After nearly blowing up my engine on a previous track day when it overreved and slewed into a corner as I changed down one gear too many, I figured that a slipper clutch would be a worthwhile investment; much cheaper than rebuilding the top end of the engine due to a bent valve.
I looked at fitting a Sigma clutch but the cost was going to be close to £900 (US$ 1,350) if you included a new set of plates that would be required to give the correct pack tolerance and to also get rid of the anti-judder rings. That was just too much to spend in one hit even if I could probably re-sell the Sigma clutch at a later date … especially when a cheaper (but decent) option is available.
I heard that it is possible to fit the 2013 Daytona Slipper clutch into the 2006-2012 Daytonas. Only the inner clutch basket and plates need to be changed as the outer basket is the same on the both models. I therefore spoke with T3 Racing to find out about the upgrade/conversion and what it would all would cost. After a little negotiation, the final price came out at almost half the cost of the Sigma unit (with new plates).
Slipper clutches prevent the rear wheel from locking up violently when changing down by using the back torque from the wheel to “lift” the inner basket using ramps in the clutch. This has the effect of separating the plates in the same way that the rider would if they pulled the clutch level in. As the clutch is activated, the rear wheel can turn freely again because it is no longer being restrained by the engine.
Once you hold the clutch assembly in your hand you see how simply this works. While the Sigma uses a mechanism that separates the plates by lifting the whole inner backet on ramps at the back of the basket, the Triumph slipper clutch works by having ramps on the inner basket which only lift the pressure plate. This is what allows the rear wheel to free wheel instead of locking up when any back torque is applied.
The parts diagram shows the 2013 Daytona Slipper clutch components needed to convert a 2006-2012 Daytona clutch. The required parts are identified with red boxes.
Not listed is the clutch cover gasket – you will need a new one.
Fitting the new clutch is actually pretty straight forward, provided you have a Haines or workshop manual and the correct tools. The steps are as follows:
- Release the clutch cable from the actuator arm
- Remove clutch cover/case
- Remove the pressure plate
- Remove all the friction plates, steels and rings (keeping them in the correct order!)
- Remove the inner clutch basket
- Fit the new clutch basket
- Add the new rings, plates and steels in the correct order
- Refit the lifter piece, seat the new bearing, fit the pressure plate and tighten the springs
- Clean the gasket surfaces, smear the gasket with sealer and fit
- Refit the cover
- Re-attach the clutch cable to the arm and adjust the tension correctly
Here are some photos taken during the removal of the old clutch center, and when fitting the new slipper basket center.
The whole job took me just under 3 hours, but I reckon I could do the next one in under an hour. Triumph recommend using a special tool to hold the clutch basket to remove the retaining nut. An alternative method is to use an air gun with the bike in (second) gear and the rear brake applied. There is no need to drain the engine oil to carry out this job.
If you think that you might re-use your original clutch at a later date, then it is really important to note the order in which you take the clutch apart and store it assembled correctly. Similarly, it is important to keep all the plates and rings in order as you dismantle the new clutch before fitting it to the bike.
After fitting the new clutch, I had to adjust the clutch cable tension because the cable was now too loose. Once I has done that I was struck by how light the clutch action is compared to the old clutch – this could be a function of the three new springs that replace the five in the older clutch unit.
Although I gave the bike a quick test to make sure everything was fitted properly and that there were no oil leaks, I didn’t have a chance to test the back torque / slipping action properly due to failing day light. However with my next track day only four weeks away, I am looking forward to trying it all out properly on track. I’m not expecting to lose too much engine braking into corners and should have the reassurance of knowing that I am less likely to overrev the engine by mistake.
I’ll report back with more feedback after my next track outing.
Update February 2016, Cartagena Spain
Spent four days at Cartagena with No Limits and really got the chance to put the new slipper clutch to the test.
This is an awesome bit of kit that you were really and quickly appreciate when approaching corners. You still get all the engine braking you had before just up to the point where the back wheel would either lock up or skip – except that it doesn’t.
It’s hard to describe but it sort of feels like “magic” as if someone is feathering the clutch for you just enough to
stop the engine overreving in and to keep the rear end of the bike in shape.
I’m not sure how much you’d use a slipper clutch on the road, but you will pretty much come to rely on it for every corner on track once you have one.
Well worth the financial investment!