Time for another update.
When we left the car on Friday it had basically no brakes. The first pedal stroke went all the way to the floor.. a second in quick succession brought the height up a bit but not enough to drive the car with.
Saturday morning, went back to the car and the first thing I did was check the pedal. What do you know, it went hard half way through the first stroke. Don't know why, don't really care.. we have a pedal, probably enough to stop the car with
I suspect Mick was right, and overnight any air in the system has percolated out of the nooks and crannies.
Crawled underneath and had a look, there was a bit of fluid weeping from the bleed nipples on the alloy calipers, so nipped them up a bit more. A few firm pedal pushes later, and no more fluid leaks, so we're all good.
With the chances of getting on the road improving, it was time to sort out one or two other minor problems. First and foremost was the rock-hard clutch. I'd asked about this problem a week or two ago in
another thread and the general consensus was that the clutch hose was rooted. I'd bought a set of braided hoses with the Mini Spares order, so there was a brand new item ready to go on. First, the old one had to come off...
This is the love/hate relationship I have with Mini's. Not nearly enough space to get tools into position without removing half the engine first. First I had to get the clutch pipe off in order to remove the hose.. that was bad enough. This hadn't been off the car in the 12 years I've owned it, so you can imagine the state it was in. In the end it came off intact, and 2 minutes on the wire wheel later:
Once the pipe was off we could get to the hose. That came off easily and as expected, was almost totally blocked. On went the new braided item, on with the pipe, a quick bleed and and Oh My God, what an amazing difference. If there's a better clutch pedal feel in a Mini, I want to see it
The last thing to do was get the wheels on the ground so we could set the toe before the first road test. The Loctite'd wheel stud had had 24 hours to cure, and as it turned out caused no fuss at all -- the nuts went on without fuss, and no hint that the stud was going to slip. Yay Loctite
I was going to set up a string line to set the toe-out, but after looking at the settings (1/16th" total toe out for both wheels.. that's less than one millimetre per wheel) I figured there was no way I'd be able to measure that with any sort of precision. In the end I aligned it by eye -- with the steering wheel perfectly straight, I adjusted the track rod ends on both sides until the leading and trailing edges of the front tyre make a line which meets the rear tyre, and then added one quarter turn of the rack to give a tiny bit of toe-out. I figured that should be plenty accurate enough to road test the car, and get it to a professional alignment shop. Eyeballing the alignment on the Bini and my brother's clubby in the same way looks exactly the same, so it can't be far wrong.
So with the caster bars set to standard length and 1.5 degrees negative camber on both sides it was off for the first road test. There were no problems at all with caliper clearance to the rest of the suspension or the wheels. Don't know what Mini Spares were fussing about, it's all good
Even with a half-height pedal, the first brake test was pretty impressive. I'm so used to giving the brakes a couple of taps before I need them that I found myself doing that automatically, and that gave me a pretty strong pedal. What's more, the pedal effort required to stop the car with the 4-pot calipers is pretty lineball with that needed with drums, only now the car doesn't try to fire you off the road -- it stops perfectly straight
Or, it would, if the car drove in a straight line in the first place. This is the geometry problem I mentioned before, the car's probably had a whack in a PO's life because with the caster bars at the standard length, the car pulled strongly to the left. The actual toe alignment was pretty good -- with the wheel straight, the car went straight.. it just pulled hard to the left.
Having a long think about this, I decided that reducing the positive caster on the driver's side while increasing it on the passenger's would reduce the tendency to pull left. It took a
lot of adjustment, but in the end the car drives in a straight line without any hands on the wheel. I haven't measured it since I got it perfect, but at one point along the way there was more than 20mm difference in wheelbase between each side
Turns out this isn't unprecedented -- my brother's clubby has at least that much difference, and it points and brakes perfectly straight.
So, with the alignment pretty good and the brakes OK, it was time to replace the 3/4" rear wheel cylinders with 'S'-type 5/8" items. In one strong brake test I managed to lock both rear wheels, (thankfully after I got the alignment right, otherwise the car would have probably swapped ends) so that's definite evidence that the 5/8" rears are a necessity with discs.
Another cow of a job, that one. First I had to drill the backplaces to take the 'S' cylinders, as they have the locating pin on the other side to the 3/4" cylinders. Next, I very nearly cross threaded both pipes when refitting them because they wouldn't sit straight in the cylinders. A couple of hours, much swearing and bleeding fingertips later, they went on straight, thankfully.
One last bleed (mine,
and the brakes) and the pedal was quite a bit better. Still nowhere near what I want, but easily the equal of drums after a couple of weeks use. Seems the smaller-diameter rear cylinders
did have a positive effect on the pedal height, so maybe my theory that my drum master cylinder isn't delivering enough fluid has some merit after all. When I get the car back to Melbourne, I'll grab a larger-diameter 'S' master cylinder and fit that, and then it should be case closed.
So that's about it. It took five long days, but we've successfully converted from drums to slotted, four piston alloy calipers and fully adjustable suspension. This is the end result.. 2 degrees negative camber looks
mean:
I still want to get a proper wheel alignment done, but after a couple of hours on the road today it feels like it's probably not necessary in the short term. The car steers and stops better now than in any other time I've owned it. In hard cornering, the front end bites and sticks, and the tail drifts every-so-slightly. Muuuuucho fun factor
It's also heartening to know that the brakes are only going to get better as they're bedded in
Anyone who like me has been wondering if this can be done -- the answer is a resounding 'yes'. 4 piston calipers clamping 7.5" brakes under 10" Contessa's -- it fits, it works, brilliantly
