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Hydroboost brake conversion

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Gary Lewis

Re: Hydroboost brake conversion

Administrator

Agree on the politics.

But, I love the adjustable link. Well done!

So, do you have the new bracket made? In other words, how close are you to having this thing wrapped up?

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Blacktop

Re: Hydroboost brake conversion

Making the bracket now. Just two adapter plates really. Need to buy/ repair the 1 5/8" mounting nut. Hoping to install asap.

1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧

Blacktop

Re: Hydroboost brake conversion

Welded the retaining nut and finished the adapter plates. Need to weld the bolts to the plates as wont be able to get to the back sides to stop them turning when installing.

1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧

Gary Lewis

Re: Hydroboost brake conversion

Administrator

Looking good!

How did the retaining nut turn out? Did you install it, clamp it, and tak it? Wanting to learn.

Gary, AKA "Gary fellow": Profile

Blacktop

Re: Hydroboost brake conversion

My brother is a far better welder than me. I got him to tig weld it for me. He managed to save it without any distortion so it’s good to use again👍

1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧

Gary Lewis

Re: Hydroboost brake conversion

Administrator

A wise man once said "A man's got to know his limitations." And, while I can weld, when it comes to important stuff I call in a pro as well.

Gary, AKA "Gary fellow": Profile

Ford F834

Re: Hydroboost brake conversion

Administrator

Blacktop, nice job! I am always happy to see a new approach and I look forward to your report on how your set up performs. It looks great!

I know this thread has taken a turn, but I did want to add a couple of notes for Gary and anyone else going for the F-450 hydroboost conversion. I don’t know where else to document this...

When Jan did his conversion in his 1986 F250, he used the existing cast iron master cylinder and HD vacuum brake pedal. He was happy with the braking power, but in time the cast iron master cylinder failed. He wanted to get away from the rust that grew in the stock MC, so I ordered him a F-450 hydroboost master cylinder and reservoir (the large diameter bore). He said he had to shim the MC out about 2mm to prevent the rod from applying constant pressure to the master cylinder. He also said that the pedal feel went from nice and soft with aggressive braking to hard as a rock with a lot of force needed to stop the truck. He said it felt like manual brakes without power assist. He said it was awful. So he modified the vacuum pedal by moving the pin to the hydroboost position. He said the difference was HUGE. Night and day. It stops way better with only a fraction of the force needed. (He also said he no longer needed the 2mm or shim to prevent pressure on the MC). Great, we already knew this, *but, he says the cast iron master cylinder set up might still have had a nicer, softer, pedal feel. Our trucks don’t particularly need the large master cylinder volume because of the smaller wheel cylinders and rear drum brakes vs. discs. So is the better choice an aluminum master cylinder from a F250/350 and a smaller bore? Perhaps the higher pedal pin is to give the leverage needed for the bore size? When I set up hydroboost on my crew cab I may strongly consider using the smaller bore master cylinder. I think I might still want the hydroboost pedal to match the booster, but that might be up for debate as well. Perhaps the pedal matching the master cylinder is more appropriate? The higher pin with the F250 master might make require less force but might be too “touchy” if the resistance is too low. I don’t have answers yet, just throwing this out there since it is news to me...

SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2

Gary Lewis

Re: Hydroboost brake conversion

Administrator

Jonathan - That's good info and interesting speculation. I got the whole F450 hydroboost setup with master cylinder and pedal, so will give that a try. But I'll hang on to the HD pedal so I can go to a smaller master cylinder if needed.

However, Big Blue will have F350 front calipers. Are those any bigger than those on 250's? (I guess I could go look, but...)

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Hydroboost brake conversion

Administrator

250-350 same calipers. But you have the later bolt on ones, not slide clips, so I can't say how much bore is in those compared to mine.

From years of modifying and racing motorcycles, I can say master/slave ratio is critical to feel and performance.
The pivot point of lever to master just changes the effort required, but it can't save/change wooden or touchy brakes

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Ford F834

Re: Hydroboost brake conversion

Administrator

In reply to this post by Gary Lewis

Jim said it... the F250/350 uses the same calipers and wheel cylinders. Heck, I am using the big F450 master cylinder on my single piston F150 calipers. Pedal does not move down much but I have NO complaints. I just wonder if one of the other master cylinders might be even a bit nicer? I get that pedal pin position is just leverage and won’t change braking, but Jan said moving it made a world of difference. I will probably try the hydroboost pedal with the F250 master out of the ‘89 if the stud spacing matches...

