16v master cylinder & servo upgrade – how to with photographs
In the spirit of upgrading brakes, here’s a revamp of a how to I did a while back when I did the servo and master-cylinder:
[b]Parts Sources[/b]
Master Cylinder:
Not sure where mine came from, it was bought as new from a show, its got a Passat part number, but it’s unclear which model or year (Its dubious origin came back to bite me later though as it wasn’t an easy fit). You can get them from late mk2 (16v) and mk3 golfs, though these often have 2 outlets instead of 4.
Master Cylinder:
Not sure where mine came from, it was bought as new from a show, its got a Passat part number, but it’s unclear which model or year (Its dubious origin came back to bite me later though as it wasn’t an easy fit). You can get them from late mk2 (16v) and mk3 golfs, though these often have 2 outlets instead of 4.
Servo:
This came from a scrapped mk2 16v golf, it also came with master cylinder (2 oulet only) and an epansion tank that I needed.
This came from a scrapped mk2 16v golf, it also came with master cylinder (2 oulet only) and an epansion tank that I needed.
[b]Preparation.[/b]
This is an increadibly messy job. You’ll need tons of newspaper & rags for soaking up spilt brake fluid, and also a means of storing and disposing of about 1 litre of old brake fluid. If you’re cracking the fuel system on a K-jet engine for access, be prepared for all the mess that involves too (i.e. Rags and newspaper for petrol spills).
This is an increadibly messy job. You’ll need tons of newspaper & rags for soaking up spilt brake fluid, and also a means of storing and disposing of about 1 litre of old brake fluid. If you’re cracking the fuel system on a K-jet engine for access, be prepared for all the mess that involves too (i.e. Rags and newspaper for petrol spills).
A good brake bleeding kit is a bonus. I use an Easy-bleed type kit, plumbed into a flat spare tyre generating about 1 bar (approx 10psi) of pressure.
Be prepared to jack the car, both for access underneath it (unless you’re really slim) and for easier bleeding of the brakes.
Tools needed are fairly minimal. 10, 11, & 13mm spanners will do for most of the brake components, A dedicated brake union spanner (sometimes called a crowsfoot) with 10 & 11mm ends could be useful on tight joints. A 17mm spanner will fit around the clevis for adjustment, an Ajustable spanner will help for odd instances when you can’t find the one you want. A ratchet set with a 13mm socket is useful, but not essentail, as most access it too tight for it. Long flatbladed screwdrivers are always useful, both for leverage and prodding and poking stuff.
Plus-Gas, WD40 or some other penetrating oil is essentail for freeing up siezed joints & bolts, none of the fixing nuts are particularly tight, but they are often painted up. You may want to use Locktite or some other threadlock compound on reassembling painted up nuts, I didn’t and it’s not done me any harm.
I found a length of gardeners wire (steel solid core, plastic coated) to be quite effective in re-positioning a particularly stiff spring, though you could probably also use string or electrical wire.
[b]Improve access to working area.[/b]
Remove throttle intake tube, disconnect airbox breather pipe, vacuum switch feed hose, brake fluid level sensor wires. For brake line manipulation and mangling it may also be easier if you move the coolant expansion tank and the fuel metering unit (though this will involve breaking the connections to the fuel pump and all the petrolly mess that entails). Obviously Carb’d car owners don’t have to suffer much of the above..
[b]Remove Vacuum feed hose[/b]
There’s a large vacuum inside the servo, so relieve this first (by operating the brakes a few cycles with the engine off), then pull the hose out. (it has retaining ridges that make it a tough fit).
There’s a large vacuum inside the servo, so relieve this first (by operating the brakes a few cycles with the engine off), then pull the hose out. (it has retaining ridges that make it a tough fit).
[b]Drain excess brake fluid[/b]
Remove a front wheel, loosen bleed nipple, drain fluid int a jamjar or something suitable, pump brake or use ezibleed type kit to speed the process. With the ezibled kit, do not put fluid in the resevoir, just use the air pressure to push the fluid through and out of the system.
[b]Loosen Brake lines[/b]
Using an 11mm spanner, and a squirt of WD40 first. Fully unscrew each retaining union and pull end hose out of master cylinder. It’s likely you’ll get some brake fluid spilling, so put down newspaper or a catch tray to prevent excess mess (I didn’t).
