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I'm working on fixing up an old 1976 F250 2nd owner ranch truck and would be grateful for some good info, I know there are many experts here.
The truck is a 1976 f250, single cab, 4x4. I believe it originally had a 390 but at some point was replaced with a 360.
Please bear with me, here is a little history with the brakes since I've had it. A year ago I went through the brakes because they felt a little 'weak' & soft pedal from what I remember. I replaced rear shoes, front pads, and some brake lines, then I replaced the master cylinder. After replacing the MS, I got a very hard pedal but the brakes do work.
The truck has dual piston calipers on the front but I when I bought the correct master cylinder the ports were on the drivers side vs the original were on passenger side of the master cylinder. At the time I didn't think much of it and just re plumbed the tubing for the drivers side ports. At this time I had no idea that the existing master cylinder must have been for a single piston caliper setup. After installing the master cylinder and bleeding the brakes, I had/have a very hard pedal. The brakes do work and it will stop the truck but very hard with very little brake pedal travel.
Fast forward to today, I started troubleshooting the hard pedal, verified I have good vacuum to the power booster etc, I decided I'd replace the booster. In researching the booster, I've discovered the booster in the truck is for single piston calipers, its like 11-1/4" diameter vs the 8" diameter for a dual piston.
So at this point, being a bit confused I'm trying to decide how to make it right. So currently today, the truck still has dual piston calipers, and a master cylinder for a dual piston calipers but a power booster for single piston calipers.
Question #1. Can I just buy a booster for the dual piston calipers and does it just bolt onto the same bracket, different bracket or straight to the firewall? Will this work? In pictures, it appears the rod is much longer for the dual caliper booster so again I'm a bit perplexed.
Question #2. Is there a way to know how the truck was originally configured (single vs dual piston) by the VIN#?
First, the fourth character of your VIN is probably a "Y", that means it came with a 360, the 390 was never offered in trucks with 4WD.
On the brakes, it sounds like you have the correct booster (P/N D6TZ-2005-H). 8.8" diameter is what the parts catalog calls for, however, double check your master cylinder. In 1976 only, the master cylinder for the dual piston calipers had a 1 1/4" bore (P/N D6TZ-2140-G) starting in '77 Ford switched to a 1 1/16" bore for the dual piston calipers, the single piston calipers used a 1" bore.
1976 was the first year F250 w/4WD had front disc brakes, before that they used drums at all four wheels.
Geez, to add to the confusion, I just checked the VIN# on the door and its an F25 which says it's a 4x2? , so I took a look at the vehicle title and it shows the same #.
So, how did it go from a 4x2 according to the VIN to physically a 4x4 highboy??
Geez, to add to the confusion, I just checked the VIN# on the door and its an F25 which says it's a 4x2? , so I took a look at the vehicle title and it shows the same #.
So, I recall now the truck has a reconditioned title but how did it go from a 4x2 according to the VIN to physically a 4x4 highboy??
Check the FRAME VIN. That's the one that counts. The one on the door isn't a "legal" VIN. The doors are too easy to change. To be a legal VIN plate it must be attached to a permanent part of the vehicle, Ford calls it a warranty plate.
The frame VIN is stamped on the top of the passenger side frame rail, between the radiator support and firewall, usually found about inline with the alternator.
First, the fourth character of your VIN is probably a "Y", that means it came with a 360, the 390 was never offered in trucks with 4WD.
On the brakes, it sounds like you have the correct booster (P/N D6TZ-2005-H). 8.8" diameter is what the parts catalog calls for, however, double check your master cylinder. In 1976 only, the master cylinder for the dual piston calipers had a 1 1/4" bore (P/N D6TZ-2140-G) starting in '77 Ford switched to a 1 1/16" bore for the dual piston calipers, the single piston calipers used a 1" bore.
1976 was the first year F250 w/4WD had front disc brakes, before that they used drums at all four wheels.
Thank you! Yes the 4th digit is a"Y".
I just measured the bore of the MS I put in a year ago and it is 1.25" so it's correct for the calipers the truck has. So the question is, can I simply replace the booster with the 8" for the dual piston caliper (The existing booster is an 11" which is incorrect).
Check the FRAME VIN. That's the one that counts. The one on the door isn't a "legal" VIN. The doors are too easy to change. To be a legal VIN plate it must be attached to a permanent part of the vehicle, Ford calls it a warranty plate.
The frame VIN is stamped on the top of the passenger side frame rail, between the radiator support and firewall, usually found about inline with the alternator.
Mike, thanks, I did look on the top of the passenger frame and even tried cleaning a couple of spots with a rust removal disk and didn't see anything.
This is behind the axle, you can see the starter. Note the little white line that looks like a crack in the frame, isn't a crack.
This is a picture of the passenger frame in front of the axle.
Mike, thanks, I did look on the top of the passenger frame and even tried cleaning a couple of spots with a rust removal disk and didn't see anything.
Oh yeah, 4WD. I think they're in a slightly different location on 4WD. I'll see what info I can find and see if I can give you a better description of the VIN location on 4WD (4WD frames are different than 2WD).
This was posted by member Redroad a couple of years ago.
"On my 76 highboy frames the frame vin is located on (passenger side) rail on top between shock mount and front cab mount."
If you have the large diameter, single diaphragm booster mounted on a bellcrank (cantilever) firewall bracket assembly, you should be able to remove it and install this short input rod dual diaphragm booster (in the following link) in its place.
....if you wanted to get away from the heavy cast iron MC that rusts, you could run a lighter, more modern aluminum 1-1/16" bore MC like the one pictured below for a 1995 Ford Explorer (NAPA p/n M3246).
