Over the ground speed ????

A couple of years ago, I purchased a 612 from an older gentleman who had kept every note, every service done, every oil change, etc., in a notebook since it was new. It was in amazing condition!

Recently, when I went to replace the drive belt for the first time, the factory belt was at least a good two inches too small. No amount of tugging, stretching, whatever was going to get this thing on. And in fact my dealer agreed, took back the belt and we proceeded to try different V belts until we found the right one.

There is no mention of this in any of the previous owner's notes, nor can I figure out why the factory belt won't fit. The only assumptions I can make are (1) misprint on the correct belt or (2) the pulleys were changed for some reason. I really doubt number 1 as the owner's manual has been correct on everything else. But likewise, I can find no reason to change out the pulley size - unless that would allow you to alter the over the ground speed somehow. In this case, it requires a large belt so the pulley diameter was apparently increased.

Any guesses on what actually was done, and if so, would increasing the overall belt size raise or lower the mower speed - if at all?

Thanks everyone!

WELCOME to LMF...

If you increase the pulley on the engine, You will Increase the speed and will need a Longer belt.
If you increase the pulley on the trans you will Decrease the speed and will also need a Longer belt.
You have to change the pulley size to have any impact on ground speed....

Measure the pulleys, that may answer the question.

One other possibility is a change in idler pulley sizes...increasing the idler pulleys will also allow for the use of a longer belt, but there is generally no room to increase idler pulley size.... :smile:KennyV

I owned a 1994 612 until this last year I sold it moving up to a 700 series. I do remember a factory update in the idler pulley and even the mounting brackets that held the idler, as I remember the angle was completely different. Never the less it solved the problems the 612 had with hydro belt slippage, but I don't remember having to install a longer belt.