Here is just what the doctor ordered..... another cam belt thread.
Ever since I bought my first belt Ducati twenty years ago, I've been using the 5mm and 6mm Allen key method; it works and although not very scientific, is a simple method. However, I've always been puzzled as to why the front belt seems looser than the rear, even though the 5mm Allen should make it tighter. A 6mm will not go between the idler bearing and the belt, so the clearance is tighter, but it doesn't seem so. Looking at the belt layout, the position of the idler and tensioner appears slightly different between the cylinders, which may explain the discrepancy.
Idly skimming through the W M last night, I see that Ducati recommends checking the slack at the bottom run of the front belt and the back run of the rear belt......Interesting, as the Allen method involves checking at the top run of the front and the back run of the rear. So, today I downloaded the Gates app to my tablet and attempted to set the tension.
First observation is how difficult it is. The tablet has to be held still without touching anything and extremely close to the belt. Any external noise stops the app from working. At first the readings were all over the place, but gradually I managed to get some consistency and some interesting results: The rear cylinder (set with a 6mm Allen) gave an average reading of 98, the front (set with a 5mm Allen) gave an average of 85. After re-tensioning, I managed to get an average reading on the front belt of 97, and left it at that. As they are almost new belts, I know that the figure should be around 112 hz, but I prefer to err on the slack side.
It IS a difficult job to get right, requiring patience; and both my thumbs are red and sore from flicking belts. I reckon that a microphone would make the job easier, if a way could be found to fix it in place, close to the belt. The run where the reading has to be taken (bottom, between the tensioner and bottom pulley and back between idler and bottom pulley) is probably the hardest to access, but gives different readings to other belt runs.
Ever since I bought my first belt Ducati twenty years ago, I've been using the 5mm and 6mm Allen key method; it works and although not very scientific, is a simple method. However, I've always been puzzled as to why the front belt seems looser than the rear, even though the 5mm Allen should make it tighter. A 6mm will not go between the idler bearing and the belt, so the clearance is tighter, but it doesn't seem so. Looking at the belt layout, the position of the idler and tensioner appears slightly different between the cylinders, which may explain the discrepancy.
Idly skimming through the W M last night, I see that Ducati recommends checking the slack at the bottom run of the front belt and the back run of the rear belt......Interesting, as the Allen method involves checking at the top run of the front and the back run of the rear. So, today I downloaded the Gates app to my tablet and attempted to set the tension.
First observation is how difficult it is. The tablet has to be held still without touching anything and extremely close to the belt. Any external noise stops the app from working. At first the readings were all over the place, but gradually I managed to get some consistency and some interesting results: The rear cylinder (set with a 6mm Allen) gave an average reading of 98, the front (set with a 5mm Allen) gave an average of 85. After re-tensioning, I managed to get an average reading on the front belt of 97, and left it at that. As they are almost new belts, I know that the figure should be around 112 hz, but I prefer to err on the slack side.
It IS a difficult job to get right, requiring patience; and both my thumbs are red and sore from flicking belts. I reckon that a microphone would make the job easier, if a way could be found to fix it in place, close to the belt. The run where the reading has to be taken (bottom, between the tensioner and bottom pulley and back between idler and bottom pulley) is probably the hardest to access, but gives different readings to other belt runs.
