Tech Article: Cutting a Harley Rear Drive Belt

NOT LONG ago my Softail spat a belt. Now ordinarily that’s a big enough nuisance by itself, not to mention the many dollars for parts and labour to fit a new one. My situation was even more complicated as I had fitted a wider Deuce wheel to my bike, necessitating a narrower belt.

cutting Harley-Davidson rear belt

So, I had in my possession a second-hand 1.5 inch wide belt with a nick on one side. How to cut it down in a controlled process?

I worked on the designer’s premise of at least 2x in a safety factor. That is, if the width of the standard Aramid reinforced belt was 1.5 inches, then reducing it to 1 inch still left me plenty of safety factor.

Too easy— just remember to cut the excess from the side with the nick in it!

cutting Harley-Davidson rear belt

A jig to locate the belt and stabilise the cutting blade was in order. Scrounging around in my off-cuts of steel I came up with a piece of channel and a section of pipe which, after much head scratching, were duly welded together. The width allowed the belt to be guided and slide through. The radiused section of pipe allowed a lead in so the teeth on the belt wouldn’t catch.

cutting Harley-Davidson rear belt

The next step was to provide a pivot point to rotate the cutting blade down onto the belt. This had to fit snugly on top of the belt to ensure the belt was located against the base. The belt is 10 mm thick so I made the necessary calculations as to where the pivot point is located. Make the bolt holes for the pivot point a neat fit as you don’t want the cutting blade flopping around. You can see I am cutting the belt flat side up.

cutting Harley-Davidson rear belt

Basic hand tools required plus an arc welder and angle grinder with one of those ‘u-beaut’ thin cutting wheels.

cutting Harley-Davidson rear belt

Next I tack welded a piece of 25 RHS to the pivot to give me something to attach the cutting blade to.

cutting Harley-Davidson rear belt

Now weld on a couple of nuts to attach the cutter adjusting screw to the jig.

cutting Harley-Davidson rear belt

This set-up will give me control of the cutter. It’s all removable to fit over the belt.

cutting Harley-Davidson rear belt

Make up a clamp plate for the cutting blade – I’ve used a replaceable knife blade. Now drill and tap some holes in the cutter arm.

cutting Harley-Davidson rear belt

Voila! What a set-up—nearly as good as a bought one! You can see that I have used a packer behind the blade to accurately set the width of cut.

cutting Harley-Davidson rear belt

The belt is pulled through by hand and the adjustment screw regulates the depth of cut. About three times around the belt to cut right through doesn’t force things.

Easy peesy pekinesy!

cutting Harley-Davidson rear belt

Now the fun part starts. Pulling out the back wheel and swingarm. Removing the clutch and primary drive and the inner primary. Why oh why does Harley have such a user unfriendly archaic system?

Tech article by Stewie from Albury

PS: I got more than 80,000 km from the last one I cut (often riding two up with luggage) so it is reliable. But you know belts, they can break seemingly without reason!

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  1. About to fit a 200 rear tyre on my 2000 fatboy. Has a slightly wider swing arm than usual and after mocking it up I think I can go from my current 170 tyre to a 200 with a thinner belt of 20mm. The 200 wheel I have bought has a 20mm wide pulley. The cuurent one is 1.5″. I am thinking of cutting the belt down while its still on the bike. The idea is to jack the back wheel up, remove the belt gaurd and set up a cutter rig direct to the belt via the belt gaurd fixings. that avoids removing the primary etc so save a ton of work. Then rotate the wheel apply ing pressure to the cutter befor just cutting off the part I dont need.

  2. Hey man

    I build the device yesterday using your tutorial and screws mostly – i am not so much of a welder. I have to replace the belt for my 19 year old BMW F650 CS which costs between 290€ and around 500€ (at BMW) here in Germany.
    I bought a F800 Belt (which can be bought from the manufacturer Contitech for about 100€) and cut it from 34mm to 26 yesterday and it looks good.

    Thank you very much!

    1. Wow. I am waiting (and waiting) for a replacement belt to come from overseas for my F650cs. $625nzd from agent in New Zealand. Managed to get one from overseas for $490 nzd. So the F800 belt is same length and teeth etc but just wider? Might be an option for me in the future. Than you for that little nugget of advice

  3. Thankyou! Just recently my 02 sporty snap a drive belt paid $400 to replace and only lasted 100ks! My options for second hand belts is great now i can trim down a wider belt. Thankyou.

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