Triumph 650cc / 750cc 5 Speed Gearbox Cluster – T120, TR6, T140 TR7 etc. – SOLD

Triumph 650cc / 750cc 5 Speed Gearbox Cluster – T120, TR6, T140 TR7 etc. – SOLD


Triumph 650cc / 750cc 5 Speed Gearbox Cluster – T120, TR6, T140 TR7 etc.

NOTE: Very important. The gear set is incomplete. The missing parts / gears are readily available as new items. Even after buying them, this is a very good value 5-speed Triumph unit gear cluster with some additional parts, such as the inner cover with the operating quadrant.

I am told that this cluster will also suit Triumph / BSA 750cc triples. However, they say that it will require mainshaft part number 57-4370.
I am also told that you can also convert a 4 speed unit and pre-unit gearboxes to 5 speed – o guarantees here.It will take more mechanical knowledge that I have to do this.

These are the parts that are for sale and shown in the pics. I have added part numbers from a parts list. Best to look at the images and use the number of teeth as your guide:

Mainshaft and gears:

  • 57-4432 – Mainshaft
  • 57-4780 – High Gear 21T
  • 57 – 4376 – 4th Gear 19T (stamped as DIA 1303)
  • 57-4379 – 3rd Gear? 18T
  • 57-4653 – 1st & 2nd Gears 13T & 16T

Layshaft and gears:

There are various gears as shown. I will only list the stamped numbers and number of teeth for you to decide what they are. It looks like High gear and 4th gear are missing.

  • 57-9000 – Layshaft
  • DIA 1302 – 16T
  • DIA 1301 – 17T
  • 57-4647 – 3rd Gear 18T also stamped “Triumph”

Selectors and other parts:

  • 57-0397 – Operating Quadrant
  • 57-4795 – Inner cover
  • 57-4364 – Layshaft 4th Gear selector fork
  • 57-4366 – Layshaft 3rd Gear selector fork
  • 57-4660 – Layshaft 1st Gear selector fork


Notes on conversion:

Please check the following links if you need further information on converting a 4 speed box:

Do the conversion at your own peril. Notes to add to the conversion comments: As well as the outer cover shift quadrant (57-4374) being shorter throw than the 4 speed, the plungers are different too. The 4 speed ones are part number 57-0406, the 5 speed is 57-4403 with a different cutaway.


International shipping available. Please ask.

Combined shipping available. 

Viewing: Please come and check it over before you buy. It is at PE28, near St Ives in Cambridgeshire.

Shipping: I usually ship to most destinations. If you don’t see a price, please ask. Thanks. International shipping available.

Collection: If you don’t want it shipped, I have plenty of space. If you can’t collect for a while, it’s not a problem. However, I will need to be paid very soon after the sale. Thanks.

Payment: Good old fashioned money on collection is preferred. I can accept payment through PayPal or by bank transfer as well.

Import Taxes: Please note that IMPORT DUTIES are not something I can control. If you are buying from outside the UK, there is a chance that you will have to pay import taxes. Import taxes vary from country to country. If there are charges to pay, it is the buyer’s responsibility to research the cost and pay the duties. The price that you see on my advert is for the item and not the item plus whatever taxes might be due.

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