Hydroboost brake conversion

You are very welcome, if you can manage the brake line fittings then the only part you have to track down is the pedal. Just to clarify, nothing between the master cylinder and the booster needs to change, and the rod between the booster and the pedal should come with the hydroboost unit. The only thing you need to correct is the stud on the pedal arm, or source the correct pedal.

Ok, after a bit of sleuthing here's what I've found, most of which is just to tell me I know what I'm doing because my info matches that of Jonathan:

My brake pedal, from the '95 F450 with hydroboost that Jim parted out (right, Jim?), is an E7TA-2455-CA, just like the one in Jonathan's pic

The master cylinder bolt holes are indeed different between the vacuum-boosted F250HD, at 3.2" c/c, and the hydroboosted '95 F450's at 3.45".  Said another way, you aren't going to put the F250 M/C on a hydroboost unit.

The F250's bore size is 1 1/8" while the F450's is 1 5/16"

But, the line fittings are the same the two M/C's.  I measure the one on the rear of the M/C @ 1.0MM pitch, .431" OD and .418" at the root of the threads - as best I can measure with the small threads.  That seems to say the little on on the rear is 11-1.0MM.  And the bigger one toward the front of the M/C has a 1.5MM pitch and measures .550/.520", which suggests it is a 14-1.5MM.  Said another way, the lines from a Bricknose F250HD should work nicely with the bigger M/C.

Now, how 'bout some pics?

Here's a comparison of the F250 M/C in front, and its big brother from the F450 in back:




And here's the F450's hydroboost unit:



And here's the hydrobooster and F450 M/C bolted together:  (Where's that competition for most cluttered shop?  )

Some people say they slot the master cylinder holes and bolt a 250/350 master to hydrobooster.

The larger bore is because of the massive front and rear *calipers* on the F450's 10 bolt hubs.

Remember, there is no drum e-brake on the 450.
Just the one on the rear of the 4x4
pattern Zf-5

It would be easy enough to slot the bolt holes .125"/each to mount the smaller master.  Especially if you have a mill.  But, then you have to do that each time you replace it.

Having said that, my first thought when I looked at the bore sizes was "That's really not that much difference."  But, then I put finger to keyboard and found a big difference:



Now, let's go back to Jonathan's post:

Ford F834 wrote

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.

This confuses me.  I found today that Huck, the Bricknose F250, had different mounting hole spacing on the M/C than the F450 does.  And Huck had a GVWR of ~8600 lbs, same as Big Blue.  And, both have the 8-lug hubs, full-floating rear, etc.  Doesn't that make then heavy duty F250's?

Here's a snippet from the catalog, which seems to say that in 1984-86 the break between LD and HD was at 8500 GVWR, but that in 1987 it changed to 7000.

Huck was a '90 F250 w/an 8600 GVWR and yet his M/C's mounting holes are closer together than the F450's.  So, how can the HD F250's M/C's bolt to the hydroboost?

I'm missing something obvious, I'm sure.  

Gary,
The cutoff for HD is 8,500 gvw. Always has been, always will.

150's (and maybe 250 ld) have a 15/16 (or 1"? CRS)
250's and 350's have 1 1/8" bore.

The 450 is a different animal, and with HD discs all around, needs to move more fluid.
Usually if you went to a bigger master the brakes would be heavy and feel wooden.

But because of the relocated pivot and higher pressure boost they don't.
If anything you have to get used to them quickly, before they put you through the windshield.

Edit: to me this suggests that a/o December 1987 Ford started using the bigger calipers on trucks as light as 7k gvw.
Not that the cutoff for what was considered HD moved.

Gary Lewis wrote

Ok, Where's that competition for most cluttered shop?  )

It looks like Matthew is making an attempt to keep up (but failing miserably)

He does have a much prettier red benchtop though!  

ArdWrknTrk wrote

It looks like Matthew is making an attempt to keep up (but failing miserably)

He does have a much prettier red benchtop though!  

That red benchtop is the finest in mover-grade cheap red protective carpet.  When we bought this house five years ago the movers left three big rolls of the stuff (they put it down to protect the floor from their handtrucks) behind when they were done.  I replaced what was on my workbench (it protects my plywood) when I cleaned the other day; at the rate I'm going, I'll be out of the stuff by 2060.

