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I have the single gear drive with the split pulley. The mower jerks and surges badly when in drive and usually about 50% it will stop moving altogether until i release and reapply pressure. I've changed both drive belts both 5/8 inch width and proper length. I've verified all pulleys are free and operational. I've even opened up the rear to check for any grinding or damage, which there was none. I'm not sure where to go from here.

If you used the correct MTD belts meaning generic non MTD specific will not work or not work for long. then my next thought would be to reopen the tranny and look at the notches on the forward and reverse gears and the sliding collar for any wear that creates a slope effect to the edge of the notch. Doesn't take much to make those gears slip and jump under load.

ILENGINE said:

If you used the correct MTD belts meaning generic non MTD specific will not work or not work for long. then my next thought would be to reopen the tranny and look at the notches on the forward and reverse gears and the sliding collar for any wear that creates a slope effect to the edge of the notch. Doesn't take much to make those gears slip and jump under load.

Click to expand...

The belts are not 5/8 they are 5L which is metric and they are thinner top to bottom that a std 5L

bertsmobile1 said:

The belts are not 5/8 they are 5L which is metric and they are thinner top to bottom that a std 5L

Click to expand...

Part of the confusion people have is the cross over books will show them as a 5/8 width and they are not 5/8 they are a propriety width and cut angle that just doesn't match the MTD pulleys

Truth be told I got the 5/8 MTD belts. Knowing now that I need a 5L explains a lot. Ill replace those and go from there. Is there a possibility that the PTO clutch can affect this at all?

Do you all have suggestions on where to get the proper belts consistently? Any Amazon sellers you trust?

If the belt is right, it will have MTD on the belt itself .
On the sleeve will be the MTD part number ( cub numbers are the same ) and a description like "front drive belt then a list of models"
MTD can also use the exact same length belt for a different purpose , like deck drive on a different model.
The actual width is 21/32" from memory ( in inches ).
The only belt cross refference I trust is Gates https://www.gates.com/ais
Put the MTD number in the part number slot and you will get a screen with the appropriate Gates belt, if there is one.
The gates belt number will be a hot link to another page with the belt number as a hot link to the description of the belt.

A bit long winded but much better than any other cross refference list which all work of effective length so in many cases you will get a belt that is too thin or too thick.

As for buying on Amazon, no one I would trust .
Most of the vendors on there do not exist.
They are nothing more than a web page linked to a few pallet spaces in a warehouse with 50,000 other product lines staffed with pickers who have enough education to go to the bin on the picking slip and count out the correct number of items.

Lots of on line shops like Jacks Small engines, Ereplacement parts, partstree, Messicks, Cubcadetparts, small engine warehouse, etc etc etc.
If the on line shop has links to parts breakdowns then they are usually a real shop as they have to pay for that link.
Or perish the though, a mower shop where the person behind the counter might actually know what the part is for.

I rely on parts tree for my diagrams. Never thought of purchasing anything from them.

I cannot find a belt that is referenced as a 5L for this part number except for one on Amazon. Even MTD lists them as a 5/8". Just going to buy from parts tree and roll the dice. I will be sure that whatever I get is stamped with MTD and the part number.

ILENGINE said:

Part of the confusion people have is the cross over books will show them as a 5/8 width and they are not 5/8 they are a propriety width and cut angle that just doesn't match the MTD pulleys

Click to expand...

Correct on the angles....... John Deere belts have a different angle also.... If you don't get OEM belts they won't last or you will have issues....

Me and Tim Gross / Taryl fixes all, tried to tell a guy about that about 2 years ago.........

This is an image I pinched off the web.
the belt you were sold was most likely a std B section which is called 5/8 although it is not, but when put under load it changes shape a little.
Compare that to the other two 5/8 belts.
the 5V and the 5L

The 5V has the same V angle as the B section but is deeper.
Murray used this belt extensively for their deck drive belt.
There is also a 4 V which has a nominal 1/2 " width
Now have a good look at the 5L
Again it is nominally 5/8 " but the V angle is a lot wider and the depth is a lot shallower.
These belts are used extensively for variable pulleys ( also called sliding sheave ) as you have on your drive.

If you fit a std B or 5V section then the belt will bottom out when the sheave is at it narrowest and as there is no grip from the bottom of the belt, it will slip.
So If you have the wrong belts top & bottom it will slip at the fastest & the slowest speeds.

Now this is just the section.
After that you have the position of the cords, and their size.
A drive belt generally will have the cords closer to the back of the belt than a deck belt which has to bend back on itself a lot.

