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Discussion Starter · #1 ·
Thanks to John Neilsen for this tidbit. I'm just wonderig how safe this is.
This was done to a B2200 Truck. NOt the CabPlus that John Wayland likes but
a light regular cab from the late 80's. Lawrence Rhodes..

Instead of adding a vacuum pump for the brakes, I raised the master cylinder
and linkage up a 1/2". This gave me more leverage on the brake pedal by
putting the linkage closer to the pivot point of the pedal. I also removed
the vacuum assist for the brakes. The spring inside the vacuum module took
30 pounds of force to compress. So, by removing it, the brake pedal was that
much easier to push. I did some test driving and it is not hard to lock-up
the brakes. They do feel like manual brakes but do not need much force to
operate. It only took me 2 hours to modify the brakes. This worked great
because I did not have to add anything to the truck and got rid of one more
thing from under the hood.

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Discussion Starter · #2 ·
It sounds like the net effect is the same as going to a smaller diameter
master cylinder, which are sometimes used on manual brake models of the same
vehicle anyway. That was common back when power brakes weren't so dominant.
In either case, you move less fluid in the same pedal travel, so you need to
keep the brake pad clearances small so as not to run out of pedal travel
before you build enough brake line pressure. I'd lean toward going with a
smaller diameter cylinder when possible because messing with the pushrod
geometry may cause side force on the master cylinder piston, which may
shorten it's life a bit, but aside from that and possibly running out of
pedal travel as the pads wear (if the adjusters aren't in good shape), I
don't personally see anything wrong with this. You might have some problems
if your rotors warp a bit from heat (which they sometimes do) and they push
the pads back further. Actually, now that I think of it, I seem to recall
my 62 Chevy having two holes in the pedal assembly from the factory.

----- Original Message -----
From: "Lawrence Rhodes" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, November 04, 2007 3:18 AM
Subject: [EVDL] Deassisting brakes. No Vacuum needed. Safe?


> Thanks to John Neilsen for this tidbit. I'm just wonderig how safe this
> is.
> This was done to a B2200 Truck. NOt the CabPlus that John Wayland likes
> but
> a light regular cab from the late 80's. Lawrence Rhodes..
>
> Instead of adding a vacuum pump for the brakes, I raised the master
> cylinder
> and linkage up a 1/2". This gave me more leverage on the brake pedal by
> putting the linkage closer to the pivot point of the pedal. I also removed
> the vacuum assist for the brakes. The spring inside the vacuum module took
> 30 pounds of force to compress. So, by removing it, the brake pedal was
> that
> much easier to push. I did some test driving and it is not hard to lock-up
> the brakes. They do feel like manual brakes but do not need much force to
> operate. It only took me 2 hours to modify the brakes. This worked great
> because I did not have to add anything to the truck and got rid of one
> more
> thing from under the hood.
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
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Discussion Starter · #3 ·
Hello Lawrence,

Did you remove your vacuum booster which was mounted on the firewall and
mounted your master cylinder on the fire wall? Looking at my vacuum booster
unit, which has a 4 inch extension neck that has four bolt mounting that
bolts to a mounting flange on the fire wall that holds a 2 inch diameter rod
grommet.

The master cylinder is a 2 bolt mounting flange that is smaller then the 4
bolt flange of the vacuum booster. It looks like a steel adapter would have
to be built and allow to extend the master cylinder out about 4 inches from
the fire wall, because I have a three inches of wire bundles running over
and under this mounting neck.

The push rod that comes from the brake peddle that goes into the vacuum
booster is different then the rod that goes into the vacuum booster from the
master cylinder. There must be some modification of these rods to make it
work like cutting them shorting, welding or use a rod coupler to connect
them together.

Roland




----- Original Message -----
From: "Lawrence Rhodes" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, November 04, 2007 2:18 AM
Subject: [EVDL] Deassisting brakes. No Vacuum needed. Safe?


> Thanks to John Neilsen for this tidbit. I'm just wonderig how safe this
> is.
> This was done to a B2200 Truck. NOt the CabPlus that John Wayland likes
> but
> a light regular cab from the late 80's. Lawrence Rhodes..
>
> Instead of adding a vacuum pump for the brakes, I raised the master
> cylinder
> and linkage up a 1/2". This gave me more leverage on the brake pedal by
> putting the linkage closer to the pivot point of the pedal. I also removed
> the vacuum assist for the brakes. The spring inside the vacuum module took
> 30 pounds of force to compress. So, by removing it, the brake pedal was
> that
> much easier to push. I did some test driving and it is not hard to lock-up
> the brakes. They do feel like manual brakes but do not need much force to
> operate. It only took me 2 hours to modify the brakes. This worked great
> because I did not have to add anything to the truck and got rid of one
> more
> thing from under the hood.
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

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Discussion Starter · #4 ·
This may not be safe. Newer vehicles have duel circuit brakes and its
important to make sure that one circuit can operate if the other has
a blown caliper, wheel cylinder, or line. This is something to check
while bleeding the brakes. Once the 1st half has been bleed the pedal
should not be able to go to the floor while bleeding the other half.
If it does the functionality of the duel circuit brakes has been lost
(making the brakes about as safe as stuff from the early '60's.)

There are lots of other issues to consider. Modifying brakes is a
touchy subject and not something I'm comfortable with. Perhaps
Wilwood makes a kit? (get some engineers involved :)

Paul Gooch

Lawrence Rhodes wrote:

> Thanks to John Neilsen for this tidbit. I'm just wonderig how safe
> this is.
> This was done to a B2200 Truck. NOt the CabPlus that John Wayland
> likes but
> a light regular cab from the late 80's. Lawrence Rhodes..
>
> Instead of adding a vacuum pump for the brakes, I raised the master
> cylinder
> and linkage up a 1/2". This gave me more leverage on the brake
> pedal by
> putting the linkage closer to the pivot point of the pedal. I also
> removed
> the vacuum assist for the brakes. The spring inside the vacuum
> module took
> 30 pounds of force to compress. So, by removing it, the brake pedal
> was that
> much easier to push. I did some test driving and it is not hard to
> lock-up
> the brakes. They do feel like manual brakes but do not need much
> force to
> operate. It only took me 2 hours to modify the brakes. This worked
> great
> because I did not have to add anything to the truck and got rid of
> one more
> thing from under the hood.

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For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 
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