuum booster. The mounting stud spacing is closer together and it will not fit. If you want you can buy and use a F250 HD or F350 master cylinder as they are cheaper and easier to find. I would recommend the 87-96 style with the aluminum body and plastic reservoir vs. the old cast iron type.

The next issue that you are going to run into with your F150 is the master cylinder brake line fittings are different (than either the F250/350 master cylinder ports or the F450 F-Superduty ports). I could not find an adapter to reduce the large diameter plug on the forward port. I ended up taking the brake line off of my project F350 and buying step fitting to fit it to the master cylinder. You can, of course, cut the line, replace the fitting and re-flare the line, but for brakes I prefer the factory tooling.

The hydroboost brake pedal is the hard part to find. A lot of F250/350 owners use their existing pedal with no complaints. If they later upgrade to the right pedal, the usual comment is that it has improved pedal feel. However, note that the F250 HD F350 vacuum pedal is different than the light duty vacuum pedal. The pin is higher. I do not know of anyone who has tried to use a half ton vacuum pedal with hydroboost, but I don’t think it would work well. I think the geometry with the rod is too different. The leverage would be even less, resulting in (probably) unacceptable pedal feel. If you can’t find a hydroboost pedal, I would at the very least try to find a HD vacuum pedal, or better yet find a machinist to move the pin. There is a guy on one of the diesel Facebook pages that offers that service. Below is a photo showing the light duty vacuum pedal (left) HD vacuum (two in the center) and hydroboost (right).

Here is the correct pin location for hydroboost:

Here is a thread on modifying the pin:

https://www.powerstrokenation.com/forums/17-1994-1997-power-stroke-technical-info/196241-converted-vacuum-brake-pedal-into-hydroboost-pedal.html?amp=1

Last comment... hydroboost brake conversion is TOTALLY worth it. It’s not that big of a job, it can be done in a few hours and puts your braking power in a whole different class. Minus modern Anti-Lock capabilities, the brakes on my ‘81 F150 are the best of any vehicle I’ve ever owned.

I need to adjust my statement on the later (87+?) master cylinders. I just looked at the one on my ‘89 F250 parts truck and it looks like the forward port may be larger, just like my ‘81 F150... sorry for any misinformation, I’ll look into it a bit more...

[ArdWrknTrk]

I need to adjust my statement on the later (87+?) master cylinders. I just looked at the one on my ‘89 F250 parts truck and it looks like the forward port may be larger, just like my ‘81 F150... sorry for any misinformation, I’ll look into it a bit more...

Jonathan,

Are you suggesting that the brake line from any bricknose large bore (250,350) master cylinder can be used?

I've reflared the nut from the (hydroboost) donor onto a 150 line before.

But, that was only once.

The other times I've done or helped with conversion it's always been a brick or aero diesel 350.

These go right together, IIRC.

ETA: the doglegs all look the same, just the pin location is higher. (56mm or 2 1/4") from the pivot sleeve?

[Ford F834]

Jonathan,

Are you suggesting that the brake line from any bricknose large bore (250,350) master cylinder can be used?

I've reflared the nut from the (hydroboost) donor onto a 150 line before.

But, that was only once.

The other times I've done or helped with conversion it's always been a brick or aero diesel 350.

These go right together, IIRC.

ETA: the doglegs all look the same, just the pin location is higher. (56mm or 2 1/4") from the pivot sleeve?

Jim, what I see is that the ‘89 F250 aluminum MC front flare nut is bigger than my ‘86 F350 cast iron MC front flare nut. Since I needed a stepper to mate that steel line to the hydroboost MC you are probably correct that the bricknose F250 steel lines will fit the hydroboost directly. I know the front flare nut from the ‘81 F150 cast iron MC was too big, and I was unable to find any fittings to reduce it. I think on a 1/2 ton you’d have to change the steel line or cut it and re flare it with a different flare nut.

The pedal legs are all the same, it is just the pin height that changes.

[ArdWrknTrk]

Jim,

The pedal legs are all the same, it is just the pin height that changes.

Thanks for your reply, Jonathan.

Quite a lot of valuable information added!

I just wanted to point this out to Gary, for when he writes up the inevitable hydroboost tutorial.