This is an F350 Dentside dual diaphram booster (long booster input rod, non-bellcrank version) and a '95 Ford Explorer MC I'm currently working on to install in a '72 F100 long bed Sport Custom.
This is the '75 F350 dual diaphragm (non-bellcrank) booster and the '95 Explorer MC in my truck. I installed the booster on my truck four years ago (in 2012) when I still had drums all the way around. Two years ago, I swapped to a Dentside F100 disc brake front suspension and this is when I switched from the cast iron 1.00" bore MC to the aluminum 1-1/16" bore Explorer MC.
Wow, that's great info. Yes I have the large diameter booster with bracket like you mentioned. So the bolt pattern on the booster would line up with the firewall mounting holes?
Is that a proportioning valve connected to the MS? Is that something I'd need also, mine does not have one.
I actually ordered the dual diaphragm (smaller diameter) booster from NAPA (NBB 5473112) today but it has a longer push rod. It's for a '76 dual piston caliper w/o cruise control which is what I have but I'm worried the push rod seems too long in the picture, and assume it mounts directly to the firewall without a bracket.
This was posted by member Redroad a couple of years ago.
"On my 76 highboy frames the frame vin is located on (passenger side) rail on top between shock mount and front cab mount."
Well here is a picture of my passenger side rail between the shock mount and cab mount. I cleaned it with a brass wire brush and looked closely with a flashlight and dont see anything stamped.<br/><br/>Anyone else run into this?
It looks like 2WD VIN's are pretty much easy to find. From what I'm seeing, 4WD, not so much. It looks like they're difficult to locate.
Here's another quote from Rouge wulf:
"Have you looked towards the front of the frame horn? My truck has a VIN stamped in the frame between the crossmember and radiator support, and another that is partly visible near the cab mount (blocked by the cab).
What about the other frame rail, and crossmember areas that others have mentioned?
I have even heard that some frames had a VIN stamped on the side rail, somewhere in the front ~18", usually on the right (pass) side."
Wow, that's great info. Yes I have the large diameter booster with bracket like you mentioned. So the bolt pattern on the booster would line up with the firewall mounting holes?
Is that a proportioning valve connected to the MS? Is that something I'd need also, mine does not have one.
I actually ordered the dual diaphragm (smaller diameter) booster from NAPA (NBB 5473112) today but it has a longer push rod. It's for a '76 dual piston caliper w/o cruise control which is what I have but I'm worried the push rod seems too long in the picture, and assume it mounts directly to the firewall without a bracket.
The 54-73112 dual diaphragm booster is the same as what I installed in my '69 F100 and is what I'm currently installing in a '72 F100 for another guy. This booster has the long input rod that connects from the booster, directly to the brake pedal (no bellcrank assembly in between). The short input rod dual diaphragm booster you would need is p/n 54-73311.
Your firewall brackets won't change. Only the boosters would be swapped out and the stud pattern on the back of the dual diaphragm booster, that bolts to the firewall brackets, should be the same as the stud pattern on your existing single diaphragm booster.
The disc/drum brake valve I'm going to mount under the booster/MC I'm working on, for the '72 F100, came off of an '82 Bullnose F150. --the valve shown mounted under the MC is just a mock-up valve I was using. It came off of a '77 F100. --the '77 F100 donated the front discs/suspension that I installed under my truck.
The disc/drum brake valve I installed on top of the steering gear box on my '69 F100 was a brand new OEM/NOS valve, still in the Ford logo box, that was for an '84-'86 Ford F150/Bronco.
Sorry to keep asking questions, I just want to make sure what I buy will work.
According to NAPA a 1976 F250 with dual piston calipers w/o cruise should use NBB 5473112 as I listed previously but the rod seems too long. For grins I looked up a 1977 F250 with dual piston w/o cc and it lists NBB 5473023 which has the shorter rod that seems like it would work mounted on the existing bracket.
Existing bracket with 'lever' mounted to firewall.
Another question about the longer shaft, is that it seems the hole in the firewall for the rod is not centered between the 4 bolt holes.
Sorry to keep asking questions, I just want to make sure what I buy will work.
According to NAPA a 1976 F250 with dual piston calipers w/o cruise should use NBB 5473112 as I listed previously but the rod seems too long. For grins I looked up a 1977 F250 with dual piston w/o cc and it lists NBB 5473023 which has the shorter rod that seems like it would work mounted on the existing bracket.
Existing bracket with 'lever' mounted to firewall.
Another question about the longer shaft, is that it seems the hole in the firewall for the rod is not centered between the 4 bolt holes.
If you're going to switch to a dual diaphragm booster, using your existing bellcrank brackets, you'll need dual diaphragm booster p/n 54-73311.
If you change to the long input rod dual diaphragm booster (54-73112), you'll need the non-bellcrank brackets and the hard plastic dust boot from a '68-'77 donor truck.
The difference between a truck with speed (cruise) control and one without lies in the shape of the boosters input rod, where the rod bolts to the brake pedal. If the (long input) booster rod has a triangular shaped eyelet, the booster is configured for a truck with cruise control. If the long input rod has a round eyelet, the booster is for a truck without cruise control.
Since your present booster doesn't connect directly from the booster and straight to the brake pedal, and since the current input rod off your bellcrank to the brake pedal is flat and not round, the eyelet shape of the input rod on your setup doesn't apply.
Booster for a truck with cruise control. (Notice the triangular eyelet on the long, round input rod).
Booster for a truck without cruise control. (Notice the round eyelet).
The booster under number 54-73023 is a single diaphragm unit.
09-12-2016, 02:32 PM
I'm trying to decide how to make it right. So currently today, the truck still has dual piston calipers, and a master cylinder for a dual piston calipers but a power booster for single piston calipers.
