[mech5496]

Hello gentlemen! My name is Harry and I am a mechanical engineer and former team member and team leader of the University of Patras FSAE team, UoPRacing, in Greece. Not quite sure how many of you are aware of what FSAE is; an international competition where engineering students design, build and race single seater cars. (More info can be found here!) I stumbled upon your forum while searching info about the Hondamatic hydraulic transmission and its possibility to be used in such a car. Thus I would appreciate ANY info you would like to share regarding dimension(s), weight and any general photos of the ATV layout, as well as any piece of info/advice/experiences on using it (comparision with belt CVT's, possible drawbacks, common issues etc).

 

[Here 2 help]

If you are refering to the Hondamatic unit used in the TRX500 ATV, the unit is nothing more than a hydraulic motor powered by an oil pump. The transmission (in reality) is a standard combination of gears that provide selection of two forward speed ranges and a reverse.

I just recently installed a new unit due to the owner trying to service it himself. He partially disassembled the hydraulic motor thinking it was the cause of a transmission noise. Unfortunately, the unit is not servicable. I could find no breakdown of parts or assembly proceedures. The owners exuberance to repair the unit was dashed by the realization that it was a $1500 non-repairable unit that required complete engine disassembly to replace and during the course of his attempt to repair, he also damaged the crankshaft by trying to hold it with vice-grips while trying to remove the lock nut from the opposite end.

The design is almost bulletproof as long as the oil is changed regularly and the correct specification oil is used. I used to work in a sheet metal production facility. Many of the machines used hydraulic motors for variable speed drives. The motors almost never failed, produced phenomenal torque and were variable speed by design.

Unlike CVT (belt driven), there is near zero slip (miniscule bypass of oil between operating parts). They are low to no maintenance and will work submerged or above surface. Failure is almost unheard of. Most failures are caused by foreign material passing through the oil supply and getting into the motor. Downside? They produce a lot of heat. Need a large reservoir of oil or method of cooling the oil supply. The hydraulic motors I had experience with there were manufactured by Cessna. They are relatively low speed, but the final drive speed may be increased by gearing (i.e. a transmission)

 

[mech5496]

Thank you! I was referring to the unit in use in the 2012 Honda Four Trax Foreman Rubicon ATV, which it seems like it is the same unit (or at least same principle) since 2001. Of course there are geared connections in there to reduce engine speed etc, but to my understanding the hydraulic unit itself it a variable speed "transmission". At a certain speed, the hydraulics "lock" transmitting power only via the mechanical gears. The advantage is having infinite gear ratios through the hydraulic circuit with better efficiency than belt CVT's (when the hydraylic unit is locked the efficiency is equal to a manual transmission actually). Does it happen to have any photos or weight of the actual unit?

Again thanks for the insight!

 

[Here 2 help]

The unit I made reference to is Honda part number 26000-HN2-A00 and was used in these vehicles:
TRX500FA 2A (07) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE266-74600001 TO 1HFTE266-74699999
TRX500FA 2A (08) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE266-84700001
TRX500FA 2A (09) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE266-94800001 TO 1HFTE266-94899999
TRX500FA 2A (11) ALL-TERRAIN VEHICLE (ATV), USA, VIN# DMY-DMY
TRX500FA 2A (12) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE266-C4200001 TO 1HFTE266-C4299999
TRX500FA 2AC (13) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE266-D4300001
TRX500FA A (01) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 478TE260-14000001 TO 478TE260-14099999
TRX500FA A (02) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 478TE260-24100001 TO 478TE260-24199999
TRX500FA A (03) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 478TE260-34200001 TO 478TE260-34299999
TRX500FA A (04) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 478TE260-44300001 TO 478TE260-44399999
TRX500FA A (05) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-54400001
TRX500FA A (06) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-64500001 TO 1HFTE260-64599999
TRX500FA A (07) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-74600001 TO 1HFTE260-74699999
TRX500FA A (08) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-84700001
TRX500FA A (09) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-94800001 TO 1HFTE260-94899999
TRX500FA A (11) ALL-TERRAIN VEHICLE (ATV), USA, VIN# DMY-DMY
TRX500FA A (12) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-C4200001 TO 1HFTE260-C4299999
TRX500FA AC (13) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE260-D4300001
TRX500FGA 2A (07) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE267-74600001 TO 1HFTE267-74699999
TRX500FGA 2A (08) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE267-84700001 TO 1HFTE267-8479999
TRX500FGA A (04) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 478TE264-44300001 TO 478TE264-44399999
TRX500FGA A (05) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE264-54400001
TRX500FGA A (06) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE264-64500001 TO 1HFTE264-64599999
TRX500FGA A (07) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE264-74600001 TO 1HFTE264-74699999
TRX500FGA A (08) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE264-84700001 TO 1HFTE264-8479999
TRX500FPA 2A (09) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26F-94800001 TO 1HFTE26F-94899999
TRX500FPA 2A (11) ALL-TERRAIN VEHICLE (ATV), USA, VIN# DMY-DMY
TRX500FPA 2A (12) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26F-C4200001 TO 1HFTE26F-C4299999
TRX500FPA 2AC (13) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26F-D4300001
TRX500FPA A (09) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26E-94800001 TO 1HFTE26E-94899999
TRX500FPA A (11) ALL-TERRAIN VEHICLE (ATV), USA, VIN# DMY-DMY
TRX500FPA A (12) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26E-C4200001 TO 1HFTE26E-C4299999
TRX500FPA AC (13) ALL-TERRAIN VEHICLE (ATV), USA, VIN# 1HFTE26E-D4300001

 

[mech5496]

Wow! That was impressive (and quick!) I will most probably need those codes if I decide to use it, so THANKS! In that system, the hydraulic unit does all the "CVT" part of the transmission, varying the output hydraulic motor speed by altering the swashplate angle relative to the axis of the rotation. The gears are there ONLY to be able to select between forward-neutral-reverse and to further reduce the speed transmitted to the wheels. It is unfortunate though that Honda selected to use a separate clutch, as the hydraulic unit could be used in a smarter manner (in parallel with a geared transmission), so that there would be no need for a clutch and the FWD-N-R selector. (That's what I plan for my system anyway, I can explain more if you want later on)

 

[Here 2 help]

Good luck on your project, I simply repair them, I don't engineer them.

 

[mech5496]

Thanks! Well, most of the times mechanics are way better than us in building something that actually works! Next time you get your hands on one, can you throw it on a scale? I would kill for some weight measurements of the hydraulic pump/motor...

 

[Here 2 help]

A used one weighs 17lb 7.2oz