However both a deck and a drive belt will have the cords deeper into the belt than a std B section belt

Finally there is the cover material which can be cotton, a cotton blend , pollyester or kevlar.

I have ignored rubber compounds but again they vary according to the purpose of the belt.

The wrong belt will work, but it will not work for as long or as well as the correct belt and can damage the pulleys by wearing a groove into the drive face from the shoulder of the belt.

I usually fit Stens belts, except for vary drives where I fit Oregon belts.
Both Stens & Oregon claim their belts are OEM but the Stens belts just don't cut the mustard on varidrives although visually I can not tell the difference.

Lawn Wizards, every one of you! Thank you so much for the help thus far! I expedited two belts that are branded MTD yesterday. Comparing the pictures of them I can definitely see the 5L profile compared to what I purchased before. Hoping they arrive this evening.

Took me a long time to get my head around belts,
I could not understand why there would be up to 7 different OEM belts for 7 different prices all supposedly exactly the same length & width.
That was untill I found the secret of the Gates catalogue cross reference
The gates equivalent of your front belt is in their Blade Runner series , 6606BR http://www.gatespowerpro.com/Comergent/en/US/adirect/gates?cmd=catSearchFrame&domProductQueryName=6606BR&returnURL=http://www.gatespowerpro.com/Comergent/en/US/adirect/gates&returnTarget=_top&gotoAdvSearch=false
Click on the gates belt name ( 6606BR ) and you will get a description of the belt in a new window.
The real length, effective length width and section
Note the belt is not really 5/8" wide.

I use this catalogue all the time in order to check if the belt my suppliers have said is OEM , really is OEM size.
Quite a few times, the effective length will be the same but the section will not and these are the ones that will work, sort of but not for as long as they should

I received the new belts and realized they were identical to the ones I was taking off. I measured the belts with a micrometer and compared them to the Gates site and they match up. The belts are branded MTD with the proper part number. When I opened the rear end the dents on the shaft were in excellent shape, along with everything else I inspected. Teeth on the gears were clean and sharp. Bearing and bushings seemed factory quality. Could the PTO clutch have anything to do with it?

no
Apart from being on the same shaft they have nothing to do with each other, unless the bolt that holds it on is loose

It acts just like you describe with the belt issue, but they are branded properly and spec out accurately. I'm not the original owner so I'm wondering if there are other parts on there that are incorrect. Or there is definitely an issue with the rear end I couldn't identify.

Okay so I am convinced this is still a belt issue but I am not sure what to do. The only thing I cannot measure is the cut angle of the belts but one is sharper than the other and Gates even shows its a 1 degree difference. I feel like If I had the same shallower angle as the the drive belt that it would resolve the issue but this is going against what the diagram says is the right belt. How would I go about finding a belt based on specs and not a part number?

OK .
time to put on the deer stalker and get the magnifing glass out Shirlock
!) closely inspect the drive pulley for polished surface at the bottom of the V.
If it is polished it it worn beyond use and needs to be replaced.

2) get a long socket extension that you can fit into a power drill and a socket to fit on the nut on top of the big pulley under the battery.
What you are going to do is to drive the pulley via the nut and watch the tensioning pulley on the top belt.
If it pulls in tight, the mower lurches forward, it goes slack, then pulls in tight and the mower lurches forward then something in the transmission is working against the drive.
Generally it will be the brake so back off the nut in the middle of the brake and see if it runs better.

A tight brake will also make the mower difficult to push when in neutral.

3) last one is harder to do but you have to watch the tensioning arm on the front belt and in particular the spring.
If it ossillates when you are driving then the spring could need replacing.
Double check the pivot points for the front tensioning arm.
If the hole is flogged out oval then the tensioner can not apply sufficient tension to the front belt.

4) put some Bearing Blue on the centre shaft of the variable pulley.
jack the rear of the vehicle so the wheels are off the ground and run through all of the speed settings.
Then get under the mower and look for the blue on the inside of the belts.
If the blue has transferred to the belt then the sliding pulley is worn beyond its limit and one of the belts is running on the shaft and not the side of the pulley.

Some photos of the varaible pulley at each of the speed settings will also be helpful but please no hand held videos.

I am just getting back to this thread and just now seen your last message. Going to try this very soon and ill report my findings.

Thank you so much for your help thus far, I owe you a brew or two!

It is a 2 way street.
I work on about 60 mowers a year and of that about 45 are just routine services.
Thus the more odd ball problems that appear on here the more I learn.
Going back over the entire thread I am starting to wonder if the tension spring on the rear ( top ) belt is the culprit.
The entire system works by varying the load on that spring.
If it is soft, stretched or in the wrong place you get reduced drive because the front belt just pushes the sliding sheave fully up and runs on the center of the variable pulley and you set SFA drive when that happens.

