Amos g/box mod.

Hi Trevor

Have you done a layshaft bearings mod too or just the sleeve gear?

I assume the advantage of the sleeve gear mod is it doesn't gear/become sloppy?

Are you prepared to share how you converted your sleeve gear? and ? mainsaft?

Mike

Hi Mike ,
Will do , i`ll take some photos and explain it all to you , and a bit more besides !

Cheers for now , trevor

Courtesy & Property of Trevor Amos

Hi all ,
Firstly , many thanks to Ed for posting the photos , what a great guy he is and if he gets on the track he surely would deserve "rookie of the year" !
Scrutiny of my notes tells its own story, excessive bush wear , with a lot of friction in first and second gear and the end of the mainshaft deflecting
making gear slection even more of a problem !
This is the sleeve gear that Mark ran with at the last Cadwell meeting , so the conversion is durable and reliable . I was initially worried about
lubrication but everything seems fine .
One word of caution , don`t bore the gear through from just one end ! Go in from each end and leave a full radius at the newly created shoulder
and make the depth no more than the bearing width . It will be a fiddle to set up for each end , but you only have to do it once , and use the
existing , ground diameter as the set up datum , that way the new bearings will be co-axial and concentric and will run like a dream !

As a final thought , how many of you dynamically balance your clutch ? It does make a difference !

Catch you all later Trevor .

Sorry Mike .
Missed out the lay shaft . Yes , this was done first and was part of the original design brief , to eliminate as many areas of parasitic power
loss as possible, i just did`nt have enough time to include the sleeve gear as Steve was clamouring for the new engine . So this had to wait
for the following 98 season , i must say that the bronze bush wear rate was staggering , dread to think what might have happened if it was
left any longer .

Fire away if there are any more queries , Regards Trevor

Brilliant engineering Master Amos (master as in engineer not as the teenager!) and using Imperial BRITISH inch units -- Brilliant!!...
Well done son!

Sorts of backs my theory that the 175 has an enormous amount more friction Losses -- hence needing a bigger flywheel -- than the 125....

Cheers!
JayBee.

Many thanks Trevor ... I think you are the only person to date to do this modification?
Have you 're-bushed' sleeve gears previously?

Regards Mike

Hi All,
I have been using this mod since 2004, I did have some issues with the bearings but is was mainly the acuracy of my machining, I sorted this out and then no trouble there after!
The moral of the story is.... Take your time and do a good job!
Cheers,
Alan

Alan do you use the same bearings as Trevor?
And do either of you have problems with oil being throw
out the open end of the sleeve gear?

Hi Mike,
I use the HK1212 (I will check if this is the correct number!) which is a metric bearing, then I grind the mainshaft end to 12.00 mm dead for the bearing internal size, it gives no trouble if you do a good acurate job.
I also pin the layshaft over to the clutch side with a central screw and washer so that there is no float on the layshaft, but this is typical of most race gearboxes and I beleive the BTW style gearbox is done the same way.
I have not changed the Sleeve bearings for a few seasons, but I should do this every second or third season just for safety as the bearings are cheap so there is no reason to take a risk.
Cheers,
Alan

In the book, "Theory Of Machines" by Thomas Bevan, there is an example requiring the calculation of acceleration and speed of a motorcycle under given conditions whilst being driven in second gear and the example gives the efficiency of transmission as 88% ...
Which means 12% of power is lost because of transmission inefficiency

If the chain drive of the system was say 98% for each of the chains -- giving 98% x 98% = 96% -- we then have 12% - 4% = 8% inefficiency for the gearbox????? Which 8% means as much as 1.6 -1.92horsepower could be lost to gearbox inefficiency. That´s about 1.3 to 1,4 kilowatts of heat ---

Where does all the heat go? Do gearboxes get really hot -- the oil must be boiling?

Gearboxes on racing Bantams are much more efficient but I still ask -- where does over a kilowatt of heat go....?