MTD 604 42" belt problem....Help

Enfield

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Hi Guys,

First time on here, I am from way down here in New Zealand and having problems with 42 inch cut ride on mower. The mower is about 10 years or so old but I have generally looked after it and had no real problems. I recently decided to re-paint the deck as a bit of rust was showing, so stripped it right down and got it sandblasted and repainted it, I reassembled and have to say that I am ex Aerospace engineer so am very particular, I record how it comes apart and don't loose bits etc.

But here is the problem i now only get about an hour out of each blade drive belt, they seem to twist and end of snapping. I have looked at all I can think of, all pulleys are free with no play, the blade bearings were new only about a year ago, it has new blades and I even just replaced the two large tension springs in case they somehow got stretched in the rebuild. I generally replace the belt every year so, so know that is not routed incorrectly. Also there was a bit of slop in the bush that goes through the upper rear tension pulley assembly, so I machined up a new one with minimal play.

Now the only thing I can see is that the upper/rear tension pulley assembly #3 in the manual appears to be at an angle, is this correct ???, there is also a corresponding bulge under the deck. it is a long shot but I am just wondering did the sand blasting somehow distort the deck around this point or maybe they dropped it. If you can imagine this area of the deck is tipping in so when the idler pulley assembly bolts to it, it tips the assembly and the pulley......is this how it should be.

Model no is 13AV604G671....if that helps

Your help would be greatly appreciated, as the grass is getting high and my patience shorter ha ha

Cheers

Darren in NZ




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bertsmobile1

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You got it in one.
The fixed pulley should be on the same plane as the other pulleys so at that angle it will run off the pulley at the slightest provocation.
Not only does the angle look wrong but it looks way too high as well.
The bottom flange should be the same height as the bottom edge of the spindle pulleys.
The top is higher to allow for deck being out of alignment with the engine pulleys , which is why it is taller.
Next is be careful with using aftermarket belts, that looks like a Rotary one. Some are really good & others are not.
MTD use non standard belt profiles ( wider usually ) and some after market belts are just standard profile belts made a little shorter to compensate for sitting deeper in the pulleys.
You can bend a pulley like that simply by fitting a belt that is way too short.
 

Enfield

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You got it in one.
The fixed pulley should be on the same plane as the other pulleys so at that angle it will run off the pulley at the slightest provocation.
Not only does the angle look wrong but it looks way too high as well.
The bottom flange should be the same height as the bottom edge of the spindle pulleys.
The top is higher to allow for deck being out of alignment with the engine pulleys , which is why it is taller.
Next is be careful with using aftermarket belts, that looks like a Rotary one. Some are really good & others are not.
MTD use non standard belt profiles ( wider usually ) and some after market belts are just standard profile belts made a little shorter to compensate for sitting deeper in the pulleys.
You can bend a pulley like that simply by fitting a belt that is way too short.

Excellent, thanks for the quick reply, I guess time to get a big mallet out and try to straighten the deck in that area, just thinking I could try to bolt a bit of steel on in that area to help pull it flat and add a bit of extra support.

Thanks again
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
Excellent, thanks for the quick reply, I guess time to get a big mallet out and try to straighten the deck in that area, just thinking I could try to bolt a bit of steel on in that area to help pull it flat and add a bit of extra support.

Thanks again

Support the deck on some 2 x 4 hardwood planks then use the big hammer 4lb or better and another block of hardwood end on
Check that the blade tips are aligned when you finish as the deck can twist a little which throws the spindles out a touch.
Same solution.
OR
Put a Ozzie fag on it & invite the All Blacks around for a BBQ they should be able to straighten it out bare handed. :laughing:
 
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