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Flywheel Puller Tool (Lambretta – M27 x 1.25) from Spitfire Tool Company

 

 

Introduction

 

An essential tool for any Lambretta owner or professional scooter workshop is a Lambretta flywheel puller. 

Scooter Surgery have become increasingly frustrated with the quality of some flywheel puller tools currently on the market because they only last about 3 months with continued use in their workshop.

 With the knowledge that the Spitfire Tool Company were already working on a new flywheel puller tool design, Scooter Surgery have set Spitfire Tools the following challenge to design a Lambretta flywheel puller that: -

• has an M27 x 1.25 external fine thread which doesn’t fail in shear, strip, gall or cross-thread during its service life.

• is corrosion resistant.

• has a significantly greater design life than 3 months.

• Can operate, even if the flywheel M27 internal threads are clogged with dirt, grease, rust etc.

• robust enough to withstand the use, in an emergency situation, of any adjustable wrench that has ‘jaws with teeth’.

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See an independent review and video of it in action here at SLUK 

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Design

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Always up for a challenge, the CEO of Spitfire Tools went about designing and manufacturing an innovative modern quality flywheel puller tool to meet the above specification.  Spitfire Tools have decided upon a minimum design life of 25 years.

As a part of the design process, Spitfire Tools looked at the failure modes of a typical flywheel puller.

It was determined that the most vulnerable part of any lambretta flywheel puller is the external M27 fine thread.

The flywheel puller tools currently available from the market place, that Scooter Surgery have used, have failed prematurely due to their continued use in flywheel M27 internal threads that have not been clean and /or undamaged. Anyway, it has up to now, not been easy to clean or repair internal threads when the flywheels are still mounted on the crank.

Damage/wear to the external M27 puller thread can occur when trying to thread or even force these pullers into contaminated or damaged internal threads on a flywheel. The fact that the puller tools are normally manufactured from inexpensive low grade carbon steel is also a major factor in the premature wear and failure of the threads.

Thread contamination and thread damage are usually the cause of ‘tight threads’ which can then easily be mistaken for the tool being fully threaded into the flywheel.  A flywheel puller not fully threaded into the internal thread of the flywheel can then cause stripping of the flywheel puller M27 threads during operation.

It was obvious to the Spitfire Tool Company that the material selection for the flywheel pullers could be improved upon. This has been achieved by selecting a more expensive alloy steel which has a greater hardness hence improved wear resistance. This alone however is not the total design solution. The Spitfire Tool Company have also designed in a ‘thread chasing’ facility which not only cleans out the threads as it is threaded into the flywheel but also re-forms any minor damage to the fine pitch threads.

Thread contamination can be defined as a substance containing either ‘burs’, ‘rust’, ‘dirt’, ‘oil’, ‘grease’, ‘grit’ etc.  The carefully selected and precise thread tolerance on the Spitfire Tools M27 thread enables the leading edges of the thread chaser to sweep any contamination into the recessed flutes on the tool as it is threaded into the flywheel. The taper design, on each flute trailing , enables the contamination to be easily collected and retained in the flutes. It doesn’t push contaminants forward into the path of the puller*.

 (*Please note: when used for the first time, the puller will need to be removed after cleaning every one or two turns to allow for the removal of the contamination from the flutes - only if contamination is found to be excessive. Spitfire Tools also recommend using a lubricant, such as WD40).

The start of the Spitfire Tool M27 thread has been designed with a unique chamfer that aligns the tool easily with the Lambretta flywheels’ internal thread. The tools mass, combined with the positioning of its ‘center of gravity’, as well as its unique chamfer, are all part of tools overall ergonomic design.

The Spitfire flywheel puller tool has a hexagon head which measures 30mm A/F for ease of use with any adjustable spanner, open ended spanner or socket.

 

Design Patent

 

The Spitfire Tool Company are the first to design a combined ‘thread chaser and flywheel puller’ which is also why the design is currently going through the patent application process and is ‘patent pending’.

 

 

 

 

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Manufacture

 

Like the Spitfire, these tools have been designed in Staffordshire England. They are also manufactured in Staffordshire England not 20 miles from the original Spitfire factory in Birmingham where the grandfather of Spitfire Tools CEO worked throughout WW2 as a Mechanical Engineer on the Spitfire engines.

The main body of the tool has been machined on a 5-axis CNC machine from a solid bar of material. These tools are precision engineered with close precision tolerances. Spitfire general manufacturing tolerance is only +/- 0.1 mm with the majority of dimensions being machined to even finer tolerances.

The Spitfire flywheel puller tools bodies are ‘laser engraved’ with the flywheel thread size ‘M27 x 1.25 pitch’ along with the ‘all important’ MADE IN ENGLAND. Every Spitfire tool is manufactured with its own serial number laser engraved on the side of the tool.

All scooterists adore Italian scooters therefore the first batch of the Spitfire flywheel puller tools will be ‘limited edition’ and fitted with Italian hexagon head set screws manufactured by VIBO BONTEMPI in Italy. They are manufactured to UNI5750 and DIN962 and are grade 8.8. These M12 x 1.25 x 40 set screws are truly ‘bravissimo’.

 

 Materials

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The material that the Spitfire ‘flywheel puller tool is made from is a closely guarded ‘trade secret’ however we can say it is an alloy steel of a very high specification selected especially for this application by the CEO of Spitfire Tools using his 38 years of mechanical engineering design and metallurgical experience.

However, just in case you’re a ‘Bad Boy’ trying to copy our tool designs and steal our intellectual property, we can confirm the material it is NOT ‘cheap and cheerful’ Mild Steel (0.3% Carbon)

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Application

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These puller tools will fit the following Italian Lambretta models: -

Lambretta Model ‘A’, ‘B’, ‘C’, ‘LC’ ‘D’ ‘LD’

Lambretta Series 1,2, 3

Lambretta J Range – Lui, Vega

 

Quality (Guaranteed)

 

Spitfire Tools have decided to ‘reach for the sky’ when selecting the material for this flywheel puller tool and it is one of the most expensive alloy steels on the market.

We feel this selection and investment in the best quality materials, as opposed to selecting the most economical materials in order to improve the profit margin, is justifiable because it launches Spitfire Tools into an unbeatable ‘Battle of Britain’ field of its own.

Spitfire Tools are quality robust tools. When our tools are well looked after, we guarantee them up to WW3.

All we ask is the hexagon head ‘jacking’ screw is routinely lubricated with ‘copper slip’ grease, or equivalent, to maintain the smooth operation between the external and internal threads. All the hexagonal head set screws are greased prior to the tools leaving the factory. All tools are subject to 100% quality inspection.

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Testing

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The Spitfire M27 x 1.25 flywheel puller tool, for Italian Lambretta scooters, has undergone extensive testing at Scooter Surgery and is now in full-time use with their professional scooter mechanics in their Lambretta workshop. This is probably the best testing facility available for a scooter tool due to the repeated and hard use the tool gets.

                                                               

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Spitfire Tool Company

Copyright SCE Ltd 2020 / The Spitfire Tool Company

Internal Use: stc ‘Spitfire Tool Company – Flywheel Puller 02JAN2020 - Word ’ doc Issue 1 dated 29/12/2020