I can say that the top spring is extremely tight. It's almost a two person job putting that top belt on. I haven't looked at it yet but I do believe that lower tensioner is bouncing back an forth. I can feel it in the pedal. Hopefully ill be able to look at it today after work.

Okay, so I jacked up the mower. the belts are still in fantastic shape as I figured they would be. I monitored the belt travel while it was running and I could control the pedal. There isn't a spring at the pedal like I originally thought. It just has a solid pivot point and it is working as it should. the variable pulley seems to be doing its job as well. What I did find was the right rear tire seems to be slipping. I can hold it in place by hand with the pedal at full throttle and can feel it attempting to grip, but as I said I can hold it still and prevent it from doing so. With the pedal depressed at about 40% it slips significantly less and this is the speed at which i can usually cut the grass without a lot of trouble less im trying to climb an incline. It seems to me that it shouldn't be slipping like it is, especially with it feeling as if it's trying to constanly grip.

That is working exactly as it should.
The mower has a diff and diffs will allow one wheel to turn when the other wheel is locked up, just the same as on your car ( unless it has a limited slip diff).

So, I went and took the rear end apart again and realized that it had a differential after the fact. I felt like an idiot when I finally realized what it was.

I double-checked everything in the rear end and all seems to be working just fine. This is the third time I've had it apart and I still feel that it's as it should be.

Further inspection there is a return spring on the pedal but it's only a return. Both belts are in fantastic shape and nothing is worn smooth. I took a few pictures to show that the belts can not bottom out when the variable pulley but I'll have to upload them later because it won't allow me to do it from my phone.

With the mower in the air and the weight off of the wheels it seems to work just fine. I unfortunately can't recreate losing power to the wheels. The top tensioner on the drive is ultra-tight and doesn't wobble at all. I was able to check this by taking the battery out and connecting it to the mower via jumper cables so I could watch the drive system while I operated the pedal.

I'm going to do some more investigating a bit later and see if I see anything different.

Ok I'll chime in ............ I read some of the longer post's and noticed something that Bert and I harp on a lot......

You haven't said anything about this part that Bert mentioned....... Worn pulley's and I don't mean bearings either....Pulleys will get worn on the inside of the grooves and make belts stretch in a sense 2 ways.....

When the pulley or pulleys are worn on the inside of the grooves people will put a brand new belt on and the belt will not grab just right.... Some people think when pulleys are worn that their belt has stretched... No a belt rarely stretches at all.... The belt sits in further in the groove and actually cant grab right....

I showed that to a customer one time... I changed a main pulley on the crankshaft and his 2 spindle pulleys and put his old belt on and it worked perfect.... He kept the new belt he bought for a spare......

Let us Know Mon Ami ~!~!

Here are the photos I promised. As you can see the belts don't come close to bottoming out.



None of the pulleys on the mower has grooves of any sort. All of them are smooth. Below is a few stock photos of them.



The idler pulleys are in perfect shape. The one at the engine I can feel but cannot see because I cannot figure out how to get the clutch off. I had to pull the engine out from the top the last time I changed the drive belt and have yet to tackle that again. The belt, however, doesnt appear to be damaged as it only has about 10 hours on it and its speced correctly.

I feel like I am missing something simple...

There is a 7/16 UNF bolt in the middle of the clutch pulley.
It is a long bolt with 2" to 4" of thread so takes a bit of undoing, particularly if a DPO has poured lock tite all over it.
Free the wires at the 2 pin plug.
The entire clutch now pulls directly off the shaft.
Dont put your head directly under it as it is quite heavy and has been know to break noses, cheek bones or smash specticles .
Once it is off the drive pulley pulls off the same way.
Some are rusted on quite solid and require heating red hot to get them off without damage.
Once off polish the shaft & inside the pulleys and coat with anti-sieze
Usually you also need to dress the key way if the key has damaged it.
Both pulleys should slide loosely up & down the shaft.

Not that this addresses your problem , but it will make things easier in future.
Now unless you polished the center of the Vari-drive pulley the belts have been running on it.
It is never that shinny.
Remember you are just sitting the belt in there, when it is under tension it will flex, distort and run deeper.
Now get a small strait edge like an Exacto knife blade and check that the pulley faces are flat and not dished front to back.
Fixed pulleys will show a wear ridge and / or shinny sections on the curve where the pulley face meets the shaft section.

