Fixing the weak links | OPINION
Innovation is a dodgy subject. Not as dodgy as the Josef Fritzl Guide to Childcare, but still contentious.
As Vespa & Lambretta performance increases, Sticky asks if progress is too fast for the rest of the scooter to keep up with?
You call that a power increase?
I always thought it funny how Superbike riders spend thousands on gaining a few horsepower for their already powerful motorcycle. If you add a couple of ponies to a top superbike with a new exhaust, the improvement might be 2% gain.
Compare that to fitting a TS1 kit to a Lambretta 200. The gain is more like 100% when you double the output of a 10hp engine to 20hp.
Power gains from modern tuning kits haven’t stopped there. For Lambretta there are engines producing in excess of 400% of the original output. For smallframe Vespas it is perfectly possible to increase the original output by a factor of 10!
If you add a few percent of strain to any engineering project then it will normally cope. Good engineers build in a margin of safety into any project. If you add 2% more power to a modern motorcycle, then the tyres, clutch and suspension are all capable of coping with the change. The power increase is within limits.
No engineer ever designs something to withstand 10 times the expected forces though. If you insist on over-stressing your scooter, by tuning, overloading or abusing it, then eventually something will break.
If you think of the drive-train as a chain, then it will always be the weakest link that breaks.
Which links are weak?
If you think back to the TS1 kit in 1985, and even scooter racing before that, then scooterists have been doubling their engine power output for a long time.
Doing so exposes weak links: the first few being the crankshaft, chain tensioner (Lambretta) and the clutch. None of these can stand that sort of strain for long without modification.
Gradually, over the course of time, parts producers all over the world have solved these problems with upgraded parts:
- Race cranks with improved bearings and rods
- Clutches with stronger springs and more plates
- Strengthened chain guides
As you improve these parts and manage to make powerful engines more reliable, the weak links shift to other places further down the chain.
Weaknesses now surface in more safety-critical components:
- On Vespa large-frames the casings themselves can crack
- On Lambrettas the layshaft, hubs and wheel mountings suffer
- On all models, the gearboxes struggle to cope
Lambretta rear hubs and shafts
Let’s take a particular case in point. In the most powerful Lambretta engines currently on sale – producing in excess of 50hp – the rear wheel, and the hub fitted are standard and were designed for 12hp machines.
The thing is; both of these components are known to have weaknesses, even in standard machines. Almost all Lambretta racers seek out the heavier Series 2 (Serveta) type rear hubs because the later Series 3/GP type are known to be weaker and can fail.
Tino Sacchi is well aware of this problem which is why he produced the current ‘Safe Hubs’ using the S2/Serveta design using tooling from South America.
He has tried to alleviate a known problem for the benefit of Lambretta riders, and is continuing to do so with another new ‘vented’ rear hub design. While it may seem illogical to put windows in a rear hub, this was done to aid brake cooling and to match the styling of the front disc brake.
In actual fact the internal structure of the ‘window’ hub – a steel centre around which the alloy hub is cast – is far beefier on the vented hubs than on standard Lambretta designs. Admittedly there were some production quality issues with the first batch of these hubs but eventually I expect them to prove stronger than the originals.
Similarly, I know of many Lambretta layshafts which have suffered failures on standard machines. Are the failures shown at the top of this page due to a design problem, or simply 40 years of metal fatigue and over-tightening?
A clue comes in the form of a story Vittorio Tessera recounted from someone who worked at Innocenti. The man had returned to the engine store in the factory to find a number of hub nuts on the floor. Inside each of the hub nuts was the thread from the end of the layshaft in it where it had snapped off in storage overnight!
There was no more to the story to explain what the cause or solution was, but it suggests that Innocenti did have a similar problem with Layshaft integrity at some stage to that being experienced by riders today.
Innocenti’s products were not perfect first time and a great many models received mid-series upgrades to solve specific issues encountered once they were on sale.
That is the way of the world.
Right first time
The problem is that some people have unrealistic expectations about what can be done to test new scooter products. Many of those producing parts are small businesses with limited time and funding. They are not NASA.
Even big firms with much bigger budgets release products that aren’t perfect first time:
- Mercedes original A-Class would roll-over in a severe swerve.
