Skip navigation

Master Cylinder for 9" break upgrade

Post

Back to the top
Master Cylinder for 9" break upgrade

Hi all. Im looking at doing or should I say my dad is helping me do (he used to be a truck mechanic and I have no clue) the 9" servo upgrade to my 1992 sportline as the breaks are a bit worrying. Question I have is what master cylinder should I use as I want to get away with doing loads of extra piping and having read through the how to guide it suggests you can do away with some or it if you get a 4/6 inlet?? Any advise from somone who has done it please?

Post

Back to the top
An original type master will do, only really need to fit a larger one when fitting different as in larger calipers, which need a larger volume of brake fluid to avoid a long pedal..

Post

Back to the top
I just built my system up and used this 4 outlet one

http://www.ebay.co.uk/itm/183008815451

Being a later cabby yours should have the brake light switch on pedal so no need for extra pieces under the bonnet.

You may find though that the original steel lines are very hard to manipulate into the new positions for the bigger master cylinder so may be a good time to replace all the brake lines with new copper ones

Current rides:

2003 BMW 330d Manual Saloon Msport
1985 GTI cabriolet black edition (42k miles)
1999 Triumph Daytona 955i Post apocalyptic, rat, brat, scrambler, steam punk, cafe racer

IMG_20190803_123357.jpg

Post

Back to the top
Silly question  but does my current cabby have 4 outlets then given what you said about been a late type so it should just be a swap for the one in your link and a bit of adjusting on the brake pipes?

Post

Back to the top
Yours should have 2 underneath with compensator valves for rear offside and rear nearside

And 2 on the side for front offside and front nearside

And obviously 2 holes for fluid pot to plug into

Those brake pipes aren't easy to bend though and if they are it normally means they are close to snapping

Current rides:

2003 BMW 330d Manual Saloon Msport
1985 GTI cabriolet black edition (42k miles)
1999 Triumph Daytona 955i Post apocalyptic, rat, brat, scrambler, steam punk, cafe racer

IMG_20190803_123357.jpg

Post

Back to the top
Are you changing the Brake Booster as in Vacuum assist, or the MC.

If you are doing a swap take care when re-centering and re-attaching the MC to the Booster.

You have to center the mc to the booster, (oil or grease the o-ring on the MC) then take the nuts down equally that is 5-8 spins on the left then 5-8 spins on the right.
Failure to do that can result in the Push-rod on the Booster becoming offset or off centered in the booster, and popping out of the fingers of the holder and that isn't a pretty thing to have happen.

Also you will want to adjust the free-play of the pedal afterwards.

I have driven the 90, 92, and 93 Cabby for years and find the brakes to be sufficient when maintained, the issue that I have seen on all of my Cabriolets are the rubber brake lines needs to be upgraded or changed as the weakened rubbers because of age Balloon when fluid is moving, why the need to change?

Rubber lines from the hard lines to the Calipers on the front and the ones over the axle.  

They make a set of Stainless Steel Jacketed lines that do rather nicely, and they make the pedal stiffen really really well.


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

Post

Back to the top
Thanks for the above advise. Im wanting to change it as at the moment the brakes just dont give me any confidence they have had new disks, pads and rear drums re built but still very fluffy unless I really stamp on them. Many have reported swapping the MC for a mk2 9 inch one makes a huge differance

Post

Back to the top
Change your Rubber bits, then power bleed it….

I have taken my 93 and 92 well over 95MPH (yep I live in the Colonies) and they stop pretty well when the cars are maintained.  I usually drive the Interstates over here at 70-80,,,,,


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

Post

Back to the top
Seconded braided lines will make the world of difference even new rubber ones would if the originals are still on after 25yrs

Unfortunately they will never be brilliant due to the location of the servo

In most cars with the engine off if you pump the brake pedal it will harden up and eventually have no movement.

This wont happen with the mk1's due to the movement / play in the connecting bar from the brake pedal to the servo, you'll probably always be able to push the pedal down around 25% however much you pump the pedal

Current rides:

2003 BMW 330d Manual Saloon Msport
1985 GTI cabriolet black edition (42k miles)
1999 Triumph Daytona 955i Post apocalyptic, rat, brat, scrambler, steam punk, cafe racer

IMG_20190803_123357.jpg

Post

Back to the top

WATERNAIR said

Seconded braided lines will make the world of difference even new rubber ones would if the originals are still on after 25yrs

Unfortunately they will never be brilliant due to the location of the servo

In most cars with the engine off if you pump the brake pedal it will harden up and eventually have no movement.

This wont happen with the mk1's due to the movement / play in the connecting bar from the brake pedal to the servo, you'll probably always be able to push the pedal down around 25% however much you pump the pedal

I don't have that issue as I don't have the Rube Goldberg brakes of the UK and RHD.  :)


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?
0 guests and 0 members have just viewed this: None.