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Brake booster disabled, fear quotient enabled... 1800 1962

howdy--

When I bought my 62 p1800 last year the brake booster had been previously disabled (has a vacuum leak, I suppose...) which requires significant pedal pressure to stop the car. My right leg now has excellent muscle tone, but now, a year later, it's losing brake fluid and needs to be replenished every two days, after which it requires about three pumps before the brakes grab and the thing stops. It's a horrible way to drive in the city. AHH! TRUCK! pumppumppumpSTOP *whew* (pant pant) Close one! (Check shorts for unwanted deposits).

So here are some questions:

* Did the added pressure required to stop the car all year long cause something to burst, hence the leak?

* I added a synthtic brake fluid I got at the gas station where the problem first arose; It was either that (it says "approoved for DOT 3 and DOT 4), or a DOT 3 fluid which I've heard is too corrosive and not recommended for Volvos. Is this synthetic stuff causing more problems?

* Does anybody have any experience with rebuilding the booster?

* Does anyone know a good laundromat?

Thanks,
Ben








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Brake booster disabled, fear quotient enabled... 1800 1962

* Did the added pressure required to stop the car all year long cause something to burst, hence the leak?

No. The booster just makes it easier to make the brakes work.

* I added a synthtic brake fluid I got at the gas station where the problem first arose; It was either that (it says "approoved for DOT 3 and DOT 4), or a DOT 3 fluid which I've heard is too corrosive and not recommended for Volvos. Is this synthetic stuff causing more problems?

Well, lets see. You have a 40year old car that may have 20 year old brake components. This is God's way of telling you it is time for new everything from the pedal to the wheels. Suck it up, bite the bullet, but don't drive the car anymore until you replace everything, including metal lines and hoses. Regular brake fluid is ok.

* Does anybody have any experience with rebuilding the booster?

Yes. There are shops around that can rebuild the booster for you. I suggest you check out the links on this list for a support group near you or one of the vendors. In addition you may want to try the group over at http://groups.yahoo.com/group/1800list/

chuck petterson
73ES








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Brake booster disabled, fear quotient enabled... 1800 1962

Ben;

Just exactly from where is your leg losing brake fluid?

By "bypassing", one presumes the booster was disonnected from the manifold and brake system, so its essentially ballast (which IMO, with their track record, it was before it was installed)...recycle that thing!...rebuilding is a total waste of time and resources.

If there's no leak, it's a bypassing master cylinder. But if there's a leak, as you state, that's a good indication of what corner to start on. It sounds like it's time for some brake work. Components are available no problem...I suggest you replace both sides at a time (and I suggest a few other things too, see: http://www.intelab.com/swem/service%20notes.htm#Braking%20System

...normally I don't like to do a whole lot more than absolutely necessary, but on a single circuit brake system, I can certainly justify it...and I suggest you do it real soon, before your brakes fail alltogether and you soil yourself for real!

Don't mix brake fluids...that's always the big rule, and you broke it...who knows what exotic reaction may have taken place, and how your seals liked it (or maybe not!). While you're into the brake system, it may be a good time to upgrade. George and I prefer silicon DOT5 fluid. Beware! The new DOT5.1 specification fluid is NOT silicon...it is a further development of the glycol based DOT4 fluid...thanks the DOT braniacs for that misleading nomenclature (logic, what logic!). See also: http://www.xs11.com/tips/maintenance/maint1.shtml
or do a search on Silicon brake fluid...there's lots of good reading out there.
My notes are at: http://www.intelab.com/swem/Amazoning%20with%20Silicon%20Brake%20Fluid.htm

Laundromats are a highly regionalized phenomemon...I suggest you "let your fingers do the walking", to find one, but its probably better to fix your brakes before you need one.

Cheers











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Link comparing brake fluids...especially DOT5.1: 1800 1962


http://www.vtr.org/maintain/brake-fluids.html








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Brake booster disabled, fear quotient enabled... 1800 1962

Pete's right.
There are new master cylinders on ebay now (search for Volvo 122)
and possibly wheel cylinders also.

I have yet to see an early booster that works. I've had 3 122s and
never used a booster in any of them. You definitely have an age-related
hydraulic problem.

I use DOT5 brake fluid. Some on this board don't like it and have made
dire predictions, but after I tested it for the Army in Panama I was convinced.
System parts last MUCH longer.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma








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Brake booster disabled, fear quotient enabled... 1800 1962

Check out the new DOT 5.1 fluid. Its not widely available yet, and a little pricey. But it is mixable with DOT 3 and 4, has higher boiling temps, and additives to manage and neutralize moisture. The even sell long life versions that can be left in the car up to 10 years! Sounds much better than DOT 5 to me. Shame about the confusing nomenclature - perhaps they'll change it to DOT 6 at some point.

EDIT - Just realized this was already discussed above...








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Brake booster disabled, fear quotient enabled... 1800 1962

The original Girling booster tends to suck the fluid out of the master cylinder. I've had bad results with both rebuilding them, and having them professionally reconditioned. If it was mine I'd eithe run servo-less, or replace it with a Lockheed.


The lack of servo does not cause extra pressure, it merely amplifies the effort you put into pressing the pedal. The brakes with or without it are no better or worse, it's just that without you need to generate more force o the pedal. If you can burst something by stamping on the pedal it's not serviceable, You need to determine here the flud is leaking. Most likely culprits are a weeping rear wheel cylinder, or out of the back of the master cylinder. New master and slave cylinders ar still available, as are hoses caliper pistons Etc. try www.cvi-automotive.se


Regards


Pete








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Brake booster disabled, fear quotient enabled... 1800 1962

has anybody ever replaced the booster with one from a 140 series? Would it even fit under the hood?








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Brake booster disabled, fear quotient enabled... 1800 1962

European spec 1969/'70 B20 engined 120's used a 140, 1800E/ES style brake setup. They use a cable clutch the create the extra space required.

Regards



Pete







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