2009-09-16

The Woody Conversion - my quest for the perfect roller weight - The Spidermax Files

Optimizing the Piaggio MASTER 500cc CVT part III

Since I can not just borrow some rollers with different weight and don´t even think of just buying them her on the island, I need to find a way to make different rollers for testing  for cheap.
So today I tried to figure out how to make my own rollers. They do not need to be perfect just as long they are safe to use and do not mess up the transmission.
First I need to find a material what is easy to work with and has the right size. I found a hollow plastic rod from a shower what was exactly 25 mm in diameter. That is the size the rollers are. So cutting 17 mm wide pieces went OK after I found that saw guide. You know the thingy where you can saw with straight or in a 45 degree angle.

I made 4 nice rollers and then the brain nagged me with the what if question.
So I brought out the hot air gun and heated the roller. The material went soft and was easily to deform. Bummer - well better than melting in the pulley. I had not measured how hot the pulleys get but when you work on a warm engine. the transmission metal parts are still pretty hot especial the pulley part with the rollers since it is not well cooled at all.

So I needed a non melting material. Wood or aluminum came into mind. So off to the hardware store called here ferreteria. The problem is it is like a ma and pa store, everything is behind the counter...
Well this as a bust, so I went for the next best thing and was looking for round wood 25 mm. Nada, so I went for my second choice a bit under 22 mm is the size of the steel part inside the roller.


Armed with my trusty precision measurement device I found a Pümpel for 1 Euro with the size wood I needed (measured all 6 in the store and they were all a bit different in size).




After removing the metal part of the roller the wood from the Pümpel was easily pressed in instead.



So I sacrificed the Pümpel for research sake and made 8 little wooden roller inserts.



To get the metal out of the roller is a bit tricky, first 2 rollers I scraped some material off until I could remove the insert. The other 2 rollers I just smacked the metal out while loosing the plastic cover from the roller side.



The wood was hammered in with a rubber mallet.



First I wanted to do all 8 rollers at once but the I thought I test it better first with half and half.
So you could call this a Colt with a Woody Conversion test.


... and for all my American friends, think Toy Story ... Toy Story ... Toy Story ...




My test setup


After a short test ride it behaved pretty close to the Mustang Conversion with the 6 rollers. I will add some measurements tomorrow and will also try the full Woody conversion.

20 km/h = 2800 rpm
40 km/h = 3500 rpm
60 km/h = 4200 rpm
80 km/h = 4700 rpm
100 km/h = 5300 rpm


A short note to the rollers
The soft plastic is around the steel just to make the rollers operate silent, metal on metal would make lots of noise. The abrasions on the roller are, from what I understand now, of no concern. The plastic is soft and when there is hard dirt inside the roller cage the surface of the plastic gets scratched permanently. This is why some rollers have abrasions and others have none. A roller does not even have to roll, it can also just slide as with the Dr. Pulley sliding rollers.
So I see no reason why I would replace them with the same new rollers while they still do their work flawless.

Update 2009.09.18
Well the full woody was a bust, just too light. But I wanted to put little steel insets in the wood anyway. The problem is, I do hot have a precision scale. When I find one I might try another time. For now I am back to my much appreciated Colt Conversion. Just removed the wood from 4 rollers and pressed the steel inserts back in. Piece of cake.

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