With the 3G conversion it took a while to get the details filled in.

what I see is that the ‘89 F250 aluminum MC front flare nut is bigger than my ‘86 F350 cast iron MC front

flare nut. Since I needed a stepper to mate that steel line to the hydroboost MC you are probably correct that the bricknose F250 steel lines will fit the hydroboost directly. I know the front flare nut from the ‘81 F150 cast iron MC was too big, and I was unable to find any fittings to reduce it. I think on a 1/2 ton you’d have to change the steel line or cut it and re flare it with a different flare

I've been incredibly frustrated in the past working on equipment hardlines.

Sure, there's always a hydraulic shop willing to make up hoses and lines,

But when you have the tools and the auto parts has coils, or brake line to length, and you need it NOW (like your bucket truck blew something in the valve manifold, or the excavator is puking 10 gpm in the customer's driveway) it makes you wish that everything conformed to an international standard. 😖

Ford's oddball left rear brake line comes to mind.

Sure, most places might have the nut or adapter, but why not stock the one line that fits a millions of Ford's spanning decades?

Harking back to my discussions with Gary about youthful parts store associates not having experience with older vehicles, it can take awhile to get it across. 😖

Keep an eye on that new member of your stable.

From what I've seen, your kids are likely to hotwire it, and take it joyriding!

[Gary Lewis]

I just wanted to point this out to Gary, for when he writes up the inevitable hydroboost tutorial.

With the 3G conversion it took a while to get the details filled in.

what I see is that the ‘89 F250 aluminum MC front flare nut is bigger than my ‘86 F350 cast iron MC front

flare nut. Since I needed a stepper to mate that steel line to the hydroboost MC you are probably correct that the bricknose F250 steel lines will fit the hydroboost directly. I know the front flare nut from the ‘81 F150 cast iron MC was too big, and I was unable to find any fittings to reduce it. I think on a 1/2 ton you’d have to change the steel line or cut it and re flare it with a different flare

That certainly is really good info. And, there is certainly a hydroboost tutorial coming - as and when I get BB's system converted. But y'all may have to remind me of this info.

I think I saved the brake lines from Huck, the Bricknose F250, so I may be in luck. And, if I get a chance to go to to the shop later today I may try to track that line down as well as the F450's master and see if it fits. (It obviously fit on Huck's plastic/aluminum MC.)

[salans7]

I just wanted to point this out to Gary, for when he writes up the inevitable hydroboost tutorial.

With the 3G conversion it took a while to get the details filled in.

what I see is that the ‘89 F250 aluminum MC front flare nut is bigger than my ‘86 F350 cast iron MC front

flare nut. Since I needed a stepper to mate that steel line to the hydroboost MC you are probably correct that the bricknose F250 steel lines will fit the hydroboost directly. I know the front flare nut from the ‘81 F150 cast iron MC was too big, and I was unable to find any fittings to reduce it. I think on a 1/2 ton you’d have to change the steel line or cut it and re flare it with a different flare

That certainly is really good info. And, there is certainly a hydroboost tutorial coming - as and when I get BB's system converted. But y'all may have to remind me of this info.

I think I saved the brake lines from Huck, the Bricknose F250, so I may be in luck. And, if I get a chance to go to to the shop later today I may try to track that line down as well as the F450's master and see if it fits. (It obviously fit on Huck's plastic/aluminum MC.)

I had no idea the pushrod pin for the brakes was higher up on the HD and 350 trucks. I'm glad I pulled my pedal assembly from an F350.

[Gary Lewis]

I had no idea the pushrod pin for the brakes was higher up on the HD and 350 trucks. I'm glad I pulled my pedal assembly from an F350.

And I'll save the one off Big Blue when I convert him.

[Blacktop]

And I'll save the one off Big Blue when I convert him.

So much useful information, many thanks for your info Jonathan👍.

If I can source the push rod and parts between the mc and booster I may well go ahead with this conversion. I remember having to alter the pedal pin on my foxbody mustang when I did a cobra brake conversion on that. I can easily fabricate new brake lines with whatever size fittings I need to suit. Will also fit the larger bore later mc and a proportioning valve in to the rear line as I still have rear drum brakes.

Thanks again guys, this forum is great!😁