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Old 06-02-2010, 10:54 PM   post #1 of 19
JamesGarfield
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Default How To Replace Belts On MTD Varidrive

Adams74Chevy emailed me and reminded me that I'd mentioned a while ago that I had a procedure for replacing the drive belts on the MTD Varidrive. So with Adam's encouraging I put it into words here.

The procedure apparently exceeds the 10,000 characters allowed for a post here, so I'll break it into 2 parts. Here's the 1'st part:

********************

INTRODUCTION:

The MTD Varidrive uses 2 special V-belts to transmit power from the engine to the Variable Speed Pulley (VSP) and from the VSP to the Tranaxle.

When working correctly, the Varidrive system is smooth and simple. But it does tend to eat belts. So the bad news is, eventually just about every Varidrive owner will eventually experience the joy of replacing the drive belts, usually once every year or two depending on hours of use. The good news, it really isn't very hard to do.

This procedure assumes a basic mechanical ability and that you're generally familar with the internal layout of this tractor.

PARTS / TOOLS NEEDED: The belts of course: MTD Part Number 754-0280 for the front, and 754-370 for the rear.

It's recommended that OEM belts be used in the drive system. Generic aftermarket belts CAN be used, but their service life will be substantially less than the MTD belts.

10mm wrench, 8mm wrench, C-clip pliers, Adjustable Crescent wrench, and bearing grease.

If you have access to 'mechanics gloves', they'll be helpful here because they avoid the inevitable scratches and dings on your hands from sharp things inside the chassis.

BEGINNING:

Contrary to some beliefs, it isn't necessary to flip the tractor over to change the belts. It can all be done with the tractor upright.

It also isn't necessary to remove the mower deck to change the belts. However, access to some areas of the tractor chassis may be easier with the mower deck removed. If you were planning to do any service to the mower deck, this might be a good time to go ahead and remove it.

For safety considerations, disconnect the battery. This avoids the possibility of not only unintentional engine cranking, but you'll be handling metal tools around in the vicinity of the starter solenoid, so it's a good idea to take this saftey step. This might also be a good time to remove the battery and clean it and check the water levels and charge it up, as needed.

It will be necessary to remove the mower deck drive belt from the lower pulley on the engine crankshaft. Raise the mower deck to the 'Blades Off" (highest position). This makes the drive belt loose. Gently slip the belt off the left spindle pulley, then slide it off the lower engine pulley, and tuck the belt loop back out of the way. It may be necessary to remove or slightly bend away the Keeper Pins from the front Belt Guard in order to take off the deck belt. These Keeper Pins are positioned near the outside of the belt so as to keep it on the pulley when the belt is loose in the Blades Off position.

Next step, go to the top of the tractor and unscrew the shifter knob from the F-N-R shift lever. Then unscrew / unbolt the two fasteners holding the top plate on the transmission cover, and remove that plate. Now you can look down inside the chassis and see the main components of your drive train.

REAR BELT REMOVAL:

This procecedure presumes both belts are to be changed. The rear belt undergoes a lot more flexing than the front belt, and it's been my experience that the rear belt will need replacing about twice as often as the front. The rear belt must come off first, then the front belt can be accessed.

The diagram at the bottom of this document shows the primary components in the Varidrive system. The Variable Speed Pulley (VSP) [F] is the heart of the Varidrive system. A detailed discussion of how the Varidrive functions isn't the intent of this document, but for now it's sufficient to say that it's function depends on a variable tension between the front and the rear belts. The main source of this belt tension is an idler pulley [E] riding on the rear belt. The spring tension on this pulley, plus the fore-aft position of the VSP, determines what effective 'gear ratio' is delivered to the transaxle.

Proceeding with removal of the upper belt, it will be necessary to loosen and move aside the bracket [H] holding the shift lever. This bracket is held in place by two 10mm bolts which are accessed on the chassis wall under the left rear fender. It's sort of tricky to reach around the tire to get at these these bolts. I haven't had to remove the left rear wheel to access these bolts, but there are times when I wished it was off. Your call.

