MTD Variable Speed Pulley system: GOOD OR BAD?

I believe most people who hate MTDs don't have a good enough idea of what they're all about and are too AYP/Murray mainstream to give a hoot as to whether these MTDs are a possible candidate for some serious romping. We'll start with a video showing the principle of operation of the VSP system, then go on to rant from there.



This is not the typical layout in most 2000+ MTD mowers [they use a rear belt arranged in a triangular setup, with the front  just running straight down the center of the chassis].  This setup still shows the base method of operation; A moveable double-v pulley with a sliding center disc moves toward and away from the driving [engine] pulley, and a spring loaded tensioner keeps the rear belt tight at all times, even with the 'clutch' pedal all the way in. The pedal is linked directly to the pivoting VSP bracket, and the 'shifter' switch on the dash/fender just limits its movement by means of a stepped bracket, fixing the position of the VSP and thus holding a constant speed. Clutch disengagement is only achieved because the pedal-in position moves the VSP so close to the engine that the front belt goes loose.

The most common problem people have with VSP trannys slipping is because of a worn/wrong rear belt, or a saggy tensioner spring. Hard 'shifts' or sticky feeling clutch is caused by the VSP unit seizing, probably because of sitting forever or just wear of the sliding disc. MTD original VSP rear belts work fine. Don't use the old rubber furnace blower belts you've got laying around. Belt width and length are imperative to proper shifting and tension. If a pulley swap is done, a different belt isn't needed, just modify the tensioner to suit the different trans pulley.

Possible modifications I can see to this system to make it more than practical in ATLT use is first, belly plates to keep trees/brush/water/mud/jenk out of the VSP. Then, as far as speed/pulley swapping goes, a larger engine pulley [will require a longer front belt] And a smaller trans-mounted pulley, as in any mower pulley swap. With VSP systems however, you have a max and min size for each pulley. Consider 4.5" the largest for the front, and no smaller than 3" in the back.

I run a 4"/4" and get a decent trail speed and slow enough crawl ratio in 'first'. Same pulley sizes are generally the guideline for all off-road/rally mowers since the combo of speed/crawl is just right. Thing is though, MTD VSP trannys are generally geared a hair faster than a typical Peerless/Spicer/Foote, so I'm sure you've noticed the speed some of these stock MTD's have compared to some hydros and gear trannys. Just making it more fun to blow your pulley-swapped Peerless buddies away on the dirt road   

I've never hated on Gear trannys, I just don't like how nobody is taking the time to make MTD's VSP a cheap alternative to the gear drive norm. They're certainly easier to come by, and parts are still readily available and cheap.

Well done, and thanks for posting it! Perhaps it will shed some light on the subject.

There are many in the go kart world (my other motorized sickness) that hate on CVT's because they don't understand them. This is an extremely similar situation. CVT's (AKA torque converters) are dead sensitive to belt dimensions, and really the only thing different with a CVT is the 100% automatic operation.

Aside from belt length sensitivity, the small pulley diameters can prove to be an issue when wet/muddy.

Good info, and very well said, jack9102!

Sweet yes mtd vari drive are almost bullet proof mines having issues right now but belt problems mainly

ive never tried to romp one, but i like em for grasscutting duty

They are good if you are messing around (like throw some ATV tires on it and rip on a dirt trail) But if you are going full out, (bumpers, very aggressive tires, big hp, mud, increased speed, submerged a lot) then starting with a strong base and frame and trans axle is going to be better foot in the right direction if that's what you want.

Id rather have a craftsman over a MTD because of a transaxle/clutch/changes are easy to make with different parts (twin cyl engines, 820 axle) and how they are much more simple with less linkages/springs, just pulleys, belt, and a clutch are the main components, less things to go wrong and to replace.

What bothers me is people saying, "oh mtd's and vari-drive is complete jenk get a craftsman" When they have no clue how the system works. Personally, id make a MTD into a racer because of how light they are and easy to lower and gut the drive system for a axle and 700, but thats what my interest is at.

Having experienced vari-drive and a transaxle and clutch ON THE SAME MOWER, i can tell you YOU have to make it reliable if you have a home made belt system, and a custom setup, factory will always be super super reliable.

Call it what you want, but when you get a near free, or free tractor, dont bite the hands that feed you.

Iv never ran a MTD. But plan to change that one day been studying the vari drive setup and ideas shoot at me from all directions. So im gonna give it a try think it would be great on my setup but thats a secret as of now. I like the idea but i like it simple. Easy to use easy to fix but its time for some real head scratchers. And i think MTD it thd place to start

the reason why I don't like this system is because it seems to go through belts a lot quicker than a standard geared system. the rear belts on the newer ones are also a pain to change due to the position of the transmission pulley. they are good for mowing, but just don't seem to take as much abuse as a geared system.

