[gmk1800]

It would change rpm and slow down acceleration,but not change the fuel mileage, only changing the final drive would effect fuel mileage.

 

[2WheelNut]

Well Gang,
As stated, I'm no engineer or designer. I only posted what I've observed. I'm used to 1650 RPM at 60 mph in our motor home, 1675 RPM in our '11 GMC Sierra 1500 Extended Cab 4x4 and, in both our VW TDI Diesels, it was 2100 RPM @ 60 mph. So, when I have to run down the road in the GL at over 2700 @ 60, it just seems to me that it's running at an RPM that is too high. So, if and when an alternate diff come out with taller gears, I for one will definitely look into it. It's not hard for me to have to grab then next lower gear if I had to, to get around a situation. To me, this is simple. If you're happy with what you're dealt with, then by all means, have a ball. The Wing, in it's entire design, is to me, a phenomenal machine. It's just that to me, it's turning too many RPMs for freeway and long distance driving. 'Nough said.
Scott

Different beasts....diesel engines redline way sooner than gas. If you had a diesel motorcycle, it would likely cruise at 60 at around 1500 RPM.

Whether you are an engineer or not, here's the bottom line that needs to be understood.

If you dropped the RPM on the wing by 20% by adding a 6th gear, you would GAIN nothing except lower RPMs and whatever longevity increase in the pistons that it might give you since they would move up and down a bit less. Neither of those actually add value to the bike. Lower RPM's don't give you anything in MPG or other performance and the longevity increase might be there but it already will go 300K miles, so it doesn't need much improvement there.

You would potentially LOSE a a few things. You'd lose top gear acceleration, you'd possibly increase the wear on your transmission, you'd increase the complexity of the gearbox (maybe it wouldn't be bad but it certainly would be more complex than the current design)

So...if you gain nothing and risk making the bike worse by losing a few things that do work well now, WHY would Honda ever want to do it? The answer is that they don't. They looked at it and decided it was better as a 5 speed.

PS...Honda has several bikes with 6 speed gear boxes. They don't have a problem putting a 6 speed on a bike if it makes sense to do so. It just doesn't make sense to do it on a wing.

 

[ARH]

My guess is Honda wants to error on the side of caution.

If your at gross weight and driving along at 75 in pretty hilly country with the cruise set you won't be lugging with their ratios.

 

[Jay Hoover]

Does anyone know if the OP ever spent the time to develop other gear ratios? This thread started a couple years ago. I wonder if anyone has ever tried to cut other gears?

The top gear on my Civic is almost identical. Right at 3000 rpms a 70mph. The Honda motors like to spin. I personally would like to have a gear that dropped the RPMs 150-200 or about what a 70 series back tire will do.

 

[skip h]

Some are talking of rear gear changes, some are talking about trans gear changes, a lot are talking of no changes.
I'm thinking of installing a Gear Vendor overdrive in my 1800.
Just think- 10 speeds forward and 2 in reverse!
Ist std, 1st over, 2nd std, 2nd over, 3rd std, 3rd over, etc!!

I had one in my gasser motorhome and I absolutely loved it!

 

[Wing One]

Good God!!!

This thread is getting more ridiculous with each post.

 

[jjsC6]

Some folks here understand the issue and a few don't:
Manufacturers design engines to run at a certain RPM with respect to speed. The calculation has largely to do with having adequate power available to overcome frictional losses (mostly air at higher speeds). If the GL1800 had taller gearing we would be hearing endless complaints about how it feels clapped out at 70. Nothing left. Had to down shift to pass, i want more HP... etc.

And the important point: the amount of force required to push the bike along at 70 is unchanged. It's not related to RPM. That is why you will generally get about the same MPG with taller and shorter tires, etc.

Of course there are extremes. If you ran the same speed in 3rd vs 5th you would see a difference. But 750 RPMs? Not so much.

The designers know all about this stuff. They choose gearing carefully so as to find the sweet compromise for driveability.

