Belt Size for Max IV with Vanguard and stock 780 clutch

[Uncle Vin]

George and I are putting the T-20 back together after I wasted the input shaft bearing. My theory is that the belt was too tight. So, I ask: what is the proper belt size for Max IV with Vanguard and stock 780 clutch (viz, a totally stock setup)? Belt brand names with part numbers would be helpful. Thanks in advance. Uncle Vin

[TalSet]

don't know if my belt that was on my max IV was the right one when i bought it, but it was a Dayco # 1092. since owning it i replaced that one with a napa snowmobile belt # 19T4300. hope this helps and say hi to george for me.

[Uncle Vin]

don't know if my belt that was on my max IV was the right one when i bought it, but it was a Dayco # 1092. since owning it i replaced that one with a napa snowmobile belt # 19T4300. hope this helps and say hi to george for me.

Thanks. I will. My machine came with a Dayco 1092 on it. I restored the machine, so I obtained a replacement belt from RR (but it was not the same brand). The replacement belt fit tight -- at least I think so. For whatever reason, the engine on my machine came mounted on small metal spacers between the table and the engine. I have since sourced an NOS Dayco 1092, in the original cardboard sleeve, from ebay for $16. The new belt is (obviously) less stretched out than the old Dayco 1092 which was on the machine when I acquired it. My latest theory is that the machine did not come with spacers from the factory, and that the prior owner installed them because the belt became stretched over time and he didn't want to spring for a new belt. What do you think? Does anyone know if a Max IV with a stock set-up and the stock Vanguard came with engine mount spacers between the table and the engine? Uncle Vin

[Mike]

Spacers are stock. That is the only way to adjust the belt on the Max IV.

[wfo]

so in other words if you take all the spacers out, then a stock new belt would set it correct ?..mine never had spacers

[Mike]

Maybe I shouldn't make assumptions. My wife's Max IV, my fathers, and one of my friends all had the same kind of spacers so I assumed they were shimmed up from the factory to get the belt tight.

[JOHNMcDANIEL0322]

just to chime in. i have a max II and im having some belt issues still. i just havent bought the new belt, because i kind of got off the project for a bit, but about how tight should the belt be with the feel of your hand thank you

[Uncle Vin]

George and I worked on my IV all day yesterday (George, you're the best) and we decided to take the spacers out. It seems to work well. The machine pulls fine and the secondary opens up like a champ at RPM. I won't know if it's spec until I try to take it through its paces -- which is a no-go on Long Island. If necessary, I will shim it up using thick washers. BTW, I checked the RI parts list and there is a listing for spacers. But I have no idea if the spacers are specified for a different engine (Kohler or 2 stroke, etc.). Mike, with the spacers installed, the belt is super tight, so much so that it was extremely difficult to get the clutch on. Moreover, the belt would squeal constantly -- especially when under a load. Now she's quiet. John, the factory manual, which I have, says that the belt should have 1-1/4" deflection. From reading other material, I understand that the key to a deflection test is to "press lightly" on the belt when checking deflection. The rub is that I don't know exactly what that means. "Press lightly" to me may mean something different than it means to the instructor. I have looked for a video on this, but to know avail. Uncle Vin

[JOHNMcDANIEL0322]

oh ok i got what you are saying. i wonder if i can do any shimmying in my max just to save alittle money on a new belt, because im only rolling about 5 to 10 mph at the absolute most?

[Mike]

John, A max II has slotted holes for the engine mount, so you can slide the motor further away from the transmission to tighten the belt. Loosen your mounts and slide it back. Once you reach the back of the slots though, you are (of course) out of adjustment. A Max IV is different since the engine sits over top of the transmission. It has to be shimmed up if the belt is too loose.

[Uncle Vin]

oh ok i got what you are saying. i wonder if i can do any shimmying in my max just to save alittle money on a new belt, because im only rolling about 5 to 10 mph at the absolute most?

5 to 10 mph is way too slow. Assuming you did not change the engine from a 2 stroke (important), then your belt may be too worn. The width of the belt is almost as important as the length. The CVT clutch relies upon a specific width belt in order to operate properly. After you tighten your belt (as per Mike's advice) take a look at the clutch while the machine is in neutral with the engine revving. Your belt should rise to the top of the primary (drive) clutch at high RPM. The drive portion of the clutch is the portion attached to your engine. If not, then it may be time for a new belt. Measure the top width of your belt and post the measurement. Uncle Vin

[JOHNMcDANIEL0322]

you know i never even looked to see if i could move it backwards. great idea thanks mike ill go try it and see what i come up with.

[larryf]

Stop me if im wrong but my belt spins no matter if the gas is on or not every other belt drive i have owned when motor is running the belt doesnt move till gas is on is that right or should it always turn with motor even at idle

[Patmax]

The vanguard spacers were, as I recall, 3/8". The Kohler didn't need them. If they were factory, they would be 1-1/4 square x 3/8" thick. Did you check the lower mounts? The rubber frame ones. Over time they get hammered down and one cheat is to shim those as well. Also the Vanguard has a higher torque rise than the Kohler, which tends to eat belts faster. (this is why in the II's there's that torque mount on the LF of the frame ). As far as tension check goes, all you want it enough pressure to take the slack out. Say no more than 5lbs of push.