1964 S type

[Norton]

Hi. I have finally replaced otter switch and connected it correctly to aed. And have kept the on / off switch under the dash. My switch controls power to the aed and is actually redundant as long as otter switch work. Aed goes off after a short warmup time. ( As Jaguar designers intended ).
But if otter switch fails closed I can turn aed off. If it fails open I can’t turn it on. To have that option will require more switches. Or a 3 position switch on the otter side of the circuit.

Have also wired in a 3A fuse on feed to this switch. There is a warning light next to the switch, this is illuminated whenever switch is on, whether aed is powered or not. Thinking of rewiring this light so it illuminates only when aed actually is powered.

Afterwards I opened the old otter switch, and found out by bending the bimetal spring a little bit it can be adjusted to open at higher temperatur. But have not tested it in hot water yet, just by heating it with hot air. Needs more hot air to operate after my «adjustment».

Harald

[cass3958]

My Otter switch closes off the AED too quickly in my opinion so I might have to do as you are doing and manually adjust the Otter switch so it closes at higher temp or buy a new Otter switch and see if that stays on longer.

[Glyn Ruck]

The Otter switch is calibrated to cut out the AED at approx 35 deg C. They are fairly easily adjusted to a higher temp.

[cass3958]

How is it adjusted Glyn the way Harald suggests by stripping it out and bending the bi metal tabs?

[Glyn Ruck]

Yes. By opening it up & carefully bending the Invar spring/tab. Container, kettle & thermometer in container nearby. You need to measure it put back in its housing for accuracy. Obviously leave tabs open. You are not going to get it right first time. Get hot water to desired temperature in container. Hold together with needle nose pliers & dip 90%> of housing in hot water.

Don't use big fat pliers or grips or they conduct heat away from the housing & mess with your precision. Hold it in hot water for long enough for housing cover & it's ears to temperature normalise. I reckon you will get it adequately accurate & you always have a cut out switch for mild weather with your fancy set up.

[John Quilter]

I'd consider doing this on my car but am very reluctant to attempt to remove the 3 hex bolts that hold it in. After years of being in place I fear dissimiliar metal corrosion would result in them breaking off.

[cass3958]

Thanks Glyn I might try that tomorrow. I reckon mine is set a lot lower than that as it cuts out after less than a couple of minutes. Pain in the backside when you drive away from home and get to a set of traffic lights two mins down the road and the bloody thing will not pull away as the AED has cut out. With a manual it is not too much of a problem as you just lift the revs and ease the clutch out but with an Auto you have to put it in Neutral to get the revs up and as soon as you put it back into gear the revs drop and you are struggling to pull away. What I normally do now is start the car on the drive and let it sit there for five mins warming up before I go out. Never in a rush so not a problem but would like to get it sorted better.

John Mine has been changed in the last couple of years so I do not have that fear now but if you want to remove the Otter switch you could always use heat first on the screws. A naked flame is likely to do damage to the cork gasket and the electrical insulation on the top of the switch but a hot air gun might do the trick. I was once told that if you heat the area up and then spray it with brake cleaner this helps to split the different materials of Steel and Alloy. When you try to release the screws turn them an 1/8 one way then back to the original position whilst hot. More heat and repeat going a little further each time. When assembling lubricate the steel screws with candle wax as this stops the two coming together in the future.

[JCS]

John
Ditch the set screws holding the Otter switch and use 2BA studs and brass nuts.

Done properly you will hardly notice the difference.

If you don’t have 2 BA studs and brass nuts let me know and I will ship you some for the shipping cost, including the drill and 2BA tap, if needed.


Norman

[John Quilter]

Gentleman, Thanks for all the advise and offer of studs but for now I think I will leave well enough alone. I do have an override switch and warning lamp. Trying to remove the screws could be problematic even with special techniques. As my late father would say removal of the switch when all is working relatively OK would be "tinkeritis" .

[Glyn Ruck]

I keep meaning to buy myself an induction coil tool to remove stubborn bolts.