Does anyone know the differences in specifications/performance of the Lucas Control Boxes 37065 and 37076?
Mark V cars parts book show 37065 as the only choice when the cars were made, and the Lucas parts book show similar. However, the 1958 revision of the Mark V parts book shows only 37076. While the revised parts book could have shown the original listing and a replacement listing, it shows only the 37076.
Your parts book must be earlier than mine.
My paper copy of the J7 parts book printed Oct '49 shows only the 37076/D.
My electronic pdf version printing info says it was revised Feb '58 incorporating AL1, AL2, AL3 and AL3A. It shows only the 37076/D as well.
The suffix /D or other letter generally indicates a minor improvement or detail change Lucas made, not a big enough change to warrant a new part number.
My Mark V has a 37076/E with date stamp 3-50, which I believe to be original to the car. It has brass set screws and posts for the wiring connections. I also have a 37076/F dated 12-52, which has what appear to be tinned or plated set screws and posts.
My XK120 has a 37065/J RF95/3 dated 10-60, also with tinned screws and posts.
The only significant difference I can see visually between the 37065 and the 37076 is the position of the adjustment screws for the points. The 37065 has them in line, where the 37076 has them offset.
Thanks for the details. My mistake on the parts books. My J7 paper and 1958 paper copies and Jaguar CD (pdf) all say 37076. It is the Lucas publications which have the two variations among them for the Mark V.
Thanks much for making the visual comparisons.
Ah, yes, once again a discrepancy of information between sources.
I have a Lucas catalogue listing applications for 1948-62 cars, and it has 37065 listed for Mark V, XK120, MGTD, Rover 60 & 75, Land Rover, Singer 9, Sunbeam Alpine and Talbot 90. The 37076 is not mentioned at all.
The XK120 parts catalogue 1958 edition lists only 37076/D.
So the replacement 37065 in my XK120 dated 10-60 really only proves that it was still in production in 1960, that it had not been totally replaced by the 37076, which would have been my first guess.
Also looking in a Lucas Technical Correspondence Course for repairing regulators, I found this statement:
“In order to make this standard unit universally applicable to all types of generators and all models of vehicles it is necessary to vary the number of turns in the compensating and load windings. The compensator windings must be made to suit the generator and the load winding to suit the external loads, that is the lighting, etc. for different vehicle layouts. Thus each type of control box has an identification number which relates it to the correct generator and also the vehicle application. For this reason the control units must not be interchanged except as recommended in the Lucas Interchangeability Lists.”
So the regulator is matched to the generator as well as the amount of lighting and things like heater fan and probably battery size. The Lucas '48-62 book lists generator 22496 for Mark V (yet another discrepancy from Jag sources) and the same for most non-power steering Jag models of the 50s, but none of the other marques I mentioned above except Rover 60 & 75.
Does it make any difference which of the two to use on Mark V? Did they use both? Maybe for different markets? The only major differences I can think of are the load drawn by semifore trafficators and tribar headlights on Home and most Export Market cars verses flashing turn signals and sealed beams on US delivery cars.