Converting belt size?

[KE4AVB]

When replacing a HB with a B belt would you go 1/2" shorter or 1/2" longer. I converting the MM OD of the HB to inches. With a 141" (3581.4 mm) OD HB it converts to 138.56 (3519.4 mm) ID B belt. IE there is 62 mm (2.44") difference between the OD and ID lengths. So do I buy a B138 or a B139?

[KE4AVB]

Nevermind. I found the 5/8 x 142 (TCU13198) belt I reject last year for being too short for a JD. When I measured it, it was 141" on the nose. At least I didn't throw that $30 belt away.

[hanz63]

Arrggg! I feel your belt pain. We stock too many and.... Whilst we are on the subject of belts, you know those new 42" Deere decks on the E series? And the adjustment bracket that they thought would be a good idea to weld on? Anyone have a a favorite GX20072 ish belt that is just a bit snugger? Some extra old style brackets and a drill maybe?

[KE4AVB]

Well since the GX20072 JD specs are .556 x 103.74 (effective length) so you could try the MTD 954-04219 which is around 1/2 x 103.25 but you can't trust any belt to be the same exact length everytime when you buy one is a miracle.

Stens claims theirs is within a +- .25" but you can't even trust that as I brought a 954-04219 belt from them that was to be 103.25" and it came in at 104". What was strange is that on the MTD 46" deck that the 103" was to on ended up with a 102" belt in the end.

JD website claims the GX20072 to be a HA belt but info I have here is that a HA is a .500 belt.

I have just scream to the top my lungs many a time when buying aftermarket belts that come in not to spec they they claimed them to be. This why I had to buy that v-belt measuring tool just to save some my nerves. Just so much miss information out there it is funny for us that try to make an informed decision. BTW it not the local JD shop that belts are wrong either as they are in the boat as the rest of us as near end users as they have depend JD factory to send the right belts.

This is what happen to cause to have belt I got now. It is aftermarket belt that I got in place of a JD belt. It was way too short even the printed specs were right. Then I got one from the dealer and it was a 1/4" short of the spec. I ended up having to walk the belt on the mule drive.

[KE4AVB]

Boy using the manufacture or my own formulas I can see why we have so many problems when vendor are selling A vs HA and B vs HB belts. None of the sizes match up without using some crazy math figures but we are dealing something that is not rigid. It least explains to me why I never can get a B belt size to match up to the HB belt size. Using the stated heights they become around a half inch shorter or longer. The heights figures has to be fudged in order to get the 3 inches differences they claim for a B vs HB of the 2 inches they claim for the A vs HA belts.

Most of us tend to use the OD lengths to find belt which are H(A or B) belts then having to convert to A or B belts or having trust the vendors have already found the right belts.

[hanz63]

Yeah it's fun. thanks for the tip on the MTD belt. I'll put it on the stretcher and compare the two. Though I don't THINK that I have a OEM Deere. I've done the same. This should work in comparing belts, but then. I forget what, but I have a half dozen Murray belts left and I never see them anymore. Thought one might match with something else, but no. Good project belt maybe...