Going hydroboost

[2stroke]

I am going hydroboost and have a question. There is an extension on the back brake line closest to the vacuume booster. What is it for and is it needed going to hydroboost. See picture item #10 attached if it posts.

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[79jasper]

Pretty sure you need that valve.
Keeps a little pressure in the lines, and sort of is the so called "proportioning valve" so to speak.
Maybe I'm lying.


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[cpdenton]

Yes. The line won't screw in to the master cylinder without it. It is just a fitting with a small orifice in it to put more pressure in the front brakes. They appear to be the same from regular MC to the hydro boost MC. They were on my two anyway. I ran the one from the hydro boost first then switched back to my original and noticed no difference.

 

[2stroke]

A little more info. The item is in the rear brake side. I saw this when I was bleeding the front brakes, the fluid went down in the front side.

 

[ifrythings]

Thats the proportioning valve as stated, the hydro mc has what looks to be the same piece but its just a spacer(has no guts) as where the non hydro has the "guts", (at least the one i have here is like this). The f450 being all discs and hydro probably doesnt need the proportioning valve like the f350 with drums that need less pressure to work then disc need. They are the same size and can be easily swapped over.

 

[2stroke]

I think it is the proportioning valve also, so when converting to hydroboost and if I use the f450 master cyclinder, it does not have this valve at the master cyclinder, so none is on the truck. This could be a problem unless I use my original master cyclinder--no one doing these conversions using the f450 master cyclinder ever mentioned this???????

 

[gandalf]

I think you're referring to the connection to the left of the "87" in the attached picture. IF that's it, and IF my memory is right, it's just a connection for the line, like a flair fitting. Those two lines, the ones with the strain reliefs, just unscrewed from my old MC and screwed into the hydroboost unit. I don't remember anything special about them.

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[cpdenton]

The lines from my original master cylinder and the proportioning valve all screwed right on to my hydroboost 1 5/16ths master cylinder. Do you not have one of these on your original master cylinder? If so, swap it over. If not, send me a pm. I have an extra.

 

[LCAM-01XA]

I think it is the proportioning valve also, so when converting to hydroboost and if I use the f450 master cyclinder, it does not have this valve at the master cyclinder, so none is on the truck. This could be a problem unless I use my original master cyclinder--no one doing these conversions using the f450 master cyclinder ever mentioned this???????

Does your truck have factory rear ABS? If no then you have a combination valve down on the frame rail that also serves as a proportioning valve, and so you should be able to use the F-Superduty master with its "slug" fitting as is. If you do have a RABS present then you don't have a stand-alone combination valve, and so you'll need the factory proportioning valve from your factory master cylinder, simply unscrew valve from that mc and screw it into the F-Superduty mc in place of the F-Superduty "slug" fitting. The need (or lack thereof) for this valve is dictated by the type of brakes on the rear axle, drums need it (unless a stand-alone combo valve is already present) and discs of the D80 size apparently do not.

 

[2stroke]

LCAM-01XA You are 99% correct except for the f450 master cylinder is a one line brake port unit the front and rear brakes are not seperate, so you cant move the valve over from your old master cylinder. You will have to keep your origanal master cylinder, and open up the mounting holes.

 

[LCAM-01XA]

What the heck F-Superduty did you find? The fronts and rears ARE separate from the factory, it's a federal safety requirement, hydraulic brake systems MUST have two independent circuits and that doesn't happen if all 4 brakes are fed from one port on the master. Sure it looks like the master has 1 reservoir, but that's divided internally partway down, you can loose all the fluid out of the front or rear brakes and the reservoir will look empty but it won't be entirely, there will still be enough fluid to actuate the non-damaged brake pair. The factory F-Superduty master looks exactly like the F350-down master, just the bore is bigger and the tank is freakin huge. Post a picture of what you're working with I got the gut feeling someone got very creative with your donor truck before you got your hands on the parts.

 

[2stroke]

I didn't get one yet, I was covering all the issues I have seen on this site--Tech posts and member posts with pictures. There were comments about the f450 master cylinder having one chamber reservoir, and pictures showing one brake line.

 

[riotwarrior]

I think you're referring to the connection to the left of the "87" in the attached picture. IF that's it, and IF my memory is right, it's just a connection for the line, like a flair fitting. Those two lines, the ones with the strain reliefs, just unscrewed from my old MC and screwed into the hydroboost unit. I don't remember anything special about them.

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I didn't get one yet, I was covering all the issues I have seen on this site--Tech posts and member posts with pictures. There were comments about the f450 master cylinder having one chamber reservoir, and pictures showing one brake line.

Clearly in the post from Ken with the picture above you can see that the MC does INDEED have two ports for two separate circuits...

 

[LCAM-01XA]

I didn't get one yet, I was covering all the issues I have seen on this site--Tech posts and member posts with pictures. There were comments about the f450 master cylinder having one chamber reservoir, and pictures showing one brake line.

I see, well no worries, like Riot said the F-Superduty master looks exactly as shown on Gandalf's pic, two lines and adapter fitting where the proportioning valve is on your truck. It's a bolt-on affair, assuming you got all the other parts.

 

[2stroke]

OK now I am really confused--not to argue if you go to the tech posts--the second page, last post on that page and read near the end of the post it says what I have been talking about, the single chamber