And now that finals are over, I can start cluttering things up again!

This is way off topic, but would you mind telling what you're studying for?

ArdWrknTrk wrote

This is way off topic, but would you mind telling what you're studying for?

I'm working on a masters degree in analytics.  I still have about 15 years to go before retirement, and I don't think my current role at AT&T is going to be around that long...so I need to upgrade.

What type of analytics?  (I assume there are different types, like statistics?)

You need to ask an actuary, Gary.

ArdWrknTrk wrote

You need to ask an actuary, Gary.

I know what an "actuary" is, but is that what a degree in analytics is prep for?

Gary Lewis wrote

What type of analytics?  (I assume there are different types, like statistics?)

I don't know that there are different 'types' of analytics, exactly, but I'm focusing on what Georgia Tech refers to as computational data analytics, which covers 'big data' and related things - managing, modeling, and visualizing very large datasets and the like.  But there's a huge dose of statistics in that (this entire semester was statistics, in fact), along with business topics and the like.  

It's a nifty program - you can look at the details here if you're curious.  And the really cool thing?  Program cost is $10 grand, start to finish, for a full masters degree from a top-tier university.  It's the deal of a lifetime.

Gary Lewis wrote

ArdWrknTrk wrote

You need to ask an actuary, Gary.

I know what an "actuary" is, but is that what a degree in analytics is prep for?

It would be an excellent background for an actuary, I suppose.  But what it's really built around (at least how I'm doing it) is analyzing huge datasets to build predictive models.  Such as what you might be interested in buying at Amazon, based on your past purchase history.  Or what websites you might be interested in, based on your browser history.

Or...whether you're a terrorist, based on phone company analysis of your calling patterns.  Fun stuff like that.

Interesting program, Matthew.  And, it is at a very good price!  

Things have come a long way since I was in college in the 60's.  I had Statistics, but now they've taken that to a whole different level.  Cool!

Unfortunately it appears that the booster units dont ship with the mc to booster rod, spring and retainer. Anyone know where I could source these from online?
https://www.rockauto.com/en/catalog/ford,1990,f-350,7.5l+460cid+v8,1126550,brake+&+wheel+hub,power+brake+booster,1884

So, essentially you're studying to become an algorithm.   🤯
In some kind of dystopian Minority Report/Blade Runner/Matrix mashup?

That's what Bluffdale is for!

I said 'actuary' because they are the type that not only calculate risk, but set odds, like bookies.
i.e. taking the over under on your career path.

So -basically- your position at ATT is to study Venn diagrams.....
Cool!   🤨

Dorsai wrote

It would be an excellent background for an actuary, I suppose.  But what it's really built around (at least how I'm doing it) is analyzing huge datasets to build predictive models.  Such as what you might be interested in buying at Amazon, based on your past purchase history.  Or what websites you might be interested in, based on your browser history.

Or...whether you're a terrorist, based on phone company analysis of your calling patterns.  Fun stuff like that.

Blacktop wrote

Unfortunately it appears that the booster units dont ship with the mc to booster rod, spring and retainer. Anyone know where I could source these from online?
https://www.rockauto.com/en/catalog/ford,1990,f-350,7.5l+460cid+v8,1126550,brake+&+wheel+hub,power+brake+booster,1884

They won't ship this way, because these are rebuilt and they need a core in return.
People who are looking to upgrade don't have a core, sooooo.

You need to look into buying NEW or sourcing one from a breakers.

Blacktop wrote

Unfortunately it appears that the booster units dont ship with the mc to booster rod, spring and retainer. Anyone know where I could source these from online?

Where are you reading that does not ship with the rod? I’m not seeing this in the description. It seems like it should be part of the reman booster but I got mine at the junkyard so I don’t have experience with a parts house unit.

Gary, maybe I need to check my facts on the HD master cylinder fitting the hydroboost booster. I know Jan is using the original cast iron one on his ‘86 F250, but I don’t know if he had to slot the holes to make it fit. When my F150 MC did not match up I checked the one that came off of my F350 and the stud spacing was wider... I just never checked to see if it matched the hydroboost. I assumed it did, but since I had the hydroboost MC I decided to use that. Maybe the HD vacuum booster stud spacing changed in ‘87?

The AC Delco unit in his link has a $20 core charge which could presumable be paid out to obtain one...