Master brake cylinder inadequate for tasks

Any one here has an idea for how toimprove the brake feel and power? The 69 Master just doesnt have the "umph" to stop well with aftermarket disc brakes...any quick fixes?

Michael

I think I saw a remotely located power booster (called a hydrovac) in Simon Hambley's pictures. He might be able to help.......

Yes, I fitted a remote servo to improve the "feel", being used to over assisted (VW/Audi) brakes in my other car. The demo car I drove without a servo did not inspire confidence.

The remote servo I used was dual circuit, so assists both front and rear. I ran a 5/16" Kunifer (Copper Nickel) line along the centre tunnel up to the servo which is mounted behind the spare wheel. Vacuum is sourced by Teeing into my Kadron's manifold balance pipe.

I blanked off one of the master cylinder front outlets with a bleed nipple and added a T after the servo to split to the front calipers.

I also had to make custom hard lines from master cylinder to servo( VW is M10x1.0, servo was UNF)

Unfortunately the servo I used has been out of production for a few months whilst the tooling is renewed. It is meant to be back on sale soon (www.s-v-c.co.uk under other products DUAL REMOTE SERVO)

There are photos in the build section of my website (www.hambly.org.uk/chesil)

Simon

Something doesn't seem right if a speedster doesn's stop well considering the brake components were designed for a VW Beetle that is at 500 lbs heavier than a speedster.
Wonder if the valve in the front brake line outlet on the master cylinder has been removed?

Alan,
What valves do you use on the master if the stock ones are gone? I put discs in the rear (CBperformance) and used the valve they recommened for the rears. (I'n not using valve for the fronts (Kghia discs) The car stops OK, but it doesn't stop any better than "Disc. on the front and Drums on the rear". (The drum brake setup used to pull to whichever side it decided, the discs cured that part, but pedal doesn't feel as solid as it did with drums either.

Thanks in advance for any tips & tricks you might have.

Greg B

I just know that I have replaced it with a new one, bled the brakes multiple times and changed lines to stainless to see if it helped..but to me..the disc brakes are not better than the originals..
I was wondering if I should try an ONeal master cylyinder

Michael,

Whats the issue? Is it complete lack of stopping ability or the fact that you have to stamp so hard on the pedal for the car to stop? The servo is only going to help with the later

I believe a bigger master cylinder (larger piston) will only make the pedal effort required higher as you loose mechanical advantage, but will reduce pedal travel.

A larger slave cylinder will reduce pedal effort at the cost of increased pedal travel (more fluid needs to be moved)

Are your rear drums correctly adjusted? You'll have pedal travel until the shoes contact the drum even if the brakes are perfectly bled (I learn't this the hard way whilst building my car having followed some bad advice in a well-known beetle chassis tuning book and used 21mm front drum slave cylinders at the back of my car to uprate them; the book failed to mention that these cylinders were impossible to bleed at the rear of the car unless inverted: result pedal straight to the floor when the rear brakes were connected despite the pedal being rock solid when only the front circuit was connected and the rear circuit blocked off)

CSP, the Germany company, sells a bit larger master cyclinder and adapter for 4 wheel disc brake application on Type 1. It should eliminate some of the long pedal(pushing down 6 inches before you feel any braking). It is rather expensive, about $300. These parts also meet stringent German auto inspection standards, whatever thats worth. I think the site is www.CSP.com There is a distributor in Southern California for CSP parts also, I think his contact info can be found in the CSP ads in HotVW and the like. To get technical, the stock master cyclinder has an ID of 19.05mm the CSP cyclinder's ID is 20.64mm. I think the fluid circuitry for the front brakes is a bit different than stock as well. Good Luck.

Joel - Thanks, I'd missed the fact that we were talking about 4 wheel discs. CSP can also be found at www.csp-shop.de

Michael,

I have this conversation many times and each time I speak about it I'm told that "You are used to Brakes & Stopping Power of current modern cars".

My of us drove drum brake cars without power assist 30 Years ago and we didn't know any better.

Now with ABS, Power Assist and Multi-Piston Calipers the 30 year old brakes seem "Lacking in their stopping ability".

I have Ghia Disc's front and drums rear.

The Ghia Front Disc are superior then my front drumbs were and if my "Pedal" doesn't feel "Right", I know I need to lend attention to the rear brake shoe adjustment.

I think most of us are compareing "Apples & Oranges" with 30 year old brake technoligy with current brake technology.

Good Luck,

Jack

Hey Simon, I appreciate your help and everyone elses too..the pedal is still somewhat spongy and it takes a lot of pedal pressure to stop. I am old enough to have owned cars without power brakes and have owned about 10-12 bugs to know what the feel should be...I will completely drain the system again in case there is still some moisture..and readjust the back brakes..

thanks

Jack hit the nail on the head, we are aquainted with having power assist/ABS etc braking and have not had the oppurtunity to experience manual brakes in quite some time.
What I've done is install a 2 lb inline valve ( available from street rod vendors) in line from the master cylinder to the rear discs I have placed it just forward of the "tee" fitting above the rear torsion arm. This reduces some of the pedal travel . On the front disc / rear drum set up, it is important to keep after the rear shoe adjustment . You'll also need an adapter from German bubble flare to SAE std. line.

I saw a 67 bus master cyl.s .for $175.oo I think at BFY or another Samba related site would that help? I have the line valves installed as required by CB perf.but all on the master cyl. 2 lb front 4 lb rear should I add or move the one for the rear disc brakes?
They stop good but the petal travel is a concern.