How to mod a late booster for MK1.

[Peter Jones]

The more I look at the Cordoba and MK III booster the more alike they look. I suspect they're interchangeable parts. That would make sense as they're practically the same car.

The only obvious difference is that the Cordoba has 4 studs to mount it to the firewall and the MKIII one has only 2. I guess you could always cut two off the Cordoba one to Make it fit in a MKIII if you had to. Otherwise they measure up the same in all dimensions.

Here's comparison shots front and rear.
From left to right - Seat - MKIII - MK1

(I'd started to paint the Cordy booster at this point)

[Peter Jones]

Here's some shots for anyone that wants to know the Diameter of the boosters.

Cordoba



MKIII



MK I

[Peter Jones]

Seat Master Cylinder FYI

[Peter Jones]

I only had one reservoir bottle and needed another. Valver suggested that the Golf / Seat ones weren't terribly attractive and suggested a reservoir off a N13 Nissan Pulsar would do the trick.

I have no idea what an N31 Nissan Pulsar looks like but I found the Nissan isle at the wreckers, popped a lot of hoods and came up trumps with a couple of these.

Cleaning up nicely here in the parts washer.

[Peter Jones]

A detailed shot of the end of the MKI booster FYI.

[Peter Jones]

The yokes on that bar across the back of the engine bay are the same casting as the one on the end of the booster, they're just machined differently.

One end is M8 with a left hand thread and the other is M8 with a right hand thread as you would expect from a tie rod. The left handed one is designated by a groove machined into the collar.

Both of these ends could be drilled and tapped to M10 and be used to convert more boosters.

The hole across the end for the pin is the same in all cases - 10mm diameter.

Here's a tip for you youngsters at home - To measure the diameter of a hole use the shank of a drill bit as a gauge.

[Peter Jones]

And just one last shot tonight of a MK I booster in it's natural environment.

(Before I pull it out of there!)

[Peter Jones]

And now it's time to actually bolt it in!

Move the cables and expansion bottle out of the way. Pull the reservoir off the master cylinder. Unplug the brake light switches.




Undo the brake lines and remove the master cylinder. A dose of WD40 the night before is a good idea.




I found the easiest way to get the booster off is to remove the entire assembly from the fire wall along with the transverse tie rod. It's easiest to get at the linkage clip on the other side of the engine bay and pull the whole rod out wit the lot. The "box" the the booster is attached to comes out with three bolts inside the cabin below the glovebox, right next to the heater pipes.




Better have a clean up in there and tidy up that wiring!

The removed assembly.




Stay tuned space cadets!

[Peter Jones]

Setting up the linkage.

The Booster rod in this car measured 130mm so I adjusted the new booster to match. I found it easiest to build it up as an assembly on the bench. I resisted the urge to paint the linkages and just cleaned them up as well as greasing all the pins and joints.



Bolted together with new M8 nylocks. I managed to drag the MK I rubber boot over the booster neck, it was a bit of a tight fit though.



Assembly bolted up to the firewall.

[Jarred]

wow pete, what a write up! Very informative and well presented., and you have a lathe! comes in handy aye?

the mk 1 community thanks you. Or at least I do.
oh and p.s. what do you have covering the top of your strut towers?