Now I have the OBS hydroboost pedal!

[riotwarrior]

this is why i constantly ***** about this,because i just knew something was wrong here and hoped someday,just this would happen.someone with the two rigs side by side could measure and see a difference.
now to find one.

This is something that's bothered me too, as the engineering principles behind the different pivot points has to remain the same from one model year to another. How can just changing from body style year to year physically change the way the engineers designed the two systems.

One member here has sworn there is no difference between OBS Hydro and OBS Vacuum pedals, perpetuating this misinformation repeatedly to many, in many threads.

Lets build a sticky and submit it to tech for said OBS Hydro boost and put this to bed once and for all.

LCAM is right the hydro boost unit it self can be flipped and I've got a friend who has one flipped. It works well I'm told.

Here you can see, what Ian has done installing an Isuzu diesel and Ford 2003 SD F350 Hyrdroboost assembly with his stock Toyota master Cylinder. Look close and you can see his custom made adapter. He built his own hydraulic lines and it turned out fantastic!

Here is a pic of the stock plate as I had it, removed studs and holes filled and ground down

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Side shot showing the Hydro/adapter/Toyota MC

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Here you can see his lines and such as well as how the upside down hydro looks

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There ya go an upside down Hydro...

Now lets build an OBS STICKY for hydro boost brakes

 

[LCAM-01XA]

Riot, in defense of the forum member you're speaking of, IIRC they were looking at the factory parts listings showing the same pedal for any and all OBS trucks. I believe Tbrumm also confirmed this fact in his older thread. And it would certainly explain how that member of the other forum who F250HDXLT quoted ordered a hydro pedal from the dealer, but got a vacuum one instead...

 

[FORDF250HDXLT]

i got no pm brother,but no worries! im so frigging happy to hear this you can't believe it.my leg muscles are getting some tired lmao!

 

[riotwarrior]

Riot, in defense of the forum member you're speaking of, IIRC they were looking at the factory parts listings showing the same pedal for any and all OBS trucks. I believe Tbrumm also confirmed this fact in his older thread. And it would certainly explain how that member of the other forum who F250HDXLT quoted ordered a hydro pedal from the dealer, but got a vacuum one instead...

No this was the persons personal experiences speaking having done a few of these swaps...

Not a big deal but I really could not understand how the physics of how these systems work would change because of a body change...it made ZERO sense to me!

 

[LCAM-01XA]

i got no pm brother,but no worries! im so frigging happy to hear this you can't believe it.my leg muscles are getting some tired lmao!

Well, crap, I did look in my outbox, and sure enough I didn't send you the PM. Monkey brain strikes again, lol!

Nevertheless, I keep an eye out for an OBS F-superduty every time I raid a junkayrd, haven't seen one in months tho, and last one was a ZF5 truck (from which I should have grabbed the trans, but whatever...)

And your issue comes not so much from the pedal itself, as from using the monster master with said pedal. Reusing your factory master with holes slotted and bore fill plug would have yielded a much much better pedal feel. Tis what I did when I first installed my hydro, and the only reason I changed that setup was cause the old master decided to dump all the fluid out the tank thru the big rubber seals on the bottom. Even now I still run a 1-1/4" master, no way in hell am I gonna put 1-5/16" on the factory vacuum pedal.

Not a big deal but I really could not understand how the physics of how these systems work would change because of a body change...it made ZERO sense to me!

Body change -> dash change -> steering column change -> pedal assembly change. Moving the pedal pivot 3/8" higher on the firewall and using the same pedal for both vacuum (low-mount, so use with pushrod dogleg pointed up) and hydro (high-mount, so use with pushrod dogleg pointed down) booster would be very easy when redesigning everything assuming there is enough offset built in the booster pushrod. Which there may or may not be.

 

[tbrumm]

Reusing your factory master with holes slotted and bore fill plug would have yielded a much much better pedal feel.

LCAM - What is the "bore fill plug" you are referring to? I knew about slotting the vacuum master, which is what I intended to do on mine, but this is the first I have heard about a "bore fill plug".

Al, I would be happy to document my OBS hydroboost install, which would include installing the booster, pedal, in-line filter, aux. cooler, slotting the vacuum master, changing the reservoir on the PS pump, etc. Maybe I would install my new steering gearbox just for good measure. I would like the opportunity to "give back" a little to the forum that has helped me so much. My only concern is the problems I am currently having with the threads crashing. I thought it was just my computer at first, but apparently others are having problems too? The problems seem to be related to the pics that are posted.

Thanks again LCAM and AL for bringing your knowledge and experience to this hydroboost discussion - it has really helped!

Todd

 

[FORDF250HDXLT]

And your issue comes not so much from the pedal itself, as from using the monster master with said pedal.

nope i used the old master due to recently replacing it when i first got my truck,so i just reamed the holes out and slid her on.
you had warned me the larger f-super master would make it worse when i asked,so i tossed that idea.

x2 on the "bore fill plug" question though.

 

[TahoeTom]

I can view page 2 of this thread, but page 1 comes with "illegal string offset" or some such garbage. This is pretty useful info and it would be nice to see the rest of it. There are other threads this happens on also.

