Morning Andrew;
We only tried the 'pedal' method of bleeding, but not only did my colleague have great problem in getting a 'pedal', when he did get one that was 'sort of acceptable', he found that constant pressure on the brake pedal slowly degraded the hardness of the pedal and the brake pedal slowly went to the floor. With regard to the brake-light switch, (we bought the switch that NANNI advises on their web-site is the one for the Mini-servo)they wouldn't fit AT ALL. The diameter of the switch thread is slightly greater than the female thread in the end 'nut' on the master-cylinder. I have subsequently discovered that the 'original' master switch possibly uses an 'imperial' thread (1/8--poss UNF )--in an Italian master-cylinder!
Hi, Tom and Andrew,
The replacement switch thread might be
10 x 1mm so 25.4!! threads per inch.
The female thread in the end 'nut' on the master cylinder might be :-
1/8th inch BSP (British Standard Pipe) thread nominal diameter = 0.383in. =
9.7282 mm. 1/8th inch BSP Tr (BSP Taper) thread is the same.
1/8th inch BSP is 28 T.P.I. This would be slightly smaller than the rep. switch thread.
There's also 1/8th NPT (American National Taper Pipe Thread) whose nominal diameter is 0.405 inches (10.287mm). Idk the t.p.i.
Idk if you said if the thread was tapered? but I'll assume it is as someone mentioned using PTFE pipe tape when fitting theirs.
Maybe you could try switch units (brake, oil pressure w/light etc) from other cars (old Mini, Ford etc) to determine what thread you require on the switch to fit the master cylinder end 'nut'.
Some of the older cheapie (like mine
) tap and die sets included a 1/8th BSP tap.... and iirc the thread gauge (if supplied) had this size included...
Looking through the various m. cyl's on the gol inelliloris website, I noticed a number of them use a 2 or 3 way union held in place by a banjo bolt. This arrangement was used on some older Fiats where there was only one outlet port on the cylinder. Maybe the switch supplied to you is designed to screw into a brake pipe union?
As you no doubt know, 10 x 1mm is a common thread on Fiat brake pipe unions.... (iirc there was also a coarser thread used in the past.)
P.S. I'm not an expert on thread sizes, just posting a few dimensions I got from my old Zeus Precision Tables pocket book in the hope they might help. If I'm wrong, I will respectfully :worship::worship: to the proper Engineers on here, I'm only a humble Mechanic
.
Al.