Any L'Cruiser brake gurus about? re:HZJ75 load balancing +Rear Drums

Hoping for some input on a problem with rear brakes on a troop carrier
[2/91manuf].
Original problem was the escape of the leading shoe on RT/HND Rear set
from the slave , creating a jammed wheel.
On inspection of all parts the system was found to totally inundated
with signs of moisture stress.
A complete clean [blow-job] together with master cylinder and load
sequencing valve replacement delivers this new (?) problem, as put
here
The brake system bleeds normally as in pedal to master cylinder
reaction when releasing and pressurizing the system.. When the system
is closed the brake pedal reacts normally. On starting the engine the
pedal depresses the standard amount. With the vehicle stationary the
pedal travel is acceptable. With the vehicle in motion the pedal
travel extends beyond 50% and only the front discs are activated on
any attempt to brake (measured or emergency). The rear drums appear to
have no pressure whatsoever exerted on them.
I am casting a suspicious eye at the load sequencing valve, primarily
because I do not understand how it works (hydraulic). I am looking for
someone to explain the theoretical design of such a
contraption
In the event I have missed something very obvious I would appreciate a
complete jerk back to reality.

thanks.

crusty

Back in the 70's on domestic vehicles, they started using a
proportioning valve for the rear brakes on station wagons and pickups at
first.

This valve senses the amount of pressure going to the front and read
brakes and shunts the pressure so the rear shoes will not lock up the
rear wheels. This is a safety thing so the vehicle doesn't have the
rear end trying to pass the front end.

With a vehicle jacked up, the front wheels lock and the rears appear not
to stop. When it is in motion, this changes because it take more
pressure to stop the fronts so the rear sees a lot more too.

Even on gravel or snow the rear wheels are never supposed to lock except
when coming to that last little bit of a hard stop.

I don't know if this answers your question or not.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)


crusty4runner wrote:
>
> Hoping for some input on a problem with rear brakes on a troop carrier
> [2/91manuf].
> Original problem was the escape of the leading shoe on RT/HND Rear set
> from the slave , creating a jammed wheel.
> On inspection of all parts the system was found to totally inundated
> with signs of moisture stress.
> A complete clean [blow-job] together with master cylinder and load
> sequencing valve replacement delivers this new (?) problem, as put
> here
> The brake system bleeds normally as in pedal to master cylinder
> reaction when releasing and pressurizing the system.. When the system
> is closed the brake pedal reacts normally. On starting the engine the
> pedal depresses the standard amount. With the vehicle stationary the
> pedal travel is acceptable. With the vehicle in motion the pedal
> travel extends beyond 50% and only the front discs are activated on
> any attempt to brake (measured or emergency). The rear drums appear to
> have no pressure whatsoever exerted on them.
> I am casting a suspicious eye at the load sequencing valve, primarily
> because I do not understand how it works (hydraulic). I am looking for
> someone to explain the theoretical design of such a
> contraption
> In the event I have missed something very obvious I would appreciate a
> complete jerk back to reality.
>
> thanks.
>
> crusty

Mike Romain <[email protected]>,went to some trouble to offer:

>crusty4runner wrote:
>>
>> Hoping for some input on a problem with rear brakes on a troop carrier
>> [2/91manuf].
>> Original problem was the escape of the leading shoe on RT/HND Rear set
>> from the slave , creating a jammed wheel.
>> On inspection of all parts the system was found to totally inundated
>> with signs of moisture stress.
>> A complete clean [blow-job] together with master cylinder and load
>> sequencing valve replacement delivers this new (?) problem, as put
>> here
>> The brake system bleeds normally as in pedal to master cylinder
>> reaction when releasing and pressurizing the system.. When the system
>> is closed the brake pedal reacts normally. On starting the engine the
>> pedal depresses the standard amount. With the vehicle stationary the
>> pedal travel is acceptable. With the vehicle in motion the pedal
>> travel extends beyond 50% and only the front discs are activated on
>> any attempt to brake (measured or emergency). The rear drums appear to
>> have no pressure whatsoever exerted on them.
>> I am casting a suspicious eye at the load sequencing valve, primarily
>> because I do not understand how it works (hydraulic). I am looking for
>> someone to explain the theoretical design of such a
>> contraption
>> In the event I have missed something very obvious I would appreciate a
>> complete jerk back to reality.
>>
>> thanks.
>>
>> crusty
>>
>Back in the 70's on domestic vehicles, they started using a
>proportioning valve for the rear brakes on station wagons and pickups at
>first.
>
>This valve senses the amount of pressure going to the front and read
>brakes and shunts the pressure so the rear shoes will not lock up the
>rear wheels. This is a safety thing so the vehicle doesn't have the
>rear end trying to pass the front end.
>
>With a vehicle jacked up, the front wheels lock and the rears appear not
>to stop. When it is in motion, this changes because it take more
>pressure to stop the fronts so the rear sees a lot more too.
>
yep..all of the above is in my database [pre-existing].

>Even on gravel or snow the rear wheels are never supposed to lock except
>when coming to that last little bit of a hard stop.
>
>
K...my experience is different, maybe the 'gadget has not been
adjusted correctly on my other Tojos?

>I don't know if this answers your question or not.
>
nup..I was really looking for a 'technical' explanation of the
hydraulics of this contraption. The Gregorys I have says "70mm
clearance at the shackle for 75series, testing and further adjustment
by a qualified operator only".
I reckon if I can understand how the contraption works I can soon rig
some test gear and at least determine/eliminate the valve as a factor
in my problem.

btw...in all of the repair I have spoken to a number of "qualified"
peers, none have ever seen the escape of a shoe from the slave
trunnion on a 'Cruiser. As to how it happened they say "beats
me"..beats me too, women drivers? <G>

thanks

crusty

I don't know what system is used on the LC, but it is likely similar
to the common Bendix type II where the parking brake actuator can
cause the shoe to escape the anchor pin. What happens is that if the
parking brake is adjusted before the hydraulic side is set, the
parking brake actuator can be expanded far enough that the shoes
actually rotate around lever and are not seated on the anchor pin when
the brakes are at rest and the "fixed" end of the shoe can escape the
anchor pin on actuation. Extreme case, but possible. Relax the
parking brake, adjust the brakes shoes, then reset the parking brake
adjustment.

On Thu, 5 Jan 2006 17:48:26 UTC crusty4runner
<[email protected]> wrote:

> Hoping for some input on a problem with rear brakes on a troop carrier
> [2/91manuf].
> Original problem was the escape of the leading shoe on RT/HND Rear set
> from the slave , creating a jammed wheel.
> On inspection of all parts the system was found to totally inundated
> with signs of moisture stress.
> A complete clean [blow-job] together with master cylinder and load
> sequencing valve replacement delivers this new (?) problem, as put
> here
> The brake system bleeds normally as in pedal to master cylinder
> reaction when releasing and pressurizing the system.. When the system
> is closed the brake pedal reacts normally. On starting the engine the
> pedal depresses the standard amount. With the vehicle stationary the
> pedal travel is acceptable. With the vehicle in motion the pedal
> travel extends beyond 50% and only the front discs are activated on
> any attempt to brake (measured or emergency). The rear drums appear to
> have no pressure whatsoever exerted on them.
> I am casting a suspicious eye at the load sequencing valve, primarily
> because I do not understand how it works (hydraulic). I am looking for
> someone to explain the theoretical design of such a
> contraption
> In the event I have missed something very obvious I would appreciate a
> complete jerk back to reality.
>
> thanks.
>
> crusty


--
Will Honea