I was messing around with the clutch and it is locked on there with a force unknown to mankind. Ill saturate it with PB Blaster regularly for the next few days to help loosen it up. That trick worked for removing the exhaust manifold bolts on my Honda. If that doesn't do it ill follow it up with some heat. Had this same problem removing the rear wheels but I have remedied that issue already.

I also noticed the clutch isn't bolted down on the sides. It just floats between a few different brackets which give it about a centimeter of turning play back and forth. And it has the center bolt as previously explained to me. Is that normal? I can take a short video and post on Youtube if needed.

With it torn down this far it's tempting to repaint it. Are racing strips a bit too much you think?

Its your mower,
Purple with pink poka dots is fine if you like it.
Got a customer who painted his ride ons yellow & pink for his 2 daughters to mow with, they loved it.
IT is a cheapness thing, the output shaft should be copper plated or at least greased during manufacture.
On the odd occasion I get a new mower for it's initial service, never seize on the PTO shafts and grease on the rear axels is always a must.
Can't charge the customer for it as it is not part of the scheduled service but it does make my life a lot easier latter on.

The clutch set up is correct a lot of people pack some rubber in there to stop it rattling , although it might have flogged out a bit .

I think I figured out the source of the issue. When I was putting everything back together again I didn't adjust the shift rod properly for F/N/R. When in forward the wheels wouldn't turn even though I heard it click into place in the transmission and all of the pulleys were turning even when the pedal was fully depressed. I backed the adjuster screw off one full rotation which then allowed the wheels to turn intermittently as they did before. Backed it off one more full turn and the over all problem is significantly better, but not 100%. Unfortunately I cannot back the adjuster off any further else reverse wouldnt engage properly. The shiftrod is connected to a slide inside the transmission that interlocks with the Forward and Reverse gears by two studs on either side of the slide. What I beleive is happening is this slide is not staying locked into the appropriate gear.

During this testing when the wheels stopped turning the belts and pulleys never slipped or stopped. All pulleys have straight flat sides as checked with a razor blade edge.

THE F-N-R lever has a detent groove that a ball bearing on a spring engages with.
Good chance it fell out while you have the cases apart.
Failing that the F-N -R gears are on a shaft with top hat bushes at either end.
The R side rarely wears but the F side does.
I have flipped a few over when I forgot ( or failed to notice ) that the bushes needed replacing.
Usually when the dogs on the F-N-R are not engaging you get a pronounced grating sound of the dogs slipping over each other.

I noticed the ball the first time I disassembled the rear and have been very conscious of its place. It is definitely seated and producing the pronounced "Click" sound as the shift rod moves through the gears.

So would the bushings be the culprit here? How would I know if they need to be changed or should I just change them anyway? Think I answered my own question there...

So after some research on the old version of the rear and the new one it seems the part I am having trouble with was a common replacement which lead to the development of the new design. Considering the cost of a new rear, or to replace all the guts with the new style parts, I think I am going to try and tinker with what I have. There is a washer behind the forward gear and I beleive that by replaceing it with a slightly thicker washer I could delay the inevitable solution of full replacement. Also If I can get the collar off I'd like to grind down the studs a bit and weld a washer on the end to reprofile them. That is if the bushing and thicker washer doesnt resolve it first.

I cannot seem to find anything listed as a bushing though. Are you referring to these?

https://www.amazon.com/MTD-941-0336-Flange-Bearing/dp/B005UAXWQ4

Also what grease would I use to replace what is in the rear?

sypherz28 said:

So after some research on the old version of the rear and the new one it seems the part I am having trouble with was a common replacement which lead to the development of the new design. Considering the cost of a new rear, or to replace all the guts with the new style parts, I think I am going to try and tinker with what I have. There is a washer behind the forward gear and I beleive that by replaceing it with a slightly thicker washer I could delay the inevitable solution of full replacement. Also If I can get the collar off I'd like to grind down the studs a bit and weld a washer on the end to reprofile them. That is if the bushing and thicker washer doesnt resolve it first.

I cannot seem to find anything listed as a bushing though. Are you referring to these?

https://www.amazon.com/MTD-941-0336-Flange-Bearing/dp/B005UAXWQ4

Also what grease would I use to replace what is in the rear?

Click to expand...

Yep,
Thems look like the animals.
First one I pulled down it was suggested I replace both and I sent the new parts back cause they were the same size & the mower clearly has a thinner flange on the drive side .
One of those Duh moments.
Just be careful there was a person doing a similar box a while back & they found the new bushes were too thick and caused the shaft to bind when bolted up.
I use tractor gearbox 00 lithium grease in all of these transaxels.
If it is good enough for a bull gear on a 10 ton field tractor it is good enough for a 1/10 ton lawn tractor.
Being thinner it flows better inside the casings and takes a lot longer to cake up.
Most of the ones I take apart, the grease is dry, so the shafts are dry & badly worn.
The thinner grease not cushion the dogs as much as the heavy grease, but if you remember to stop before you change and to take your foot off the brake as you do so the dogs have some wiggle space it should not make any difference .
Down side is it does tend to leak a little through the axels but most can live with that till they invent white grass.

