Gear reduction explanation

[dingy]

Randya started discussing ratios in the following thread. This was regarding some work he is doing to his bike this winter.

 

http://www.venturerider.org/forum/showthread.php?postid=551974#post551974

 

I thought I would start a new thread along these lines hoping to give a little better understanding to where all those ratio numbers come from.

 

I confuse easily, so here is same info in a different format.

 

All numbers are from the corresponding bikes service manuals.

 

 

1st Gen Ratios (From 1986 Service Manual)

Primary reduction 87/49 (1.776)

Secondary Reduction- Middle Drive 21/27 (0.778) x Final Drive 33/10 (3.300) -- Total Reduction (2.567)

1st 39/15 (2.600)

2nd 39/22 (1.772)

3rd 31/23 (1.347)

4th 31/29 (1.068)

5th 29/32 (0.906)

 

 

Royal Star Ratios (From 1996 Service Manual)

 

Primary reduction 85/51 (1.666)

Secondary Reduction- Middle Drive 21/27 (0.778) x Final Drive 33/10 (3.300) -- Total Reduction (2.567)

1st 39/16 (2.437)

2nd 30/19 (1.578)

3rd 29/25 (1.160)

4th 29/32 (0.906)

5th 21/28 (0.750)

 

RSV Ratios (From 1999 Service Manual)

Primary reduction 87/49 (1.776)

Secondary Reduction- Middle Drive 21/27 (0.778) x Final Drive 33/10 (3.300) -- Total Reduction (2.567)

1st 43/17 (2.529)

2nd 31/19 (1.632)

3rd 30/25 (1.200)

4th 24/25 (0.960)

5th 22/28 (0.786)

 

 

1st Gen VMax Ratios (From 1995 Service Manual)

Primary reduction 87/49 (1.776)

Secondary Reduction- Middle Drive 21/27 (0.778) x Final Drive 33/9 (3.667) -- Total Reduction (2.851)

1st 43/17 (2.529)

2nd 39/22 (1.772)

3rd 31/23 (1.347)

4th 28/26 (1.076)

5th 26/28 (0.928)

 

 

 

The primary gear reduction is between the crankshaft and the clutch pack.

 

The secondary gear reduction is from the middle drive through the rear axle gear case.

 

All of the gear reductions first list the driven gear # of teeth, followed by the drive gear # of teeth, this ratio is then shown last. For a given comparison between the four bikes listed, the higher the ratio number, the more acceleration & low end power the bike will have. Lower numbers translate into higher speed. This is when comparing the same point in the drive train.

 

In the case of the secondary gear reduction, there are 2 sets of gears. 1st is the middle drive set, followed by the rear axle drive set.

 

The secondary gear sets also accomplish the task of taking the engine/transmission rotation and turning it first 90 degrees to attach to the drive shaft, then 90 degrees again to drive the rear wheel.

 

In the case of the Vmax, the power increase that is often discussed in the rear axle gears. These gears have 9 teeth on the drive gear and 33 teeth on the driven gear.The 1st and 2nd Gen Ventures and the Royal Star all have 10 teeth on the drive gear and 33 teeth on the driven gear. The VMax ratio provides for more acceleration and low end power, but sacrifices top end speed.

 

Three bikes, 1st Gen, RSV & VMax have the same primary gear ratio, and middle gear ratio. The difference is in the transmission & rear axle drive ratios. The Royal Star also has a different primary ratio in addition to the transmission & rear axle drive ratios.

 

What this all translates to as it moves through the drive train is shown next.

 

1st picture shows inside of clutch housing looking up and forward towards the gear on the end of the crankshaft. Only the back quadrant of the gear can be seen. This gear is on the center line of the drive shaft, on right side. This gear mates to the clutch pack seen in next picture.

 

The clutch pack provides a means of interrupting the flow of power to the transmission. The friction discs in the clutch pack are connected to the outer clutch housing, which has the larger gear seen at the bottom of the clutch pack. The steel plates are attached to the inner clutch boss. When the clutch lever is depressed, these two sets of plates allow the motor to rotate, while the transmission is not turning.

