Rear Suspension - A Guide for Rotax engined Aprilia V-Twins

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mangocrazy
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Rear Suspension - A Guide for Rotax engined Aprilia V-Twins

#1 Post by mangocrazy » Sun Jan 01, 2012 9:51 pm

Please note - this topic is a work in progress - the information here will be added to as appropriate.

Purpose/Rationale/Acknowledgements

This thread is an attempt to gather all the available information in one place on the subject of rear suspension options for the Aprilia Falco. This information may also be useful and applicable to the Futura. It will be of some use to RSV Mille and Tuono owners who want to know more about the evolution of the suspension layout on their machines, but is restricted to earlier models (RSV Mille up to and including 2003 model, Tuono up to and including 2005 model).

It is also only fair to acknowledge one’s sources. The first spreadsheet matrix shown below is a reworking of that originally compiled by Masta-C on the AF1 Forum. Without his original as inspiration, my alternative version is unlikely to have seen the light of day. Likewise, the great majority of the material included here has been supplied by other posters, here and elsewhere. You know who you are and we thank you for that.

This thread is intended to be locked. This is not to stop the addition of new material (far from it!), but to ensure that the thread does not lose its purpose or become confusing or contradictory. If you have any additions, corrections or suggestions, please PM myself or Andy (D-Rider) and we will arrange to update the material here.

Background

Every motorcycle has its faults, and some have more than others. It is the general view of long-term owners that the Falco is/was a superb motorcycle, marred only by the Original Equipment (OE) Metzeler MEZ3 tyres (easily changed), ‘Rest of World’ sidestand (alternatives are available) and the OE ‘Blue spring’ Sachs shock. The OE shock is basic, relatively unadjustable and unforgiving in operation and falls a long way behind the general excellence of the rest of the bike.

The OE Falco shock is adjustable for preload (via castellated collars and a C-spanner) and rebound damping. Compression damping is fixed (i.e. non-adjustable) and there is no provision for raising (or lowering) the ride height. Overall rear suspension action is crude and harsh, and the unit’s shortcomings are particularly exposed on poor road surfaces. The general opinion is that no matter what you do with the limited adjustment available, it doesn’t make an improvement. It’s a cheap unit, built down to a price, and performs accordingly. It is also (allegedly) not rebuildable.

Had it not been for the fact that the Falco is blessed with a ‘sister’ bike in the RSV Mille which possesses suspension (and chassis) components that were (initially at least) directly interchangeable, we would probably be discussing the virtues of aftermarket shocks here. But the RSV Mille (and later the Tuono) have provided Falco owners with a ready-made and comparatively affordable suspension upgrade path. With such an opportunity available, it would be rude to refuse it…

Interchangeability – RSV Mille 1998-2000 (1st Generation)

The RSV Mille was launched in the 1998 model year, and a year later the Falco followed in its slipstream. While they targetted different audiences, there was a great deal of commonality of parts between the two. As the sheet below shows, in their early years the Falco and the Mille used the exact same dogbone and triangles; only the shock was different. The only exception to this rule is the RSV Mille SP; there is absolutely no commonality of rear suspension parts with that and any other mainstream model.

As a result, the standard ‘White spring’ Sachs Mille component is a drop-in replacement for the OE Falco unit. While the manufacturer was the same, the Mille Sachs is a far superior item. It boasts full adjustability; preload, rebound damping, compression damping and ride height are all adjustable. The unit is also fully rebuildable. The only minor snag is that on some units the Schrader valve may need relieving with a Dremel or similar to stop it fouling the subframe. This varies from unit to unit; some will fit, others won’t. The best course of action is to specify the fitment of a recessed valve when the unit is serviced.

For the 2000 model year, the Mille ‘R’ was introduced, and this had a number of uprated components, not least of which being the Öhlins shock. This is also a drop-in replacement for the OE Falco unit, but as this model was only produced for one year, these shocks are of necessity scarce. This shock boasted the same levels of adjustability as the ‘White spring’ Sachs (preload, rebound damping, compression damping and ride height) with added Öhlins build and component quality and bling factor. Ahem. Öhlins code for this shock is 46PRCL (see below for explanation).

For a while Aprilia offered a bespoke Öhlins shock for the Falco as an upgrade part that was matched to the OE Falco linkages (triangles and dogbone) and had a vertically mounted compression bottle (RSV/Mille bottles were oriented horizontally). This shock has a part number of AP941 in the list below. This worked perfectly with the OE Falco subframe and swingarm, but simply will not work when a Falco has an RSV/Mille swingarm fitted. Clearance issues rule this combination out, so if you wish to fit a Falco-specific Öhlins shock you must use an OE Falco swingarm.

