How-to: F250 Booster and Master Cylinder Swap | Ford Explorer Forums - Serious Explorations

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How-to: F250 Booster and Master Cylinder Swap

jmdirk

Well-Known Member
Joined
July 22, 2004
Messages
238
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13
City, State
Ottawa, Canada
Year, Model & Trim Level
'93
After doing my SAS and trying to get the brakes setup, I just could seem to get a good feeling in the pedal. Between swapping my 1st Gen to a 2nd Gen rear axle with disc brakes and the larger 79 T-bird calipers on the front axle, I wanted to get some better performance out of the brakes since at the time, they felt worse than stock.

This led me to do a bunch of calculations about which master cylinder etc to use to get the most of of my new brakes.. All the background can be found here:http://www.explorerforum.com/forums/showthread.php?t=424023

All the research and calculations led me to the decision to swap in a booster and master cylinder from a 1993 F-250. The larger MC should give a much firmer pedal feel and the larger booster will make up for any pressur e loss as a result of the new booster. For me, I had already pulled out all the 4WABS from the truck, so there was none of that stuff to deal with.

Start off by pulling the stock master cylinder;
- Disconnect the brake fluid level switch from the passenger side of the master cylinder reservoir
- Remove the front and rear brake lines from the master cylinder. Make sure you leave the reservoir cap on - this will help minimize the amount of brake fluid that will leak out all over the place. You can also pull as much fluid out as possible with a syringe or vacuum pump
- remove the 2 bolts securing the master cylinder to the booster and the master cylinder should just pull off

You should have something that looks like this:
IMG_20150329_130125.jpg


Ignore the the mess of wiring to left, you probably won't have that. My biggest concern on this whole thing was the space for the larger booster. The stock booster is 8.75" and and the F250 one is 10.75". It's an extra inch all the way around. You can see that there already isn't that much space between the booster and the wiper motor about it.

Next is to remove the booster itself:
- undo the spring hose clamp from the vacuum check valve and remove the hose.
- go into the cab under the drivers side dash. On the brake pedal you'll see where the booster push rod connects to the brake pedal. Remove the spring loaded pin to release the push rod and brake pedal switch from the brake pedal.
- There are 4 nuts on studs that are securing the booster to the firewall. Remove the nuts and you should then be able to pull the booster out

Booster gone
IMG_20150329_132429.jpg


There's two, possibly three, clearance issues with this swap; 1) the wiper motor; 2) the steering shaft and; 3) for me at least, my aftermarket shock tower was in the way. For stock vehicles or others I'm not sure if this will be an issue. Also, the clearance to the guard on the steering shaft may be an issue for automatics since the shifter linkage cable secures to the guard. Automatics may have more of a clearance issue than manuals.

Next I removed the wiper motor to give myself a little more clearance to maneuver the booster into place:
- remove the access panel in the center of the firewall by removing the three hex head screws holding it in place.
- Here's what you'll have inside:
IMG_20150329_134052.jpg


The wiper motor arm is coming out from the firewall on the right. On the shaft you have the arm going to the drivers side wiper (you can't really see it since it's going away from you). The piece you see on the peft is the linkage for the passenger side wiper.

- On the end of the shaft is a special spring circlip, which attaches like this (thank you autozone for the picture):
0900c15280262ed0.jpg

- Once you get that off you can pull the arms off the shaft
- Remove the 3 bolts securing the wiper motor bracket to the firewall and disconnect the wiring and you should be able to pull the wiper motor free

IMG_20150329_135140.jpg


Comparing the two new boosters:
IMG_20150329_132050.jpg

IMG_20150329_132140.jpg


Once you have all that stuff out of the way you can put in the new booster. It will take some wiggling to get it in place, but it's not that bad. The bolt holes line up exactly.

Here's the new booster in position:
IMG_20150329_143353.jpg


Very little clearance to the guard over the steering shaft
IMG_20150329_143530.jpg


Once you've got that in place, put the nuts back on from inside and hook up the brake pedal to the push rod.

On the booster itself, the push rod for the master should extend between 0.980" and 0.995" from the face of the booster. Connect your vacuum line to the check valve

Back under the hood, putting on the new master is pretty straight forward, slide it over the studs, and use the 2 nuts to secure it.

I have finished hooking up the line yet. The ports on F250 MC are 9/6-18 for the front and M18 x 1.5 on the rear. The rear port is designed to take a factory style pressure limiting (proportioning valve). I still need to figure out and get the correct fittings. I'm using a adjustable proportioning valve so I don;t need the factory one.

Once I get the right fittings I'll get it all bled etc. and see if that was worth the effort
 



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Going to be a a while before I finish it up. Realized that I order the wrong MC. I have no confidence that I'm going to find the right fitting for the rear port without having it leak.

Went ahead and order a different one from RockAuto. Hopefully doesn't take too long to get here
 






What is different on it? Just the fittings? What was it for? Thanks and nice job.
 






The first MC that I bought was for a 93 F250. The front port would have been okay, but the rear port normally has the proportioning valve threaded into it. It's an M18 x 1.5 fitting. I've found a few fittings I could adapt to it but a) there's no guarantee that it would start leaking because of the design (it's not a normal inverted flare or bubble flare type fitting) and; b) Rockauto had some Napa MC on clearance for $25 - I'd probably spend more in fittings.

the second one is from a 2000 F250 super duty. The fittings are pretty normal. It's a bit larger than what I wanted. 1-1/4" instead of 1-1/8". Not ideal, but...

As long as it fits the booster I bought I should be fine. If it doesn't I'm going to be a bit frustrated. Ford's pretty consistent with the bolt pattern etc on the masters
 






I finally got around to installing the new master and it's made a huge difference compared to the stock setups. In my case it's made a big difference, the pedal is firm but not hard, and it seems to have plenty of braking power.

Still need to really get it out there and test it some more and get the rear bias adjusted properly, but so far I'm happy with the result.

For the record, the booster I installed was from A1 Cardone, p/n: 54-74400 (http://www.cardone.com/Products/Product-Detail?productId=5474400&p=rock)

And the master I installed was Napa p/n: NMC M3378
(http://www.napaonline.com/Catalog/C...e-Master-Cylinder-New/_/R-NMAM3378_0493490884)

Both were bought form rockauto. The booster was $120CAD (including a $50 core charge) and the master was $25CAD

Wouldn't recommend this for a setup with stock front brakes. But a good upgrade for those using the big bore single calipers on D44s. Again, I think it's fairly crucial to use the bigger booster along with the bigger master to get the proper performance out of your brakes.
 






Any updates on this. I really like the idea. I just put a new booster and master cylinder on my ex and its still kind of soft.
 






Thank you jmdirk for taking the time to share this with us, I'm still working out all the kinks on my d44 sas in my '01 st, I am very grateful to know my first test drive should expect goofy brakes.. I'm gonna follow your thread and will post a review/changes on my application!!
Three thumbs up for sure..
 






I know I’m a little late but;
Can you hook the wipers back up?
What about those “hydro boost” boosters for the 250? They would take up less room I think.
 






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