 

The shaft that is in the center of the 1st picture is the main axle shaft of the transmission.

[ATTACH]53660[/ATTACH]

 

[ATTACH]53661[/ATTACH]

 

The 3rd & 4th pictures are of the transmission assembly.

 

3rd picture is of a 1st gen main & drive axle assembly. Top is main axle, gears left to right are 5th, 2nd 3rd, 4th, 1st. Bottom is drive axle, gears left to right are Middle Drive gear (Bevel cut, Helical gear), 5th (machined on shaft), 2nd 3rd, 4th, 1st.

4th picture is a cut from the 1st gen VMax service manual showing these in the lower motor case.

 

[ATTACH]53662[/ATTACH]

 

[ATTACH]53663[/ATTACH]

 

5th picture is of rear axle gear case. Drive shaft attaches on left side and drives another set of bevel cut, helical gears. Drive gear is inside case. 6th picture shows driven ring gear.

 

[ATTACH]53665[/ATTACH]

 

[ATTACH]53664[/ATTACH]

Gary

Edited February 2, 2011 by dingy
Corrected VMax 4th gear ratio

[Venturous Randy]

Hey Dingy, this is exactly what I was hoping for in some more discussion about the different gear ratios that have been available on these bikes. Below, I have attached a chart from an earlier post by Squeeze that I got my data from. The only discrepancy I have found is the primary drive numbers where Squeeze notes that the Royal Star is 1.666 rather than 1.776 noted on everything else as you did. He did not note the specific number of teeth on the drive and driven gear for that model like the rest and the only thing I found that was close to the gear numbers would be 90/54 that equals 1.667.

It is my feeling that those that have complained about the RS being underpowered and not having enough power to pull sufficiently under 65mph have had to deal with that transmission being a bit higher geared than the RSV.

Anyway, you did a great job in this post and I hope it gets more discussion.

RandyA

 

 

[dingy]

I added the Royal Star info to the first post. I found manual online that listed gear teeth & ratios.

 

The Royal Star numbers are interesting, all indicate a significant change towards losing low end power and acceleration capabilities.

 

Gary

Edited January 28, 2011 by dingy

[Venturous Randy]

I added the Royal Star info to the first post. I found manual online that listed gear teeth & ratios.

 

The Royal Star numbers are interesting, all indicate a significant change towards losing low end power and acceleration capabilities.

 

Gary

 

Thanks, I needed that.

Yes, it looks like Yamaha went too far in the initial changes on the Royal Star. Now, I have not tried to figure how the difference in the primary drive ratio fits in.

RandyA

[Squeeze]

Thanks Gary, great Job as always !!

 

 

I added the RS-Data you aquired to the Comparison Sheet, hope this helps a Bit.

Edited January 28, 2011 by Squeeze

[BradT]

I think I got most (some) of that. In theory you should be able to calculate what one revelution of the engine means (in each gear) to the tire rotation (or mph).

 

Has this been calculated by anyone ?

 

Brad

[dingy]

I think I got most (some) of that. In theory you should be able to calculate what one revelution of the engine means (in each gear) to the tire rotation (or mph).

 

Has this been calculated by anyone ?

 

Brad

 

 

If you knew the circumference of the rear tire you could then start to make some calculations.

 

All the ratios are there to do this.

 

An excel spreadsheet would be real handy for this.

 

Somewhere I seem to remember a chart that was posted with some figures along this line.

 

Pegscrapper comes to mind, but that is a guess.

 

Gary

[Squeeze]

You could download a small Freeware Program called Gear Data. I'm sorry to say, but it's only in metric Dimensions and in german, but it's the only program i know off.

 

http://www.svs-tools.de/5.html

 

I already translated the most of the Fields in this Thread .... http://www.venturerider.org/forum/showthread.php?t=12800 in Post #15

[LilBeaver]

I had done this a while back (because I am a nerd like that).