Well, seems I damaged the clutch while trying to remove it. The blades aren't engaging anymore. Any special work that can be done on one of these before I chalk it up as an expensive mistake?

The wires break off just where they go in to the clutch itself.
A common problem caused by the copper wires work hardening due to vibrations.

Sounds repairable to me! Once I can get the blades spinning again ill order the flange bearings and some grease. If I can talk my wife into spending some time in the garage with me i'll get her to take pictures for a how-to.

sypherz28 said:

Sounds repairable to me! Once I can get the blades spinning again ill order the flange bearings and some grease. If I can talk my wife into spending some time in the garage with me i'll get her to take pictures for a how-to.

Click to expand...

Carefully cut the insulation back from the end and look for a broken wire.
Resist the temptation to solder.
Screw in a small self tapper and fit eye terminal to both wires.
Do one at a time and mark the clutch + & - as some are polarity sensitive .
Get some liquid electrical tape and smother the connections when you have finished.
Give them 4 or 5 heavy coats then find a spot for a cable tie to hold the wires very tight onto the clutch.
A repair I do once or twice a season that I pinched off Taryl Fixes All.
Prior to that I soldered and all 4 of the soldered repairs failed within 3 years

Seems something else failed on the clutch because the whole circuit is dead. Waiting for payday to order a new one with the flange bearings. C'est la vie.

Another thing that bothers me is the height of the blades. It has 6 positions and anything below 5 just scalps the ground. I thought it may have been an adjustment but there aren't any for deck height. When It is at its top position the lifting arm is touching the frame. When its at 3 or lower it's resting on the ground. I assumed the tires were the wrong size but they arent. Do you think it would hurt anything to just get taller tires? Any other tricks I am missing?

sypherz28 said:

Seems something else failed on the clutch because the whole circuit is dead. Waiting for payday to order a new one with the flange bearings. C'est la vie.

Another thing that bothers me is the height of the blades. It has 6 positions and anything below 5 just scalps the ground. I thought it may have been an adjustment but there aren't any for deck height. When It is at its top position the lifting arm is touching the frame. When its at 3 or lower it's resting on the ground. I assumed the tires were the wrong size but they arent. Do you think it would hurt anything to just get taller tires? Any other tricks I am missing?

Click to expand...

Try energising the clutch with some jumpers.
They are expensive and it there is a wiring problem you have just wasted a lot of beer money.
Double check the wires on the mower side.
I use an old headlamp as a test light to put a reasonable current draw just in case a terminal is hanging by one strand.

As for blade height, have you adjusted the front drag links ?
they wear which allows the front to drop and the back to raise so it bottoms out on the underside of the mower.
You should have about 1/2" height difference front to back.
Check by turning the blade strait ahead and check both blades as of there is a little difference left to right.

I energized it off the battery with jumpers I made. I confirmed with a multimeter that the circuit is open somewhere. I drove screws down as deep as I reasonably could hoping that maybe the break is just deep down but nothing worked.

honestly didn't notice any adjustments on the front. ill check that out.

Apologize for the delay. Haven't had the time to work on this just yet. Aiming for this weekend.

Unfortunately, this project had to take a seat for a while until we get our finances in order and get the maintenance done on our cars. I have a plan of attack but I need a few parts first. Flange bearings, clutch, and some odds and ends. My landscaper loves the fact that this is taking so long, that's for sure.

I compared the schematics of the old and new style rear end and it seems to be possible to upgrade my existing rear with new style parts for much cheaper than buying a whole assembly. That is assuming that I cannot repair the one I have of course.

Finally, time to start working on this project again. I purchased the two different flange bearings for the transmission and will compare with my micrometer to see how much of an improvement it will be. If there is still any play I am going to swap some of the washers as well.

I just wanted to put out a final word on this. I was able to successfully resolve this issue. The spacers beside the drive gear in the rear end were worn down to the point of causing a fair amount of wobble on that gear. Replaced the bushings and swapped the spacers, which Lowes refers to as 3/8 14g machine bushings. Once all of the play was out the issue was completely gone!

The highlighted parts below are the ones I replaced. Using my micrometer I swapped with ones that are thicker and eliminated the play on gears #7 and #8.