• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)

A-type Overdrive & Gearbox



I would appreciate some feedback on your experience with this transmission combo (A-type OD only please).

I am interested to know:

1. how often you have issues with your A-type overdrive?

2. what they typically were.

3. did you need to pull the transmission to fix them?

4. if you winter your car; any OD issues in the spring due to non-use?

5. how many miles have you got out of your clutch, gearbox and OD before it needed to be overhauled? What problem (if any) required it to be pulled?

Sorry for the length. I have a decision to make.


Great Pumpkin - R.I.P
Once it's actually in good condition, it can be trouble-free for 100,000 miles or more. I've kind of lost track of how many miles I've put on mine since Herman van den Akker rebuilt it for me some 10 years ago, but it has to be over 50,000 miles so far and it's still working great.

The only issue I've had was that sometimes the clutch would slip when engaging in 2nd gear at full throttle. Herman offered to fix it if I would bring him the OD, but I opted to not worry about it (and not shift at full throttle in 2nd gear). While I was moving it from the wrecked TR3A to the current TR3, I measured and adjusted the operating pressure myself, with the result that it never slips now.

Oh, and the operating switch sometimes comes loose on the dash

Winter tends to be prime driving season around here, so no help there.

Lou Metelko

Jedi Trainee
In 2002 John Esposito from Quantum Mechanics rebuilt the transmission and overdrive in my TR2 and now some 25,000 miles later there have been absolutely zero issues with either! I do change the fluid and wash the filter every other year and per John's instructions I use Valvoline 30wt non-detergent.

If you are decideing between a Japanese five speed or the A-type then there is no question as to which you would be more pleased with. Just be sure that it is rebuilt by John or someone at his level of expertise.

Lou Metelko
Auburn, Indiana
TRA in Fort Wayne, Indiana in 2011


Hello neighbor. I've had this gearbox in the TR250 since 1985 when the A-type OD was rebuilt. I have had a few problems but these have always been electrical and either related to a poor connection (I hate Lucar connectors) or failure of the solenoid. The solenoid was replaced in 1989. A few years ago, I had problems with slow engagement. I hadn't realized but that little drip, drip on the garage floor each week can add up. The gearbox/OD oil was very low. This was not enough to hurt the gears, but enough to prevent the necessary pressure build up required to engage the unit. Once I topped off the gearbox, the OD opperated correctly. I use 20W-50 Valvoline.

Geo Hahn

Country flag
+1 on the John Esposito recommendation, though perhaps you already have prospective unit in mind.

I have only had my OD for 5 years (about 25,000 miles) but no problems so far.


Country flag
Only issue I've had in 4 years was when I put in some off brand non-detergent 30 wt oil in it. Overdrive wound up engaged full time, I caught it without causing damage - a quick clean of the bypass valve and a changeout to 20W50 VR1 and haven't had any problem since. Only need for pulling was a worn out clutch disk. My main existing and minor issue with my gearbox is slightly tired syncro rings but I don't see the need to fix anything yet.


Jedi Trainee
I will +2 on Esposito as well, I did have to wait a full summer for the unit.

I don't drive the 250 much and it did take some getting use to having the OD stalk near trafficator stalk but have it down now and it is an effective Trans.


Darth Vader

70,000 miles on a TR4A transmission with A-type overdrive that was driven daily for 5 years with no problems at all with either. I rebuilt the transmission myself but the overdrive was bolted on as-is with only a cleanup of the filter and accumulator piston areas and replacement of the rear oil seal. I'm unsure of the mileage on the overdrive but it came off of a TR3 transmission. Clutch was still working fine as well with the same mileage.



For anyone who's looking, there is one just listed on eBay (not mine).
Similar threads
Thread starter Title Forum Replies Date
Got_All_4 TR6 Refurbishing gearbox with A type overdrive Triumph 7
T A-type overdrive / gearbox trouble shooting Triumph 69
H TR4/4A A-type overdrive pump Triumph 4
D TR2/3/3A Type A overdrive not engaging Triumph 0
D TR2/3/3A Type A overdrive not engaging Triumph 16
M TR4/4A A type Overdrive Oil Leak Fix Triumph 3
Graham H TR2/3/3A A type overdrive Triumph 6
KVH General TR Type A Laycock Overdrive Questions Triumph 8
C TR2/3/3A A-type overdrive drain plug oring Triumph 1
J TR4/4A TR4 A Type Overdrive Part mixup Triumph 4
CJD TR2/3/3A A type Overdrive Seal Triumph 9
T Spitfire J Type overdrive Triumph 2
T TR2/3/3A Question on A-type overdrive solenoid Triumph 21
BillyB62 TR2/3/3A Type A TR3 Overdrive Wiring Triumph 13
T TR2/3/3A Question on A type overdrive spec for "clutch movement from direct to overdrive" Triumph 7
M_Pied_Lourd TR6 J Type Overdrive High Pressure Filter Cap-Major Problem Triumph 6
R A Type Overdrive reassembly question Austin Healey 3
R TR2/3/3A A-Type overdrive question Triumph 8
T TR2/3/3A My A-Type overdrive rebuild project, some questions Triumph 36
T TR2/3/3A Will Spitfire D-type overdrive work in TR3 with TR4 transmission? Triumph 3
R Overdrive [Type A] brake ring gaskets Austin Healey 1
R TR2/3/3A Overdrive [Type A] Brake Ring Gaskets Triumph 14
J General TR D Type overdrive not working need suggestions Triumph 5
Gordon_Dedrick TR2/3/3A A type overdrive installation Triumph 7
T TR2/3/3A Type A Overdrive, Physical Differences between Roadster Brands? Triumph 2
T TR2/3/3A Type-A Overdrive Handling Differences Triumph 9
A TR5/TR250 A-type overdrive questions Triumph 25
71tr TR6 Overdrive Mount / J-type on A-type frame Triumph 1
D TR6 76 TR6 J Type Overdrive Triumph 7
Gordon_Dedrick Testing an A type overdrive Triumph 20
Simmo I need help with J Type Overdrive Triumph 15
Q "A" Type Overdrive Annulus End Float!! Triumph 4
D A type overdrive question. Triumph 3
John_Mc J-Type overdrive for sale on CL Triumph 4
KVH More on A Type The Overdrive Triumph 2
Coyote1 J Type Overdrive engage problem Triumph 3
J A Type Overdrive Triumph 17
K TR6 TR6 J Type Overdrive...Link to Schematic? Triumph 3
O J Type Overdrive Conversion Triumph 19
Marvin Gruber J type overdrive unit on BCF classifieds Triumph 2
HerronScott TR4/4A TR4A A-type overdrive and Moss Europe TR2-4A cat. Triumph 2
TR3TR6 J-type overdrive question Triumph 5
CinneaghTR A-type Overdrive Model Number Triumph 14
71tr J-type Overdrive Pressure Port Question Triumph 2
R_Lyle TR6 J-Type or A-Type Overdrive for 1972 TR6 Triumph 18
TR4A_IRS Looking for a J Type Overdrive? Triumph 0
7 question after testing a J type overdrive Triumph 5
mgedit Fluid for J-Type Overdrive Triumph 22
Got_All_4 A type overdrive that has been sitting for years Triumph 6
Tinkerman Type A overdrive Triumph 7

Similar threads