The spread sheet is setup so that all you need to do is vary the tire DIAMETER and the sheet does the rest. I computed it based on what I MEASURED my rear tire to be +/- 0.25 inches. If you would like, you can also change the RPM in the sheet and it will automatically recalculate the different speeds.

 

Each workbook contains two different worksheets; one in English units the other in metric.

I have also attached PDFs of each for those of you that do not have Excel, Open office or some other program to read .xls files.

 

*_*_*_*_*_*_*_*_*_*_*_*_*_

UPDATE:

I have now modified the sheet to allow one to input the tire size [good idea Squeeze]. I have left the option for the user to input a measured size too, if you want to do it that way. On the sheet there is a box where you will need to specify "1" or "2" (actually it is either "1" or NOT "1", but whatever) so that the sheet will know which method you would like it to use to calculate the speeds.

I do not know where the redline is on the 96 Royal Star, so I simply extended the RPM scale out to encompass whatever is necessary. Same with the VMax.

I have NOT incorporated any tire slipping factor in these - yet. I may or may not add that.

 

Hopefully I typed everything in correctly. Let me know if you find any mistakes. It is late and I am tired so there is a good chance I screwed up typing one of the ratios in.

 

Have fun.

Edited January 30, 2011 by LilBeaver
Forgot to attach files; Updated attachments - 1st gen, 96 RS, Vmax

[Squeeze]

I had done this a while back (because I am a nerd like that).

The spread sheet is setup so that all you need to do is vary the tire DIAMETER and the sheet does the rest. I computed it based on what I MEASURED my rear tire to be +/- 0.5 inches. If you would like, you can also change the RPM in the sheet and it will automatically recalculate the different speeds.

 

The workbook contains two different worksheets; one in English units the other in metric.

 

 

That's not bad, but you need to add a Tire Slip Factor to the Calculations. You can expect 3 Percent Slippage as a Minimum Value.

 

Also, it would be easy to add a Tire Circumference Calculation instead of entering Diameter or Circumference Value.

[LilBeaver]

That's not bad, but you need to add a Tire Slip Factor to the Calculations. You can expect 3 Percent Slippage as a Minimum Value.

 

Good idea. I hadn't really thought through that - when I did this originally (not long after I purchased my bike) I was just interested in a 'ball-park' figure as I wanted to know roughly what the RPMs were at my shift points since I did not have a tach.

 

Also, it would be easy to add a Tire Circumference Calculation instead of entering Diameter or Circumference Value.

 

Sorry, I do not really understand what you are suggesting with the 'tire circumference calculation'.

The way I have it setup is that all one has to input is the diameter of the tire (which I figured was the easiest thing to measure) and then it calculates the circumference. I left that separate from the actual speed calculation for a few reasons. 1) I was curious about the variation in speed based on a new and fully worn tire (which required the tire size to be variable 2) It made it easier to trace silly errors in the way I typed out the formulas 3) I wanted to use the circumference for a different calculation that is not included on the sheet that is in here 4) It allows for easy adjustment for other vehicles.

[Squeeze]

For practical use, it's easier and more usefull if you enter the Tire Size and calculate Diameter and Circumference, instead of calculate or measure these Values ...

 

Us Vmaxxers use the GearData Proggy a Lot, because we change the Rim Sizes plus Tire Sizes on the Maxxes fairly often and you can see the Outcome of a Change within Minutes.

 

Here's the Formula for calculating http://www.kfz-tech.de/Engl/Formelsammlung/Reifenberechnung.htm

 

If you inherit this in your Sheet and just calculate the Circumference as an Result in i.e., B6, and allow the User to change the Circumference in B7 for further Calculation, it would cover anything you need to have. Of Course, a Cell for Slippage Value should be added, related to B7.

[LilBeaver]

For practical use, it's easier and more usefull if you enter the Tire Size and calculate Diameter and Circumference, instead of calculate or measure these Values ...

