Belt Drive Transmission and Villiers Gearbox

[Tim]

Villiers Gearbox and Belt Drive

For the bike I have just completed I have used a villiers 2T / 4T 4 speed gearbox.I like the box as it is compact and easy to mount onto the Yanmar type engines as the front of the box is a flat surface and is a. The clutch is readily convertible to a dry belt drive of the "V" type rather than a timing type belt as it is more forgiving and cheaper + larger range of belt sizes available

The mainsaft length means the engine need to be mounted slightly off-center in the frame by about 20mm
All parts of the gear box are available from http://www.villiers.info/ site and are reasonably priced

Good bits
The drive is based on "A" section (With of the belt) and is a friction type drive so absorbs shock loading from the engine at low speed / RPM giving a smooth ride even down to idle speed

I based the system on low cost Fenner type taperlock pulleys available from Bearingboys http://www.bearingboys.co.uk the taper lock system doesn’t require a keyway on the engine shaft so taper type engine can be readily used

Good alignment is desirable however the belt can work with as much as 5mm misalignment

Only basic machining is needed to convert the wet clutch to dry clutch

Very low noise compared with chain drive

Costing
75mm 3 grove A section pulley (Engine) £9
Taper lock BUSH to fit pulley to the engine £6
175 MM 3 grove pulley for the clutch £18
Three “A” Section 33 inch belts £9


47mm X 35 X 7mm sealed thin bearing for the Clutch £6
Sheet of PTFE 3mm Sheet for Clutch Shim £12
Random sprocket to make the new clutch centre £3


Mounting Plates
As the Honda Superdream frame is a spine type frame . I chose to create a aluminium L plate to mount under the engine on the existing bolts and mount the gearbox. I used 12mm Aluminium plate and chose to use shoulder bolts to join the two pieces but they could be welded. The gearbox has a flat front face making the job simple and aluminium can be ready cut using a wood work type bandsaw.

The engine holes are slotted to allow belt tension adjustment (15mm) and at the top of the gearbox a rose joint to help support the box and assist in tensioning the belts.





The Clutch

The clutch basket and sprocket are riveted together I drilled these out and machined the pulley to fit over the existing sprocket , care taken to ensure the middle of the 3 belt groves is in line with the middle of the old sprocket to ensure no undue stress loading is placed on the centre bearing . the assembly can then be re-riveted together.

This is a wet type clutch, the plates perform better dry however the original supporting rollers in the centre don’t! the 47mm sealed bearing is fits in to the centre of the original clutch drum but you need to make up a new centre to fit the bearing (See Photo)

The centre support hub that mounts the drum onto the mainshaft and is the inner bearing surface for the rollers is need to be machined down to fit inside the sealed bearing. Being tempered steel unless you have access to grinder this is difficult. As this is not splined I machined a new centre up from a sacrificial sprocket.

I was concerned that the small 47mm bearing may struggle to support the drum and belts so I used 3mm PTFE plastic sheet to make a circular shim one for each side if the drum to prevent any lateral loading to the bearing and support the drum alignment. This also sorted out the difference in the new bearing being wider than the old rollers . I did drill and fit a grease nipple that is accessed between the final drive sprocket and the new centre.

How well does this all work?

My concerns over belt tension Vs slippage Vs overloading the bearing were unfounded and I currently run the belts very lightly tensioned and there is no indication of slippage or pulleys running excessively hot.

Tensioning the belts only requires fraction of a mm movement and haven’t need to adjust them since fitting (Currently 200 miles)

Will the slip in torrential rain? Unknown but I am a fair weather biker so I will never know , I guess you could easily make up a shield to keep the worst off.

Noise is virtually silent

Clutch performance, I used clutch plates that would be long past there service life in wet / oil use and after an initial setting in period they function well giving a light clutch and no slippage / temperature rise on the steepest of hills. There may be issues in heavy / urban use unless the air flow is sufficient to cool the clutch – I will report this when I find out
The best bit is I can glance down and take great pleasure in watching the belts rushing around the pulleys when riding along, how sad is that?


Gearing
Primary ratio is
75mm over 175mm so 2.33:1 ratio

Secondary 18 tooth over 37 tooth rear so 2.05:1 ratio



This gives a Gearing Engine top speed approx 58 mph

Thinking out loud

This was about a factor of 4 times easier to build than my previous wet chain drive primary and belt tolerances are forgiving

Could you get away with using the original rollers and a method of packing with grease? It would reduce the conversion to only one pulley machining operation.



