TR 4 / 4A gearbox identification

[Jonathan Smith]

I’m looking for an A type overdrive TR4 or 4A gearbox and would appreciate if any one could help with how I can check the gearbox to ensure it’s a TR gearbox - gearbox and overdrive  serial numbers or any other visible notification marks or  things to look out for 

Jonathan 

[Bob Smith]

Jonathan, Genuine original TR4 & 4A gearboxes have a number stamped on the LHS of the gearbox casting where the clutch release cross shaft is located.

TR4 gearboxes are stamped CTxxxxx & 4A gearboxes are stamped CT5xxxx and upwards.

I have a spare TR4 overdrive gearbox & "A" series overdrive that is no longer needed as my TR4 has now been sold.

[Jonathan Smith]

10 hours ago, Bob Smith said:

Jonathan, Genuine original TR4 & 4A gearboxes have a number stamped on the LHS of the gearbox casting where the clutch release cross shaft is located.

TR4 gearboxes are stamped CTxxxxx & 4A gearboxes are stamped CT5xxxx and upwards.

I have a spare TR4 overdrive gearbox & "A" series overdrive that is no longer needed as my TR4 has now been sold.

Thanks Bob. PM sent re gearbox 

[rcreweread]

12 hours ago, Bob Smith said:

Jonathan, Genuine original TR4 & 4A gearboxes have a number stamped on the LHS of the gearbox casting where the clutch release cross shaft is located.

TR4 gearboxes are stamped CTxxxxx & 4A gearboxes are stamped CT5xxxx and upwards.

 

Jonathan/Bob 

I have no wish to disagree with Bob ( and I'm not sure I am but it depends on how you read Bobs response) but my info on gearbox numbering shows that TR4 gearboxes were stamped CT up to somewhere in the late 50000s and 4A units CT from there onwards. For example the following may help:

TR4  -  CT 7040

TR4  -  CT 13037

TR4  -  CT 56830

TR4  -  CT 57298  

TR4A  -  CT 63616

TR4A  -  CT 69471

I don't know what the exact changeover point was but I'm sure someone with more knowledge than me will be along shortly to confirm.

As for TR4/4A  A type overdrives, the info I have states that early TR4 ODs were serial numbered  22/61374,  later TR4 and live axle TR4A ones  were 22/61712,  and all IRS  4A, 5 & 6 were 22/61753 or sometimes 22/61985.

Do bear in mind that most original A type ODs are likely to have been rebuilt at least once and many non TR A types have been converted to full TR spec such that the only differentiating aspect is the serial number on the casing, Some rebuiders remove these original plates and replace with their own, numbered to equate to the particular application they are being sold for and their own sequencing - nothing wrong with this at all, in my view, but nobody can know where that OD actually originated so if you you are adamant you want a genuine, original A type, the above info will hopefully help

Hope this helps but if you want any further info, then please get in touch

Cheers Rich 

 

[Footstuck]

Hi to all

I don't know if this is the latest thread on Gearbox numbers but  .  .  .

The picture is from my box, and I first bought the car in or around 1981, its an E Reg car.

Does this number look good as an original Gearbox? It haas an A Type overdrive?

It looks to have a date stamp 11/1/66 although look for yourselves and see what you think.

I have never swapped the box so if the numbers do not tally It must have been changed prior to my first period of ownership,

as my friend owned it for 17 of those years.

If i get a Birth certificate, will it give me any Info on G/box numbers? if so where would i get one?

Thanks for any help .

Regards Nick

 

 

 

[John Morrison]

Yes nick,

slots in perfectly with the above

John.

[Ralph Whitaker]

Hi Nick.  You can get a "Birth certificate" as you describe it from BMIHT at Gaydon, cost around £40 I think, but the gearbox and axle numbers are not shown, at least not on my Heritage certificate, and gearbox and axle numbers did not correspond to engine numbers, and engine numbers did not always (if ever) match chassis (commission) number.

Ralph

[Footstuck]

Thanks for the help.

The gearbox stamping is approximately 200 or so digits away from the chassis number, so I guess that’s close enough  as you can hope for?

Thanks again

regards from Nick

[stuart]

6 hours ago, Footstuck said:

Thanks for the help.

The gearbox stamping is approximately 200 or so digits away from the chassis number, so I guess that’s close enough  as you can hope for?

Thanks again

regards from Nick

Theyre never exactly the same due to applications elsewhere.

Stuart.