Jump to content

  • Do you own an ATV or UTV? Join our Forum!

    Join QUADCRAZY ATV Forum today for FREE! We keep these forums clean and user friendly. All first posters will have to wait to have their content reviewed and approved. Once your first post is approved, you will no longer need to got through an approval process. To gain immediate approval and a NO ADS experience, consider subsribing to our Premium Membership.

2007 Honda 400 Rancher 4x4 ATV squealing sound when shifts into drive(TRX400FA7)


Recommended Posts

D88F704E-9175-4D26-AA03-8E26E04E2E54.thumb.jpeg.730ff5f6d611b8623f69d3bef2f4aa15.jpegFirst time working with a Honda-Matic transmission. I didn't even know what I was getting into when I purchased this running beat up farm workhorse quad with black oil. I was thinking I could tear the cases apart and find the bad bearing, causing the random squealing noise when you put it into gear and give it gas. Upon opening the engine covers, I Learned about the Honda Matic automatic transmission and realized there's more than just an electronic shift motor going on in these quads. With my learning curve in major education mode, I'm now wondering two possible culprits to the squealing as I've torn the motor down and am staring at the Honda Matic transmission.

Two possible issues:

1. The bearing that is squealing is unfortunately inside the hondamatic unit hydraulic transmission which is apparently not serviceable? A new unit is $1,900 to replace it! Yikes!
2. The pull starter rope snapped and someone replaced with the wrong pull starter rope that eventually became severely worn out and the centrifugal lever/catch shows signs of wear from rubbing against the housing.

Thinking now the pull starter has nothing to do with a squealing that loud, so my attention is now on the Hondamatic unit, 
Has anyone gotten inside their cases to inspect the Honda Matic transmission?
There's a only 1or 2 videos out there that are not helpful for tear down and inspection.
I understand it can't be rebuilt but wondering if anyone has looked deep enough into one to clean it out from running dirty oil? Possible identify bad parts.

I refuse to believe Honda is engineeering these as completely non-serviceable?

Thinking I will try to disassemble the Hondamatic unit m. Hopefully get into it and get all the dirty oil out and replace with fresh? Any special tools needed?

Any and all thoughts/experiences with Hondamatic units would be great conversation for me..


Link to comment
Share on other sites

This may be useful...



Automatic transmissions have been used in some All Terrain Vehicles (ATVs) for many years, but until the introduction of the Hondamatic hydraulic transmission, ATV automatic transmissions used a traditional belt drive and pulley system. The fully automatic dual-mode Hondamatic transmission featured on the 2001 Honda Fourtrax Foremanš Rubicon (TRX500) provides these features, and is compact, quiet and extremely reliable for use in agricultural, rural, and recreational applications.

The usefulness of the Hondamatic transmission is maximized when combined with the computer-controlled, dual-mode continuously variable change program or the Electric Shift Program (ESP), already in use on the Fourtrax Foreman ES (TRX450ES) and Rancher (TRX350FE/TE) ATVs. The ESP allows the operator to select higher or lower output ratios, providing precise manual control of the Hondamatic transmission.

Soichiro Honda recognized the efficiency and convenience of hydrostatic drives and incorporated the Badalini stepless transmission design into the Juno scooter in 1962. Honda engineers continued to develop their own versions of hydrostatic transmissions and incorporated them into snow blowers, lawn mowers and smaller power equipment. Honda Racing Corporation (HRCš) also applied this technology to the RC250 in 1990-'91. The RC250 was a limited-edition, works-type motocrosser that used the continuously variable transmission to maximize torque output and optimize reduction ratio selection.

In a very simplified description, the Hondamatic hydraulic transmission uses the engine to drive a hydraulic pump that forces hydraulic fluid through sequential pistons. On the other side of these pistons, the pressurized fluid enters a second set of pistons that push against an angled plate (called a swash plate). Because the cylinder body holding the pistons is splined to the output shaft, the pressure exerted on the swash plate causes the cylinder body to rotate. When the angle of the hydraulic motor swash plate is adjusted, the cylinder body (and, therefore, the output shaft) rotates faster or slower, resulting in higher or lower output drive ratios. When either of the two automatic transmission modes (D1-Maximum Performance or D2-Maximum Torque) is selected, the Engine Control Unit (ECU) continuously monitors input from six sensors to position the motor-side swash plate at the optimal ratio. Using the ESP mode, the ECU instructs the control motor to move the hydraulic motor plate to preset angles to simulate specific gear selection.


