Hondaline Speedo Drives Mythbusted

[atcmatt]

So today I got my NOS speedo drive from atc500x. Thanks for that Dom. Anyway I took the thing apart to grease it all up and had my 250es one apart also next to it. Now it's common misconception for people to think that these drive gears are geared differently to make up for the 22inch vs 25inch tyre size, either
in the pinion gear or the ring gear. This is a myth. Both speedo drive units share the exact same ring gear and pinion gear. Therefore making all the parts interchangable. The ES one is stamped HA0 and the 250sx HA6.

It is beyond me why Honda sold them as seperate items. Why not just have one part number for the lot of them. It would be great if someone had the means or want to take apart a 350x or 250r one and compare that to the ES and SX one. I know the outer housings are a different shape but I would bet the internals share the same ring and pinion also, maybe just in a backwards setup.

Anyhow, just thought this might be of interest to someone.

I have used the sx speedo drive gear on my 350x speedo setup and I bet it will read fairly accurate.

Cheers.

Matt

[redsox]

where is the difference made up? in the speedo itself?

[jeswinehart]

Nah, the speedo heads and trip meter heads are definitely all the same (several different mounting brackets for different trikes). Tire sizing could be the only difference judging by Matts observations.
And adding into the confusion not all the speedo drive units are marked with any stampings.
Perhaps it really is only the axle sizing hole and direction of rotation ???

[wonderboy]

For the record, what is the tooth count on the output gear (the one connected to the speedo cable)? Also, are the gears a worm drive configuration (I'm assuming), or a conventional ring and pinion like an automotive axle?

[jeswinehart]

Yes, worm gears.

[atcmatt]

Didn't count the teeth to be honest. Just meshed the gears together and did a visual. What I'm saying is I think they all do the same thing and John is right in saying it might just be the axle size and the way they spin. They must have a 10% tolerance or something in accuracy. They are a pinion and ring gear I guess but not 100%.

[redsox]

is the front axle diameter on the ES the same as the SX? I can't imagine that the identical drive goes on a 22 inch tire and a 25 inch tire. the difference has got to be made up somewhere. If the axle is greater diameter in the ES then I suppose as long as the ratio is maintained in the housing and drive body of the speedo than the internals could remain consistent. ?? its interesting.

[atcmatt]

Axle diameter is the same. Right through ES,SX,350x,250r. Axle size has nothing to do with it at all. Very interesting. Maybe just a gimmick for Honda really. Who cares what speed your doing, as long at the needle moves right! :D

[Marty]

I have noticed that the sport atc speedo drives 200x, 250r and 350x,mounted turn different than others to activate speedo needle.

[redsox]

so the odometer is also dogsh!t?

[Marty]

Odometer is not dogs t! What it means is drives for ATC 200x, 250r, and 350x mount on opposite side of 200s, big red drives!

[redsox]

right. i understand that. my point is that these things are either wildly inaccurate (which i can't believe) or that there is a mechanical explanation for the difference in tire size from machine to machine. it can't be accurate and the same. So, how is it different?

[El Camexican]

right. i understand that. my point is that these things are either wildly inaccurate (which i can't believe) or that there is a mechanical explanation for the difference in tire size from machine to machine. it can't be accurate and the same. So, how is it different?

Based on my cable drive speedo street bike experiences I would disagree with you accuracy's doubts. 10% is nothing when you consider how the diameter of an ATV tire varies with speed and these weren't even destined for street riding, so its doubtful they ever had to pass any sort of DOT test.

[redsox]

it surprises me very much that honda would not QC that. at least make an attempt. one less tooth on the drive gear or something. AND they have different part numbers? but they're identical? am i the only one that thinks thats weird? i agree that with the relativly low travel speed of these machines, its close to moot, but the mileage is a significant difference over time.

[El Camexican]

it surprises me very much that honda would not QC that. at least make an attempt. one less tooth on the drive gear or something. AND they have different part numbers? but they're identical? am i the only one that thinks thats weird? i agree that with the relativly low travel speed of these machines, its close to moot, but the mileage is a significant difference over time.