Next, place the Speed Selector lever (on the right rear fender) in 7 (highest gear). This will have the effect of moving the VSP carrier fully to the rear of it's travel, which reduces the tension on the rear belt. An assistant may be helpful for the next step. Grasp the Tensioner Pulley [E] and pull it against the spring tension (away from the belt) while you or the assistant slips the Rear Belt [I] off and over the top of the Tensioner Pulley. You can then gently let the Tensioner Pulley return to where it will come to rest in contact with the large Transaxle Pulley [D].

Using a pair of C-clip pliers, remove the C-Clip from the top of the VSP shaft. This will allow the VSP to be lifted slightly, which will give some extra clearance for the belt.

Slip the Rear Belt off the top pulley of the VSP, and then off the Transaxle pulley. It may be helpful to lay down at the rear of the tractor and look up under the back wall of the frame, so as to see how the Rear Belt comes off the Transaxle Pulley and clears obstructions. Lastly slide the Rear Belt behind the Shift Lever Bracket [H]... and now you'll be able to pull the belt all the way out of the tractor.

With experience, you can do this in about 15 minutes just to remove the Rear Belt. If you were only changing the Rear Belt, here's where you'd jump to putting in the new one. If you're replacing the Front Belt too, then continue.

FRONT BELT REMOVAL:

With the Rear Belt off, you'll be able to get the Front Belt off the VSP. I recommend servicing the VSP bearings at this time, since you'll have everything removed and accessable.

Place the Speed Selector lever in the PARK position. You should see this action move the VSP position forward, and this will reduce the tension on the Front Belt.

Next we'll remove the Front Belt from the Engine Pulley. This requires removing the Belt Guard [G] which held the Keeper Pins we moved earlier. There are 4 bolts either 8mm or 10mm (depending on model) which hold the Belt Guard in place.

With the bolts out, the Belt Guard will come down and foward out of the chassis. Now the loosened Front Belt can be slid off the engine pulley.

It isn't necessary to remove the engine pulley in order to change the belts. However this is a good time to inspect the inner walls of the pulley to check for excessive wear or pitting. Any rust pitting should be buffed out gently, to give a smooth surface for the new belt. And the pulleys can actually wear out. They work in a rough environment -- high speeds, high loads, and grit can make the pulley inner walls wear down, such that a new belt might not last long with them. Inspect accordingly.

Some models of the tractor have an extra Idler Pulley [C] on the Front Belt. It seems to depend on the engine -- twin cylinder tractors usually have this pulley, and singles seem not to have it. If it's present on your tractor, it may be necessary to loosen and remove it to allow the Front Belt to come off. It's a simple single bolt through the chassis floor.

At this point you'll be able to lift up the VSP on its shaft, enough to allow the Front Belt to be removed from the VSP. It may be necessary to adjust the Speed Selector position to locate the VSP away from chassis parts. I have usually had to loosen / remove another Keeper Pin mounted on the VSP shuttle -- you will see clearly what is required to get the belt off. With the Front Belt off the VSP, it can be pulled out of the chassis.

SERVICING VSP BEARINGS:

The VSP has a difficult life. It's worth inspecting this component now. You can lift it off the spindle, keeping careful track of shims both on top and below. The center disk should spin around freely, and slide back and forth freely. There should be no rust on the inside of a recently used VSP, although some slight rust is often seen on those that have been sitting for a while.

The entire VSP should spin freely on its spindle with no grinding detected by ear or by hand. The bearings can be replaced if necessary. If the bearings look good, relubricate them with high-temp automotive grade disk brake wheel bearing grease, and reinstall the VSP, keeping track of the shims. Don't get grease on the inside of the VSP. Don't reinstall the C-clip until later after the belts are back on.

INSTALLING NEW FRONT BELT:

I've always hated it when a manual glibly says 'Installation is just the reverse of the disassembly procedure.' Actually in this case that is fairly true, but we'll go through the steps anyway.

Thread the new Front Belt under the chassis in general position. Adjust the VSP shuttle for optimum clearance in the chassis, and lift the VSP slightly on its spindle. Loop the Front Belt first onto the top pulley (it's easier that way), then thread it down to where it's seated in the bottom pulley. Move the VSP shuttle all the way forward (PARK on the Speed Selector), and thread the front of the belt onto the upper engine pulley. If you loosened / removed the Idler Pulley [C], reinstall it now.

Reinstall the Keeper Plate [G], but not the Keeper Pins yet.