Operating Principles
The Hondamatic transmission is a hydromechanical continuously variable transmission with a fixed-volume piston pump and a variable-volume piston motor in opposition on the same shaft. As the Hondamatic is a closed circuit, any excess hydraulic fluid from the Hondamatic system is recirculated to the transmission using a separate charge pump. The Hondamatic transmission uses standard engine oil as hydraulic fluid.

Upon engagement by the centrifugal clutch, the engine turns the transmission's pump-side outer body, causing the fixed-angle pump-side swash plate within to rotate, sequentially stroking the pump side pistons. This action draws low-pressure fluid into the pistons, which discharge high-pressure fluid (corresponding to the input torque). The fluid is distributed to the high-pressure circuit by the distributor valve on the pump side. The distributor valve on the motor side opens and feeds the high-pressure fluid to the pistons on the motor side for the suction stroke. Each distributor valve is eccentrically synchronized to the rotation of its respective swash plate, ensuring that fluid is transferred at the proper time. The amount of fluid discharged depends on the angle of the motor-side swash plate. The greater the slant, the farther the pistons move and the more fluid they transfer. This additional volume transfer makes the motor side less efficient, resulting in a differential based on the volume transferred. As the motor-side pistons travel down the slope of the motor side swash plate, the fluid pressure is drawn through the pistons and rotates the motor-side cylinder body (which houses the pistons). As the cylinder is splined to the output shaft, the output shaft also rotates, transferring power to the drive train.

When the motor-side swash plate is perpendicular to the pump axis, the pistons do not stroke (therefore, oil is not discharged). In this condition, oil cannot flow between the pump and the motor and the motor is hydraulically locked (1:1 gear ratio). An overdrive is achieved by adjusting the swash plate to an angle beyond perpendicularity to the pump axis, creating a drive ratio of 1:0.84.

As the pistons begin their travel back up the motor-side swash plate, they begin their discharge stroke. The hydraulic fluid is transferred back through the motor-side distributor valve and into the low-pressure circuit of the body. The fluid then passes through the pump-side distributor valve, where it is timed to the suction stroke of the pump pistons.

Distributor Valves
The hydraulic fluid is transferred between the pump and motor piston chambers by the sprue-type distributor valves arranged radially around the shaft. The pump-side and motor-side distributor valves are eccentrically arranged on the shaft and are aligned to time the transfer of low-pressure and high-pressure fluid in tune with the direction and inclination of the pump and motor swash plates. As the cylinder rotates, the eccentrically arranged valves slide in and out of the cylinder body, opening and closing the paths in the body.

Compression Braking and Pressure Control
During normal running, the check valve in the pump-side cylinder feeds hydraulic fluid into the low-pressure circuit. The check valve is open when the hydraulic pressure in the low-pressure circuit drops below a specified level and, upon achieving the proper pressure, closes to prevent backflow. Under engine compression braking conditions (where the rotational force comes from the wheels), the motor side becomes a pump (driven by the input shaft) and the pump side becomes an hydraulic motor. In this situation, the high- and low-pressure circuits in the Hondamatic body are reversed. The Hondamatic transmission uses a separate check valve to feed hydraulic fluid to the engine braking low-pressure circuit.

Pressure control valves vent excessive high-pressure fluid into the low-pressure circuit during both normal running and compression braking conditions.


Torque Amplification
The input reaction force torque from the engine is transmitted to the pistons that are fixed within the rotating cylinder. This force is then transferred through the cylinder to the shaft (mechanical power train). When the ratio is 1:1 and the motor side swash plate exerts no reactive force against the motor cylinder, the input torque is transferred directly to output torque with no amplification. When the angle of the swash plate is increased, the reaction force increases, amplifying the output torque. The total output torque is the sum of the input reaction force torque and hydraulic output torque.

