Just took off my dash mounted rheostat for the dash lights. Not working and very rusty. Knob is in great shape. Would like to buy one in good working condition. Probably all '37 & '38 Cadillacs and LaSalles has these. They are mounted below the left bottom edge of the steering column on the dash. Thanks for any replies... John Lehman... CLC# 26365...
Mmm, not sure about this one John, none of my cars have a rheostat for the dash lights but they both have a little sliding switch mounted under the dash. The manual and wiring diagram does not state what sort of switch it is so either all my cars are missing the rheostat or yours is an aftermarket.
Does the knob perfectly match the rest of the dash knobs?
Also rheostat are waste of amps. Whether slide or turn type.
Hello Steve. All cars 30's to now have rheostats. How else can you control the intensity of the dash lights. Don't you remember the type of light switch, when you rotated the knob you could dim the dash lights? There is a rheostat connected to the light switch. Cars now have a separate slide ( rheostat ) switch to change the brightness of the dash lights. A rheostat is a manually controlled variable resistor. Thus lowering voltage to it's components. By lowering voltages it creates a certain amount of heat. The rheostat is original to my '37 LaSalle and should also be on similar Cadillac models. Probably by the early 40's they figured out how to put the rheostat on the light switch to make dimming the dash lights easier. My dash light rheostat switch looks like a early radio volume control switch. Cadillac part # 1419475. Description: Instrument lamp rheostat. MPL says # will fit 37-50,60,65,70,75, and 85 models. Must have been a 1 year item for Cadillac/LaSalle models. Thanks guys... John Lehman... CLC# 26365...
My '37 75 Series has the rheostat John describes. I think I remember this discussion before and some had the knob type and some had the sliding type. Harry
Quote from: 1937 LaSalle coupe on March 16, 2014, 08:49:38 AM
Hello Steve. All cars 30's to now have rheostats. How else can you control the intensity of the dash lights. Don't you remember the type of light switch, when you rotated the knob you could dim the dash lights?
I'm fully aware of what a rheostat is John I run my heaters through them but my 36, 37, and 38 cars have not had them on the dash light circuit nor has there ever been a hole in the dash where they fit, so if they were fitted under the dash on a separate bracket it usually meant these items were accessory's as were fogs, spots or backup lights. My cars all have a sliding on/off switch and I've yet to have a 30s car where the brightness of the dash lights warranted dimming but as I said, I could be unlucky enough to have bought cars where they have been removed if they were standard. Does the MPB make any reference to them as extras?
My 38 LaSalle didn't have one and it is not shown in the 38 wiring diagram either, only the three position slide switch, but I see that one is shown in the 37 wiring diagram and is listed as a light switch and rheostat. So it must have only been offered in 37.
Tom Beaver
The rheostat switch on my '37 is located on the bottom edge of the dash pointing toward the floor, simular to the tripometer reset. It has a round knob about the same size as the tripometer. If it weren't snowing and so cold I'd go take a picture of it. Harry
Guys,
Can someone post a pic? I may have one.
Bob
John, I think I have to agree with Steve about the dash light rheostat, I had a 1938 Lasalle 5067 convertible now a 1938 Fleetwood 7567 2 Dr convertible, I have seen a lot of those cars of the era, I have friends that have some, look at wiring diagram, look in parts book, look at mechanical books and none of them mention dash light dimmer rheostat ??? but any way do you really need a rheostat on dash board considering the low brightness of those lamps?.
Michel
Guys,
Again... my little 42 MPB to the rescue. LOL! Group # 14.2245 rheostat, instrument lamp.
One fits 35 LaSalles & all 1936 cars. The other one fits all 1937 cars.
HTH, Bob
The snow is pretty much over at 6". Here's a picture of the rheostat on my '37. I have the dash panel off so you can see the complete switch. The blue wire is of course not original, it is feed for a fog light switch that was added on. Harry
Thanks Harry for the photo. I guess this switch is used on models '37 and before... Guys, I still need 1 if anybody has a old parts ' 37 LaSalle or '37 Cadillac except model 90... John Lehman ... CLC# 26365... Thanks for all comments...
Gents,
I found this explanation in the 38 Data Book:
"Another innovation is the unique method of lighting
these instruments at night. The opaque dials are
illuminated by supplying light on the edges of the
glass covers. Instrument faces may be seen clearly,
yet never glare. The rheostat dimming switch is,
therefore, no longer required. A three-way lighting
switch is provided underneath the panel at the center.
At night the driver throws this lamp switch to right
when he enters the car illuminating the ignition
lock light in addition to the instruments. After starting
the engine he turns on the headlamps and throws
the instrument lamp switch to the left. "
I thought I had seen mention of the rheostat previously, so I looked it up. This is from the free downloaded version made available by the GM Heritage Center Media Center.
HTH,
Craig
Thanks for the input Craig. I checked the '37 Data Book and owner's manual and there was no mention of a dash light dimming feature. I guess it had been in effect for several years and not an innovation or change until 1938. Harry
Harry and all,
This mention was buried in the text of the 37 Data Book, page37!
"A combined rheostat and switch provides bright or dim
instrument lighting and is located on the bottom flange of
the instrument board to the left of the steering column."
I think I have too much time on my hands..lol
Craig