Using an 11mm spanner, and a squirt of WD40 first. Fully unscrew each retaining union and pull end hose out of master cylinder. It’s likely you’ll get some brake fluid spilling, so put down newspaper or a catch tray to prevent excess mess (I didn’t).
[b]Remove Resevoir[/b]
Pry it off the 2 mounting holes with a flat blade screwdriver, try to pull it straight out rather than bend the spigots, they could snap.
[b]Remove Master Cylinder[/b]
Use a squirt of WD40 on the 2 retaining nuts on each side of itand then a 13mm spanner on them, the master cylinder should pull straight out quite easily.
Use a squirt of WD40 on the 2 retaining nuts on each side of itand then a 13mm spanner on them, the master cylinder should pull straight out quite easily.
[b]Release return spring[/b]
Remove the outer splitpin and washer from the spring mount. The spring is pretty tough, so when it’s prised free of the clevis, be prepared for it to spring around to it’s rest position (both arms parallel). Then extract the spring.
[b]Loosen servo retaining nuts[/b]
The tops ones can be accesses from above with a 13mm ring spanner (small crank angle) The bottom ones are better accessed from under the car, Use a socket & ratchet for greater leverage. Remove & retain nuts & washers.
The tops ones can be accesses from above with a 13mm ring spanner (small crank angle) The bottom ones are better accessed from under the car, Use a socket & ratchet for greater leverage. Remove & retain nuts & washers.
[b]Uncouple servo pushrod linkage[/b]
The pin on the clevis is shrouded by the supporting bracket, so pull it clear by pulling the servo away from the bracket. Find the retaining clip on the bottom of the pin, and by inserting a long thin screwdriver via the side of the bracket, prise open the clip enough to slide it off the pin. Extract pin.
The pin on the clevis is shrouded by the supporting bracket, so pull it clear by pulling the servo away from the bracket. Find the retaining clip on the bottom of the pin, and by inserting a long thin screwdriver via the side of the bracket, prise open the clip enough to slide it off the pin. Extract pin.
[b]Remove Servo[/b]
The servo can now be extracted, which sounds easier than it actually is due to the amount of crap still in the way. Move the coolant expansion tank to allow greater space.
The servo can now be extracted, which sounds easier than it actually is due to the amount of crap still in the way. Move the coolant expansion tank to allow greater space.
As the Clevis is drawn clear 2 felt ring pads on the pivot arm will drop clear, retain these for refitting (see photo for lower pad)
[b]Prepare New Servo[/b]
The clevis linkage on the 16v servo is different to the standard Scirocco clevis in 2 ways: the size of the holes for the pin, and the lack of a retaining spring locating hole. The standard Scirocco clevis thus needs to be fitted to the new Servo, but be sure that it extends the same distance from the servo body.
It is on a 10mm threaded rod coming from the servo, but can be very stiff, if necessary, drill out the rod from the clevis.
[b]Slacken off linkage[/b]
A common problem in the fitting of a 16v servo is excess pressure in the pushrod which gradually applies the brakes as you drive. Slacken off the pushrod across the bulkhead by loosening the lock nuts and twisting the rod (it has a reverse thread on the driver-side linkage). The locknuts are often painted to prevent slippage.
[b]Fit new Servo[/b]
Refitting of the new servo is pretty much the reverse of removal, manoeuver it into position, and line up the clevis with the pivot arm (it may help to jam it in one position). Remember to re-insert the felt pads. The clevis pin should drop in with little resistance, refit the retaining clip.
Refitting of the new servo is pretty much the reverse of removal, manoeuver it into position, and line up the clevis with the pivot arm (it may help to jam it in one position). Remember to re-insert the felt pads. The clevis pin should drop in with little resistance, refit the retaining clip.
[b]Refit return Spring[/b]
The return spring should be located onto the bracket first, and with one arm positioned on the bracket, draw the other arm out to meet the servo clevis. To assist I used some gardeners wire to pull the spring out from a distance, increasing the force I could apply in an otherwise tight space.
The return spring should be located onto the bracket first, and with one arm positioned on the bracket, draw the other arm out to meet the servo clevis. To assist I used some gardeners wire to pull the spring out from a distance, increasing the force I could apply in an otherwise tight space.
[b]Prepare New Master Cylinder[/b]
If the master cylinder was not fitted to the servo, ensure it will fit (obvious, but the piston on mine was 5mm too long and had to be cut). For convenience I dry fitted all components on the bench first.