Shift Mechanism
As previously discussed, the output shaft speed is controlled by the angle of the motor-side swash plate. The position of this swash plate is determined by the ECU, which uses various pieces of information to send commands to the control motor that moves the swash plate arm. The signals used to determine optimal Hondamatic output are:

Throttle opening (throttle sensor)
Vehicle velocity (speed sensor)
Engine speed (rpm) (ignition pulse generator)
Hondamatic motor-swash-plate angle (angle sensor)
Gear position (gear position switch)
Control mode and map (mode/map switch)

In the fully automatic modes (non-ESP), the ECU is continuously monitoring these signals. When a change in motor swash plate is deemed necessary, the ECU sends a signal to the control motor, which moves the ball screw (attached to the swash plate arm) via reduction gears. There are two rider-selectable automatic modes: D1-Maximum Performance and D2-Maximum Torque. The D1 mode emphasizes higher engine horsepower output for riding performance, while the D2 mode maximizes torque output performance. Within these rider-selectable modes, there is a choice of standard output ratios (Drive) or lower output ratios (Low) using the automobile-like shift lever. Reverse can also be selected using this gear lever which engages a reverse gear located in the subtransmission.

When the operator selects the ESP feature, the UP and DOWN buttons on the handlebar switch are enabled. When the appropriate button is pressed, the ECU commands the control motor to move the swash plate to the next higher or lower preset position.

The Hondamatic transmission is the first continuously variable transmission of its kind. Housed within a compact, fully sealed assembly, it uses the principles of hydrostatic drive, mechanical power transfer and modern electronic controls to create a unique hydromechanic drive. Unlike traditional belt drives, the Hondamatic is quiet, maintenance-free, rugged, impervious to external contaminants and features true engine braking.

Test Ride | Features | Specifications
Top Of Page | Honda Index | New Models | Home

Copyright © 2000 by Motorsports Network. All Rights Reserved.

Link to comment
Share on other sites

What makes you think it's a squeal from inside the cases ? Did you find any metal shavings or dust in the cases when you stripped it ?

Could it be an engine mount squealing ? Exhaust rubbing ?  Something like that..

I'd be really doubtful that anything inside there could be making a squealing, and under throttle, without there being signs of wear, and probably heat.


Link to comment
Share on other sites

Exact conditions when I purchased it:

bad battery

only pull started.

Started up, a bit rough on idle, but otherwise is decent running order, put it into fwd and no sounds, put it into reverse, no sounds, fwd again and the squealing started with gas and forward motion between 3-8mph. It was unique enough and alarming enough that I figured it was a bad transmission bearing, like a bearing freezing and the shaft was rotating in the bearing. so I just decided to investigate for something obvious with that much noise. Found the previous owner probably hasn't changed the oil recently as the entire protective pan and drain plug were caked in with debris and dried stuff(Took me good 30-45 min to clear it out and find the drain plug). Oil didn't register on the dip stick, but did have oil in it. Was very black, but not burnt smelling or dirty with shavings. Just looked like it wasn't changed in a long time. When pulling the piston and cylinder, I expected worse, but the piston rings had obvious wear and carbon build up on the exhaust side of the piston rings and oil rings, but nothing was seized.

All good questions to ask, but I'm very sure it wasn't a brake rotor, CV joint, or wheel bearing.

Ive been studying the posting by MECH(thank you) on the design and operation. Makes me think that with this design, Honda knows the robustness of it, however the design uses the engine oil as the Hydraulic fluid for the Hondamatic unit. I would think this would be a concern for  exactly my situation with lack of engine oil maintenance. However, the last section reads:

" the Hondamatic is quiet, maintenance-free, rugged, impervious to external contaminants"

So I'm not sure exactly how they keep it "impervious to external contaminants" if it's in the engine oil? I'm guessing they must be referring to other transmission belt transmission type technologies?

Anyhow, all good thoughts, I still have to get the Hondamatic transmission out of the cases and look further/closer at it. I'll post my findings.

if anyone has any diagnostic info aside from what's in the manual, I would appreciate the suggestions.

Link to comment
Share on other sites

  • 4 weeks later...

I may have found a problem.

Most cranks I've worked on, the bearings are an interference fit, so the crank must be pulled into the bearing with a crank puller, or the bearing installed into the case and the crank is pulled into the bearing, etc.

I've found upon inspection before splitting my cases that my crank actually spins freely inside of the roller bearing, could this be the problem?

Does anyone know the tolerance or clearance of the Roller Bearing to Crank?

I should have the cases split for further inspection this weekend and will advise what I learn...

See video clip attached.



