Lambretta Cassette Clutches – Part 1: AF ‘Road’ & CP ‘Smooth Master’ | REVIEW
So, you are looking for a decent Lambretta performance clutch and fancy one you can fit without a compressor tool but you’re not sure which one to fit? I just removed an AF Road clutch after 8 years of abuse to fit a new Casa Performance Smooth Master so here’s a closer look at those two options.
In part one we’ll take a close look at my well used and abused AF Road, then in part 2 we’ll concentrate on the Smooth Master.
AF RAYSPEED 6-PLATE ‘ROAD’ CLUTCH: From £235
What is it?
The 6-plate ‘Road’ is a cheaper, Indian-made 6-plate clutch which follows the design of the AF Rayspeed Surflex ‘Race’ clutch. Rayspeed had the Road version produced to fill in stock levels when they were struggling with supplies from Surflex.
Production costs have been reduced by machining components from castings rather than from billet. The clutch uses motorcycle-style plates with a non-cork-based friction material and 12 ‘ears’ (tines) on each plate. A dedicated crownwheel is included with the kit in either 46T or 47T. An alternative crownwheel costs £80.
Assembly of the clutch could not be easier thanks to the ‘cassette’ design which allows the complete clutch to be removed and replaced as a single unit without the need of a clutch compressor. The cassette arrives fully assembled and ready to bolt in.
A dedicated tool is included in the kit, allowing you to hold the clutch while the centre nut is tightened. With no central tab washer, the nut is now retained by a combination of Belleville washer (we explain that in the video further on) and a dab of Loctite. The clutch centre actuator contains a bearing and is a simple push-fit into position.
The one problem we found on assembly was that the crownwheel was not machined perfectly concentric. This resulted in a slight variation in chain tension as you rotate the clutch. This situation is less than ideal but relatively common even in standard clutches, poorly made crownwheel bushes or duff front sprockets. On the AF clutch the variation was not excessive and we simply adjusted the chain guides so that the chain never became too tight.
The main objective of upgrading from the standard four friction plates is to obtain a clutch that can handle a greater power output without requiring a clutch lever action which would trouble Hercules. In that respect, the AF Road is a reasonable compromise.
It is stiffer than standard but still light enough at the lever that my wife can use it around town. Having said that; when I first met her she was an alligator wrestler in the circus.
The one down-side of the motorcycle style plates is that the clutch bites more suddenly than with traditional cork plates. It is not completely ‘on’ or ‘off’, but the biting point is narrower than usual and requires some acclimatisation.
The AF clutch was first fitted to my Avanti TT225 test engine, in possibly the most arduous configuration for testing a clutch: a torquey motor producing 20 ft/lbs and 4.4:1 final drive gearing (TV200 15×46). With that set-up the clutch would briefly slip in the higher gears when you set off and the engine was cold, but unlike a cork clutch, which would quickly burn out if it started slipping, the AF Road seemed to grip harder once warm and would then behave normally. When used with the 5-speed Cyclone box and 19×46 sprockets the clutch spins faster so it has to transmit less torque. In that layout, the AF clutch behaves impeccably.
- The most obvious advantage is in cost. The AF Race version is built to tighter tolerances but costs £400 whereas the Road version retails for a reasonable £225
- Component parts are available separately (e.g. friction plates £22 a set)
- Weighs less than standard: only 1.6kg for complete clutch and crownwheel
- Machining is not perfectly concentric or even tidy
- Narrower biting point
- Will slip when faced with really powerful engines
VIDEO | Sticky checks over his 8-year-old AF Road clutch
It’s had a hard life
It recently dawned on me that I’ve been using the AF Road clutch for eight years without ever once undoing the screws that hold the plates together. It was in my engine when I toured 15 European countries visiting Serbia and the Ukraine. In all that time it’s never given me a moment’s grief and I’ve never needed to carry a clutch compressor. The clutch comes out as a single unit and goes back together the same way.
Upon stripping the engine recently I found that the ears on some of the aluminium clutch plates were mushroomed over and burred. One of the ears had even broken off and was lying in the oil, but this is after 8 years of abuse, with various engine configurations up to 25hp. The rest of the clutch appears fine and certainly, the steel crownwheel looks good for reuse because the softer aluminium of the clutch plates have not sawed into it.
If you are building a very high-end engine producing over 25hp then this is probably not the clutch to go for. Certainly, the original Surflex version is better made and will cope with more power before slipping. However, for the majority of us, running more mildly tuned engines, then this is a very good value clutch system that is reliable and simple to fit.
It may not be the prettiest clutch on the planet, and a little ‘fettling’ to tidy up any machining burrs before fitting is probably wise, but I certainly can’t criticise its performance or value for money. With a new set of clutch plates, I’d expect it to do another eight years. Great value for money that!
You can find the clutch here, but AF Rayspeed haven’t really caught up with the webshop revolution yet so you’ll have to use Google to find somewhere to purchase one directly.
Words, pictures and video: Sticky
Coming up in part 2 tomorrow…
We look at the CP Smooth Master clutch, a serious bit of kit and some of the other alternatives on the market.
SLUK currently supply CP and Readspeed clutches