Sounds crazy, I know, but consider the cost to Honda to R&D that extra tooth on the drive for a vehicle with tires that can grow 6 inches at speed. It was a crap shoot to calibrate them from the get go. I don't read a lot of street bike reviews as of late but back in the 80's when I was immersed in such things I recall the magazines reporting large discrepancies in speedo VS actual readings during the tests. It's just not something the manufactures seemed to care about.

As far as the 2 part #'s thing I can't say as it relates to Honda. It's the one brand that will never take up space in my shop, so I have no personal experiencing parts searching for them, but I've seen Yamaha & Ducati (Cagiva) make a duplicate part and change the part number, or discontinue an old part and keep selling it for a newer model even though it still fits the old vehicle.

[daddy420big]

so how much different is there really bc i have a trip meter for a 200es and was woundering if i could use it on a sx or 250es . iam talking about the drive peace and use as a speedo

[Marty]

Physically they look the same but both drives spin opposite direction when mounted!!!
Both drives mount on whatever side the application is for and both need to spin clockwise to activate speedometer or odometer. So a 200s speedo drive that mounts on right side of forks be placed on a 200x or left side fork and expect speedo to work. And speedo drives go on specific side the have a boss on wheel that drives speedo gear.

[atcmatt]

I really just feel like these were a money making thing for Honda. They were never meant to be 100% accurate. Take it for what it is I guess and enjoy your needle that moves on your speedo on your vintage ATC. Cant beat that. I love that I have them on mine just for the cool factor. The 200es one wont work on a 250es and sx BTW.

Matt

[wonderboy]

Based on my math comparing the different front tire sizes, I get a range of speedo accuracy from roughly +6% to -6%.

For example, if the speedo is assumed correct for a 350x with a 23.5" front tire (stock) at 55 MPH, then a Big Red at the same vehicle speed would indicate 51.5 MPH and a 250SX would indicate 58.5 MPH.

My example picks the 350x as the baseline since it is in the middle of the tire size ranges. If the speedo is accurate on the smallest tire (say the 22" front on the 250SX), then it means that the biggest tire (the 25" on the Big Red) would be +12% (roughly).

Keep in mind also that this is a percent error, so the slower you go, the smaller the actual speedo error in MPH.

Whichever the case may be, I think the speedo accuracy is fine by me.

[atcmatt]

Fair point. I reckon your bang on the money!

[Roo Rides]

Question? I have a speedo and drive gear that came off an 84 200es and I want to put it on an 86 250sx
How does one go about doing this ?
I was told to convert the drive gear but I haven’t a clue of how to do that.
If that’s what need ls to be done could you do a step by step instructions to help me out ?
Thanks brother!

[Dirtcrasher]

The ES had a 25" front tire, the SX had a 22" front tire. IDK which side the brakes are on but the drive is opposite the brakes, it will only spin in the correct direction on a model with the brakes on the same side.

The speedometer will not be accurate, not very close either being that far off. If you just want to see a speedometer needle move, just rig up an XR drive and sell the ES drive to someone that wants the correct drive.

You cannot swap internal parts because nothing is available, it's not much use to you without a 200ES unfortunately...

[kb0nly]

I have a speedo on my 200ES, OEM original, and compare that to GPS its always off +/-3mph or so, they are only so-so accurate... LOL...

I have a GPS speedo on my 81 200 and 82 200E, those are more accurate then the OEM cable driven speedo. In the end, for most they just complete the look of having all the options installed. I have speedos on all of ours because we city ride them here and we are required to follow the speed limit in town, so go over 30 which is plenty easy and we could be ticketed for speeding.

[atcmatt]

You and use the worm gear out of a cb400 into the 200es speedo gear and it will work on a 250sx/250sx. That’s what I have on mine. Speedo, like mentioned is not entirely accurate but it’s not too far off.