Not all 1/2 x 86 inch v belts are the same length.


Well-known Member
I got tired of ordering a 86 in v belt off
I had to buy a Gates 1/2 x 86 belt locally to get
the right length for a friend's JD lawn mower.

Not all V and flat idler pulleys are the same
either. I finally bought metal pulleys instead of
plastic pulleys they claimed were for JD. A 3
inch metal pulley is actually 3.25 inch diameter,
the exact size I needed.

I had to replace the metric bolts with 3/8 inch
bolts to fit the metal pulleys. One bolt I had to
cut out.

I'm done with this mower and will never volunteer
to work on it again.
Good reference for future
Some are measured inside and other is outside , probably why you come up short
George, I keep a spare belt on hand for my King Kutter finish mower that I have behind my 8N.
I have gotten 2 years out of the one that is on it and I mowed a bunch with it this morning.
Idler pulleys I can get for it at a place about 6 miles from here.
I hate working on lawn tractors with the deck underneath.
A lot of catalog listing use 'pitch length' instead of inside or outside. I think that's roughly the length at the midpoint of pulley shoulder contact.

To make matters worse, a lot of OEM equipment belts are not even numbered lengths but specific for a fit. Replacements are usually not sized that way, just close. Case garden tractors used a special width. Parts store 1/2 will sorta work, but not for as long as OEM fit.
Many name-brand equipment manufacturers use specially-sized belts instead of industry standard sizes. ....The sole purpose is to keep their parts business profitable.
And for a lawn mower u cant just go and buy any v belt. They will not last due to them being run forward and backwards over pulleys and tighteners.
Kevlar belts are needed for mower deck belts.
This is a drive belt.
Interesting , thanks , I had issues with the Sears craftsman 42 inch deck belt 93+and 3/8 ? or some such weird measure on that deck . I got one at Autozone , L belt luckily that worked . Too long ago , remember all the details of that project .
Geo you picked the wrong trade, if you were a plumber are HVAC man while on your parts run you could have stopped and had lunch all on the customers clock.
FYI, Over 50 years ago I worked my way through
college as a commercial HVAC repairman at
Bethlehem steel mill in Burns Harbor, In.
Not just belts.

Couple years ago when tires were scarce, needed an 11L-15 for my bale wagon.

Only place I could find one was Priority Tire.

You can see how well that worked out. I'll admit I never noticed it until I had it mounted.
Tire on right is Cropmax, tire on left is the Agstar I bought from Priority. Both stamped 11L-15 12 ply.

Priority Tire said since it was used (mounted on a rim) nothing they can do. Did offer me $10 off another tire. Gee, thanks.

Wound up putting the small tire on the back, wasn't even touching the ground in the front.
Just imagine what the next guy will go through after you changed the parts you did. Sometimes its just easier to pay upfront than go through what you did.
When I did the belts on my garden tractor, I wrote the sizes under the hood with paint pen. Oil filter # also.
I use a sharpie and write the belt size and the size of socket I need to remove the blades.

My friend's tractor doesn't have a hood.

The problem I ran into is a 1/2 x 86 belt I bought off Amazon is smaller than a Gates 1/2 x 86 belt. Go figure.
The belt you bought from Amazon was a 4L860.

The belt you bought locally from Gates was an A86 belt.

A 4l860 belt is not the same size as an A86. They are measured differently, outside circumference vs. inside circumference.
I bought a pickup from the City of Lincoln NE. On the bottom side of the hood the oil plug size was given and the fact it held 5 quarts of 5W30 oil (1995 Ford F150 302). Then on one side of the hood they wrote down every oil change starting in 1996. The only thing they didn't do was write the oil filter model down. The pickup is the color of a traffic cone and the black Sharpie writing shows up as well now as it did 27 years ago when they wrote the first oil change down.
Absolutely correct. Just went through all this on a John Deere SRX75. JD mowers are very picky about using JD belts. Crossover charts call out the same length, but they (other belts) will slip. JD uses unique widths on the outside, and on the inner part of the V. I found out the hard way. Finally found this out from buck toothed Daryl on Youtube.

Using the correct machine model number George could have gotten OEM parts or their generic equivalent quite reasonably with no ''mods'' and drama.

But that's NOT how George does things.
Do things your way. Please don't give any crap
for doing things my way.
One OEM pulley form JD is $30 plus tax.
Both metal pulleys from amazon are Under $30.
Same with belts.

I was saving a friend some money.

I'll just say again, NOT all 86 inch belts are
the same length.

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