404 brake saga

robmac said:
I spent almost an hour yesterday diagnosing a fault in an electronic project I had just built. Only to discover I'd installed an LED backwards. :nownow:

The fault was found without test equipment and solely by careful inspection.

I was most deflated after finding it. :crazy:
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I can relate to that. Hooked up a DS18B20 temperature probe the other day. No reading.... still no reading... what's going on? Picked it up to see if warming it with my fingers would help... burnt my fingers.

Oh yeah, they are 5 volts, not 12 volts. Wrong side of the regulator chip. Probe in the bin too.
 
Beano said:
.... and leave a bit of time between each step for your mind (even your subconscious) to mull it over and pop up a solution.
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Or for the Froggers to come up with a solution...

But yes, I have walked away from it for now. My son is away for a week from tomorrow, so I have some time to tackle this carefully.
 
PS clamping off the rear hose produced a good pedal and braking ,so the problem on mine was defiantly in the rear ,and i had just replaced the wheel cylinders complete ,thus swapped out the valve ,apart from a faulty cylinder theres not much else back there that can go wrong
 
pugwash said:
PS clamping off the rear hose produced a good pedal and braking ,so the problem on mine was defiantly in the rear ,and i had just replaced the wheel cylinders complete ,thus swapped out the valve ,apart from a faulty cylinder theres not much else back there that can go wrong
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There's an idea, I could just plug the outlet on the four-way at the front for testing.
 
Clamping the torque tube brake hose requires no disassembly nor it is necessary to loose fluid or bleed the the the system. :wink2:
 
robmac said:
Clamping the torque tube brake hose requires no disassembly nor it is necessary to loose fluid or bleed the the the system. :wink2:
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Umm... ok, but I feel like that wouldn't be all that good for the brake hose?
 
Slightly off topic. A tip given me back in my 404 days [sigh].
If replacing the vacuum hose from the manifold to the booster allow for an upward loop in the hose to prevent petrol vapour finding its way into the booster diaphragm.

Also experience severe brake locking on, bled off fluid at master cyl to get mobile only, not a fix. Replaced equaliser valve at axle*.
Later, reasons unknown I replaced the original booster with a VH 44. Simple/tidy installation. Boost not as severe as original, approximated the same as none boosted drum type.

*A bit wary of eliminating equaliser and fitting a "T". Was informed that brake lock up would occur ?
 
Yes , removing equaliser will cause lock up. Original booster was meant for Thermostable drum brakes, too much boost for discs, dangerous really, but no worse than most new cars have these days. Maybe that's why ABS is fitted ? LHD 404s had a proper mastervac, but no room in RHD cars.
 
Wildebeest said:
Later, reasons unknown I replaced the original booster with a VH 44. Simple/tidy installation. Boost not as severe as original, approximated the same as none boosted drum type.
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Wildebeest, on this, how did you find the brakes with the VH44? Still ok, or too much effort required? (Very fit young male driver in this case.)
 
GRAHAM WALLIS said:
Original booster was meant for Thermostable drum brakes, too much boost for discs, dangerous really, but no worse than most new cars have these days. Maybe that's why ABS is fitted ? LHD 404s had a proper mastervac, but no room in RHD cars.
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Graham, as per my question to Wildebeest, does this mean you think the lower boost VH44 is an acceptable option for the disc brake 404?
 
Gilow said:
Graham, as per my question to Wildebeest, does this mean you think the lower boost VH44 is an acceptable option for the disc brake 404?
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Originally had the large, Bendix/Lockheed? Hydravac designed for the cars with twin trailing shoe Thermostable brakes. The VH40 would have been a replacement. VH44 is OK as long as you are happy with whatever the pedal pressure is. I took the booster off my 309 rally car to fit a balance bar setup and for me it was unusable, so after a year of so of trying everything to get some stopping happening I refitted the booster. On the other hand I recently bought another rally car, unmentionable on this forum but very historic, and the brakes on that work fine without booster, pressure required but it does stop.
 
GRAHAM WALLIS said:
VH44 is OK as long as you are happy with whatever the pedal pressure is.
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Thank you, this is reassuring. The system felt fine with the VH44 that was in there. If it comes down to replacing the booster, I think I will vote with my wallet on this one. Just waiting on some decent weather to get back to work over here. The car is in a dry garage, but it's just too miserable out there to feel like crawling around under an old car.
 
Just a follow up on all this, for anyone looking to do their 404 brakes.

I had to do this all to a tighter budget than I would have preferred, so this limited some of the options, but here's how I ended up.

The car already has new brake cylinders on the rear wheels, and the front disc calipers are operating smoothly and showing no sign of leakage so I left those alone.

I bought a new VH44 booster, the same as the one that was in the car already, for about AU$100 from a big online place in QLD. I do not know how long this booster will last, probably not 50 years, but it feels OK, and it should last the year or two it will be needed.

I had the master cylinder rebuilt for an insanely good price from Wayne at Better Brakes in Southport, on a tip from a forum member here.

I had new flexible hoses all round made by Power Brakes in Adelaide, the existing hoses were not original, but I felt they were old enough to be worth replacing.

The rear pressure limiter was seized and very rusty. So I fitted an adjustable brake pressure limiter, supplied by Power Brakes, between the the solid brake line under the middle of the car and the flexible hose to the rear axle, and replaced the rear limiter with a simple three way T fitting, also supplied by Power Brakes. Then I adjusted the limiter through a bit of trial and error heavy braking, bringing down the pressure until the back wheels just stopped locking up under very heavy braking. (used about 50% of the adjustment range.) This is probably inferior to the auto-adjusting sort, but the lad never takes passengers so the one-off adjustment is a reasonable approach as the load on the back does not change by more than the weight of the fuel.

All up, the job cost about $450, which was a bit painful but could have been worse.

The brakes now feel terrific. Pedal pressure is perfectly reasonable, more than my Toyota van, but a lot less than my old Renault 10 or my Mini K. (Yeah, ok, both of those are unboosted.) Pedal travel is about right too.

If the car were to be kept for more than a year or two I would have considered spending much more and even looked hard at a dual circuit brake setup, but it is just being used as a local runabout at low speed and the lad is looking for something with airbags etc as soon as he finishes school and gets a job.

I hope this helps someone in a similar situation, thank you to all for the contributions and advice.

Matt
 
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