HFT Swash Plate electric motor

Knob

Member
Site Suporter
It seem the HFT swashplate moving electric motor will live on DN for about 100k km, maybe a bit more. And then it seems to fail, at least in some cases. Mostly the motor's permanent magnets seem to break loose. This small electric motor is a soft spot of the DN-01.
Without this motor the DN will not go anywhere, some of those Honda stealerships even may suggest you to buy a full new HFT unit for $6000 as a fix...
And this small electric motor as a spare part is priced by Honda also pretty high. Dealers probably will not keep it in warehouse therefore time of delivery may be long. This is one unpleasant situation.

So I decided to look around for maybe there are some aftermarket motors available while wheather is still good.

Have to say I couldn't find any aftermarket swashplate electric motor for DN available. Sadly and sorry.

Found out that very similar motor is used on some Honda ATV's with similar hydrostatic transmission. BTW they call it Hondamatic, not HFT on ATV's, but basically these transmissions are very similar.
And this very similar electric motor for ATV transmission as aftermarket component (from our colleagues in China) is available for around $40...50 USD, this is for about 10x times less than the motor for DN as a Honda OEM part (probably also produced by our colleagues in China, as Honda uses a lot of components made in China nowadays, even on DN).
Looks like worth to check it out, eh?

So I got my hands on both versions of those electric motors, the aftermarket one for ATV and another OEM for DN.
These motors look like twin sisters at first glance! No big differences, same kind of installation surfaces, same kind of electric connector, same outer dimensions, same kind of O-ring gasket... BUT!
The electric motor for Honda ATV transmission has 11 teeth on it's axle. And motor for DN's transmission has 12 teeth on it's axle!
Did Honda hired some really bad minded engineer to work for them or is it arranged by demands from the pure evel himself working in their marketing department??
So otherwise these motors look exchangeable, only there is a different amount of teeth on axles. And therefore the axles diameter differs also a bit. And no - these motors from ATV and DN are not direct replacement for each other!

But this is not yet the end of the story! I'll open these motors and will take a look inside of them. There may be a possibility to exchange the shaft itself, it seems to be removable. Or maybe the part with permanent magnets may be usable from the aftermarket ATV-version, because the breaking loose magnets seem to be most problem part for these motors. Or maybe we can figure out some more use of those cheap ATV electric motors to fix the expencive DN's motor...
So the story will continue.
Meanwhile enjoy the photos about these both electric motors.

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Knob

Member
Site Suporter
Yes indeed it may be possible to install the rotor from one type to another. But.
A bit confusing is I see there are available two versions of the ATV shift motor, both ment for the same ATV model and production year, but one has 12 teeth and another has 11 teeth. Like these ones:

- 12 teeth seen on photo:
https://www.ebay.com/itm/271288428364

- 11 teeth seen on photo:
https://www.ebay.com/itm/174901092949

The third possibility may be to take from el cheapo motor the new part with permanent magnets and use it on DN's original old motor, possibly it will fit. And let the rotor itself to be restored, if needed. I know at least those guys who service the professional power tools are capable of performing this kind of service.
 

Alexandre

Member
Second link point to an equivalent to Honda ref 31300-HN5-A11, can't see a Honda ref for model #1... By the way, I visited the maker's site https://caltric.com/c-1390556-powersports.html but no mention of power shift motors and can't find a catalog. But they seem to have many starter motors - which I guess is another cross-exchange possibility!
 

Knob

Member
Site Suporter
Let's continue the story about similarities and differences about OEM and chinese aftermarket transmission control electric motors. Please look first also at photos in post No 1. in same branch.

The electric motor consists of three major parts, let's name them the Front End (FE) and the Back End (BE).
FE includes the brushes section with ballbearing. BE has permanent magnets glued in it and a bushing supporting the rotor's axle back end.
And there is ofcourse a third part: the rotor.

As we know the most common issue is the glued in permanent magnets included in BE will get loose and the rotor will destroy them into pieces, so in the end the electric motor will not work anymore.

Permanent magnets getting loose is also a problem in some m/c generators, fortunately less in Hondas and more suffer from this Suzukis as little as I have seen. So this glueing the magnets is more like common technological problem, not related only to this particular transmission control motor.
Probably there may exist also a brushes wearing out issue, but this is less complicated as any shop capable of fixing starter motors can easily install new brushes into such an electric motor.
So let's concentrate on the permanent magnets issue, because if the magnets are loose and broken into pieces it is not possible to fix them back any more. Magnets will develope new magnetic poles if broken into pieces for every piece and it is not possible to glue them back together. Welding is also off the list.

Today had some spare time and dismantled both electric motors I have at hand, the Honda OEM (DN-01 only related part btw!) and a chinese aftermarket ATV part.
Both motors are very similar, so here is a tested (on the bench) cheap fix you can also try for situations when the OEM motor's permanent magnets will break down.
I can't guarantee it will 100% work for you, but I think at least it is worth of trying.

Both Back Ends have similar shape and permanent magnets installed (glued) into them in similar way, two C-shape magnets visually close enough at same angles.
Both rotors have 9.0 mm axle diameter in both ends.
Both rotors have outer diameter 35.0 mm.
Brushes working areas look similar enough, also diamater of this area is same.

I did installed the OEM part rotor with OEM Front End into the chinese aftermarket motor's Back End. It fitted. It turned freely. And it worked! The motor combined OEM Front End and chinese aftermarket Back End together started to turn normally.

So in the case there are permanent magnets broken loose in your DN's transmission control motor, maybe you can solve the situation:
1. Open the old problematic motor and make sure the rotor part together with Front End part is still usable. If needed, let it checked in starter motors shop.
2. If the rotor part together with FE are still usable (it may need new brushes and reconditioning of rotor's contact surfaces and so on, all considered as pretty normal service stuff), then buy the cheap chinese aftermarket electric motor ment for Honda ATV (analog for OEM part 31300HP5601, here is one example).
3. Use the rotor and Front End part from old motor and install the new Back End part from the chinese aftermarket motor together. You may use a new FE bearing too from chinese motor.

Probably this hack will help you out for some time and maybe even save you couple of hundreds green ones.

BUT DO NOT INSTALL THE NEW ROTOR FROM AFTERMARKET MOTOR MENT FOR ATV! THIS ROTOR HAS 11 TEETH INSTEAD OF 12 TEETH ON DN'S MOTOR AND WILL NOT FIT RIGHT WAY INTO DN'S ENGINE SIDE! YOU MAY DESTROY YOUR HFT IF INSTALLING THIS 11-TEETH ROTOR!

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BobF

New member
Excellent analysis and research - spot on. My DN has only about 8k miles on it, but this fix is certainly one to remember for the future
 


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