The engine in the wing is actually pretty respectable by modern standards. It has a high percentage of torque and HP on tap at a very wide range of RPMs. It's a very compliant beast. I'd wager that most wing riders, if they got on a sport bike would find it very awkward... They'd stall and they would shift early and they would bitch about having to keep it above 5000 RPMs to get anything out of it...

Want to improve your MPGs? Or improve your quarter mile time?
1 - remove barn door windscreen. Use stock or smaller and keep it set low.
2 - remove the 200 pounds of add on geegaws (example: compare the weight of stock pegs with floorboards)
3 - loose the trunk rack and all the air wings
4 - loose the car tire (I know, heresy. but compare the weight and rolling resistance...)
5 - Do the maintenance. fresh oil, gear oil, lube etc.
6 - keep the tires aired up toward the higher end of tire manufactures recs (note I did not say honda recs)
etc

That is a very simplistic view with a lot of assumptions that have been proven wrong thousands of times over in the automotive world. It assumes that all the eight speed transmissions and taller top gear overall gearing are just for bragging rights.

If nothing else, more gears allow the engine to be operated in a narrower band of its peak efficiency to offer better economy and performance. That is a proven fact and the reason that so many cars (including recent new Hondas) are going to CVTs.

 

[chrisashbrook]

That is a very simplistic view with a lot of assumptions that have been proven wrong thousands of times over in the automotive world. It assumes that all the eight speed transmissions and taller top gear overall gearing are just for bragging rights.

If nothing else, more gears allow the engine to be operated in a narrower band of its peak efficiency to offer better economy and performance. That is a proven fact and the reason that so many cars (including recent new Hondas) are going to CVTs.

As long as I don't have to manually change them.... :lol:

 

[kniterider]

Every experience I have had over the last 20 years or so has proven the thought line that to get the best gas mileage you want the engine putting out just the amount of horsepower to accomplish the required task at hand. My 68 chevelle SS 396 375 HP,, had the factory 4 sp. manual. It was running almost 2600 at 70 mph.. ( it was balanced and blue printed by Motion Chevy in New York for a redline of almost 8200 rpms. I instALLED A GEAR VENDORS INLINE OVER DRIVE WITH A 30% ODRIVE. GAS MILEAGE WENT FROM 16 MPG AT STEADY STATE CRUISE TO ABOUT 21

MY 1998 4 WD gmc DIESEL )6.5 TURBO) WITH STOCK 4 SPEED AUTO) AVERAGED ABOUT 14 MPG ON TRIPS TO 18.5 WITH THE GEAR VENDORS OD.
Soo hell yes if somebody comes up with a rear diff. gear change ,,, I am first inline.. If not as soon as the bugs are worked out of tthe CTX 1300D i am first in line for that

 

[twincamboy57]

Hi Guys,

I have been working on this GL1800 final drive gear modification for the last five years and I have solved the problem.

I as same as those who are not satisfied with Honda's original gear ratio did a lot of research and development in coming up with the right ratio.

The Honda's original differential gear ratio is 2.75:1 meaning the drive shaft has to turn 2.75 times to turn the rear wheel 360 degrees (one complete turn). This ratio is way too low and it feels like driving a semi truck especially in the first gear as well as 2nd 3rd 4th and 5th

First time, I made a gear ratio of 2.416 : 1 which gave me a drop of approximately 300 RPM going at 70 MPH and my bike still had plenty of power in the fifth gear going at 70 MPH. My bike with the new modified final did 70 MPH at 2700 RPM on a dyno . It was low but not low enough and I didn't like it so I went on to developing another ratio which is 2.2857 or rounds off to 2.286:1.

The drive shaft goes into the final drive gear housing in 14 degrees in angle, it is not straight and my pinion gear being bigger than the Honda's original I had to bore out the hole slanted with 14 degrees in angle in the housing to make room for bigger headed pinion gear to allow clearance.

Honda OE pinion head size is 56.3 mm in diameter and housing bore diameter is 57 mm
My pinion head size is 61 mm in diameter so I bored out the housing to 61.5 mm.

