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Re: [ST] Belt Drive



kindly translated by Neil Anderson (Scottie Dawg), who unfortunately is no longer receiving the digests from the ST list.
cheers
Jonathan

Translation of http://www.t5net.de/t5-riemenantrieb.htm
Belt drive for T5

This was discussed in late 2000 in the T5 Forum.  Having to oil your chain
again and again gets a bit irritating, especially if you are used to final
drives which need less maintenance.  Juergen was feeling a bit spoilt after
his years with Harley and Buell bikes, so he decided to build a belt drive
for his Triumph Speed Triple.  Working with a local company, he made a test
kit for his Triple.  Then, with a friend, he set up a contract for full
production.

[Picture 1] Special milling tools are used on gear milling machines to put
the profile on the high quality aluminium.  Since this is a specialist
product, it's not that cheap, but for around DM 1300 (Euro 650) you can have
a totally maintenance free final drive.

[Picture 2] Both pulleys are fitted with side plates to prevent the belt
from slipping off the pulleys.  The front pulley had to be a bit smaller
than usual to fit in the space available, but with 23 teeth it is still in
the permissible size range.  The rear pulley has 57 teeth, which gives a
ratio of 1:2.47, slightly lower than the original 18/43 (1:2.39), so it is
comparable with an 18/44 ratio on the usual chain sprockets.

A higher ratio is also possible, but not with the standard Buell belt that
Juergen used, as the eccentric adjustment is already close to the limits of
its range.  The new Polychain GT2 would be the current best choice.
Ideally, the next longer belt size would be used with a larger rear pulley
to give the standard 18/45 ratio.

[Pictures 3 & 4] To install the belt drive, you need to remove the swing
arm, just as you would with a chain.  No other modifications are necessary.
The pulleys are designed so that they are a bolt-on replacement for the
existing chain sprockets.  There is 3-4 mm space between the rear pulley and
the frame and 5-8 mm between pulley and tyre, depending on the size of the
190 tyre used.

[Picture 5] The advantage of this bolt-on construction is that it gives the
TUV authorities less chance to object.  In Germany, mechanical modifications
to vehicles must be approved by the TUV.  The first 700km were ridden before
registering with the TUV.  Adjustment of the belt drive proved to be a
little fiddly, as the eccentric only allows fairly coarse adjustment.  The
belt tension was set up to remove slack from the belt, but not to be
completely tight, to allow for compression of the suspension.  Following
discussions with the TUV, it should now be no problem for bikes with the
bolt-on belt drive kit to be approved as individual modifications.

[Picture 6] On the left, you can see the front pulley under the original
sprocket cover.  The slots in the sprocket cover were milled in afterwards.
As space is limited, the individual parts of the front sprocket need to be
assembled directly on the gearbox output shaft - it's a bit fiddly, but it
works.

The belt manufacturer gives a life of 400,000 km for this belt on a 27 tooth
pulley, so the life will be less on the 23 tooth pulley used here.  But even
if the belt only lasts 100,000 km, the belt drive is still cheaper than a
chain drive over the same distance - chain & sprockets might need to be
replaced every 20,000 km, giving a total cost of around DM 1,500 over
100,000 km, plus the cost of chain spray.

[Picture 7] If you are interested in one of these belt drive kits, please
contact Juergen Bleimund by EMail at : B-L-GbR@xxxxxxxxxxx

If possible, at least three people who want the same pulley sizes should
contact Juergen at the same time, to avoid cost increases for production of
a single kit.




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