 

Us Vmaxxers use the GearData Proggy a Lot, because we change the Rim Sizes plus Tire Sizes on the Maxxes fairly often and you can see the Outcome of a Change within Minutes.

 

Here's the Formula for calculating http://www.kfz-tech.de/Engl/Formelsammlung/Reifenberechnung.htm

 

If you inherit this in your Sheet and just calculate the Circumference as an Result in i.e., B6, and allow the User to change the Circumference in B7 for further Calculation, it would cover anything you need to have. Of Course, a Cell for Slippage Value should be added, related to B7.

 

OH oh oh - Excellent! I understand what you are talking about now. Thanks for that. I will add that in as well. I will have to come back to it later though as I am about to run out to take care of a few things.

 

Thanks!

[BradT]

I had done this a while back (because I am a nerd like that).

The workbook contains two different worksheets; one in English units the other in metric.

 

Nice job. These numbers seem pretty close, I hit 143 kph measured on the GPS in third gear when I hit the rev limiter.

 

Brad

[dingy]

The workbook contains two different worksheets; one in English units the other in metric.

 

Nicely done.

 

Cells are formatted with absolute references to make it very easy to copy RPM's to higher ranges. I would guess you have some experience with Excel.

 

Gary

[LilBeaver]

Nicely done.

 

Cells are formatted with absolute references to make it very easy to copy RPM's to higher ranges. I would guess you have some experience with Excel.

 

Gary

 

Thanks. I guess I may have used Excel once or twice before...

[OscarV]

Great information on this post.

 

One question....I just put a VMAX final drive on my 2008 RSTD (with Hannigan sidecar). Does anyone know how this change affects the speedometer and odometer readings?

 

I've searched the forum and haven't been able to find this information.

 

Thanks,

Oscar

[krispy]

Dingy:

 

All interesting stuff here. Surprised at how much the gears have differed thru the models/years.

 

In the original post, looking at the 3rd picture, did the picture get reversed, or do you have the gears (1st, 4th, 3rd, 2nd, 5th) backwards? Or is it me that has it turned around. In that 3rd picture, isn't the top shaft the driver, and the lower shaft the driven shaft? If the top shaft is the driver, wouldn't 1st be on the far right, with the smallest gear driving the biggest gear? I absolutely reserve the right to be confused/wrong about this. Straighten me out, as I've never been inside one of these (or any other MC transmission).

 

Another question.... in photo 3, it appears that all gear sets are meshed all the time. Is that true, and if so, how does the transmission cause only one set of gears to engage? Probably not using the right terminology here, and maybe don't know enough to ask a logical question, but I tried. :think:

[dingy]

Dingy:

 

All interesting stuff here. Surprised at how much the gears have differed thru the models/years.

 

In the original post, looking at the 3rd picture, did the picture get reversed, or do you have the gears (1st, 4th, 3rd, 2nd, 5th) backwards? Or is it me that has it turned around. In that 3rd picture, isn't the top shaft the driver, and the lower shaft the driven shaft? If the top shaft is the driver, wouldn't 1st be on the far right, with the smallest gear driving the biggest gear? I absolutely reserve the right to be confused/wrong about this. Straighten me out, as I've never been inside one of these (or any other MC transmission).

 

Another question.... in photo 3, it appears that all gear sets are meshed all the time. Is that true, and if so, how does the transmission cause only one set of gears to engage? Probably not using the right terminology here, and maybe don't know enough to ask a logical question, but I tried. :think:

 

Krispy,

 

You were correct about the gear order being inverted. I have corrected the first post. Still working on that left & right thing.

 

I am trying to find an animation that I had seen at one time that illustrates how the shifter forks engage the dogs on the various gears by sliding them on the transmission shafts.

 

Gary

[BradT]

Krispy,

I am trying to find an animation that I had seen at one time that illustrates how the shifter forks engage the dogs on the various gears by sliding them on the transmission shafts.

 

Krispy nice question.

 

Gary, hope you find it as that would be interesting to see.

 

Brad