1st Generation : 29 teeth on the ring gear and 12 teeth on the pinion 29/12 = 2.417:1 (2,700 rpm at 70 mph)

2nd Generation : 32 teeth on the ring gear and 14 teeth on the pinion 32/14 = 2.286:1 (2600 rpm at 70 mph) Perfect !

This time with 2.286 : 1 ratio final drive installed on my bike rides very smoothly at both low and high speeds and I feel the gear ratio is just about perfect. With the new ratio final gear I went for a test ride with my wife in the back and rode up to Big Bear mountain in California, 6700 ft altitude and I had no issue with the power going up in low gear or high gear. Keep in mind that the Goldwings have 1800 cc motor which is the same as some of those compact cars.
GL1800 Goldwings have plenty of horse power and torque

Honda's original final gear (Engine RPM) My modified final gear (Engine RPM)

70 MPH in 5th gear @3,000 RPM 70 MPH in 5th gear @2600 RPM
85 MPH in 5th gear @3500 RPM 85 MPH in 5th gear @3100 RPM

95 MPH in 5th gear @4000 RPM 95 MPH in 5th gear @3500 RPM

My goal was to achieve adequate engine RPM at all speeds.

My idea was not so much for better gas mileage but rather easier riding at all speeds. If I wanted a better gas mileage I would get a smaller bike, but obviously I sure do get better mileage with the engine working less.

FYI attached are the photos of my gears and a video clip of dyno test showing lower RPM.

I have several guys who have installed my final gears and they love it.

I will post more information later with dyno test result.

Safe ride,

Henry

 

[Ron Fuller]

Very interesting.

Ron

 

[MichaelB]

Hi Guys,

I have been working on this GL1800 final drive gear modification for the last five years and I have solved the problem.

I as same as those who are not satisfied with Honda's original gear ratio did a lot of research and development in coming up with the right ratio.

The Honda's original differential gear ratio is 2.75:1 meaning the drive shaft has to turn 2.75 times to turn the rear wheel 360 degrees (one complete turn). This ratio is way too low and it feels like driving a semi truck especially in the first gear as well as 2nd 3rd 4th and 5th

First time, I made a gear ratio of 2.416 : 1 which gave me a drop of approximately 300 RPM going at 70 MPH and my bike still had plenty of power in the fifth gear going at 70 MPH. My bike with the new modified final did 70 MPH at 2700 RPM on a dyno . It was low but not low enough and I didn't like it so I went on to developing another ratio which is 2.2857 or rounds off to 2.286:1.

The drive shaft goes into the final drive gear housing in 14 degrees in angle, it is not straight and my pinion gear being bigger than the Honda's original I had to bore out the hole slanted with 14 degrees in angle in the housing to make room for bigger headed pinion gear to allow clearance.

Honda OE pinion head size is 56.3 mm in diameter and housing bore diameter is 57 mm
My pinion head size is 61 mm in diameter so I bored out the housing to 61.5 mm.

1st Generation : 29 teeth on the ring gear and 12 teeth on the pinion 29/12 = 2.417:1 (2,700 rpm at 70 mph)

2nd Generation : 32 teeth on the ring gear and 14 teeth on the pinion 32/14 = 2.286:1 (2600 rpm at 70 mph) Perfect !

This time with 2.286 : 1 ratio final drive installed on my bike rides very smoothly at both low and high speeds and I feel the gear ratio is just about perfect. With the new ratio final gear I went for a test ride with my wife in the back and rode up to Big Bear mountain in California, 6700 ft altitude and I had no issue with the power going up in low gear or high gear. Keep in mind that the Goldwings have 1800 cc motor which is the same as some of those compact cars.
GL1800 Goldwings have plenty of horse power and torque

Honda's original final gear (Engine RPM) My modified final gear (Engine RPM)

70 MPH in 5th gear @3,000 RPM 70 MPH in 5th gear @2600 RPM
85 MPH in 5th gear @3500 RPM 85 MPH in 5th gear @3100 RPM

95 MPH in 5th gear @4000 RPM 95 MPH in 5th gear @3500 RPM

My goal was to achieve adequate engine RPM at all speeds.