Link to comment
Share on other sites

It does seem a bit loose, but I doubt that oil soaked part is going to make a squeak.

So when you say it went into forwards and was quiet then reverse and it was quiet and then forward and it made the squeak..  Do you think it was the shifting that changed something, or was it just a matter of time needed for the squeak to start ?

It's really important to diagnose things before we pull them apart, because we can't do any tests or find the technique that will repeatedly and predictably cause the issue once they are apart. If we don't know the technique to repeatedly get the issue to manifest, then we can't test things after the repair to be confident we have fixed it. We might have just temporarily cured the symptom without fixing the problem.. 

If I was you Mat, I'd be putting it back together and riding it and testing it till I'd found the problem. I definitely wouldn't be splitting the cases. Oily parts don't squeak. Squeaks that appear within a certain speed range only, don't sound like anything from inside the engine to me..

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By Jim Denton
      I was gifted four King Quad 300's, they were used to tow portable snow guns around the slopes. All of the plastics are trashed and racks bent up from rolling down the mountain. The lone Quadrunner is a 98, and will be the initial point of focus, as it reportedly ran before being parked in the field of lost dreams. 

    • By Mikey69
      Heres my story. Kinda long. I guess I was a late bloomer when it comes to quads. I had never ridden a quad in my life. Rode Dirt Bikes as a kid growing up. Back in Oct of '06 I found a Mustang on craigslist. Took it for a test drive one morning before work. Fast car. 351 Cleveland. I had planned on meeting the guy again after work. For some strange reason thats still to this day beyond me, I stopped in Hillsboro MotoSports on the way home from work. I had 6 Grand on me. There was a left over '05 sitting by the front door. It was on sale for $4999. It was $5499 OTD. I didnt even look at anything else. I knew nothing about quads accept I thought it really looked coool and I had the money in my pocket to buy it. I was sitting on it when the salesman walked up and asked... "Can I help you?" Without hestitation I pulled 60 Ben Franklins outta my front pocket and said "I want this Quad. Load it up in my truck." It was just about dark by the time I drove away from the shop. BTW, I didnt bother to ask my ol lady if I could buy it. LOL. Anyway, I took it by the house and showed her. She was kinda stunned but not mad. We drove over to a friend of mines house and unloaded it. I took it to the field across the street from his house. HOLY CHIT!!!!! I was surprised by the power. I had it for about 2 weeks and took it to Sand Lake. I was there a few hours and rolled it on a banked turn at the top of the bowl right before you get to the one-ways. When it rolled, I flew off and landed on my belly. The quad came bouncing and landed on my back. For a month I couldnt even walk. I was scared of it. I considered trading it for a 250EX. Went back to the shop. The salesman said..."Dude!!! You dont want a 250EX!!! Trust me. Just get used to it" I still wasnt convinced. I put it on craigslist for $4000. Calls were coming in. I had a guy that wanted to come look at it that evening. I decided to take it for one last ride at Browns Camp before I sold it. I was still afraid of it. After about 5 minutes I started feeling comfortable on it again. I decided right then, I loved my Honda 450 and would learn how to ride it instead of selling it. That was late Nov of '06. Work was slow for a Painter in Oregon. My new job everyday? Going to Browns Camp and ridding my Quad. I bought my Girl Friend an '02 Blaster. I rode my 450 for 4-6 hours almost every single day for 3 months. And yes, I know my way around Browns Camp pretty well. LOL. In March I bought her an '06 TRX250EX (Thank God I didnt trade my 450 for one of those) LOL Since then, I have become totally addicted to quads. I love them. Couldnt imagine not owning at least one quad. Luckily I have two. My "07 was $6500 OTD in July of '07. Bought it for my Girlfriend. Traded in her 250 EX. A month later we broke up. So, I wound up with two Honda 450's.
    • By JohnKramer
      I replace everything involving fuel and it still won’t work. 
    • By Georgia
      I bought this quad new.  When my quad gets warm, It starts skipping at around 2,000 rpm and won’t idle.
    • DIY like a pro! Shop from over 1,000,000 Repair Manuals at eManualOnline.com! As low as $14.99 per manual. Shop now.
    • By Malcolmconyers
      After riding around neighborhood with kids gear indicator just shows dashes along with eps not working at all after cycling on when key is turned to on position
  • Gallery Images

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...