Some facts about J type Overdrives and a question.

[Richard the old one]

I have just come across a document on the Canley Classics web site that states that the working pressure within a J type O/D is adjusted to suit the engine of the car for our 1500cc dolomites it is 350psi but when a J type is fitted to a Stag it is set to 550psi by adjusting the relief valve setting. The document does not state what the pressures are for an 1850 or a Sprint. I am assuming this may be the reason why it does not engage a smoothly as it should if you fit the wrong build standard unit.

I know that for a 1500cc dolomite you should fit an O/D Tally part number 25/115867/***** for a car with a 3.89:1 axle and a
25/11868/**** for a car with the later 3.63:1 axle.

I also have a spare O/D which has a tally plate part number 25/115869/***** can anyone please tell me what model of car this was built for?

I would also like to know what part numbers were allocated to the Sprint and 1850cc dolomite O/Ds.

[Galileo]

I did a bit of research when I was looking for an overdrive box for my Sprint (never mind the purists, enjoy the quiet cruising!)

rr/xxxxx yyyyyy

rr = Reduction percentage
x = Type i.e, 115876 late TR6, 115835 T2000, 115868 late Dolomite 1500
y = Serial number

25/115869 I believe is for a GT6.

Found this site a great source of info on J type overdrives, http://www.buckeyetriumphs.org/technica ... 1/JOD1.htm

Edit: Typo