INSTALLING NEW REAR BELT: (continued in next post)
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Old 06-02-2010, 10:57 PM   post #2 of 19
JamesGarfield
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Default Re: How To Replace Belts On MTD Varidrive (2'nd part)

And here's the completion of the procedure:

********************

INSTALLING THE NEW REAR BELT:

Move the Speed Selector back to 7 (highest gear). Thread the new Rear Belt into the chassis, sending a loop back under the chair to the big Transaxle Pulley. Loop one side of the Rear Belt between the Shifter Bracket and the chassis inner wall, then you can reattach the shifter bracket with the two 10mm bolts. They're blind threaded, so just make them snug, not too tight or they can strip.

Lift the VSP slightly and thread the belt onto the top pulley. Pull back on the Tensioner Pulley [E], and some pressure will be required to squeeze the belt into position between the Tensioner and the Tranny pulley. Get as much of the belt started onto the big transaxle pulley as possible, then go to the back of the tractor and look up from underneath to finish the rest. With the shift lever in Neutral, you will be able to turn the transaxle pulley by hand and finish seating the belt.

Inspect all belts to see they are properly seated on the pulleys and not dragging on any other parts. After that inspection, you can reinstall the C-Clip on top of the VSP spindle.

COMPLETION:

Crack open the first of whatever beverage you drink, because we're almost done. Replace the top plate on the transmission cover, and thread on the Shift Lever knob.

If you removed the mower deck, reinstall it as desired. Reach underneath and bring up the mower deck belt, and rethread it onto the lower engine pulley. Reinstall / Straighten belt keepers as needed, and (my preference) thread the mower deck belt lastly over the left pulley spindle.

Reconnect the Battery.

Count your tools (you know, to find the one that always gets left under the hood somewhere).

Exercise the Clutch pedal a few times to see that it moves properly. Crank up the motor, and take off slowly. The manual says there's an interval of 'break-in' time where you may not see much difference between the highest 2 or 3 gears, until the new belts seat in to the pulleys. Whether or not you notice that, you DO want to have eyes and ears (and nose) on alert for the first few minutes, to check for unusual noises or vibrations (or smoke), that would indicate something wasn't put back right. Inspect and correct as needed. Then proceed to Beverage #2 and rejoice that you just gave your Varidrive another lease on life, and saved about $100 (I'm guessing) in regular shop rates in the process.
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Old 06-02-2010, 11:13 PM   post #3 of 19
Adams74chevy
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Default Re: How To Replace Belts On MTD Varidrive


Awesome write up.
I will be printing this out for use in the very near future.

Thanks,
Adam
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Old 06-03-2010, 02:57 PM   post #4 of 19
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Default Re: How To Replace Belts On MTD Varidrive

I hate having a lot of "stickies" at the top of a sub-forum but in this case, I'll make an exception.

There are a huge number of lawn tractors out there with this drive system. This should be a sticky!
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Old 06-03-2010, 11:37 PM   post #5 of 19
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Default Re: How To Replace Belts On MTD Varidrive

Great write up. Not only helpful, but indispensable!
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Old 06-03-2010, 11:50 PM   post #6 of 19
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Default Re: How To Replace Belts On MTD Varidrive

You're right guys, this is good info. and to James Garfield for the great writeup .

Thus a sticky it is .
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Old 07-27-2010, 12:53 PM   post #7 of 19
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Default Re: How To Replace Belts On MTD Varidrive

Thats easy compared to a rear engine vari drive belt change.
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Old 07-27-2010, 01:00 PM   post #8 of 19
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Default Re: How To Replace Belts On MTD Varidrive

very good info wish i would have had this when i did my very first one lol ...
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Old 11-14-2010, 08:15 PM   post #9 of 19
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Default Re: How To Replace Belts On MTD Varidrive

[SIZE="4"]
The local Recreation section of a Borough parks and recreation section, bought two lawn tractors with this type of Vari-drive. They brought one to me to replace the rear belt, which i did, Took it back, returned it a month later, with the new belt "fried" and shredded.
I wondered how they did it, so i asked, and the man said they use it to "drag" the base paths on the ball fields, and drag a big garden cart around! They haul big loads of rocks and gravel and other stuff.
When i did the belts, i removed the rear fenders, and that made it much easier. I told him they'd better research the next type they buy!
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Old 03-21-2011, 09:35 AM   post #10 of 19
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Default Re: How To Replace Belts On MTD Varidrive

Does this info apply to all MTD models? I have a MTD 695 (Model # 13AF695H352) I just looked at the belt that goes up to the engine and IT IS VERY BAD. There are chuncks out of it.

