Packard Forum Index » Pre-War (1899-1942)

I read that the r11 overdrive is a better overdrive. Would that fit in 1941 160-180 cars? Also what years were they used.

The R9 was prone to a specific issue under certain abnormal circumstances. It worked well for many years but whether the R11 is a better unit is open for discussion. Because of a different and much simpler internal construction the R11 alleviated the R9 issue so maybe is perceived as a better unit. No question it is less complicated and easier to service electrically because of less wiring and a relay and solenoid that because the R11 OD was used by other mfgs, is now being reproduced and is easily found. The only R11 electrical item subject to wear and not repro'd is the lockout switch -- also used on the R9. Not the case with most other R9 electrical items which are specific and starting to be expensive and harder to come by.

Packard replaced the R9 with the R11 during early to mid 22nd series production and used it in various forms until the end. For your purposes, the transmission and OD unit used with 356 engines is of heavier construction with a larger diameter transmission input shaft and an extra planetary gear in the OD unit. For your 41 which has the 356, you will be limited to finding a trans with the R11 from a 48-50 year and only one coming from a Custom with the 356 engine. If your car already has OD, that trans/OD combo will be a more or less direct fit although you may need to do some bracket or cross member or driveshaft flange modifications. Some of the postwar trans cases had dual bolt patterns to accommodate the earlier mount locations but I do not know if they all did. The lockout cable and solenoid will move to the drivers side so may also take some bracket work. I have not looked at prewar conventional body cars with OD but others who have done OD work on them say space is very tight around the cross member and X frame area on those models. If your car does not already have OD then it will be a much larger project sourcing parts but others have done it.

For details on the R9 issue you might check out the Aug 15, 1947 Service Letter Vol 21 #15. Unclear if you already have OD but If so and your R9 is in good condition and functions well, perhaps just adding the safety switch would give peace of mind. For details on how the R11 unit differs and works from the R9 look at the Feb,1 1949 Service Counselor Vol 23 #2. For a bit of what is involved in replacing an R9 with an R11 in a Clipper or 22nd series model, information on a replacement kit is in the April 1. 1949 Service Counselor Vol 23 #4. I have read bits in other letters where the R11 OD kit could be installed in earlier models if they had the R9 issue and a customer so requested and bought a kit. As far as fitting an R11 in a 41 model, it would seem possible keeping the caveats on engine size and working space in mind. The Service Counselors mentioned as well as others with bits about the R11 are available for download on this site.