- Audi’s first TT was prone to spin-out in the wet.
- Tesla electric car’s auto-pilot function recently caused a fatal collision.
- Come to think of it, even NASA got it wrong sometimes with the Space Shuttle.
These are all firms with enormous budgets for testing, but still they release products that needed improvement. Development is continual evolution, but it’s much better if nobody dies in the process.
How can I be sure it is good?
If you are buying a replacement part, how can you know if it is better or worse then what you already have?
In truth you can’t be sure. Some replica and tuning parts are crap. The best thing you can do is let experience guide you.
All the cars named above had some kind of official approval for the road (DoT, TuV or whatever) but still they had problems. Approval is a reassurance of certain manufacturing qualities but the approval bodies can’t test every example or scenario so it comes with no guarantee.
Good-quality products like SIP’s tubeless wheel rims entered the market marked with ‘not for highway use’ (and therefore without official approval). However with an excellent safety record and sufficient sales to justify seeking approval, the SIP rims are now TuV-approved.
In reality the product quality is no different, but the piece of paper is vital for those seeking to legally use tubeless rims on the road in countries like Germany.
It’s not perfect, but in our corner of the universe, it’s often the best we have. Scooter racers abuse products to the limit and break stuff, but when it goes wrong they are wearing leathers and there’s no oncoming traffic.
Many of the top manufacturers supply products or even support their own teams with a view to rapidly testing and improving parts in the most adverse conditions.
Even so, it’s not perfect. The stresses of road and race use are different.Very few racers ride a scooter with an additional 120kg load of girlfriend, camping equipment and cans of Special Brew bungeed to a wobbly back rack.
If the advice comes from someone who has thoroughly tested a product themselves then that’s pretty good. But if it is from a forum ‘expert’ or who never rides anywhere, then does their opinion really have any weight? You may as well ask the fat bloke down the pub.
On the other hand, if you take your advice from people who ride a good distance then they can tell you for sure what works and what doesn’t.
Many of the scooter dealers who used to rally or race no longer ride classic scooters any more.
All the guys at Rimini Lambretta Centre still ride scooters, often long distances testing parts like the BSG 305 and prototypes for forthcoming Casa Performance products. Tino Sacchi regularly puts his parts through trans-continental endurance jaunts and Martin Robinson puts in the miles testing products for various manufacturers. There are others who still ride; feel free to name-check them in the comments below.
You can’t beat first-hand experience, particularly for safety-critical components.
Many websites now allow users to review the products on sale. A good technique is to discount the very best and very worst reviews – those possibly from partisan supporters or enemies – and concentrate on the overall satisfaction of other users.
Make a judgement
If I look at one layshaft with an 18mm thread compared to one with a 16mm thread, then logic dictates that the thicker one is going to be stronger if all other factors are equal. I’m also capable of understanding that if a wheel is held on with 8 studs instead of 4, then it is held on more securely (all other factors being equal).
Are all other factors equal? No of course they aren’t. A 32-stud hub is not necessarily any better than a 4-stud hub if it’s been made out of cheese.
Stick with what you have
If you really have no faith in peer advice, manufacturer testing, official approval or track testing then you can stick with only genuine original equipment factory-fresh parts. That’ll work well if you leave your scooter completely standard and for as long as you can find New Old Stock parts.
However, if you do want to upgrade the performance, don’t be surprised if your Vespa engine casing can’t cope, or your standard Lambretta chainguide ends up mashed in your gearbox.
In praise of the innovators
Personally, I think we should be thankful that there are those willing to invest money in trying to eliminate the weak links in 40-year-old commuter scooters.
Doing so is a thankless task because there are also those who wait until a product is perfected, then copy it. They often cut corners and quality and sell it for less because they have no development costs to pay. The less said about that practice the better, but there are a few examples here.
SLUK supports the innovators not the replicators and we urge you to do the same.
Nobody is forcing anyone to buy these parts, but we should all be happy that they exist and are being developed by dealers, road riders and racers.
Eventually stocks of original parts will come to an end. Then the choice will often be sub-standard items that are being sold in ‘Original equipment’ packaging by big companies who should know better, or ‘high performance’ upgrade parts.
Of the two, I know which I’d prefer to use.
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