BAD. the mtd systems i've moded for pulling where terible. the belts are slightly wider than a 5/8 belt and the angle on the sides is different. this means that if you change the pulley and you need a longer belt, the system will slip.

I'm loving all the feedback guys

I never intended to use a VSP system for a puller, or a serious, axle-deep mudder, I'm just talking about a general romp around the woods and the occasional mud hole, then rip nice n quick back up the street kinda driving. They are definitely not the strongest system, but I'll say that in my experiences, they were stronger than Foote transaxles...

They're also nice for cruising and such because the 'shifting' action is so smooth, and speed is easily changed without the jerking of a typical gear-drive shift. Geared transaxles are definitely the choice of intense, all-in/balls-out mud bogging/drag racing/pro stock circle track racing/pulling/etc.

I'm sure VSP systems eat belts quicker than standard setups, if for any reason, that the rear belt is moving a lot faster, and is always being pinched hard by the VSP. My 15.5/42 has had one belt put into it since I've owned it, and I ride it fast and hard. My suggestion to anyone experiencing short belt life on a VSP tractor is to make sure the VSP pulley grooves are as clean and flat as can be. If anything looks corroded/pitted bad or rusted [they have steel and aluminum parts], etc, replace it or junk it unless you can live with it. Also check your pulley alignment and every other pulley's condition. Belly plates will extend belt life too, because they keep the trees/dirt/jenk out of the system.

All in all, I think MTDs make a fine entry-level machine, as well as a good all-around machine to beat around on and pull a light trailer with a cooler, just cause they're so common and cheap and the same goes for their replacement parts. They're nice cause of their light weight, being easy to work on/mod, and generally good engines on their frames stock [I'm not saying the Formula 15.5 is any good, btw. Tecumsehs are jenk imo. not so much internals, but carbs. omg.. teccy carbs...*stabs eyes out*]

I Well if these are so common an cheap why cant i find em. And the one i did find he said i could have the FNR for 100 if i pull it.   Yea right.   But im lookin for. Some if any one can help link in my signiture.

No idea man, they're a dime a dozen up here in canada, and apparently other users have found them to be fairly common too    I got my 2006 in ok condition [but COMPLETE] for less than 100, and the last 3 MTDs I've owned and run into the ground were under 110. I paid 100 for a 175 series machine in running order that had FAT hours on it, used it for grass cutting.

Guess it depends where you're looking.

jack9102 wrote:

No idea man, they're a dime a dozen up here in canada,

Speak for yourself- there's friggin' NONE around here! LOL I been trying to lay hands on one, just to help prove what can be done with them, and test-drive some potential improvements!

honestly after having a old cast iron transmission.. i wont go back unless i get one for free. Cast Iron is so much more bulletproof than any mtd or peerless (aluminum) rear end.. This is in an offroader of course. in a racer. a cast iron tranny is not ideal due to gear reductions.

Doc Sprocket wrote:

I been trying to lay hands on one, just to help prove what can be done with them, and test-drive some potential improvements!

Doc, could you tell me about these potential improvements?

jack9102 wrote:

I believe most people who hate MTDs don't have a good enough idea of what they're all about and are too AYP/Murray mainstream to give a hoot as to whether these MTDs are a possible candidate for some serious romping. We'll start with a video showing the principle of operation of the VSP system, then go on to rant from there.



This is not the typical layout in most 2000+ MTD mowers [they use a rear belt arranged in a triangular setup, with the front  just running straight down the center of the chassis].  This setup still shows the base method of operation; A moveable double-v pulley with a sliding center disc moves toward and away from the driving [engine] pulley, and a spring loaded tensioner keeps the rear belt tight at all times, even with the 'clutch' pedal all the way in. The pedal is linked directly to the pivoting VSP bracket, and the 'shifter' switch on the dash/fender just limits its movement by means of a stepped bracket, fixing the position of the VSP and thus holding a constant speed. Clutch disengagement is only achieved because the pedal-in position moves the VSP so close to the engine that the front belt goes loose.

The most common problem people have with VSP trannys slipping is because of a worn/wrong rear belt, or a saggy tensioner spring. Hard 'shifts' or sticky feeling clutch is caused by the VSP unit seizing, probably because of sitting forever or just wear of the sliding disc. MTD original VSP rear belts work fine. Don't use the old rubber furnace blower belts you've got laying around. Belt width and length are imperative to proper shifting and tension. If a pulley swap is done, a different belt isn't needed, just modify the tensioner to suit the different trans pulley.

