Nrliftedranger
Full Access Member
ive seen on a few posts it appears that some guys are running the factory superduty master ... which is setup for 4 wheel disc.. most of our trucks are disc an d drum... whats best
Nick
Nick
hydroboost.... what master cylinder??
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gandalf
Senior Member
My hydroboost came as a unit, the master cylinder, the boost unit, and the hoses. The master cylinder is a 1 5/16 size. That's a replacement for the original 1 1/8 unit I removed. It seems to work well. Keep in mind, I have a cabover camper pretty permanently mounted on the truck. I've crossed the scales at 10200 pounds.
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Hey Nick; Look at U-haul web site, I seen a hydro boost unit on there couple days ago.If you need one.
tbrumm
Full Access Member
There is a bit of debate in the OB community as to what MC works best on our trucks with HB and I am sure others will weigh in on this. Some say the 1-5/16" MC works best because you get more fluid volume to the brakes. But, you have to remember that the 1-5/16" MC was put in for use with 4 wheel disc brakes on the F-Superduty, and the stock brakes on the F250/F350 weren't necessarily designed for quite as much fluid volume as the F-Superduty brakes. When I did my HB conversion this summer, I reused my 1-1/8" MC and have been happy with the results. The pedal feel is very good in my opinion and the brakes really bite well. The best mod I have done to the truck! Probably the most important thing to do when upgrading to HB is to use the correct HB specific brake pedal for your generation of truck.
Nrliftedranger
Full Access Member
i have a complete take off hydro boost unit master cylunder linesa nd ps resivoir just was unsure on proper master cylinder since superduys had 4 wheel disc and our older trucks are disc and drum
icanfixall
Official GMM hand model
For a very long time I felt the hydroboost brakes were over rated. Reason for this is my 1979 chevy C30 has them. I felt they were no better than any other vacuum assist brakes on any other chevy or ford truck. So I investigated this further and found out the brake line pressures of both hydro and vacuum assist brakes. the vacuum assist is around 1000 lbs where the hydro is around 2200lbs... Well that made me look more into this . So I found a hydroboost and a new master cylinder in a wrecked truck at a pick n pull and got a good price on it. The install was simple. All the factory line were easy to connect to the larger 1 5/16 master cylinder. I bought new hoses and a rebuilt power steering pump with the 2 return line connections. I really am impressed with the peddle feel. I don't have the dropping brake peddle any more when we come to a stop and then begin to roll from the reduced fluid pressure on the front brakes. You see our rear self adjusters never have worked correctly. So the rears get way out of adjustment and the fronts take over doing most if not all the braking. Then as we stop and pressure is continued on the brake peddle the rear out of adjustment shoes begin to fill the wheel cylinders reducing the pressure on the fronts. Hence the roll away at a stop feel. I don't have the feel any more plus I use about 1 to 1 1/2 inch of peddle travel to stop. Its one of the best items we can upgrade our trucks with and the stopping proof is apparent to anyone that has felt this.
84TD
Full Access Member
I used a new unit and lines from rock auto and an astro van MC, forget what year, maybe 87? Auto zone carried these little brass brakeline adapters so I could use my factory lines. used locktite on the adapters and teflon on the brakelines. Been going great for a few years now.
FYI not bashing.
Never Never use Teflon tape on fittings in a Hydraulic system. Paste containing Teflon is OK
Using Teflon tape on the brake line fittings is a no no. If any of that Teflon tape shreads gets in the brake system, it can cause havoc. "Example" If you had to take a line apart (unscrew the fitting) then screw it back in without cleaning the female fitting and you get shreads of Teflon in the system, it's possible to have brake failure.
84TD
Full Access Member
thanks for the tip, ill be sure to be careful if I ever take it apart.
All ya have to do is the math on which MC is best. The size of the brake cylinders has no bearing on the volume, only on the filling time. If you take a 1-1/8" and put 50 lbs foot pressure on it, you get ~1580 lbs system pressure, take the 1-5/16" and put 50 lbs foot pressure on it and you get ~3200 lbs system pressure. That system pressure is mutiplied by the size of the brake cylinder piston area. If either MC size does the job for the stopping load, thats all that matters.
This kinda concures with what icanfixall found.
This kinda concures with what icanfixall found.
we want the f450 hydroboost setups for your trucks right?
I cant find the one on uhhaul ebays site
I found it. But it's for a GMC, don't know if you can use it or not.
http://www.ebay.com/itm/UHR601-GMC-...Parts_Accessories&vxp=mtr&hash=item2580fc2949
http://www.ebay.com/itm/UHR602-FORD...Parts_Accessories&vxp=mtr&hash=item2ecba19cff
http://www.ebay.com/itm/Brake-Hydro...Parts_Accessories&vxp=mtr&hash=item2ebc3c09d2
http://www.ebay.com/itm/UHR608-GMC-...Parts_Accessories&vxp=mtr&hash=item2ecb1bcf1d
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IIRC some have adapted the GM hydroboost to work with Fords. Personally, I never saw the point...given that you can bolt an F-450 HB unit in place (and IIRC you can still get a unit from rockauto or similar if you can't find one in a junkyard or Fleabay), and while I don't have any numbers to back this up, I've driven a few GM vehicles with hydroboost and felt that they didn't have as much stopping power as equivalent Fords.
To the original question, I've never driven a hydroboosted Ford with the smaller master cylinder, but the ones I've driven with the F-450 master cylinder will stop you RIGHT NOW
One thought...yes, the F-450 master is meant to operate disc brakes on the rear axle and could therefore move more fluid than it should; I wonder how much that's offset by the fact that rear brakes are often not properly adjusted on these trucks? Maybe that means the rear brakes will do more of their jobs? ...just thinking out loud, and we all know how dangerous that can be 
...
tbrumm
Full Access Member
If you decide to go with new components, check RockAuto.com. They seem to have the best prices. They even stock the Motorcraft HB unit.
icanfixall
Official GMM hand model
I have found the easiest way to know if the rear brakes are out of adjustment is to apply the parking brake. If it sets more than 3/4 way to the floor the rears are way out. Now another way of checking is a bit risky. Apply the parking brake about 1/4 of the way to the floor. Drive the truck and see how the peddle stops the truck compared to how it stps normally. I'm betting dollars to donuts your applied parking brake changes the stopping feel and it holds at any stop lite. These tests will prove beyond any doubt whats going on. Then you decide to manually adjust the rear shoes or install hydroboost and never again have rolling into intersections..
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