Vari-drive information request

[jmelton86]

If the pedal goes strait to the flloor with no resistance, a spring has fallen off or is in the wrong position or a bolt has fallen out.
If the pulley is totally buggered, the mower will still drive and the belt won't go slack.
The front belt pulls against the rear belt which has a constant spring pressure on it.
By varying the load applied by the pedal, the belt that is pulling hardest against the varidrive pulley will force the sliding sheave away & thus turn on a smaller diameter.

So something you did properly, has come undone.

It is usually the short top belt, because it is the hardest to get at and on a lot of insallations you have to drop the tranny to get the belt on the pulley.
If that is your installation ( Vari drive at the far back ) then the prime suspect is the top belt tension pulley & I would guess you have not put the spring back in the correct position or the spring ( or pivot) has fallen off.
If you insist on throwing a lot of money at it just note that the diagram is wrong and the 3 pulleys all marked 35 are not the same, one of then is flat & two are V.

So get back under there with a good strong light and recheck.
I always mark spring anchor points with a paint pen and take photos before anything gets pulled off because the same frame is used for dozens of different mowers so there are holes all over the place and it is real easy to slip the spring into the wrong hole

It is actually quite easy to access the belts. A buddy of mine and I replaced both belts within an hour. You can get directly to both belts via the battery tray and temporarily separating the rearend/gear case assy.

Nothing has fallen off. The top belt is intact and working as it should. All pulleys are spinning freely. I replaced both belts so I have inspected everything twice now. Haven't messed with the vari-drive thing (never messed with one) so I'm trying to finger out what all I should replace.

 

[jmelton86]

There isn't anything that could have shifted/ loosenend/ etc so, it has to be that pulley thing.

I dropped the deck and laid under there (getting like 5 stickers in my back) messing with/ fumbling with everything for a few minutes.

 

[bertsmobile1]

If the Vari drive pulley is totally wrecked, bearings broken up and sliding sheave rusted solid into position, the thing will still work.
It might only drive in the lowest settings or be a fixed speed, but it will work.
This I know because that is the condition of the mowers I work on.
However if the spring tension is relaxed it won't work.
The new belts were a bit stiff so if spring 20 or 22 was put back into the wrong hole then the set up will work for little while the go too slack once the belts have conformed to the pulleys.

So back to the original suggestion.
get a good strong light and look for fretting marks where the springs rub on the frame.
Most of these, the springs simply go into a hole and there are a lot of holes.
The springs do loose tension and in particular the top belt spring.

Now it is possible that the belts have worn the contact faces on the sliding sheave to a point that the belt can no longer grip but I am yet to see one on this set up with the common pulley.
The set ups with two sliding sheaves as used on a lot of Stiga mowers are different as it is possible for both pulleys to be at their smallest diameter but not on this set up where both belts run on a common pulley.

The OP says the belt ( I assume he means the bottom one ) seems like it is 2" too long.
That means the center to center distance between the pulleys would have to be 1" shorter than it was and there is no way you get that much movement from collapsed bearings.
However if the spring is in the wrong place or the bottom belt routed wrong through the clutching pulleys you will get a sudden slackness in the belt.

It would be really helpfull if we knew why the belts were being replaced in the first place and if the owner checked to new belts against the old ones.

Now replacing all the pulleys & sheaves will not hurt and will improve the perormance of the mower, if the spring tension is wrong, it will only be for a short time & will not have fixed the problem.

 

[SeniorCitizen]

In case I wasn't previously clear, in this picture the center portion of the pulley system must easily move up and down with both belts removed or it will not operate as designed.

 

[jmelton86]

If the Vari drive pulley is totally wrecked, bearings broken up and sliding sheave rusted solid into position, the thing will still work.
It might only drive in the lowest settings or be a fixed speed, but it will work.
This I know because that is the condition of the mowers I work on.
However if the spring tension is relaxed it won't work.
The new belts were a bit stiff so if spring 20 or 22 was put back into the wrong hole then the set up will work for little while the go too slack once the belts have conformed to the pulleys.

So back to the original suggestion.
get a good strong light and look for fretting marks where the springs rub on the frame.
Most of these, the springs simply go into a hole and there are a lot of holes.
The springs do loose tension and in particular the top belt spring.

Now it is possible that the belts have worn the contact faces on the sliding sheave to a point that the belt can no longer grip but I am yet to see one on this set up with the common pulley.
The set ups with two sliding sheaves as used on a lot of Stiga mowers are different as it is possible for both pulleys to be at their smallest diameter but not on this set up where both belts run on a common pulley.

The OP says the belt ( I assume he means the bottom one ) seems like it is 2" too long.
That means the center to center distance between the pulleys would have to be 1" shorter than it was and there is no way you get that much movement from collapsed bearings.
However if the spring is in the wrong place or the bottom belt routed wrong through the clutching pulleys you will get a sudden slackness in the belt.

