Navigating the intricacies of vintage motorcycle maintenance can often lead to online forums and discussions. A recent conversation thread highlights some key points concerning fork spring spacers, particularly relevant for owners of a 1980 Bmw motorcycle. Let’s delve into the insights shared and expand on the advice given, ensuring you have a robust understanding for your 1980 BMW restoration or repair project.
The original poster was seeking advice regarding fork spring preload spacers for their BMW. The discussion began with the practicality of using online forum search functions, quickly pivoting to the core issue: fork spring spacers and achieving the correct fork sag.
One helpful suggestion immediately directed the user to utilize Google with a specific site search query to find relevant discussions within a BMW motorcycle forum. This is a handy tip for anyone troubleshooting issues on niche vehicles like a 1980 BMW. The conversation then touched on the material for spacers, specifically PVC, and its suitability compared to original materials.
The debate around PVC versus aluminum spacers is an important one. Expert sources like Tom Cutter, as mentioned in the original post, often advise against PVC due to potential brittleness and disintegration over time. Duane Ausherman’s webpage, linked in the discussion, also reinforces this point, stating BMW originally used aluminum spacers and cautioned against the long-term reliability of PVC in this application. For a classic machine like a 1980 BMW, maintaining originality and durability is often prioritized.
The conversation then shifted to the crucial aspect of fork sag. A rule of thumb mentioned is aiming for approximately 1/3 of the total fork travel as sag when the bike is off the center stand and the rider is seated. This translates to roughly 2.5 to 3 inches, though another expert, Snowbum, suggests closer to 2 inches of sag. Achieving the correct sag is vital for optimal handling and ride comfort on your 1980 BMW.
The discussion also brought up aftermarket spring options, specifically Progressive Suspension springs and Wirth springs. The original poster mentioned purchasing new German Wirth springs for their 1980 BMW. However, the forum contributors and Duane Ausherman point out a potential issue with some aftermarket springs being shorter than OEM specifications, often requiring spacers to compensate. This can reduce fork travel and may not be ideal for achieving the intended suspension performance for a 1980 BMW.
Duane Ausherman’s insights are particularly valuable. He emphasizes that springs requiring spacers to achieve proper tension might be improperly designed. He also notes BMW’s shift away from spacers in later designs, highlighting the potential compromise in fork travel. While Progressive springs were a common replacement, concerns were raised about them being too stiff and not always providing satisfactory performance for all riders of older BMWs, including the 1980 BMW models.
The original poster, facing these conflicting opinions and observations, decided to take a measured approach, considering starting with a 1-inch spacer to assess the impact on their 1980 BMW‘s front suspension. This pragmatic approach is sensible when dealing with vintage motorcycle adjustments.
A key question raised in the forum was finding the correct fork spring length specification for a 1980 BMW R100T. Consulting a 1980 BMW R100T repair manual or parts fiche would be the most reliable way to ascertain the factory specification. These resources often provide detailed information on components, including spring lengths and preload settings.
Finally, the topic of short preload springs that might sit atop the main springs was mentioned. While less common, these could be aftermarket solutions or related to specific model variations within the 1980 BMW range. Further investigation into parts diagrams for the specific 1980 BMW R100T model would be necessary to confirm the existence and purpose of such springs.
In conclusion, maintaining the front forks of a 1980 BMW requires careful consideration of spring choice, spacer usage, and achieving correct fork sag. Expert opinions and factory specifications, combined with a methodical approach to adjustment, are crucial for ensuring optimal performance and ride quality for your classic 1980 BMW motorcycle.
