hydro on a 520

[418a 0]

I,ve got a 520 It's a worker!!!I had to change motors out because the onan 20 blew up replaced with a 16 onan I can't get it to speed up at all,maybe 1 or 2 mph at best if I change the pulley size would it harm the trans.blow seals etc. I would just like to go faster than whats it doing now .The fluid and filter has been changed and all michanical setting have been checked no belt slipping. The pulley on the 16 is about 1/2 inch smaller than the one one the 20, I just don'tthink that would slow it down as much as whay=t its doing.Any ideas!!!! The tractor is just for pushin snow and wagon pulling, firewood, so I don't need the clutch.Thanks Brian

[TT-(Moderator) 1,145]

The engine pulley should be 5 1/4" and anything smaller will make a difference.

If you have a "gear drive" WH (8 speed) engine pulley, it is only 4" and will slow things down considerably.

If the engine is turning 3400-3600 rpm with the original pulleys, don't expect more than 7 to 7.5 mph out of the tractor.

Another option would be to install taller rear tires. B)

[418a 0]

TT Thanks!! The pulley is locked on the crank so I would have to cut it off if I wanted to fix that problem I f I change the rear pulley out to a smaller one that would be the same just reversed?? Just wondering what or if I will blow seals or not,if i did do that ,Is there a by pass valve in the trans that stops the trans from blow up from too much pressure. or just get bigger tires. Brian

[TT-(Moderator) 1,145]

Installing a smaller rear pulley to restore the original ratio is a possibility - and if you're lucky and get the size right, you can still use the OEM drive belt.

There are relief valves in the Eaton hydro to prevent excess pressure, but I doubt that you'd be making enough pressure to open them unless you go crazy on the pulley size change.

Or............

If you aren't afraid to do a "body lift" on the rear fender, check out these tires!

[418a 0]

TT Thanks again Thats a good price on those tires might get a set!!Well I've gone into the trans and broke the cast pulley on it come to find out its off set I have a 4 inch pulley that I'm going to put in its place might have to bump out the idler pulley a little but will work,and those big tires ,I'll get out of the wood really quick Will keep you posted on the fab!!! Brian

[dr74go 1]

I know that the different pulley sizes will change the speed of the transmission. If the speed is slower now compared to before the engine change, I would take an educated guess that it is a pulley issue.

If changing the pulley doesn't work, here is another thing to check. I am assuming this is a 520H. Look for dirt and grease built up in the slots on the cam on top of your transmission. My 520H was slower than I expected when I got it. I adjusted everything and it still didn't seem as fast as it should be. My cam was moving very little, so I removed the bolts, one at a time, and cleaned the slots. Mine is now about twice as fast as it was.