Revisiting Jaguar Clock Repair: The Smiths Gold-Plated Contacts Conundrum

Gentlemen, please note that Mark Willows didn’t discover the two service bulletins from 1965 and 1966; I did from scouring the internet. So if there is an error here in the E-Type clock inference (still to be determined), it’s mine, not his.

However, Mark does claim that the transistorized clocks do not have contacts. (Note: he also doesn’t have a repair kit for them.)

It’s the first service bulletin from 1965 that makes the contradictory claim that the clocks are both tranistorized and the gold plated contacts chatter and burn.

What Jaguar in 1965 had a transistorized clock?

Perhaps “transistorized” refers to the diode that was added to later clocks to help prevent the contacts from burning? That would solve the mystery of the service bulletin’s contradictory claim.

When I had my Speedo and Tach rebuilt, I also had my clock repaired using electronics… keeps excellent time… check with was relatively inexpensive… as I recall…

That, to me, is a false claim of a new transistor clock- but you certainly may be correct!

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I wholeheartedly agree, but I wouldn’t put it past Jaguar to do this as a sales tool.

We can use simple deductive logic to solve this “crime:”

Would Jaguar (via Smiths) introduce an improved, fully transistorized tach mounted clock and not install it in the E-Type and sedans in 1965? Indeed, we know that a diode was installed in the gold-contacts/balance wheel clocks in ca. 1965, but we didn’t see separate clocks until later, I’m pretty sure. is Mike Eck, and he does a great job with Smiths clocks. As I understand, he performs a PCB conversion similar to Clocks4Classics on the tach mounted Smiths clocks, but replaces the entire mechanism in the later center mounted clocks, as they can’t be rebuilt (from what I understand). In those clocks, you can have your choice for the digital movement to run off the car battery, or use a separate AA circuit.

I’m not very familiar with the 420s, but photos on BaT of a 1967 model show the clock as being mounted in the center of the dash pad above the center gauges. As I understand it, both the 420 and 420G were introduced in Oct 1966, and had the square clock mounted in the dash top crash roll. However, as service bulletins P.44 (Nov 1965) and P.50 (Sept 1966) both predate this, any “transistorized” clocks must have been fitted to earlier models. I have found a photo on p.87 of “Jaguar All the Cars” by Nigel Thornley (admittedly a volume with some inaccuracies) of what is claimed to be a later Mark X with a centrally mounted square clock in the top of the dash pad. Unlike the photos of 420s/420Gs (where the clock in incorporated in the padded dash), the clock is fitted to a wood surround about 5" wide, which would, no doubt, inflict a nice bump on the head of anyone who collided with it! Perhaps this is the introduction of the “transistorized clock” that had the problem?

Is it just me, or does the title of this thread read like the title of a Tom Wolfe book?


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What models in 1965 would have transistorized clocks? The E-Type, MK2, 3.8S and Mark 10 all had similar dashboards with the tach mounted clock. I can’t think of any other models.

But you are correct about the 420G, introduced in 1966. I did a Google search and found this photo of a new style clock in the middle of the dash:


Thus, we still have the conundrum in 1965 of “chattering” contacts in supposedly “transistorized” clocks (which have no contacts), and no indication of the introduction, as of that year, of truly transistorized models.

Who said that transistorized clocks have no contacts? There was a brief period where self winding car clocks had both…the contacts triggered a one shot transistor circuit, which wound the spring. The advantage being that the contacts were isolated from inductive load, so no sparkies. Timekeeping still depended on the physical motion of a balance wheel. Whether or not it was ever the case with Smith’s I don’t know. Quartz stepper movements followed later.

Still shaking my head about having to “bump start” your clock after battery disconnect.

That’s a classic tech bulletin, right in there with “leakage, weepage, and seepage” for oil leak warranty (BMW Motorad if I recall correctly).

Mark Willows of Clocks4Classics stated the following in discussions as I was preparing the writeup (see original post): “Smiths did later produce some transistorised clocks but these did not have contacts.”

Mark is a clock maker and I defer to his knowledge of the various automobile clocks of the day.

Note there were no transistorized Smiths clocks in 1965 when the first of the service bulletins was released.