Lambretta cassette clutches – Part 2: CP Smooth Master | REVIEW
In Part 1 Sticky gave us a good look around his well used and abused AF Rayspeed Road clutch. After using it for eight years, including a little ride to Ukraine and back, he’s swapped his Yorkshire (Indian) clutch for an Italian one. Here’s what he thinks of the Casa Performance Smooth Master clutch (pictured above).
VIDEO | Smooth Master clutch explained
What does it do?
The 10-spring Smooth Master performs a few tricks that most other clutch systems don’t.
- Adjustable spring tension. By fitting either 5 or 10 springs you can vary the tension at the clutch lever. According to the Casa Performance boys, 5-springs should be fine for my TS1 and easy to pull at the lever -even with a standard side casing. With the full 10-springs, they reckon the Smooth Master should be able to handle 40hp but obviously the lever action will be much tougher. This is where the rack-and-pinion CasaCover, or the Chiselspeed clutch cover conversion, come in to reduce hand strain.
- The Smooth Master has a central pressure plate incorporating a thrust bearing, but the centres are swappable (two supplied) so it works with LI/SX/TV side casings, or with GP side casings. The flat GP centre has a threaded hole to help extract it from the retaining O-ring.
- The other trick is that it incorporates four round rubber donuts in the crownwheel which absorb harsh gear or clutch impacts, extending the life of the gearbox, chain and clutch.
Doesn’t my Lambretta already have a cush drive?
If you already have a standard-type engine then yes it does, on the front sprocket. You could argue that you don’t need two systems doing the same job, however:
- There are engines that don’t have a front cush-drive, such as the BSG 305 and also Tino Sacchi’s Targa Twin. I didn’t think the gearchange felt that clunky on the Targa Twins that I tried recently at TD Customs in Germany. On the other hand, prolific Brummie Lambretta customiser Gary Dickenson criticised the harshness of the clunk when he engages gear on his Targa 250. The Smooth Master clutch, with its inbuilt cush-drive, is a made-to-measure solution for the Targa Twins.
- A second cush-drive doesn’t do any harm in a Lambretta. Indeed it was the original solution that Innocenti fitted to the early LI models with their cush-drive crownwheel. These sprung crownwheels seem to have been abandoned in favour of solid ones, only because they were unreliable (prone to falling apart like Vespa ones) and more expensive to machine. A second cush-drive (that doesn’t fall apart!) should actually be a good thing for gearbox and chain life.
The Smooth Master has six friction plates which are Lambretta layout (six steel ears per plate, unlike AF’s 12 thicker aluminium ears per plate). The top and bottom plain plates are thick aluminium, the rest are steel.
The clutch centre can hold up to 10 springs. Assembly is by 10 Torx-head screws, without need for a clutch compressor. Again the full clutch can be removed from the crownwheel as a unit once you remove the special slim clutch nut and washer from the centre.
Like the AF clutch, a special holding tool is required to torque the centre nut, but no tab washer is needed.
One of the poshest features is something that you won’t see at all. Other clutch systems that are machined and then heat-treated tend to distort during the hardening process. This leads to eccentricity and variable chain tension, exactly as found on the AF Road.
The previous Casa Performance solution was to have hardened parts ‘rectified’ after hardening, which means re-machined after heat treatment to rectify any distortion and make things run perfectly concentric again.
More recently they have managed to skip the rectification stage by using another heat treatment solution which takes place in a vacuum and does not introduce significant distortion. What they spend in the considerable additional cost of the heat treatment they save in the parts not needing to be re-machined afterwards.
As for the cush-drive element, yes the gearchange definitely feels smoother and less clunky. It’s a really noticeable improvement but it wasn’t so bad before that I considered it to be a problem. Think of it as a life without ice cream – if you never knew ice cream existed you could manage quite merrily without it. Once you know what ice cream tastes like though, it’s not a treat you’d like to live without.
I had an expensive motor without a cush-drive on the front sprocket, then it might be a different story. This system could be a major asset there.
You can buy the Smooth Master here.
- Will definitely improve the life of the transmission and protect the teeth of vulnerable Lambretta gearboxes.
- Adjustable spring pressure according to number of springs. In the future they plan to supply 2 different spring tensions so you can mix and match for four different set-ups from one clutch.
- The crownwheel can be disassembled and alternate tooth number chain-rings can be fitted.
- Carefully machined and heat-treated for concentricity
- The crownwheel runs on a proper needle roller bearing and not a plain bush
- Expensive – it’s far more than double the cost of an AF Road clutch
- Lambretta-style steel friction plates have fewer, slimmer ears than the AF clutch and therefore are more likely to mark the clutch bell.
- At a shade under 2kg the Smooth Master is heavier than a 1.6kg AF Road clutch but still lighter than an Innocenti 4-plate.
There are so many good Lambretta clutches available on the market now that I’m constantly amazed that anyone thinks there’s a need for another.
Some other good alternatives that I’ve tested include:
LTH ‘Leidolsheim’ 7-plate.
A motorcycle-plate solution that works great and is pretty much fit-and-forget. 480 Euros in steel or 566 Euros for the Ultralight version with an aluminium basket (shown above). You can get one from SIP.
Readspeed ‘Red Devil’ 6-plate
This is an affordable evolution of the Lambretta design with a good quality centre spider, plates and Crownwheel. The Red Devil works well and costs £299.
Casa Performance ‘Power Master Standard’ 7-plate (Purple)
This is a version of CP’s highest performing clutch, only without the cush-drive basket in order to fit standard engines and side-casings. Priced at £470.
Text, images and videos: Sticky
SLUK Supply Casa Performance and Reedspeed clutches