Aprilia V60 Rear Suspension.JPG
Aprilia V60 Rear Suspension.JPG (304.08 KiB) Viewed 16212 times

Interchangeability – RSV Mille 2001-2003 (2nd Generation) & Tuono 2002-2005

For 2001 Aprilia revamped the Mille quite substantially. Among the many changes made, the linkage ratio of the rear suspension was reduced by employing a dogbone and triangles with markedly different dimensions to the previous model. This required a shock with greater travel, a softer spring and different valving. Crucially, the frame and swingarm mounting points for the dogbone and triangles did NOT change, and so the later shock(s) can be used on the Falco providing it is partnered with the matching dogbone and triangles. This is vitally important. Note that the Falco suspension has stayed constant throughout its model life.

If an early Mille or Falco shock is used with later dogbone and triangles, it will give a punishingly firm, almost rigid, ride quality. If a later Mille or Tuono shock is used with early Mille or Falco dogbone and triangles, it will produce an excessively soft and over-compliant ride quality. It bears repeating that the shock and the dogbone/triangles must be from matching model years. The only exception to this rule is if the shock has been re-valved and re-sprung to match the dogbone/triangles in use. However it is normally simpler and cheaper to source the correct dogbone/triangles to match the shock in question.

As with the 2000 model year RSV Mille, the 2001-2003 model came in two shock variants. The standard RSV was fitted with a fully adjustable Sachs shock, but this time equipped with a Yellow spring. The Mille ‘R’ was fitted with an equivalent Öhlins shock, also fully adjustable. A year later the Tuono was announced, and that followed exactly the same pattern shock-wise. Suspension components from the 2001-2003 Mille and the 2002-2005 Tuono are completely interchangeable and identical.

Interchangeability – RSVR / RSVR Factory 2004 on (3rd Generation) & Tuono 2006 on

Aprilia further revamped the RSV in 2004 (dropping the "Mille" tag - the base model becoming the RSVR and the premium version the RSVR Factory), but this time the changes were more fundamental. From a suspension point of view, the changes made in this revision effectively exclude the use of 3rd Generation components on the Falco. The major difference was that the shock length from eye to eye was reduced by over 10mm. This may not sound significant, but it is.As a result of this change, the 3rd Gen RSV shock is 0.5 mm shorter eye to eye than a standard OE Falco shock, even at maximum extension.

This means that using a 3rd Gen RSV shock on a Falco would reduce rear ride height by a fraction from standard, when most riders agree that rear ride height on a Falco needs increasing to sharpen the steering. The only circumstance when this shock could be recommended was if a vertically-challenged rider wanted to reduce ride and seat height on their Falco. In that circumstance, ride and seat height could be reduced by a little under an inch compared to OE Falco, if using all the available adjustment. However this would also make the Falco steer more like a cruiser/Harley than the sports bike it really is. This option needs very careful thought before proceeding and cannot be generally recommended.

Aprilia also saw fit to ‘update’ the triangles and dogbone on the 3rd Generation RSVs (and 2nd Generation Tuonos). It is unsure what (if any) change in the linkage ratio was caused by these changes, as the spring code for both 2nd and 3rd Generation Öhlins shocks was unchanged. This is the clearest indication that the linkage ratio change was either non-existent or insignificant and that the dogbone/triangle change was made for reasons of packaging (i.e. space).

What is of far greater concern is that there have been reports of the 3rd Gen triangles fracturing with disastrous consequences. This has occurred on that part of the triangle where the section has been ‘waisted’ to an apparently unacceptable degree. As a result of this, use of the 3rd Gen triangles cannot be recommended and, for the reasons given above, neither can use of the 3rd Gen shocks.

Shock types and fitments

Shocks fitted as OE to RSV Milles and Tuonos were either made by Sachs or Öhlins. This is not to say that other shocks cannot be used; we have heard of Nitron, Penske, WP, Maxton, Hyperpro, Wilbers and Hagon shocks all being used successfully on the Falco. But information on these aftermarket shocks is of necessity difficult to come by and this guide will (initially, at least) confine itself to information regarding Sachs and Öhlins shocks. If you have information on other fitments, please let us know and we will add that information to this guide.

In addition to providing OE shocks to Aprilia, Öhlins also supplied a range of aftermarket shocks via their distributors (Harris Performance Products in the UK). These shocks tended to differ from the OE shocks in that they specified a remote hydraulic preload adjuster. A list of OE and aftermarket Sachs and Öhlins shocks appears below. Note that certain information (such as supplied spring rate) has been taken verbatim from the AF1 Forum site. We would welcome any information which would corroborate or disprove these figures, as it is the author’s opinion that some of this information is down to guesswork or assumption.

Aprilia V60 Shocks.JPG
Aprilia V60 Shocks.JPG (195.62 KiB) Viewed 16212 times

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