Gary Lewis

Re: Hydroboost brake conversion

Administrator

Yes, Jim said it. But, he also said I have the later calipers, which may be bigger. The rotors are slightly bigger, so maybe the calipers, or more correctly the pistons are.

Anyway, I'm gonna give the F450 setup a try. Some day. After I win the RSK battle and get a short block 460 and install the heads and intake. And, and, and....

Gary, AKA "Gary fellow": Profile

Blacktop

Re: Hydroboost brake conversion

In reply to this post by Ford F834

Interesting point regarding the best MC to use.
I'm going to try using the stock size '84 cast iron mc on my hydroboost and see how it goes. I have a stock disc drum system other than the hydroboost I'm soon to fit. With the vac type brake pedal, I think the angled hydraboost mounting bracket from the mustang will make it work as the angle appears to be good. If after fitting, I am not happy, I might try moving the pedal pin.

1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧

ArdWrknTrk

Re: Hydroboost brake conversion

Administrator

In reply to this post by Ford F834

Jonathan,

The master/ slave ratio will determine multiplication after the pedal, but the pedal is where you get your feedback, so I can definitely see that moving the pin will change how the brakes feel (to you. not how they perform)

Heck, a mechanical linkage can be set up to be progressive -or regressive- but it is the ratio of pin to pivot and pedal to pivot that determines travel and effort for the driver.

That is why I wanted to separate pedal ratio from hydraulic ratio.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Ford F834

Re: Hydroboost brake conversion

Administrator

My understanding is that the higher pin gives you greater leverage and less pedal effort to apply braking. The larger F450 master cylinder requires more force, not because of volume but because the force is distributed over a larger plunger surface area. Gary, the F450 wheel cylinders are absolutely gigantic compared to any of the pickup brake components. If the later D60 cylinders are bigger it’s nothing compared to the F450, which also has huge dual piston rear disc calipers. I don’t think you *need the F450 MC volume... but I promise you won’t be unhappy with it either. I’m not unhappy with it on my F150, and if I don’t like the F250 master on my crew cab I’ll be putting the F450 one on.

ArdWrknTrk

Re: Hydroboost brake conversion

Administrator

. Did I say volume and not piston crown area?

Sorry.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Hydroboost brake conversion

Administrator

Jim - Didn’t catch it, but you are right, it is the surface area.

Jonathan - I know I’m going to like the later style M/C over the cast iron one, and since I have the one from the F450 I’ll use it. It’ll look SERIOUS under the hood. 😉

And, I’ll bet I like it. I’ve never liked the brakes on Big Blue as they are soft and have too much travel, and I’ve always been impressed with how hard and quick those on Blue are. So to have BB’s quick and firm will be a joy. 👍

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Hydroboost brake conversion

Administrator

Just remember not to put yourself through the windshield.

I had a hard time letting those parts go to a better home than mine. *sniff

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Hydroboost brake conversion

Administrator

I’ll try to remember to be gentle with the brakes.

And I really appreciate all the work you did to remove and ship the parts, as well as to share them. 👍

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Hydroboost brake conversion

Administrator

I'm glad all those 450 parts went to good homes.

The cab was probably the cleanest one I've seen around here, and Theo's '95 Flareside was so rotten it was dangerous.

Bill ended up with the entire dash (in gray) and the AC system with underhood box/plenum.

The Zf and parking brake are still over at Don's, afaik.

Those 10 lug Superduty axles are hard to find!
And they were in great shape.... right out to the tires.

IDK, but I hope they didn't go through the shredder.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Ford F834

Re: Hydroboost brake conversion

Administrator

In reply to this post by Gary Lewis

Gary, you will love the results. That was the one thing I hated most about driving the crew cab in town was inadequate brakes. Perhaps my vacuum booster wasn’t up to par, but that big heavy beast didn’t stop worth beans. I could make them lock up if I really stood on the pedal, but until they locked up they felt soft and unresponsive. Made me think of the runaway 18 wheeler song where the guy thought about opening up the door and dragging his foot 🙄. The hydroboost will catch you by surprise the first couple of times you use it, but you catch on fast 😉.

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