Norton Laid down TTI gearbox

Dose anyone have any idea on how to lighten the clutch up on a laid down TTi Gearbox?
It uses the triumph lifter on the inspection cover just feels really heavy compared to a standard norton laid down gearbox

I have the same problem on my -59 Manx with a TTI box. The laydown gearbox has less clutch movement than the AMC gearbox fitted to featherbed bikes. The Commando has even more clutch movement.
The first thing you can do is to change clutch lever to one with shorter fulcrum to nipple distance.

Third possible thing is to redesign the TTI clutch lifter, I have not figured out how yet.
Forth option is to fit a Commando clutch.
Fifth option is softer springs which might slip.
Sixth option is do clutchless shifts. Works OK for me on upshifts, not so easy down.
Seventh and last, do train so you will have a stronger grip. Not my cup of tea.

Brian Riley said:

Dose anyone have any idea on how to lighten the clutch up on a laid down TTi Gearbox?
It uses the triumph lifter on the inspection cover just feels really heavy compared to a standard norton laid down gearbox

Click to expand...

Mike40M said:

I have the same problem on my -59 Manx with a TTI box. The laydown gearbox has less clutch movement than the AMC gearbox fitted to featherbed bikes. The Commando has even more clutch movement.

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There are several variables here, and you are throwing them all in one basket. You need to investigate the possible causes in depth!

* Are you using a clutch lever with the recommended pivot radius? The internal activation mechanism may have a different ratio to Norton's original gearbox, so it's likely you will have to replace your lever. TGA may be able to advise.
* Are you using the best (new!) clutch cable available? I guess that's Venhill's Featherlight cable, but there could be another brand also.
* Is your clutch cable optimally routed?
* Different internal throw ratios affects cable/lever pull. A throw ratio greater than 1 means cable pull is higher than if the throw ratio is 1 or less.
* Desired throw ratio depends on requirements of your clutch of course. Does TTi offer different mechanisms? There is a ramp and an associated bearing ball (x3) at the two discs which provides the lift.
* Clutch friction: Is your clutch housing and clutch center notched? This will increase actuation force immensely by friction.
* Spring load: Stiffness ratio and pretension obviously affects cable pull and work at lever.
* Your clutch actuator mechanism may have a flaw and cause friction. Grind and polish as needed. Ensure parts are well lubricated.

I hope this helps.

- Knut

The fourth option works very well.

I had a hydraulic clutch kit on my Commando but when I fitted the TTI I decided there was just no need.

The Triumph lifter mechanism and Norton diaphragm clutch are a perfect combo !

The Newby clutches work with the short throw laydown boxes.

Brian Riley said:

Dose anyone have any idea on how to lighten the clutch up on a laid down TTi Gearbox?
It uses the triumph lifter on the inspection cover just feels really heavy compared to a standard norton laid down gearbox

Click to expand...

Ensure that you have the correct clutch lever pivot ratio - preferably 7/8" from the pivot to the centre of the cable nipple. TTI have also produced a different ramp on their Triumph type three ball clutch pushrod mechanism, but this would not be my first point of call from experience with now three motorcycle builds with TTI boxes and NEB style clutches. (Photo of a lever I shortened the pivot on when I couldn't obtain one with the leverage required)

A very good starting point - "The first thing you can do is to change clutch lever to one with shorter fulcrum to nipple distance". Preferably 7/8". Many after market levers are as much as 1 1/16" (or more).