There’s nothing more frustrating than a slow internet connection, but having to push a slow self-drive mower is a close second – it DRIVES ME CRAZY!!! So it ends now, today we’re going to fix it, and it will pull as good as the day you bought it.
So what’s the problem with a Honda lawn mower that moves slowly? A slow-moving Honda mower is commonly caused by a slack drive cable. Adjusting the tension will fix it.
Other possible causes include:
- Drive belt loose
- Drive belt worn
- Worn drive axle
- Worn out transmission
Don’t concern yourself with these other possible causes just yet. They are less likely. We’ll get to the most likely cause, adjusting the drive cable tension.
Self Drive Types
The Honda self-propel system is good, but like all mechanical equipment, it needs maintenance. Diagnosing a drive system incorrectly is an expensive mistake. A new Honda transaxle will cost several hundred dollars, so we’ll avoid jumping the gun.
Tests are not difficult, but you’ll need to execute them correctly to avoid burning time or replacing parts needlessly.
Whichever type you have, the cable will be adjustable.
If you need video help, check out “Self drive common faults video.” It walks you through the diagnosing process step by step – Adjusting the drive system, replacing drive belts, wheels, drive pins, and axle drive gears.
Adjusting The Drive Cable
I love working on Honda mowers. The designers are a thoughtful bunch. It’s rare that an engineer ever thinks about the guy fixing them. Anyway, before adjusting the drive cable, we’ll first need to locate it. Honda uses a few different type setups. The HRX uses a bail lever as stop/start control and a speed adjustment lever beside the throttle lever.
The Honda Smart Drive uses a single control on the handlebar, this type of self-drive is a little less difficult to adjust. I have included pictures of each type set up, together with the adjusting procedure.
Adjusting The Honda Smart Drive
The problem is, as you know, likely to be a stretched cable. In other words, the cable is too long. The whole procedure is made simple by the nice people in Japan, and adjusting won’t take more than five minutes.
Drive cables are made up of an outer cable and an inner braided cable. The inner braided cable does all the work and stretches over time. The solution is simple, remove the access cable. Honda’s solution – fit an adjusting screw in the middle of the cable.
The adjuster works by splitting the cable into two, and by adjusting the screw anticlockwise, it pushes the two halves of the drive cable away from each other, taking up the slack on the inner braided cable.
Smart Drive – The Smart Drive self-propel system has an adjuster built into the cable, and it’s located halfway down the left-hand handlebar.
Adjusting – First, open the lock nut. You’ll need two open-ended 10mm or 3/8s, or adjustable wrenches. Screw the long adjusting nut anticlockwise – this takes the slack out of the cable and gives you more drive power.
If you over-adjust it, you’ll find pulling the mower backward difficult. So just back it off until you find the sweet spot. Tighten up the lock nut when you’re done with the adjusting. This keeps it dialed in.
Adjusting The Hrx
The HRX has a self-drive cable adjusting screw mounted on the speed control panel. As you have turned off the gas and pulled the plug wire, it’s safe to turn your mower to the side.
Before adjusting, set the speed to high. The adjusting screw has a lock nut that must be loosened and backed off to allow for the cable slack take-up. When adjusting, pull the cable until the cable slack is gone, run in the lock nut, and tighten.
As with all self-drive mowers, if you over-adjust the cable, it will make reversing the mower difficult. The wheels bind. To fix this, back off the adjuster a touch until the mower is free to reverse.
Adjust – Set speed to high, loosen the lock nut, and pull the cable.
Loosen – You’ll need two 10mm or 3/8 wrenches or adjustable wrenches.
Tighten lock nut – pull out the slack and tighten. Test reverse and readjusts if necessary.
Drive Belt May Be Loose
Lawnmower drive belts have a difficult job, and they work in a hostile location. But they’re pretty tough. It’s not unusual for a drive belt to last years and years. But they do eventually wear, they stretch, and the walls get thinner, which makes them even longer.
A belt that’s too long will slip, and a slipping belt won’t transfer the engine power to the wheels. This is especially noticeable going up hills or in heavy grass. If you have a blade engage control on your Honda, you’ll really notice it as you apply the blade.
A worn belt will often be noisy and can cause vibration. To check the belt, we’ll need to turn the mower over, but before we do, let’s make it safe to work on.
Remove the plug wire and turn the gas off.
Now turn the mower on its side with the air filter cover facing the sky. If you turn it up the other way, gas will leak from the carburetor, and you’ll need to replace the air filter.
Loose – The belt should deflect by no more than 1/2 inch. More will cause the belt to slip and result in a slow drive.
The belt may be difficult to see, a cover will likely need to be removed, and old dry grass will cover the transmission and belt, so we’ll need to clear it first. I use shop air to blast it, but a small clean paintbrush works too.
Now that you can see the belt check it for wear. You’ll need an inspection light. Since you have removed the plug wire, it’s safe to turn the blade.
This also turns the belt which allows you to inspect all the way around it. If your model has a blade engage lever, put it on and have a helper hold it or use a clamp. This allows you to turn the belt by turning the blade.
If the belt is in good shape, check the deflection. About 1/2 inch is good. But you don’t need to get caught up in measurements. Just use old-fashioned common sense. If it looks really loose when you squeeze both sides of the belt together without much effort, then it’s loose.
Drive Axle May Be Worn
The drive axle on a mower is simple, really. It should be referred to as a trans-axle, though. By trans-axle, we mean axle and transmission combined. I wrote a more detailed explanation of trans-axles here for those that are interested (internal link).
The axle is connected to and driven by the transmission. These are all one unit, and parts aren’t available, so when they fail, which is pretty rare, you just swap out the whole unit. Check out the Amazon link below for drive system parts delivered to your door.Amazon Drive System Parts
Trans-axle – Honda transmission and axle combo are known as trans-axle.
Drive Pins – Wear out on older mowers and cause the drive to slip. Drive pins are crucial to the whole trans-axle assembly.
An axle drive pin, as its name suggests, is a pin that transfers power from the axle to the wheel. It’s spring-loaded and, combined with the drive gear, allows the mower wheels to move backways with little resistance when reversing the mower.
The axle pin is under extreme stress as it carries all the torque from the transmission to the wheels. These little guys wear out all the time.
Transmission May Be Worn
Honda transmissions are tough, yes in my workshop I have replaced a few, but to be fair to Honda, the mowers were old and driven like a hire car. When you’re fixing mowers for as long as I am, you can spot an unloved mower from across the valley.
The transmission as you know is a solid-state unit, no parts are available. If it fails the whole unit gets changed out.
Replacing the tranny isn’t very complex but it will require a selection of wrenches, some C clip pliers, and some patience.
Tranny – Honda transmissions are pretty good and they need to be.
How do you adjust the throttle on a Honda lawn mower? The throttle is controlled by a cable. The cable can be adjusted at the rear of the throttle housing on the handlebars, also on the engine where the cable meets the throttle linkage.
Honda lawn mower rear wheels locked up? If the drive cable is over-adjusted, the rear wheels will lock when pulled backward. Release some tension on the adjuster. It’s located halfway down the left handlebar.