Pokey

This look familiar to anyone? I’ve tried polishing to no avail..

The alternator itself is grounded through its mount.

Sorry, misunderstood. Are you asking about the black wire with the ring terminal? That looks like a chassis ground. The loom has one up front for the light circuit. Or are you asking about the “missing” wire in the pigtail? I don’t claim to know but would guess it is for the indicator light we don’t have.

My guess to the starter, on its way to the battery.

For posterity, the combination Zetec with the Caterham 6-speed seems to work with these hydraulic release bearings (slave): Ford F5RZ7A508BA, F5RZ7A508BB, 94ZT7A564BA, 94ZT7A564BB Sachs SB60093 Sachs 3182 654 208 AMS Automotive N1767SA LuK 510 0067 770 LuK LSC273 Perfection Clutch 360062 I can personally vouch for the Sachs 3182 654 208 and the Perfection Clutch 360062. The others should work but beware of one possible caveat in differences in the casting where the nipples are located. I've seen some derivations that look to expect to have the top of the slave protrude out the opening in the bell housing which only works if the slave is aligned with the hole.

Thanks @CarlB, same here, I didn't use a LUK-273 but the equivalent. I've installed a pedal stop and a new slave cylinder and all seems to be working as it should.

Thanks @MV8. Sounds like you agree that the pedal stroke increasing could account for the failure then? BTW, I bled using suction from the slave’s bleed screw after assembly.

Long story short, hydraulic fluid dumped from the slave onto the bottom of the bell housing. We replaced the slave, bled, and the same thing happened. The original slave's manufacturer is unknown, but the replacement was a Perfection Clutch 360062. The two look identical down to the first four digits of the number stenciled on the casting as shown in the picture below. The release bearing touches the clutch's fingers but does not look to be depressing them. When the clutch pedal is operated the release bearing does not move. That's the facts, now comes the random thoughts: I took the clutch off to inspect, and while it seems unlikely I installed the clutch disc backwards, and unlikely that I could have cinched down the pressure plate had I done so, and it isn't clear how doing so would cause the fingers to become unmovable, if the fingers were stuck in position then what could have happened is the slave cylinder seals failed as the hydraulic fluid had to go somewhere. Note that this thought does not explain why the original slave failed in seemingly the same manner. The clutch pedal does not have a stop, or more precisely the stop appears to be the bulkhead, which over the yeas has deformed outward by a centimeter or more. Assuming the master cylinder can move more hydraulic fluid than the slave can accommodate, and that the pedal-induced bulkhead bulging allows more pedal movement and hence more fluid leaving the master, then, again, the slave cylinder's seals would suffer as a result. This would also explain why the original slave failed, but it also requires that while bleeding the clutch I pressed down to where the pedal pushed on the bulkhead. I can't say that I did or did not as I wasn't paying attention. Operating the pedal now using only half of the pedal stroke still results in hydraulic fluid transfer onto the floor of the bell housing, so that either means the clutch fingers are immovable or the slave's seals are so utterly destroyed that the resulting pressure isn't enough to move release bearing against the fingers. Anyone every experience anything like this? And those with a Zetec/6-speed setup, do you happen to know what slave you have installed?

Not sure if I posted anything at the time, but I had one cylinder running colder that I eventually traced back to the ignition signal coming from the ECU. For me the symptoms were more binary than for you, all of a sudden I (partially) dropped one cylinder. Granted, symptoms were more or less acute depending on driving conditions, and I don't know if the MBE ECU in these 420's fails the same way every time but perhaps you are chasing this gremlin? The definitive test is to put your ECU into another car and see if the problem follows, but I got to that point in troubleshooting by using a logic probe starting at the coil and working my way back in the wiring harness until I was convinced it was the ECU signal.

Assuming COP, a logic probe tester at the coil is the easiest way to rule out everything electrical upstream.

I'm looking at two steering racks. The first was manufactured in the early 2000's and is stamped as shown in the picture. The second was recently purchased and has a different character string stamped in the same place as the other rack, plus another character string stamped on the opposite side of the circular hole. That other character string matches the Caterham part number for an 8% rack. I'm told that the older rack is a 22% ratio, but lock-to-lock they are identical at just shy of two full rotations. Right now the new 8% is installed but I'd like to replace with a 22%. I'm thinking that I was told wrong, that the older rack is also an 8% ratio but am wondering if anyone can identify why lock-to-lock isn't the best way to tell. Maybe I need to pull the rack on the car and bench them together to see if the tie rods move the same distance? That wouldn't seem likely as that would mean one rack can turn the tires more than the other, but?

An alternative to a dry sump that seems to fit the need is Raceline's low profile wet sump: https://www.raceline.co.uk/products/part_section.asp?SectionID=40&CategoryID=2.

Given it is a roller my pick are wheels.

I can't see any way to adjust - it has a single attachment point that is round, not slotted. Nevertheless, I did try backing out the bolt and wiggling the sensor to see if it would have any effect on idle and it didn't.

I've ordered a new sensor. The $25 will be worth it even if for ruling out one of the possible causes.