new to this thing.. sorry bout that

 

Back to referencing my original post....I have replaced my brake booster with one for a '78 F350, also putting on a new master cylinder since the bolt holes on the old one for an F250 did not line up. Now having a little difficulty getting the brakes to bleed up. I bled the new MC, but can't seem to keep the brake pedal from going to the floor when bleeding at each wheel.

I read in my Haynes manual that if the truck is over 6800 lbs. GVW, I need to pull out the pin in the front of the proportioning valve to bleed the fronts correctly. Here's the problem...not sure what the correct GVW is on my truck. The VIN on the cabs reads the truck is a F100 with a 360, but the truck is a 3/4 ton chassis with a 460. So, would it be over 6800 lbs? Do I just pull the pin out anyway and bleed the fronts?

 

Back to referencing my original post....I have replaced my brake booster with one for a '78 F350, also putting on a new master cylinder since the bolt holes on the old one for an F250 did not line up. Now having a little difficulty getting the brakes to bleed up. I bled the new MC, but can't seem to keep the brake pedal from going to the floor when bleeding at each wheel.

I read in my Haynes manual that if the truck is over 6800 lbs. GVW, I need to pull out the pin in the front of the proportioning valve to bleed the fronts correctly. Here's the problem...not sure what the correct GVW is on my truck. The VIN on the cabs reads the truck is a F100 with a 360, but the truck is a 3/4 ton chassis with a 460. So, would it be over 6800 lbs? Do I just pull the pin out anyway and bleed the fronts?

 

Did you bench bleed the new brake master cylinder. The new brake master cylinder will need to be bench bleed off the truck.

https://www.ford-trucks.com/user_gal...=94660&width=0
https://www.ford-trucks.com/user_gal...=94664&width=0

While brake master cylinder is off, verify brake power booster rod length https://www.ford-trucks.com/user_gal...=94721&width=0 .

 

Still having a little difficulty getting a firm brake pedal feel. I checked and adjusted the booter rod length to the specs listed in your post, but I'm still not sure what to do on the rod in the proportioning valve. I was never able to find the correct VIN# on my frame, and the one on the door is incorrect. Basically, the truck has a 3/4 ton frame, so does that mean I pull the rod out when bleeding the front brakes? If so, what can I use to keep the rod out? I noticed there is a metal clip you can get that expands to keep the rod out, but where do you get one of those?

Also, does it make a difference if the engine is running when bleeding the brakes? So far I have done it with engine off, but didn't know if that is the correct method after replacing the booster & master cylinder.

 

No you don't need the engine running.

Here are the instructions:

 

What should I do when I can't find the correct vin# on the truck? I have not been able to determine what the actual GVW is of the truck is without it.

Also, I noticed the rod on the proportioning valve only pulls out about 1/16th of an inch. Is that how far it should pull out?

 

On passenger side (right side), towards front of top frame rail, right behind the radiator support body bushing, you can find the stamped vin number on frame rail.

Have you tried adjusting the rear brake shoes?

1/16" to 1/8" is about right. Can hold the metering rod in place with a neddle nose vise grips.

 

i found out my problem was a bad brake booster.... good luck

 

I'll be working on the truck tomorrow, so I will try to locate the VIN# on the frame and let you guys know so we can determine the GVW. I replaced the rear brakes about 3 years ago, but I'm not sure if I adjusted them out far enough to the drums (learning as I go along), and I'm not sure if the self adjuster is working properly on the r-rear. I may have to take that apart this winter and re-work since I also need to replace the parking prake cables.

Thanks for all of the continued advise. I'll get this corrected one of these times.

 

CJF, If you are going that deep into the brakes,get yourself a return spring and mounting kit as well.
It's called a Combination Kit.
At rockauto
Raybestos Part = $5.00

http://info.rockauto.com/Raybestos/D...=5450,view=top


Motorcraft part $13.20

http://info.rockauto.com/Motorcraft/...?BRSK7225A.jpg



Those brake return springs don't last forever.

 

Is the brake pedal coming back up? or is the brake pedal going down?

 

The brake pedal comes back up, but a little more slowly than before. The brakes are good enough at this point to stop the truck, I just think bleeding one more time with pulling the proportionging valve pin will hopefully get the pedal to feel a little more solid and not travel too far down towards the foor.

I've kind of left that problem for another few that have popped up (it's always something, right?). My wiper motor decided it's last day on earth was this Saturday morning, so I spend the weekend pulling another from the junyard and putting it back into my truck. This could probably be the single most difficult think to get to. I tested the junkyard wioper motor and it worked fine. Got everything hooked up and the dash back together and found out the wiper swing-arm brakets under the dash are not lined up with the cycle of the motor. The wipers stop on the upswing, not downswing. I think I have to unhook the bracket and rotate the wiper braket 180 degrees to get it to work properly. Hopefully I'm not the only guy to make this mistake. I'm just not looking forward to taking part of the dash apart again and scratching up my arms to get at it.

After that, it's back to the brakes! One thing does work great...I put in a seat out of a 1997 that has power lumbar support. I switched out my tracks, wired the lumbar, and it works great. Can't belive how much more comfortable it is.

 

Keep us posted...