16-06-2020, 02:57 PM
Hello Ian. You are quite right in that R40's and R47's are similiar but have significant differences. The R40 is made from thicker brass and the rim is much heavier. The rim is deeper and thicker than the R47 and engages with the bowl differently to the way the R47 rim engages. On the R47 there are three lugs rivetted to the rims and three slots in the bowl into which they engage. On the R40 the lugs are on the bowl and the slots are in the rim.
A major problem with the R47 is the ease with which the rims become detached, depending on three springs pushing the reflector onto the glasss. A technique which I use on my new lamps is to omit the bottom lug and replace it with a 4BA screw through the rim into a nut silver soldered to the inside of the bowl.
The reflectors for R40's fit R47's although they are often not fitted with pilot bulbs.
There are plethora of ways in which R40's are fitted to the car which sometimes make them impossible to convert for A7's.
Regards Stuart
A major problem with the R47 is the ease with which the rims become detached, depending on three springs pushing the reflector onto the glasss. A technique which I use on my new lamps is to omit the bottom lug and replace it with a 4BA screw through the rim into a nut silver soldered to the inside of the bowl.
The reflectors for R40's fit R47's although they are often not fitted with pilot bulbs.
There are plethora of ways in which R40's are fitted to the car which sometimes make them impossible to convert for A7's.
Regards Stuart