Tech Tip: Clutch & Brake Lever Fulcrum Spacing
Have you ever felt or used a clutch lever before only to find you have to be the incredible Hulk to pull it in?
Have you tried changing out your clutch springs for a softer set only to find that didn't fix your stiff clutch problem?
Sound familiar? Keep reading..
If you haven't already figured it out today's Tech Tip topic is on both clutch and brake lever assembly's (mostly clutch though) and how they may have the hidden solution to your strained hand and stiff clutch problems.
I will also cover some points on how to obtain a better clutch and brake feel at the handlebars and you don't have to be an "expert" mechanic to do the job.
Let the levers do the work
Many folks from time to time will give us a call complaining about how there clutch lever is too stiff. First they tried new springs, then another brand of springs, then the adjustment, then a new cable and then they give up and live with it...
When riding a motorcycle it's the little things that can distract you such as a gauge not centered, a mirror lower or higher than the other or perhaps the triple-tree is slightly "tweaked". It's the little things like a stiff clutch that take the pleasure out of riding a vintage British motorcycle.
What causes a "stiff" clutch?
There are many key indicators that could cause a stiff clutch. Further below I will cover all points and also give you some tips on how to overcome this problem.
|Clutch springs too stiff||Install a set of softer rated clutch springs - measure the length and use a spring tester to measure the pressure|
|Clutch not adjusted properly||Check to ensure that your clutch rod screw is properly adjusted and it not applying to much pressure on the road causing a stiff and uneven clutch|
|Cable has rough action||Check to ensure that your cable is properly oiled and lubricated. Replace cable if necessary|
|Fulcrum spacing is not correct||Select a clutch lever or brake lever assembly that has a closer hole fulcrum spacing to give you more leverage|
If you didn't catch the last tip it's called fulcrum spacing. Fulcrum spacing is the distance from the clutch or brake lever pivot hole to the clutch / brake lever barrel hole... also know as the fulcrum.
The quick definition of fulcrum according to Wikipedia is: "A fulcrum is the support about which a lever pivots".
How fulcrum spacing works
Think of leverage when working with clutch and brake levers. Fulcrum spacing on levers work exactly the same way.
The closer the fulcrum spacing is the more leverage you will have and the less pull you will have.
The further the fulcrum spacing is the less leverage you will have with more pull.
It's a trade off
Most vintage Triumph and BSA singles and twins would have a 7/8" fulcrum spacing on the clutch while the triples would have a 1 1/16" fulcrum to suit there clutch design.
Most brake assembly's have a 7/8" - 1 1/16" fulcrum with some exceptions. Typically brake fulcrum spacing is somewhat forgiving.
Now I'm not saying that fulcrum spacing will solve all stiff clutch problems but it will substantially help and is worth checking.
How to measure fulcrum spacing
Measure from the center of each 2 diameters as shown on a clutch lever in the photo above
Measuring the fulcrum spacing is very easy and can save you a lot of uneasy riding.
- Identify the 2 fulcrum pivoting positions
- Use a ruler or caliper and measure from the center of each hole
- Remove pivoting screws to make measuring easier and more accurate
Levers on the market today
EMGO clutch lever with a 1 1/16" fulcrum spacing
Many levers on the market today are coming in one of 2 types of spacing. Almost 100% of the manufactures today are not informing us retailers about the spacing so you will have to ask your supplier or measure yourself.
Most of the levers that Classic British Spares stocks today will have a 7/8" fulcrum spacing which is ideal for most vintage British motorcycles (singles and twins) unless otherwise stated.
Companies like EMGO are producing great quality levers however the fulcrum has an 1 1/16" hole spacing for the clutch lever which is not suited for singles and twins but instead for the triples.
There was a test done on the 1 1/16" fulcrum clutch lever by some fellow members on britbike.com One member noticed a -4 pound difference when switching from 1 1/16" to 7/8". Click here to checkout that thread.
Need a 7/8" fulcrum lever set?
New set of 7/8" fulcrum clutch and brake lever assembly
If you are in need of a set for your Triumph or BSA single / twin feel free to take a look at some of our stock below. Most levers can be used on a wide range of vintage British motorcycle whether you have 7/8" or 1" bars.
Let us know your fulcrum spacing
Measure your fulcrum distance and let us know what your measurements are by leaving us a comment in the section below.
Remember you can use this same information on other marks of vintage British motorcycles.
If you are having clutch issues be sure to check your fulcrum spacing before going any further.
Thanks for reading