Changing Brake Master cylinder

[olly22n]

Hello,

What is the best way to change the brake and clutch master cylinder on an S4 with strombergs?

From what i can see the engine is going to have to come out/be moved?

Are there any tricks that may help me out?

[europatek]

No need to remove the engine. Just remove the carbs and access is much easier. I've just rebuilt both master cyls on my S4. Mine has Dellortos, so just removed them. Access is even better if you remove the coil also.

[olly22n]

I can't see how i can remove the cards (strombergs) without lifting the engine?

[69S4]

Hi Olly. Removing Strombergs is (mostly) easy. Unhook the throttle and choke cables, pull (undo any clamping screws first) off the fuel lead, take off the airbox and the engine breather pipe. This lot should take you about 5-10 mins. Then, look where each carb bolts to the inlet manifold. There you'll see a couple of nuts with odd W profile washers which, if you flex the carbs, look like they haven't been done up properly.

There's two of these visible at the top of each carb and a third, less visible, underneath - 6 in total. Undo all of these (the bottom one on the rear carb is hard to get to, the others easy) and the carbs will pull off as a set. The hard to get to nut will come off, it just needs a bit of patience.

Best to replace the O rings you'll find in there. They're important to getting the engine running properly.

[billwill]

Er, you did not say whether it is left-hand drive or rhd.

Which makes a big difference WRT the brake & clutch masters.

[olly22n]

RHD,

Bill, do you have any pictures of these nuts, i can't see them?

[billwill]

It was Stuart said that..

Mine has Dellortos so I don't know exactly what he meant, but here is the stromberg page from the manual'
http://www.datahighways.co.uk/photos/ogu/strombergs.jpg

I suggest you print it out. to make it bigger & clearer.

I think Stuart meant the nuts which have the flat circular spring washers under them. They should only be tight enough to press the o-rings to the metal. The rubber of the o-rings then lets the carbs vibrate a bit (or is it vibrate LESS than the engine).


If new washers have been fitted they may be a rubber bush between two metal cups, like mine.

[billwill]

You probably don't have the emission control stuff, so here is the pucture without that.

http://www.datahighways.co.uk/photos/og ... ergsuk.jpg

[olly22n]

I have seen them, i can't see hoe it is possible to get a spanner near them let alone undo the nut?

[billwill]

You need smallish open end spanners for Webers & Dellortos, probably the same for your Strombergs.

Small socket set might be needed. And maybe a springy flexy drive handle for the small sockets.

Looks like you need a trip to a toolshop.

The underneath ones are easier to get to once the air box is removed. You reach down with your elbow ending up towards the radiator and your hand under the carbs.

[69S4]

I have seen them, i can't see hoe it is possible to get a spanner near them let alone undo the nut?

The four on the top are easy - an open ended or a ring spanner will shift them. The bottom one on the front carb you can get to easily once the airbox is off. The bottom one on the rear carb is tricky. It's easier if you have the cables and the fuel line out of the way but you're still going to have to contort your arm a bit, like Bill said.

If you loosen off the linkage clips that fasten the throttle spindles together you can take the front carb off separately and that will give you a bit more access to the remaining bottom nut. Personally I prefer to leave them linked together as you don't have to rebalance them when they go back on. Whatever spanner you use on the last nut it'll only come undone one flat at a time so it'll take a couple of mins once you've worked out how to contort your arm. It won't be very tight and I've found that a 1/2" open ended spanner cut down to about 4" in length works about as well as you're going to get.

If you've not done this before it might all sound a bit daunting but there's not much in the way of disaster mode if you get it wrong. Apart from the one awkward nut it's all just a case of taking your time and not forcing anything. From opening the bonnet to staring at the last nut should take about 15 mins.

[billwill]

Just to complicate the issue, the manual does say that you should progressively undo these nutes, so that you don't distort the fit.

But in my opinion that only applies to the first turn or so as the spring washers will prevent any distortion after that.

[Lincoln62]

For those difficult nuts just get a cheap spanner and bend/cut/grind it until it fits.

Pete
66S2

[billwill]

For those difficult nuts just get a cheap spanner and bend/cut/grind it until it fits.

Pete
66S2

You may need to hold the spanner in a vice and heat it with a blowlamp until cherry-red to be able to bend it (be very careful!)

I seem to recall having to do that with a double-ended ring spanner to get at the nuts on the bottom of the master cylinders.

Ah.. Here is one I made earlier
Originally modified for the master cylinders, it has proved very useful in all sorts of places.
Also shown is a bendy twisty handle thingy with a small socket wrench on the end.