 

[LCAM-01XA]

nope i used the old master due to recently replacing it when i first got my truck,so i just reamed the holes out and slid her on.
you had warned me the larger f-super master would make it worse when i asked,so i tossed that idea.

x2 on the "bore fill plug" question though.

Should have said "deep bore spacer plug" - the plunger coming out of the Ford vacuum booster sticks out farther than that of a GM hydroboost (what I'm using), so plopping a Ford master on a GM hydro results in lots of free pedal travel till GM plunger finally reaches bottom of Ford master bore and starts pushing on the pistons inside. Thus a spacer is needed to fill the gap between the two so that plunger starts pushing on pistons right off the bat. The fact that you're using your factory master directly with the F-Superduty hydro by just slotting the mounting holes shows this is just an isolated issue with my specific combination of parts at the time, so don't worry about it.

 

[kawamatt]

I would like to hopefully add a bit of information regarding manual shift trucks and hydroboost pedal. If we can make the safe assumption that all F-Super Duty trucks had hydroboost then we can get the Ford P/N for a complete replacement pedal assembly for F-Super Duty manual shift trucks from Ford TSB 93-22-10. Link

This TSB deals with abnormal clutch and brake pedal shaft bushing wear and calls for replacing the entire bracket with a new and improved bracket that has a larger shaft bushing bearing surface. The TSB details two P/N's for improved brackets. F3TZ-2455-A which is specified for F150/250/350/Bronco and which towcat has shown here and F3TZ-2455-B which is specified for F-Super Duty trucks. Now, I haven't seen a picture of P/N F3TZ-2455-B nor is there much on google related to this P/N, but I am suspecting that this F3TZ-2455-B bracket is the clutch/brake pedal bracket for 92-97 manual shift hydroboost trucks.

Also, it appears you can still buy this bracket. link

 

[kawamatt]

Some more info I came across supporting the fact that there must be differences in vacuum assist brake booster pedal and hydro assist brake booster pedal. Obviously post #1 of this thread proves this, but some additional pictures can't hurt.

I got these pictures from another fullsize Ford forum and they show very clearly the result of using the vacuum assist pedal with a hydroboost unit.

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You can see clearly how much higher the pushrod opening is on the hydrobooster as opposed to the vacuum booster. This, when used with a vacuum assist pedal, translates to an extreme pushrod angle and what appears to be a significantly lower riding brake pedal. Obviously also the difference in leverage that would be felt.

 

[riotwarrior]

.....Body change -> dash change -> steering column change -> pedal assembly change. Moving the pedal pivot 3/8" higher on the firewall and using the same pedal for both vacuum (low-mount, so use with pushrod dogleg pointed up) and hydro (high-mount, so use with pushrod dogleg pointed down) booster would be very easy when redesigning everything assuming there is enough offset built in the booster pushrod. Which there may or may not be.

Now we are talking about moving a pedal assembly 3/8" higher on fire wall, then a different pin, I'm not certain but now we ARE changing things other than FIRE WALL.

Bottom line, physics dictates that a pedal and the pushrod PIN that is MOVED closer to the pedal hinge itself will provide greater leverage and less travel than a pin position lower on the pedal arm. Moving the entire assembly up and using a 3/8 modified pushrod does not mean you will get the same leverage....

maybe I'm wrong on this but what do I know???

Just saying,

Physics are what we are talking about here and those principals remain constant no matter what we are talking about

This is basic leverage principal.

Al

 

[War Wagon]

So, I had previously believed that on an OBS hydro conversion that the pedals vac and hydro were the same. It now appears that this is not true. I bought a hydro/master assembly from an '88 FSuperDuty. It appears now that I need a different pedal. Do I need the OBS FSuperDuty pedal or will a brick FSuperDuty pedal be the same? I know where 3 brick FSuperDutys are, but haven't been able to locate a OBS FSuperDuty. Also if I'm reading correctly I should not use the FSuperDuty master but use my current F350 master with the hydro conversion. I know I need to get the pump reservoir with the 2 returns, but do I need an FSuperDuty PS pump? I only ask because someone told me, and I have no idea if this person is credible at all just someone who was putting in their 2 cents while I was at the parts counter, that the pump outputs were different and I needed a different pump. Also I seem to see mixed answers on wether or not I would need a different proportioning valve. Also, my local dealer who I buy from told me the double return inlet reservoir is obsolete, and they are usually really good. Someone set me straight. I'm trying to get the right combination together.

 

[kawamatt]

You need an F-Super Duty pedal from a truck with your same body style. I assume your wanting to put this hydroboost on your 94'? There is no guarantee that the hydrbooster from the 88 will have the same bolt pattern for the firewall as what your OBS has.

In regards to your pedal question, did you read post 25?

Seems like all your other questions have been asked and answered in this thread.
http://www.oilburners.net/forums/showthread.php?55266-Hydroboost-questions

 

[FORDF250HDXLT]

trying to find a 92-97 f-super/450 auto brake pedal is like a needle in a hay stack.
not having much luck.i just hope it doesn't turn into a drw pickup (w/ 3.55's) axle hunt.that sucked ars too.
on the bright side,my leg muscle is feeling relief with me just knowing what the issue is.half the battle is over lmao.