• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR2/3/3A Need Help Identifing Tranny with Overdrive

Share this page

C

Chuck Murphy

Senior Member
Country flag
Offline
My friend acquired a tranny with overdrive for a TR3A - but I think it is for something else (TR6??). Can you help identify it?
Tranny: numbers on case are 306812 WYE E336/R. Fluid filler hole on top not drilled - fluid is filled thru plug on side on tranny; three switches on top (2 for OD and 1 for reverse light??); no bosses on sides of tranny like on my TR3A.
Overdrive: numbers are 221 61985/ 005963B. Looks like OD on my TR3A but brass name plate is on side on OD rather than on top of unit.
Chuck
 
The 61985 would indicate that the overdrive is from a 71-72 TR6. Should be a number stamped on the case near the clutch lever that identifies the main gearbox (which may or may not match the OD, I have a TR4 OD on the back of my TR6 gearbox).

Should work in your friend's TR3A, but there will be a few adjustments to be made. Slot the holes in the crossmember, make longer studs, that sort of thing. I had to shorten the clutch pushrod.

PS, if your buddy's TR3A is early enough to have the filler on the top; then he will also need to modify the transmission tunnel to clear the starter bulge on the TR6 gearbox. It is possible to keep the filler hole by either adding the hole to the TR6 top cover, or what I did was rebuild the TR3A top cover with the TR6 shift rods & forks. If your friend opts to keep the TR6 cover, then he'll probably want to modify it to accept the TR3 shift lever (just drill out the holes on side of the shift tower).

Gearboxserialnumber_zpsb8268f06.jpg~original


PPS, I'm kind of sorry I didn't run the wires to the backup light switch. A backup light was available as an option at the time and there have been several times that I wished I had one.
 
Chuck, that 306812 number is a casting number. The transmission serial number should start with a "CC" or "CD" and be stamped either on the clutch cross shaft boss as shown in TR3driver's post or if it is out of a later TR6 it may be on the bulge for the starter on the other side of the transmission case.
 
Chuck- some other visual clues for a quick check - is the output flange round or square - round would be a later car such as a TR6, and possibly a TR4A, square would be something like a TR4. No boss on the side of the case says 4 syncro. Input shaft, if it sticks out past the bellhousing flange is pre TR250 I think- TR6 gearbox would have the input shaft shorter and within the bellhousing.
 
Back
Top