1964 S type

[cass3958]

As my late father would say removal of the switch when all is working relatively OK would be "tinkeritis" .

Yep the old saying of "If it's not broke don't try and fix it"

[RollyTG]

Wow - I keep learning stuff. Never heard of induction coil heater device but it sounds really handy - pricey though. I know I am going to have to tackle those little screws on the otter switch because one of them is already broken off. Perhaps someone can enlighten me as to what a 2BA stud is and my day will deemed fruitful. Thanks gents.

[cass3958]

BA is a type of thread such as UNF or Metric. BA come in different sizes number 2 being quite small at 0.185 dia in inches or around 4.7mm.

So what Norman is suggesting is that you remove the old screws and then drill out the holes and re tap them in 2BA then fit studs which stand proud of the alloy and have a small nut on top so when you want to remove the Otter switch in the future you are undoing a steel nut on a steel stud rather than trying to remove a steel screw from an aluminium threaded hole.

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[RollyTG]

Thanks Rob. I figured it was something like that but I have never heard of BA before. I guess other size studs would work also, no?

[cass3958]

Yes you could use metric but I think Norman was trying to keep the replacement studs to imperial which is what Jaguar would have used in the 1960s.
Jaguar used UNC (course) and UNF (fine) threads but on the smaller nuts and bolts for some reason they would use the BA threads. Throw in a couple of Whitworth threads on the SU carbs and you have a right mess trying to find a nut to fit when you drop one on the garage floor.

All the bolt heads are different sizes so you have to have a set of Imperial and Whitworth spanners to hand.

Not surprised everyone changed to metric threads apart from the Americans who persist in using an adjustable wrench?

The Americans got around Metric and Imperial nut sizes by having a double ended adjustable wrench. One end is marked with an "I" and the other with an "M" so as not to confuse them.

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[Norton]

The otter switch can be opened without removing it from the engine. Then find out whitch way to bend the metal to increase operating temperature. Use heatgun. Replace and testrun. Repeat as necessary. Find a way to hold it in place witout bending tabs until you are satisfied.

One of my bolts had seized and broke off. I felt that would probably happen when I started to undo them. Probably the reason it was removed from circuit and an on / off switch was fitted. I decided to go ahead anyway, as I wanted an operating otter switch and had a spare. ( and later I found out it can be adjusted without removing it..)

Harald

[RollyTG]

Thanks Rob. Love the American double-ender. I have been here 17 years now so I might have to get one of those. Would a 2BA be like 4 mm?

[John Quilter]

The otter switch can be opened without removing it from the engine. Then find out whitch way to bend the metal to increase operating temperature. Use heatgun. Replace and testrun. Repeat as necessary. Find a way to hold it in place witout bending tabs until you are satisfied.

Looking at the photo of one opened up earlier in this thread, I do not see how I can be opened up while in place as both triangular sections seem to be penetrated by the three mounting bolts (or nuts and studs if modified). Can you explain how this is done. Thanks.

[Glyn Ruck]

The Otter switch cannot be opened without removing it from the engine (unless broken). It cannot be opened up while in place. The plastic is moulded into the top plate with 3 bolts through it. The bolts require to be removed to remove the top plate & then the 3 tabs bent back to separate the top plate from the housing.

A hot air gun is no good if you are aiming at a target temperature. You require the switch loosely assembled when measured. The air gap between the outer housing & the Invar spring is crucial to calibration. Thus dipping in hot water at a known temperature as I explain.


One I took apart. My car still has a genuine original "Otter" brand red switch.

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[Norton]

Sorry, ofcourse it cannot be opened without removing. I was doing some wishful tinking without parts in front of me. Promise to not do it again..

Hotgun can show if you are going up or down in temperature but it must be checked. It was part of my impossible plot.

However I was able to drill out the seized and broken bolt. Maybe just luck.

Harald