I decided to install my Hydroboost unit today. I was called into work at 2am so I ended up with a whole day off.
I undid that difficult little clip and then removed the brake switch from the pedal shaft.
In order to do this, you must either pick open/spread the gap visible on the other side of the clip in the picture with two picks or, as I did insert a flat bladed screwdriver in the gap/slot and twist so it spreads the two halves apart which will allow the clip to slide over the raised head of the stud.



I then removed the 4 nuts holding the Vac booster onto the firewall and removed the vac booster.





I inserted the hydroboost unit into the hole and went inside the truck to bolt it up.



This is when I noticed the angle on which the shaft hooked up to the pedal. No good!
I tried flipping the hydroboost unit which would fix that problem but it wouldn't fit in the hole in the firewall.
Bugger!
I also noticed the shaft is 10mm longer than the Vac booster shaft from the face of the mounting plate to the brake pedal.
There is also around .5mm gap around the pedal attachment (ie. the hole in the hydrobooster shaft is slightly larger than that in the vac booster shaft). I don't believe this is an issue?
I'll take the hydrobooster to work and make up a plate to replace the mounting plate that came with the hydrobooster. I'll have the hole in the centre made 'in the centre' like the vac booster rather than the current offset hole of the hydrobooster. I'll make it out of 10mm stainless plate.



Howard



Last edited by hquick on Fri Aug 10, 2007 4:35 am; edited 1 time in total

Boy you do nice work howard. You must be a very patient man to take all those pictures and explain things to all of us.

I don't know you personally, but I like you anyhow.

Lol! Thanks.
I enjoy doing this stuff and if it helps someone else out, then it's all been worthwhile.
Some of you guys help me out with sending me stuff on occasion so this is the only real way I can repay the favour.

Howard

I know it's kinda weird that I would say that, but I think you can tell a lot about someone by their work and attention to detail.

Hope all your mods work out good.

Got your email and will post here.

Didn't notice that the shaft was offset from the
four mounting bolts when did mine, but looking
back at the pic's, do see that it is offset.

Don't know if the angle inside is 90 or not and
will take a look later to take a pic if I can get
underneath there with the camera.

NOTE that the plate is hardened and to not
take up any of the pedal stroke by bending.
Know that because the first replacement didn't
come with that plate and in trying to remove
that huge nut, found that the plate is harden
(on the OEM).

When researching mine, found that there are
a few different pedal shaft lengths. As my
first one was too long or short (can't remember)
and returned it for a proper length and one
with the plate already attached.

There has been a couple on this board that
did the conversion and wonder if they documented
this, or is yours different (right hand drive and all).

Betcha used a Greenlee to punch that offset half hole...

Here's the pic's from mine (black one is OEM) and
the one ton dually MC.

Thanks Ben,
I really need to know if the connecting rod needs to be at 90o to the pedal connection.
I imagine it would be best that way.
James. B....can you remember what yours looks like, angle wise at the pedal end?

Howard

Mine's centered, but this one was built by Hydratech as a bolt-in replacement. Trucks with OEM Hydroboost have different pedals for a shorter stroke in the master cylinder I believe.

The one on my truck is installed upside-down.

Thanks James,
That's really handy to know.
I've got the machinist at work making me a new mounting plate tonight out of 10mm thick stainless plate.
He's going to put the hole in the centre.
The 10mm plate thickness will help to shorten the connecting rod. If it's still not enough, I'll cut it, thread it and make it adjustable same as yours.
Is yours connected at roughly 90o to your pedal?
Can one of you guys get me a pic of the rod attaching to the pedal showing the angle?
I've scoured the net but can't find anything and for some reason I can't register on the Hydratech forum to ask the question.
Did you drill a hole in the bottom of yours James?
It's recommended on te Hydratech site if you mount it upside down (Which I will also be doing).

Howard

Your machinist might have to counter bore to
allow enough thread engagement of that big
nut on the Hydrobooster body.

My Sub is over at the shop, so can't
take pic's till tomorrow the earliest.

Since the hydrobooster is sealed, not sensitive
to orientation (should not be). What hole?

Just make sure the shaft does not bottom out
and that the stroke vs pedal travel acceptable
(bottoms the shaft before runs out of pedal travel).

Think the angle is going to be important to the
switch, as it couples to the pedal and shaft
to sense actuation. That is the only thing I
can think of that is affected by the angle.

OR maybe the switch senses taking up the slop
between'm. Play with or if someone know, chime in.

Thanks Ben,
yeah, I've asked the machinist to counterbore the centre hole for the reason you mentioned.
Something I wanted to ask. The studs are hardened. It's going to look ugly, black studs on a polished stainless background. Can I use 10mm (same size as studs) stainless bolts or do they really need to be hardened? I can't see why it would be an issue, it's only the pressure of my foot on the bolts when I push the pedal and there's no way I'm ever going to break 4 10mm bolts with foot pressure.

Howard



Last edited by hquick on Thu Aug 09, 2007 1:15 pm; edited 1 time in total

Not so much breakage, but performance...aka response time & feel.
That very small bending will take time and some of the stroke,
which will translate to performance both in time it takes
and the stroke it consumes.

Plus over time, that slight bending or whatever will work
the metal (fatigue) and failure when you don't want it
or need it the most.