Thanks
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Old 03-21-2011, 12:41 PM   post #11 of 19
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Default Re: How To Replace Belts On MTD Varidrive

Quote:
Originally Posted by hankejp View Post
Does this info apply to all MTD models? I have a MTD 695 (Model # 13AF695H352) I just looked at the belt that goes up to the engine and IT IS VERY BAD. There are chuncks out of it.

Thanks
Hi Hankejp,

This procedure applies mainly to the MTD-600 chassis. This model covers a very wide spread of 'rebadged' names such as Murray, Wards, Sears, Yard Machines, and more. Basically if it says 'Shift-On-The-Fly', or 'Varispeed', or '7-speed', it's probably based on the MTD-600.

You may also see the MTD-700, which is the dual-range version of this drivetrain. I haven't had my hands on one of these yet, but as I understand it the VSP and drive belt arrangement is still basically the same on these.

I would believe that your MTD-695 would fall into this category. These drivetrains admittedly do not have a whole lot of ground-engagement pulling power, but they are simple and inexpensive to manufacture. For the average residential homeowner, they will provide many years of good service. When they go bad, it's usually the belts which wear out and start fracturing and loosing chunks of rubber, as you have seen on yours.

The purpose of creating this procedure is to show that it isn't really necessary to pay a shop big bucks to fix up the Varidrive -- it can be done by the average home mechainic, for just the cost of the belts. Let us know how it goes for you.
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Old 05-02-2011, 10:08 AM   post #12 of 19
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Default Re: How To Replace Belts On MTD Varidrive

i had a troy bilt now mtd with the same type problem - called troy bilt and they said easiest way to change the drive belt is remove electric clutche and engine mount bolts. lift engine just enough to slide belt on and reverse process. worked for me.
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Old 05-06-2011, 09:32 PM   post #13 of 19
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Default Re: How To Replace Belts On MTD Varidrive

Great write-up, it is appreciated very much and will come in handy for my FIL's Huskee aka MTD 660 which somehow I have been volunteered to repair for him.

Thanks again Ron
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Old 05-07-2011, 02:08 AM   post #14 of 19
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Quote:
Originally Posted by ranchkingron View Post
Great write-up, it is appreciated very much and will come in handy for my FIL's Huskee aka MTD 660 which somehow I have been volunteered to repair for him.

Thanks again Ron
Ron,

I'm really glad you liked the write-up. It pleases me that I've been able to share my experience with others, and help as I can.

One thing I kinda wished I could have added to that write-up, is you might want to consider wearing 'mechanics gloves' while doing this procedure. These gloves are a mylar-kevlar fabric mesh, which allow you to pick up and handle small parts, while protecting your hands from scratches and nicks.

The odd angles and reaches one has to do into the chassis to access these parts almost always leaves one with a bunch of scraches and scrapes on the hands. Personally I prefer to celebrate the finish of such a job with a cold drink under a shadetree, rather than bandaids .

Take care all and thanks again for the kind words.
James
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Old 05-20-2011, 12:27 PM   post #15 of 19
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Quote:
Originally Posted by JamesGarfield View Post
Ron,

I'm really glad you liked the write-up. It pleases me that I've been able to share my experience with others, and help as I can.

One thing I kinda wished I could have added to that write-up, is you might want to consider wearing 'mechanics gloves' while doing this procedure. These gloves are a mylar-kevlar fabric mesh, which allow you to pick up and handle small parts, while protecting your hands from scratches and nicks.

The odd angles and reaches one has to do into the chassis to access these parts almost always leaves one with a bunch of scraches and scrapes on the hands. Personally I prefer to celebrate the finish of such a job with a cold drink under a shadetree, rather than bandaids .

Take care all and thanks again for the kind words.
James
Thanks again James It went together very smoothly and made the FIL happy so I owe you one.

And to let you know you are so right gloves are a must when doing this job and I have always used them since I learned a long time ago no matter how careful you are something will always bite you and I have the scars to prove it.

Ron
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