does anybody have a non boosted 123 master cylinder?

[t walgamuth]

i once saw a euro bmw 7 series with no booster and would like to do this on my 280e if such a thing exists.

tom w

[psfred]

Why? You won't be able to stop the car.

Any BMW with no vac booster has hydroboost brakes, not manual unboosted brakes. When the PS pump gets worn, they rattle when the brakes are applied.

To the best of my knowledge, MB has not used hydroboost brakes in automobiles. GM does in trucks.

Peter

[t walgamuth]

no actually i believe they just reduced the diameter of the master cylinder and thus got enough pressure to stop the car very well. although you did have to push a bit harder, the feel was excellent.

i dont think the car i drove had any hydraulic boosting. i have had suburbans with the diesel and i know what that looks like.

tom w

[psfred]

Then you risk running out of pedal travel under hard braking when pad wear can become significant -- the original Chrysler disk brakes were notorious for having the pedal sink to the floor on long downgrades or severe braking. You won't always have time to pump them up in an emergency.....

MB has never used manual disk brakes.

There is a reason for having the booster in there, leave it alone.

Peter

[t walgamuth]

i think your fear of the travel becoming excessive is untrue. the disc pucks do not recede when not being pushed, so the amount of travel should not increase with wear.

you know for a fact that mb has never used manual discs?

i do appreciate your interest though. i suspect you may be right about the factory not providing manual discs, but i hope you are wrong.

since bmw offered them that way i suspected that mb may have too. it often works that way. in fact the bmw mc may very well bolt up to a benz. it wouldnt surprise.

in addition to the bmw i think i have seen toyotas and porsches with manual disc brake setups.

tom w

[psfred]

Benz started using disk brakes in 1958, I believe, and switched all cars to 4-wheel disks in 1962. The earliest ones were front disk/rear drum, and had a remote booster for the fronts only, but all four wheel disks have had a vacuum booster every since, no exceptions that I know of.

Why do you want manual brakes? They are in no way an improvement.

Cars without vaccum boosters these days have hydroboost, not manual brakes. BMW has used them since the early 70's on the top of the line models, and I'm sure Toyota is doing the same thing.

The only cars with manual disks were very early Chrysler and Ford applications, and they were dropped very quickly due to excessive pedal pressure and pedal travel problems. I've driven a couple, no thanks.

The difficulty is the volume of the reduced size bore in the master cylinder. The pads DO retract quite a bit if the seals are working correctly, and the volume needed to compensate for pad wear, although much less with semi-metallic linings than with asbestos pads, is not insignificant. Having the pedal hit the floor during a panic stop or a steep downgrade is nasty.

Peter

[t walgamuth]

well, i saw and drove a bmw 733 euro with four wheel discs and no booster, and those brakes arent much different than a mercedes of the same era so no matter what your experiences are i believe if i had the right master cylinder it would work.

and i suspect if i could find out what type of cylinder that beemer had it would work on my 84.

so again, thanks for your input and concern but i will keep looking.

tom w

[psfred]

BMW 733 has hydroboost brakes. That's how I know the PS pump rattles when it gets worn....

Peter

[t walgamuth]

you have one? is yours a euro spec car? what year is it?

i think i would have noticed a hydrobooster on the fire wall.

the one i looked at may have been something other than a 733. 730..728? i am not sure. it has been nearly 20 years.

tom w

[Carson357]

Originally Posted by t walgamuth

you have one? is yours a euro spec car? what year is it?

i think i would have noticed a hydrobooster on the fire wall.

tom w

all of the 733's has the hydro boost brakes, the "booster" is actually a nitro chamber like mercedes has for the self leveling suspension systems.
it attaches to the bottom connection block in front of the master cyl, i think all bmw's of that era had it except for 3 series 533,633,733,535, 635 and 735 US and worldwide models. i will see if i can get you a picture this evening from mine

below link shows the accumulator and connection block where the accumulator attaches

http://images.google.com/imgres?imgurl=http://www.************/assets/product_images/hardpart/34331152825.jpg&imgrefurl=http://www.************/se1.asp%3Fdept_id%3D170&h=107&w=200&sz=3&hl=en&start=2&tbnid=omVXTuqy9C3otM:&tbnh=56&tbnw=104&prev=/images%3Fq%3D733i%2Bbrake%2Bbooster%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Doff%26rls%3Dcom.microsof t:en-US

http://images.google.com/imgres?imgurl=http://www.************/assets/product_images/hardpart/34331152825.jpg&imgrefurl=http://www.************/se1.asp%3Fdept_id%3D170&h=107&w=200&sz=3&hl=en&start=2&tbnid=omVXTuqy9C3otM:&tbnh=56&tbnw=104&prev=/images%3Fq%3D733i%2Bbrake%2Bbooster%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Doff%26rls%3Dcom.microsof t:en-US

[t walgamuth]

ok, i looked at my bmw 2002 book and i see that you are apparently correct.

it shows a remote booster, and the mc mounted on the firewall looks just like a non boosted mc.

so the seven that i drove must have had the same system with a remote booster.

so what i saw was what i saw but i didnt see the whole story. i just assumed that the mc had a smaller bore to make more power.

thank you for your patience in informing me so politely.

i am sorry for my stubbornness.

so there must not be any mbs that have unboosted discs either.

darn!

i am still going to try for a manual steering gear though!

oh and it doesnt look anything like the hydraulic boosted brakes on a gm diesel truck. more like the remote hydrovac that was on my 52 pontiac ambulance when i got it..... which didnt work and i simply took off and made a by pass on the brake mc. with a very short brake line.

tom w

[psfred]

Not mine, not Euro spec, but I have no reason to a Euro spec car wouldn't have power brakes. Two "extra" brake lines will be all you see, the pressure reservior probably won't be on the master cylinder like it is on the Chevy.

BMW has used hydroboost on brakes for a long time, 25 years or more that I know of. Better brake feel, I suppose.

Detroit resisted disk brakes for a long time because they require a power booster for normal driving, and they didnt' want to spend the $15 per car for power brakes....

Peter

[Carson357]

here are some pictures of my 1979 733i

[t walgamuth]

thanks guys for your generous help.

tom w