How to mod a late booster for MK1.

**Peter Jones** · 11-01-2008, 08:57 AM

Originally Posted by 425i

I read in Australian model engineering magazine that after 40 years practice with cut off tools become easy to use.
They advised that until you have 40 years experience use a hacksaw.
I know a guy who built a full size triple expansion steam engine and he uses a hacksaw.
The best way i have found is to take off as much as you dare with the part off tool and then hacksaw through the rest with the lathe turning as this makes it much quicker.
The worse thing is persisting with the part off tool and then just when you think you are going to do it this time it catches and it bends at 90 degrees right were you are trying to part off and the job goes bang bang bang into the bed of the lathe . Followed by a clunk as you chuck it in the bin

Nick

That makes me feel a bit better!

Thanks Nick!

Pete

**Peter Jones** · 12-01-2008, 08:09 AM

I could have sworn I had the brake pedal switch out of the Cordoba I wrecked around here somewhere! Never mind a quick scrounge the the many boxes in my garage and I came up with this brake switch arrangement. Anybody recognise the parts?

If you guessed "Normally Closed reed switch from a domestic alarm sysytem" - Congratulations!

I traced the wires from the original switches to under the dash, wired in a relay and used the reed switch to control it.

As a bonus I now get a re-assuring click from the relay when I use the brakes, It's nice to know that the brake lights are working.

This may not be permanent, I'll see how it goes for now.

It all sits up out of the way of your feet. Adjusting it wasn't too bad, only took a few minutes to get the spacing right.

Pete

**Valver.** · 12-01-2008, 08:44 AM

Great work!!!!!!

**Peter Jones** · 12-01-2008, 11:05 AM

But how does it all work?

Just to recap what parts have been changed.

Cordoba 20.6mm Master cylinder and Booster.
Cordoba Rear drum brakes.
New standard solid discs.
'79 GLS calipers (see photos above for style)
Two new front brake lines.
Penrite brake fluid.

Well first off it does actually stop the car in a much shorter distance than the old brakes.

Very little pedal effort is needed to get the front tyres (195/60/14 G'Grids) scrabbling for traction. I suspect the lack of wheel alignment is causing them to loose traction a little sooner than they should at the moment.

Subjectively the old brakes felt firmer and more effort was required but I don't think the old booster was working which is what started me on the journey.

I have a theory that as both my cars were GLDs the boosters were dimensioned to work with the diesel vacuum pump and not manifold vacuum. I imagine that a dedicated pump would produce a better vacuum and the booster wouldn't need to be as big as a petrol motor. Comments anyone?

I took the car for a blast through an industrial estate with good visibility a no traffic and tried a few hard stops. Pedal feel is soft compared to the basically unassisted system that was before. but there's not doubt you're going to stop! Braking distances are much shorter. Rear proportioning seems about right. The car pulls up in a straight line and didn't exhibit any tendency to pull to either side nor was there any steering wheel input required to keep it straight.

After the run the front brakes were smoking from the fresh paint baking on. They were pretty hot and the rears were hot too but not nearly as hot as the fronts.

I couldn't get the back to break away with a mid corner stab on the brakes so I guess the front rear balance is about right. There's no rear load proportioning valve in this model BTW. The rear wheels are plumbed straight to the master cylinder.

I copied the plumbing methodology of the original system which is the same as the Cordoba and connected the wheels in a diagonal split. That is to say Front left and rear right work off one circuit and vice versa for the other circuit..

Having boosted brakes again is going to take a little getting used to. With the vacuum disconnected the pedal is rock hard and engages quite high, with the vacuum connected the booster seems to do all the work for you.

I'm running out of time these holidays to pop the other booster and 22mm master cylinder into my other car - that might have to wait a little while for when I've got a weekend free.

Pete

**Jarred** · 12-01-2008, 12:31 PM

good to hear pete. might have to have a crack at this someday.

**Golf Loon** · 14-01-2008, 07:35 AM

Fantastic write up Pete.

I reckon the Cordy and Mk3 boosters are the same except for the mounting tabs.

I always swop over the booster and master cylinder together. Mixing and matching wont work.

I hae seen the rod welded on before, but your way is better and neater.

FYI guys a Toledo is like a Mk2 in that it has the bigger booster and master, but with the correct fitting for a Mk1 already on the end!

I have plenty of Cordy and Toledo Boosters for anyone that wants and Pete will get his commission

**Oneofthegreats** · 14-01-2008, 10:47 AM

Absolutely awesome write up Pete on this thread & all your other braking thread's.

Very clear instruction's & picture's to go along with the before & afters.

These types of thread's are what make's this forum a great place to visit & also help's out any DIY'er.

It's an absolute credit to have you on here.

There's no way I'd have the patience to go through & post up all the pic's.

Can't wait for the next project.

**pepperwhite** · 24-02-2008, 10:52 PM

Peters way is obviously better but this way takes 5 mins (if you have a mig handy)

do the required measurements
grind down the stem (sorry the photo is bad.)

weld

cheerio