An example of that slight bending is the front caliper of
our era vs current, which was changed to a stiffer
caliper (bridge from piston side to anvil side). The amount
of bending is not visible, nor much, but significant to
both the feel and performance.

So, the bending of the new plate and the stretching
of the four bolts/studs has a lot to do with the feel
and performance of the pedal stroke.

Grade 8 SAE min for USA which is a grade 10.9 metric. They
polish up nice, but don't get them hot, as that will reduce
the hardening (strength)....but....they will then rust. Paint'm
with clear. Stainless can not be heat hardened like alloy
steel and have not seen a grade 8 stainless.

With the counter sink, the nut will be below the surface
and the housing/shaft sticking out. How will you get a
socket past the housing/shaft?

You might have to make or buy a very LOOOOONG
socket.

I've made special sockets for stud mounted SCRs,
which were in the 1,000 amp range. Pig tail with
a lug on the end.

Cut the socket in half and weld a length of water
pipe between the socket halves. That will then
allow the housing/shaft to fit inside.

Thanks again Ben, I appreciate your detailed input.
I completely understand and agree with what you're saying, however I've gone from a 3mm hardened plate to a 10mm stainless plate.
With the size of the plate (around 4.5" square") and being mounted with 4 10mm bolts I don't see how it could be an issue.
I could understand if I was still using the 3mm plate and swapping the bolts for stainless there is a teeny, tiny, minute chance of flex and eventual (like in 1000 years) chance of a bolt letting go, but I would think there'd be more chance of flex in the firewall than the 10mm plate.
Looking at James' unit, those bolts look like stainless to me. Are they James?
I would really like to use stainless button head allen key type bolts.
Also, the nuts on the back of the studs are standard, cad plated nylock type nuts. Wouldn't the thread strip before those bolts would break?

Just more thoughts.

Oh, and it's not that I'm big on the bling factor, it's simply wanting to be able to keep things as clean as possible. I'm not a clean freak but the way I look at my engine bay (actually the entire drive line), if it's clean, I can see if a problem (ie. oil leak) appears.

One more thing...the hole I mentioned earlier is as a drain hole for water and possible break fluid. There is a slot machined into the hydroboost unit which usually faces down. On the Hydratech forum the tech guy says it's a good idea to either machine a slot or drill a small hole on the opposite side if your mounting the unit upside down.

Howard

P.S. I'm depressed! I just got to work (6am) and found that the machinist has only got as far as cutting out the plate and machining the edges as well as drilling the 4 mounting holes. He's on Arvo shift so he's not back again until 3pm. I wanted to atleast mount the hydroboost over the weekend.
I'm not going to rush him because I want a good job done. Hopefully tonight he'll finish that and the fittings for my marine intake fuel rails so I can braze them together over the weekend.

Didn't know you were going that much larger in bolt size.

You should be okay with significantly larger dia bolts of any grade.

Ditto the plate.

Actually, the original bolts are 10mm also.
I wonder how performance would be affected (possibly improved) by sandwhiching the firewall between 2 pieces of plate?
Inside the truck, the nuts sit directly on the firewall. In effect all of the force is only being taken by those flanged nuts each being approx 3/4" in dia.

I guess it's overkill...but if I'm going to do it, now's the time!

I just realized what you were talking about here

Quote:

Betcha used a Greenlee to punch that offset half hole...

The firewall has an oval hole in it. I haven't made any adjustments to that. I really don't want to cut any part of the truck body...anytime. Water leaks and drill swarf means rust!

Managed to find a cable for my camera.
This is where my machinist friend got to last night.




I've since found some 10mm button head allen key type bolts which I'll use instead.



Last edited by hquick on Thu Aug 09, 2007 9:05 pm; edited 1 time in total

I had a spare hour this afternoon so I knocked this up.







Howard

Nice work !

If the torque is going to be large (and think it will
be, but don't know what it is), the tabs will bend.

Consider bridging them together (the open area
ground off) so that the tabs will not bend as
easily.

Betcha a cheater bar will be in the works...

I thought about that Ben, and I might still do it.
If the plate is only counterbored enough to fit that spanner the tabs will be braced by the edge of the hole so shouldn't bend.

Do hope the counter bore wall will be enough, but
stainless is pretty soft in this regard and can't
be hardened enough, nor is the cross section
enough.

It really should be caged so the forces are distributed
to become only torsional and not just a bending moment.

Been there, done that early in my racing days. Koni
shocks in a McPherson strut and didn't have the tool.
So made my own, but still in college and hadn't had
my strength in materials classes, yet....

The pins I used were just plain steel and bent to
'almost' ruin one shock ($75 bucks each when
was making $3.50/hour). Ended up replacing the
home made pins with store bought, hardened
roll pins.

Why wrench sockets can be made from powdered
metal (sintered). It's hard enough and the forces
are torsional, not bending moments. Why air wrench
sockets so expensive...they are not powered metal
but forged & machined from single hunk.

Stainless table top !!!!! Your shop reminds me of
my uncle Bill, who taught me my 'hands' stuff. He
owned a custom sheetmetal shop specializing in
stainless commercial & industrial kitchens.

Arrived at work this morning to find some goodies left behind by the good machinist elf.







Turns out, I should be just able to get a large adjustable wrench (we call them a shifter) on the nut.

Howard