My idea was not so much for better gas mileage but rather easier riding at all speeds. If I wanted a better gas mileage I would get a smaller bike, but obviously I sure do get better mileage with the engine working less.

FYI attached are the photos of my gears and a video clip of dyno test showing lower RPM.

I have several guys who have installed my final gears and they love it.

I will post more information later with dyno test result.

Safe ride,

Henry

Henry, you rock!
How soon will you have some to ship? You have my phone number already.

Mike in Tacoma, WA

 

[sur48]

Just for the sake of discussion lets say I could change the final drive gear ratio on the gl1800 to drop interstate type driving by 500 rpm's. I'm using 500 as thats pretty much how much the rpm's change from 4th to 5th and I like some others I know would really like a 6th gear type rpm at interstate speeds. What do you think the average rider would be willing to part with to have that kind of mod done? It would involve removing your final drive (not difficult at all) sending it in having a new gear set installed and of course properly set up and you re-installing it. I don't want to get into whats it made out of or is it reliable or any other type of tangent issues. Lets just keep it simple. I ask this question to find out if it would be worth going thru all the monkey motion a set of properly designed gears would cost to do this...I am considering it obviously or would not throw it out there. My question is aimed at those that feel as I do that the rpm's could come down for interstate type speeds so mpg doesnt take as much of a hit. Thanks fellow riders

70 series tries will do the same thing. Pluses are smoother ride at 70 mph less from of course. No better fuel mileage, a little sluggish on from stop acceleration 70 series tire is all I run now

 

[DillTm]

I find this entire article interesting. So, early on, someone said a 10% drop in RPM may only save about 5% in fuel economy. So taking my bike for instance, I get 40 mpg. A 5% savings means I can get 42 mpg. That equates to approximately 13 more miles per tank. That means to save a gallon of gas, I'd have to fill up the total 6.5 gallons 3.23 times. Cost saved would be estimated at $3.50. Now using the estimate to make a new final drive gear of say $800, I would have to save $800/$3.50 X 3.23 fillups X 6.5 gallons. At 42 mpg I would have to put 201,561 miles on the bike to amortize off the savings of fuel cost. That assumes everything being the same throughout the ride. It just is not worth it to me.

 

[Racer57]

While some use their spare time to theorize why something may or may not work, others actually put their spare time to productive use.

 

[GoldWingrGreg]

Well done Harry. I too had always considered doing the same and then marketing a drop in final drive product. But I always held off knowing that the added strain on the transmission will lead to more transmission problems, and 5th gens already have too much of that.

 

[cycledude]

I have always been very well satisfied with the stock gearing, the only thing that might possibly make me interested in changing would be possibly greatly increased mpg But I suspect mpg change will be pretty small.

 

[twincamboy57]

Henry, you rock!
How soon will you have some to ship? You have my phone number already.

Mike in Tacoma, WA

I would have them at the end of this month or early April.

Thanks,

Henry

 

[MichaelB]

Sounds good. Thanks.

 

[weengers]

I find this entire article interesting. So, early on, someone said a 10% drop in RPM may only save about 5% in fuel economy. So taking my bike for instance, I get 40 mpg. A 5% savings means I can get 42 mpg. That equates to approximately 13 more miles per tank. That means to save a gallon of gas, I'd have to fill up the total 6.5 gallons 3.23 times. Cost saved would be estimated at $3.50. Now using the estimate to make a new final drive gear of say $800, I would have to save $800/$3.50 X 3.23 fillups X 6.5 gallons. At 42 mpg I would have to put 201,561 miles on the bike to amortize off the savings of fuel cost. That assumes everything being the same throughout the ride. It just is not worth it to me.

Understandable if your reason for doing it was to save fuel. That would not be my reason nor do I think it was the reason the designer did this.