It would be really helpfull if we knew why the belts were being replaced in the first place and if the owner checked to new belts against the old ones.

Now replacing all the pulleys & sheaves will not hurt and will improve the perormance of the mower, if the spring tension is wrong, it will only be for a short time & will not have fixed the problem.

The belts were replaced in the first place because the mower wouldn't move. I assumed the drive belt went out.

I replaced both drive belts with ease. All pulleys, etc worked correctly at that time so, I replaced both drive belts.

It FELT LIKE the belt was too long. It not only happend before I replaced the belts but, even after I replaced the belts and after the next paragraph.


I replaced both drive belts and the mower moved like it should for 15 or so minutes. After that the pedal went to the floor and it stopped moving. See original post.

 

[bertsmobile1]

In case I wasn't previously clear, in this picture the center portion of the pulley system must easily move up and down with both belts removed or it will not operate as designed.

I know what you are saying and I am not disputing it.
However if the sliding flange is rusted solid in one position, the mower will still move , it just won't change speed, and their will be resistance to the speed control pedal.
If the speed control pedal goes strait down with no resistance it is not pulling against the spring & front belt.
So the vari drive pulley will make no difference.

IF it dosent move and there IS resistance to the speed control pedal then you would suspect the diff & Forward/ reverse sliding dog or even the input shaft.

 

[bertsmobile1]

Now we are getting somewhere.
Were the new belts the same as the old belts ?
how did you decide which belts to buy ?
Off the mower serial numbers or by comparison to the old belts ?
How long have you had this mower, ? since new, Second hand ?
Have the belts been replaced before ?
Before it stopped did it drive through the full speed range, or would it only tun at low speeds ?
This is the first sign of worn belts, so if it was not doing that then something else cause the mower to stop.

What troubles me is your assertion that the belts were easy to replace.
They are a PIA to remove usually as the springs are near impossible to remove and even harder to replace.
I might be a little on the old and feeble side but I had to make to spring pullers specific to each & every model to get Varidrive springs off & on.
If it was really easy, something is wrong with the assembly.

Pull the deck, stand the mower on its bum ( mind fuel or battery acid spilling ) and take some photos WITH A REAL CAMERA NOT A SMART PHONE then post them so we can see how it is hooked up.
My gut still says the springs are not tight enough.
The rear belt should be tight enough to bow a jig on if you are a fiddle player and the front tighter still.
It is all about spring tension

 

[Boobala]

Go to this site (clik link )

.............http://www.mymowerparts.com/pdf/MTD-Service-Repair-Manuals/

clik on these manuals .... good pics & diagrams ...Troybilt is an MTD made mach.

A. 770-10578

B. 770-10579

 

[jmelton86]

Now we are getting somewhere.
Were the new belts the same as the old belts ?
how did you decide which belts to buy ?
Off the mower serial numbers or by comparison to the old belts ?
How long have you had this mower, ? since new, Second hand ?
Have the belts been replaced before ?
Before it stopped did it drive through the full speed range, or would it only tun at low speeds ?
This is the first sign of worn belts, so if it was not doing that then something else cause the mower to stop.

What troubles me is your assertion that the belts were easy to replace.
They are a PIA to remove usually as the springs are near impossible to remove and even harder to replace.
I might be a little on the old and feeble side but I had to make to spring pullers specific to each & every model to get Varidrive springs off & on.
If it was really easy, something is wrong with the assembly.

Pull the deck, stand the mower on its bum ( mind fuel or battery acid spilling ) and take some photos WITH A REAL CAMERA NOT A SMART PHONE then post them so we can see how it is hooked up.
My gut still says the springs are not tight enough.
The rear belt should be tight enough to bow a jig on if you are a fiddle player and the front tighter still.
It is all about spring tension

I got the MTD part #s off of the mower itself. They are also listed in the owners manual. Again, I used OE MTD belts.
I got the mower secondhand. It drove as it should for the first cut after I got it. The pedal went to the floor so, I assumed the belts stretched and replaced them.
They have not been replaced before this.
Before it stopped moving, it drove at all speeds. Not only before I replaced the belts but, even after I replaced them until the pedal went to the floor again.
What springs are you talking about? The only spring I had to work with was from the tensioner on the smaller drive belt. I did have to use two hands on it but, still.

 

[jmelton86]

Go to this site (clik link )

.............http://www.mymowerparts.com/pdf/MTD-Service-Repair-Manuals/

clik on these manuals .... good pics & diagrams ...Troybilt is an MTD made mach.

A. 770-10578

B. 770-10579

Thank for the link but, all I have to do is go to searspartsdirect.com and type in my model number.