I noticed a brake fluid leak between by master cylinder and power brake booster, as well as the sound of air escaping from the booster, so I decided to change it.

Here's where the problem lies. I have a '74 F250 with dual piston calipers, so I ordered the booster for that application, however it didn't match the old booster at all. I checked some pictures of boosters, and the original booster on the truck is for a single piston caliper truck. The pushrod on the back of the new booster is much longer than the old booster, and it looks like it would require a different mounting bracket to mount it to the firewall. Is that correct?

Some other questions....Did F250's with dual piston calipers have a different mounting bracket for the power brake booster? Would putting a booster for a single caliper piston back on work, or is that probably the cause of it going bad? Since the VIN# of this truck shows it should be a F100 with a 390 (instead of it being a 3/4 ton chassis), is it possible that the previous owner didn't change out the brake booster if he swapped out the cab to a different frame?

Thanks for the help

 

Every booster has a number on it.

Just read the FT-number on the push rod and use that for the replacement.


This is the rebuilders application number you should need

2511083

http://www.precisionrebuilders.com/p...ogPHB-0398.pdf

 

Assuming the old booster on the truck was the correct one? I ask this because the truck is a 3/4 ton with dual piston calipers. The old Bendix booster looks just like the replacement for a 1/2 ton with single piston calipers.

 

The part number and link are for your application.

An illustration of the booster can be found on page 83.

 

I also found an illustration of the booster you referred to on Advance auto, and it is the one I had purchased. However, the old booster on the truck looks like the one for a single piston, part# 2510468.

The push rod on the new booster looks way too long to fit on the mounting bracket to the firewall. Did they make different mounting brackets for the 1/2 & 3/4 trucks?

 

There were several differences in boosters.

That's why the FT-xx Number on the push rod.

I wish that other web site for boosters was still up and working

 

Part # 2510468 is the fulcrum style linkage. You You can use the brake booster and master cylinder off a 1978 F350 2WD. It is a dual diaphram booster and will supply the need brake pressure for your dual calipers. The rear brake line to master cylinder will need to be retrofitted with a 3/16" brake fitting line.

 

That is exactly what I have on the truck now. I thought that booster was for a single caliper? Were these fulcrum style linkages only on the F350? So I would need to get a booster for an F350 instead of the F250? Just want to clarify so I make sure I get the correct part.

 

Will need to get the brake power booster and master cylinder for a 1978 F350 2wd.
Sometimes the auto part stores will sell the booster and master cylinder as an assembly and are less expensive in price, or you can buy each saperately.

The brake lines currently on your truck mount on the right side of brake master cylinder, the F350 brake master cylinder will mount on the left side. With the brake lines attached to the F150 brake master, rotate the brake lines to mount on the left side. The front brake line should be place in front after rotating the brake line. Then disconnect the brake master cylinder (F150). You will need one 3/16" brake line adapter. You can find the brake line adapter at most Auto parts store. With a double flaring tool, flare the brake line with the correct brake line adapter.

Make sure to clean and grease the pins on the pivot points on fulcrum assembly.

 

Okay Uncle Buck, why a 78 booster for single piston calipers on a 74 truck that has dual piston calipers ?

 

ok, I'm going to have to chime in here.. my brake booster on my 79 F250 crew cab 4x4 is dying so I was going to get the F350 booster.. not as straight forward as I thought I guess . Can I just get the F350 4x4 booster and put it in there? It has the master cylinder with the lines coming out the drivers side (I think ).

 

Mil1ion, The cab was probably swapped in from a F100 or F150 truck or the power brake booster and master cylinder was swapped in from a F100 or F150 truck.
The 1978 F350 brake power booster with the extra capacity dual brake master cylinder will supply the much need F250 dual brake calipers with the much need brake fluid and pressure and enhancing the brakes system .

Slow, does your current brake power booster have the fulcrum style brake linkages as shown in picture? and does you current system have cruise control?

 

Thanks for all of the pics and advise. I think I'm going to go with the booster from a '78 F350 for my F250 with dual piston calipers. The more I think about it, the cab must have been put on the 3/4 chassis, but the booster was never upgraded. I have the fulcrum style mount, so it looks like they made a dual piston booster for only the F350's in 78 and up with that mount.

 

A reminder, the rear brake line at the master cylinder will need to be double flared with the 3/16" brake fitting. Make sure to bench completely bleed the brake master cylinder before installation on brake power booster.

 

So I looked at my truck. Driver side master hookups. I couldn't see if it had a fulcrum style mount.. this is where it connects to the brake pedal side? Do you have to remove it to see? It has some plastic thing covering the attachment on that side.