Skoda Rally Blog

With the Sunseeker coming up in just 5 weeks time, some progress was needed on the Seat.  While most of it was OK, the brakes were definitely not the way I wanted them; they have been converted from the original servo-assisted setup to a non-servo bias-adjustable setup with individual cylinders for the front and rear, plus of course the massive AP Racing front brake setup.  While this sounds impressive, it wasn’t in practice – an immense amount of pedal pressure was needed, which meant there wasn’t a lot of control.  They were powerful, but to get the power you needed to put the kind of effort usually only seen in a final of World’s Strongest Man.  Not a good combination, really, and even on a short stage it was tiring.  Doing an 11-mile forest stage would definitely be ‘interesting’.

So, it was time to improve matters.  First up was to remove any chance of a routine ‘service’ based issue giving these problems – while it was unlikely, it was worth checking anyway; so, it was time to change the brake fluid and bleed the entire system.  The car had been laid up for a couple of years so the fluid needed changing anyway.  With the old stuff syringed out of the master cylinders, a problem struck.  The front brake calipers’ nipples were looking very worse for wear (a combo of having been mis-spannered and also beaten up with stones), and a couple didn’t want to come out.

Bad Nipple

Given that the calipers are £800 a side new, I didn’t want to mess things up, so bought an expensive wall-drive socket to give the best chance of removing them.  And the £12 paid off, as they all came out OK.  £4 then saw them all replaced!  I’ve never understood saving money on things like this – it always comes back to bite you.

Good Nipple

There’s a link pipe between the inner and outer parts of the caliper, and this was stone-damaged too, so that was replaced – another time I was glad I had a bunch of tools as making the brake pipe up took minutes to do.  Then, bleed all the brakes, refit everything and go for a test drive.

Still terrible.  However, in the meantime I’d done some reading about brakes, and found some very interesting info on the Stoptech website – in a very informative help sheet about such brake setups, it mentioned that the ‘pedal ratio’ of most standard setups was wrong when converting the system over as mine had been.  The ‘ideal’ ratio is 6.2:1, so it was time to see if my setup was the same.  I made some measurements, and found that mine wasn’t anywhere near – it was 4.3:1.  This would mean that a LOT more effort would be needed to get the same pressure on the brakes, which made sense given the way the brakes felt.

In short, out came the pedal, and it was then re-drilled to give a ratio of 6.2:1 by making the distance between the pivot and the brake pushrod 40mm instead of the previous 58mm.

The new hole is B, the old hole is A, and the pivot is C in the picture.

I put it on the car (without reinforcing it yet) to see how it went.  Fortunately unlike other pedalboxes I’ve worked on before it’s fairly easy to do, and within 5 minutes I was out in the car, and it was transformed.  Still needed a bit of a push when cold, but instantly felt much better; the payoff is more movement in the pedal, but it feels fine now – before it was horrible, and now I have some real control – it was easy to take the brakes to the edge of locking up.

To finish off, it needed to come off, and then have some strengthening done – there was a hole right next to the new one, originally, which needed welding up, plus the inside of the pedal was also only single-skinned so this was beefed up, painted and then refitted.

The errant starter motor was next, a quick grease of the appropriate bits freed it up – it’s not perfect (although it looks like new on the outside, it was clearly badly reconditioned!), but it works OK and doesn’t stick now.

The car is pretty much all set now, I just need to fit the bias adjuster, making up a new plate to mount it in, but that can be done tomorrow. One thing I did notice on the test drive is that it really does go well!  The Sunseeker should be magic.