If the master cylinder was not fitted to the servo, ensure it will fit (obvious, but the piston on mine was 5mm too long and had to be cut). For convenience I dry fitted all components on the bench first.
Remove the proportioning valves (if fitted) from the old Master cylinder and fit them to the new one. They should be fitted to different ports, i.e. One front one rear.
[b]Fit new Master Cylinder[/b]
It’s worth doing a few trial fits of the master cylinder with the servo in place, especially as (most likely) the outlets will be in different places. When bending brake lines, try not to include any sharp corners. The brake lines should also be positioned to retain the diagonal split, so a front and rear brake will be same outlet pairs.
It’s worth doing a few trial fits of the master cylinder with the servo in place, especially as (most likely) the outlets will be in different places. When bending brake lines, try not to include any sharp corners. The brake lines should also be positioned to retain the diagonal split, so a front and rear brake will be same outlet pairs.
[b]Attach Brake lines[/b]
When doing up the unions, remember that its easy to cross thread them if the brake pipe is pulling them out of square – this would wreck the master cylinder, especially if it’s an alloy one. Note the rear lines go to the proportioning valves on the right of the master cylinder, they’ve also been crossed to maintain the diagonal split.
When doing up the unions, remember that its easy to cross thread them if the brake pipe is pulling them out of square – this would wreck the master cylinder, especially if it’s an alloy one. Note the rear lines go to the proportioning valves on the right of the master cylinder, they’ve also been crossed to maintain the diagonal split.
[b]Fit Fluid Resevoir[/b]
Use a spot of brake fluid to lubricate, push the resevoir fully home until it sits flush with the rubber unions on the cylinder.
Use a spot of brake fluid to lubricate, push the resevoir fully home until it sits flush with the rubber unions on the cylinder.
[b]Re-Fill the system[/b]
Fill the resevoir (carefully) with fresh brake fluid, then bleed the system from each wheel, in diagonal pairs (I started from the nearside front, as it was the one I’d bled the system from). Periodically check the level of fluid in the tank, and refill. Use an easy-bleed type kit for speed and convenience.
Fill the resevoir (carefully) with fresh brake fluid, then bleed the system from each wheel, in diagonal pairs (I started from the nearside front, as it was the one I’d bled the system from). Periodically check the level of fluid in the tank, and refill. Use an easy-bleed type kit for speed and convenience.
[b]Adjust the linkage[/b]
Whilst working the brake pedal, try to dial out most of the slack by turning the linkage, leave a fraction so it does not load the servo when the pedal is at rest.
Whilst working the brake pedal, try to dial out most of the slack by turning the linkage, leave a fraction so it does not load the servo when the pedal is at rest.
[b]Re-connect all the other stuff[/b]
Try to get it all as you found it, I know it’s difficult with all the hoses found on a k-jet engine, but it makes testing easier if you can actually start the car.
Try to get it all as you found it, I know it’s difficult with all the hoses found on a k-jet engine, but it makes testing easier if you can actually start the car.
[b]Test thoroughly[/b]
It’s best to be sure the brakes are functioning at all before leaving the drive or garage, you can then evaluate their full performance on a quiet backroad in relative safety.
It’s best to be sure the brakes are functioning at all before leaving the drive or garage, you can then evaluate their full performance on a quiet backroad in relative safety.
[b]Notes.[/b]
Obviously this is just edited highlights, for easy reading I’ve removed steps like ‘spill brake fluid all over floor’ and ‘drop spanner repeatedly on your face whilst lying under the car in a puddle of petrol and brake fluid’.
Obviously this is just edited highlights, for easy reading I’ve removed steps like ‘spill brake fluid all over floor’ and ‘drop spanner repeatedly on your face whilst lying under the car in a puddle of petrol and brake fluid’.
Due to my fairly bizarre sources of parts, the job was harder than it could have been, I’ve detailed some of the more common problems that may be encountered, but certainly not all of them.
The Mk2 golf expansion tank is an odd, asymmetrical shape, thus it gets pretty friendly with the TB intake duct on K-jet cars:
This hasn’t proved to be an issue in this installation, but could be in others, if so be ready to swap in another expansion tank, the original one may not fit as the spigots are spaced differently.
And that’s it.
From an original post by Giles aka Skyrocketeer
Outstanding piece of explanatory work and great pics! Well done, thank you.