Possible modifications I can see to this system to make it more than practical in ATLT use is first, belly plates to keep trees/brush/water/mud/jenk out of the VSP. Then, as far as speed/pulley swapping goes, a larger engine pulley [will require a longer front belt] And a smaller trans-mounted pulley, as in any mower pulley swap. With VSP systems however, you have a max and min size for each pulley. Consider 4.5" the largest for the front, and no smaller than 3" in the back.

I run a 4"/4" and get a decent trail speed and slow enough crawl ratio in 'first'. Same pulley sizes are generally the guideline for all off-road/rally mowers since the combo of speed/crawl is just right. Thing is though, MTD VSP trannys are generally geared a hair faster than a typical Peerless/Spicer/Foote, so I'm sure you've noticed the speed some of these stock MTD's have compared to some hydros and gear trannys. Just making it more fun to blow your pulley-swapped Peerless buddies away on the dirt road   

I've never hated on Gear trannys, I just don't like how nobody is taking the time to make MTD's VSP a cheap alternative to the gear drive norm. They're certainly easier to come by, and parts are still readily available and cheap.

hey i totally agree with this post considering I have a 98 MTD with the 7-speed varidrive system, anyways ive been trying to get more speed out of it, but working from the back doesnt change anything but i figured if i change the engine drive pulley i might get some more speed. i was thinking about a 4.5 on front which was like you suggested. it currently has 3.5 on the front and 8.5 on the back. how much speed do you think i could get in 7th with a 4.5 on the engine?

craftsman1963 wrote:

jack9102 wrote:

I believe most people who hate MTDs don't have a good enough idea of what they're all about and are too AYP/Murray mainstream to give a hoot as to whether these MTDs are a possible candidate for some serious romping. We'll start with a video showing the principle of operation of the VSP system, then go on to rant from there.



This is not the typical layout in most 2000+ MTD mowers [they use a rear belt arranged in a triangular setup, with the front  just running straight down the center of the chassis].  This setup still shows the base method of operation; A moveable double-v pulley with a sliding center disc moves toward and away from the driving [engine] pulley, and a spring loaded tensioner keeps the rear belt tight at all times, even with the 'clutch' pedal all the way in. The pedal is linked directly to the pivoting VSP bracket, and the 'shifter' switch on the dash/fender just limits its movement by means of a stepped bracket, fixing the position of the VSP and thus holding a constant speed. Clutch disengagement is only achieved because the pedal-in position moves the VSP so close to the engine that the front belt goes loose.

The most common problem people have with VSP trannys slipping is because of a worn/wrong rear belt, or a saggy tensioner spring. Hard 'shifts' or sticky feeling clutch is caused by the VSP unit seizing, probably because of sitting forever or just wear of the sliding disc. MTD original VSP rear belts work fine. Don't use the old rubber furnace blower belts you've got laying around. Belt width and length are imperative to proper shifting and tension. If a pulley swap is done, a different belt isn't needed, just modify the tensioner to suit the different trans pulley.

Possible modifications I can see to this system to make it more than practical in ATLT use is first, belly plates to keep trees/brush/water/mud/jenk out of the VSP. Then, as far as speed/pulley swapping goes, a larger engine pulley [will require a longer front belt] And a smaller trans-mounted pulley, as in any mower pulley swap. With VSP systems however, you have a max and min size for each pulley. Consider 4.5" the largest for the front, and no smaller than 3" in the back.

I run a 4"/4" and get a decent trail speed and slow enough crawl ratio in 'first'. Same pulley sizes are generally the guideline for all off-road/rally mowers since the combo of speed/crawl is just right. Thing is though, MTD VSP trannys are generally geared a hair faster than a typical Peerless/Spicer/Foote, so I'm sure you've noticed the speed some of these stock MTD's have compared to some hydros and gear trannys. Just making it more fun to blow your pulley-swapped Peerless buddies away on the dirt road   

I've never hated on Gear trannys, I just don't like how nobody is taking the time to make MTD's VSP a cheap alternative to the gear drive norm. They're certainly easier to come by, and parts are still readily available and cheap.

hey i totally agree with this post considering I have a 98 MTD with the 7-speed varidrive system, anyways ive been trying to get more speed out of it, but working from the back doesnt change anything but i figured if i change the engine drive pulley i might get some more speed. i was thinking about a 4.5 on front which was like you suggested. it currently has 3.5 on the front and 8.5 on the back. how much speed do you think i could get in 7th with a 4.5 on the engine?

Here is a thread that I'm writing up on the subject. I'm not done with it but will have what you are asking in it already. I even give comparisons to a riding mower with traditional engine/transaxle setup for a better idea. Yes, it also covers pulley swaps too.

Link;
https://www.atltf.com/t5355-vari-drive-with-5-speed-transaxle

It's pretty lengthy but a good idea to look over all of it because it covers all the little details on how it works and to maintain it too.

ok thankyou so much ill check it out