Last 2 gearboxes purchased from Ebay seized / incomplete 2T villiers engines £30 and £12 and then spent £15 on seals, gaskets, parts

I am happy field any questions

[olafur]

Hi Tim i like your setup, I got a punsun - royal enfield box - suzuki gxr 400 can i use single V belt ? and what sise of pully on engine and gearbox, i see a man
in sweden use suzuki box, but the belt has to go on the flywheel side and nothing on the other side, or can the flywheel be put on the other side ?
This is my first diesel bike i do, i have done cars - unimog - boats. what is the best box to use ? you got Villiers gearbox, i have seen 3 speed villiers,
I just wanted a strong box but not strong price, so far i have spent £200 Thanku olafur

[coachgeo]

Hi Tim i like your setup,...- unimog ...

Since it has been more than 6 months since Tim posted in this thread you might want to email him also so he know's a question has been asked of him.

Also.... good to have another Unimog person around. Are you also on Benzworld.org? Excellent Unimog discussions there.

[Tim]

Hi Tim i like your setup, I got a punsun - royal enfield box - suzuki gxr 400 can i use single V belt ? and what sise of pully on engine and gearbox, i see a man
in sweden use suzuki box, but the belt has to go on the flywheel side and nothing on the other side, or can the flywheel be put on the other side ?
This is my first diesel bike i do, i have done cars - unimog - boats. what is the best box to use ? you got Villiers gearbox, i have seen 3 speed villiers,
I just wanted a strong box but not strong price, so far i have spent £200 Thanku olafur

Hi Olafur
The sizes of the drive pulley I used was really defined by the smallest pulley that would fit over the clutch drum. Then I calculate the nearest size of the engine pulley to give a top speed of 60mph @ 3400rpm. If you go this route and give me your wheel diameter, rear sprocket and front sprocket teeth , max rpm and desired top speed I can help calculate the front engine pulley size.

You could use a single belt but the more load it carries the shorter the working life and adjustment needed, the 3 belts give a large redundancy and working life and therefore infrequent need to adjust the tension .
I like the Villiers box as its easy to mount too and best of all very simple to convert and run as a dry clutch. I used a 4 speed but you a 3 speed would work fine as the diesels have generally a consistent good torque output throughout it rpm range.
Sticking with Taperlock pulleys and v belts is very cost effective , very low noise and after 4000mils has not required and maintenance or adjustment .
Bearing boys website has lots of good help and price and a calculator to determine belt length.
http://www.bearingboys.co.uk/Bearings-1 ... fAodKDK9iA
I hope this help
Cheers Tim

[olafur]

Hi Tim i am new to this so not doing it right, my wheel is 208 cm - rear sproket 43T - front sproket 15T - primary drive same as yours 175 - engine 3600 rpm so
3600 rpm at 90 mph Thanks olafur

[Tim]

Hi Tim i am new to this so not doing it right, my wheel is 208 cm - rear sproket 43T - front sproket 15T - primary drive same as yours 175 - engine 3600 rpm so
3600 rpm at 90 mph Thanks olafur

Tyre Circumference 2.800m
Rear wheel sprocket 43t
Gearbox final sprocket 15t
Clutch pulley diameter 175mm
Max required speed 80 mph / 144kmh @ 3600 engine rpm

Rear wheel rpm @ 144kmh
144000 mphr
(144000/2.800)/60
875 rpm
Secondary Drive
Rpm gearbox @144kmh
875x(43/15)
2507 rpm
Primary Drive
3600/2507
1.4359: 1 ratio

So Engine pulley will be
175/1.4359
121.8 mm diameter for the engine pulley rounded down to 120mm
The nearest preferred size would be 118mm diameter Bearing boys part no SPB118/2 (£14gbp) V Pulley I used 3 SPA 13mm belts but you could go to 2 SPB as the belt speed is higher and the drive pulley larger has a larger wrap for the belt to grip . I think the 3 look better!

I think 90 is a bit high for 20bhp and would gear it for top speed of 80 mph

[alexanderfoti]

Tim, where did you get your 175mm 3 groove pulley from, bearing boys doesnt seem to carry them?

[nelly001]

thanks for sharing this with us im using an albion 3 speed possibly from a villiers and intend to do the same as you .already been on bearing boys eyeing up pulleys and taperlocks.any more information on converting to dry clutch would be great not sure on atatching the pulley to the old sprocket.