I had been told by a couple of early-Volvo owners that I would be able to take the two reservoir M/C from a later 1800 and bolt it into my 1965 1800, in place of the single reservoir. Today I pulled a very clean dual cicuit M/C from one of my parts cars, and set it on the bench next to the new single circuit M/C I bought for my 1800S. I think my advisors were lying. I can't see any way that these M/Cs are interchangeable. At the very least, one bolts up vertically (6 and 12 o'clock) and the other bolts up at 3 and 9 o'clock.
How say you all?
JD

OK, I be the newbie that disagrees. But first Hello All and I'm an old guy who has been running, fixing and striping 1800s for 20 years. IMHO the low level light / buzzer on a single circuit brake system is a waste of money and time. Unless you need a verification after that old steel line has split and your peddel hits the floor. It helps with the (I like the term) Pucker factor that your 65 is stick and that you have an E brake if you don't panic or if someone else isn't driving your S. Certain things that are higher tech are well worth doing, get creative and you will make it happen. think outside the box for a M/C and get an adjustable proprotional valve. I upgraded my 64 Ford to dual circuit and front discs for that very reason. OH, did I mention I can't spell and when a line split on my 62 P1800A it was a good pucker :)

Okay Wayne, I can't spell either, so don't sweat the small stuff.
I would be open to any suggestions as to alternative M/Cs that will bolt in. I don't wnat to change axles etc and swap over the later brake system, I only want to have dual circuits (with a propotioning valve). Do you have one in mind that would fit?
JD

Sorry about the slow reply, but I was looking for a link I thought I had saved on Masters and valves. Well of coarse I can't find it. While thinking about your question something else gave me pause. Does the 65 have the remote booster as my 62 did? That might complaicate the job. BTW I disconnected my booster on the 62 and drove it for 300k as I felt the original power brakes were to sensative. An adaptor could be made to fit just about any master, you would then have to make up a longer push rod. matching your current bore size is also important. I wish I could be more help but thats all I have right now.

I removed the booster when I bought the car, and use tromp power only. Builds character and leg muscles.
JD

I asked for a good link on the forum I own (Ford small block engines) and this link all should save and read the info tech thats there. Lots of input on masters, valves, pedal effort etc. enjoy the read

http://www.mpbrakes.com/

Why do you want to change? The only reasonable dual circuit deal you can
make easily is front/back. That is very little safer than single circuit
since you only get about 20% of your braking on the back wheels.
If you want to do a REAL dual circuit system you gotta get new front calipers
and a lot of new lines and at least one balance regulator.

--
George Downs Bartlesville, Heart of the USA!

Hi George;
It would perhaps be only a perception of enhanced security, in that if one circuit failed I would have a second circuit that would provide some amount of braking, no?
I do not wish to go the full blown route of changing over the entire system and hub assembly, but had been told that I would be able to make an improvement simply by swapping M/Cs from one to the other. Obviously I was misled.
I do have a small warning system that was developed by the late Sandy Will ( British Columbia's vintage Volvo guru) for the single circuit braking system, that I intend to install on my 65. It produces an audible warning signal if brake fluid level drops.
JD

You can get a brake fluid level warning setup from lots of
late model german cars; they've got a float and a pair of wires
and I assume when the float goes from normal to abnormal the
state of the two wires change from open to closed or the reverse.
I put one of these caps on a 122 because I lost the original cap.

As far as the dual circuit system goes -- you've already got
a redundant brake system in the form of the emergency brake. Try
driving around with just the e-brake. That is exactly what you
would have if you lost the front circuit on a dual-front-and-back
system. I've driven (8 or 9 miles) with just the e-brake and I
could lock the rear tires with just that.

Lastly, think if what happens to the behavior of the car if
you go from 4 brakes to 2 all of a sudden. If you are forced to
resort to the e-brake, at least you are already on full pucker
before you start hitting the brakes as opposed to hitting the
brake pedal and having something totally unexpected happen because
you lost the front or rear brakes.

Which is better:
hit brakes
foot hits floor and car doesn't slow down
full pucker
use e-brake while fully aware that something terrible is in progress

or

hit brakes
rear tires lock up
car spins

chris

I enjoy your use of the word "pucker". It conjures up an amusing site.
I too have used the e brake while braking from time to time. However, I read your post such that one should drive with a hand on the e brake at all times. Is this what you are saying?
JD

Oops, I mis-read your message...

Should you drive around with your hand on the e-brake? Probably
not. If you lose all your brake fluid all at once *and* you need
to hit the brakes hard, you're now in serious trouble. If you
have the dual circuit system and you lose the front brakes, you
will either hit what you're trying to avoid, spin, or not hit it.
If you have the single circuit system, you're probably just going
to hit it.

There is also the issue that if you have a single circuit system,
you're more likely to notice something wrong with your brakes before
it becomes critical.

I think the best solution is a warning light / buzzer attached to
the master cylinder and awareness that the e-brake is a good
alternative once the warning light turns on.

I have driven a 122 with no fluid in the hydraulic brake system.
It was very early on a sunday morning; I drove about 8 or 9 miles.
As a preliminary test I tried locking up the brakes with the e-brake
and indeed I could. Stopping distances were quite a bit worse than
using a functional braking system but at lower speeds it was somewhat
safe. Thankfully nothing (or nobody) jumped in front of me on that
trip.

If you drive with just the e-brake, you will see exactly how the
car will behave if you lose the front half of the brake system on
a 67.5 style dual circuit system. If you're okay with it, go for it.
I personally wouldn't say that it is any safer than a single circuit
system and may in fact be less safe. A warning buzzer attached to
a float in the master cylinder would be a far easier and better
safety device.

And, having lost all braking power in a mid 80s buick while going
down a steep dirt road, pucker is indeed the correct verb. I also
learned why some cars have emergency brakes and others have "parking
brakes."
chris

IPD sells a cute little conversion kit for that problem.