Misc maint questions

Trev · Jun 13, 2002

I have a JD 4300 that just turned over its 50 hours, so I did the 50 hour service on it myself at the recommendation of the dealer. One odd thing was that they recommended straight 30-weight oil for summer use. I went ahead and took their advice, but now I'm having second thoughts. People tell me I should have used JD Plus-50 oil. Certainly I can't use 30-weight during the winter, but is there an advantage to it during the summer?

Second question: my JD 272 rear finish mower needs the blades sharpened after hitting a few rocks. I thought I'd buy three new blades, then I could rotate them as one set is being sharpened, etc. Do most people just raise the mower on the 3pt hitch, put jack stands under it, and then just remove the blades with an air impact wrench? Or do you remove the mower deck completely so you can lift it with something and really get in there to clean it and whatnot?

If I put on new blades, can I just give them a quick hit with the air wrench to tighten them, or do I need to be careful about torquing them down to exactly the right value?

TIA for any thoughts!
Bob

GlennT · Jun 13, 2002

I've got a JD 670 and the local dealer recommended that I use a straight 30W oil. I questioned this so I called and talked to one of John Deere's technicians who recommended the same thing. I live in central Texas and we have long periods of warm or hot weather. I would have thought that a multigrade oil was better for your needs in New York. Regarding the mower blades, I simply tighten them good and tight on my riding mower and the mower on my tractor. That's worked for many years; however, it doesn't necessarily mean that it's the right way to do it. It really doesn't take that much longer to torque something down so why not do it if you would feel more comfortable with it?

hazmat · Jun 13, 2002

It really doesn't take that much longer to torque something down so why not do it if you would feel more comfortable with it?

I agree. You'd be surprised how easy it is to overtorque and damage even fair sized bolts. Especially with an impact wrench.

If you properly torque the bolts, they will be easier to get off in the future as well, (just in case your compressor dies and you have to use a wrench)

If you don't already have one, Beam style torque wrenches are very cheap & never need calibrating. Ratchet style ones are much more convenient to use, but cost a bit more.

cowboydoc · Jun 13, 2002

Trev,
I just put in Rotella 15W-40 and be done with it. Rotella has been specially formulated for diesels especially with soot removal. This is absolutely imperative if you don't use off road diesel. You won't have to worry about your oil in the winter or summer then.

With regard to sharpening the blades I put mine up on some jack stands in the shop and clean the deck and take the blades off and sharpen them. I know alot of guys that do have two sets of blades though. I've got a grinder right there so really no sense in having two sets for me. If a guy didn't have a grinder handy though it would be nice to have two sets.

I always torque mine down. Those bolts can get rusted on there and if you combine that with overtightening them with an air wrench you will have one heck of a time getting them off. I also will put some anit sieze on them to help with getting them off next time as well.

Hillbilly · Jun 13, 2002

Richard,
Have you ever used an orbiting grinder on your blades?Just curious,I know a bench grinder you can hold the blades on a rest and get a true edge.I bought a Makita orbiting grinder and that is the most handy little tool to have.I just raise the bush hog up and put a block under it so it cannot drift down and have at it.It saves me the time and hassle of having to take the blades off.I have on occasion picked up a piece of barbed wire and the Makita is sweet to get the wire off if you ever get it wrapped around the blades.

Trev · Jun 13, 2002

Thanks guys.. sounds like good advice.

Hillbilly, so you sharpen your blades without even removing them? Do you ever run into problems with balance? I gather normally people stick a nail in the wall and sit the blade on it to see if it's balanced.. and then grind some metal off until it stays level. How do you deal with this?

Thanks,
Bob

MikePA · Jun 13, 2002

Do you ever run into problems with balance? I gather normally people stick a nail in the wall and sit the blade on it to see if it's balanced.. and then grind some metal off until it stays level. How do you deal with this? 

I don't have an answer but I was thinking about this as well...Even finish mowers hit objects that ding the blades up and unless you manage to hit the same object, the same way, at the same point on each side of the blade, and take the same size ding, the blade is no longer balanced. Odds are that a normal ding in a blade will unbalance it a lot more than uneven sharpening.

So, what would be wrong with sharpening the blades while they are on the deck, measuring the width of the sharpened area of the blade and if they're the same, they're balanced? I bought one of those blade sharpeners (angled stone with a nylon guide) you use with an electric drill and thought using the aforementioned method or making the same number of passes on each end would suffice. Thoughts?

Trev · Jun 13, 2002

...So, what would be wrong with sharpening the blades while they are on the deck, measuring the width of the sharpened area of the blade and if they're the same, they're balanced?

Sounds good in theory, but you're way over my head Mike. I don't even know how to sharpen a blade to start with. I gather some people argue that the blade should actually be left somewhat dull, because then it will remain in the same state for a longer period of time? Maybe I misunderstood their argument.. but they were talking about leaving a certain curvature on the front edge. Does this make any sense?

The only thing I'm fairly sure of is that my blades need some work. /w3tcompact/icons/wink.gif I actually cut a rock in half with my finish mower! /w3tcompact/icons/blush.gif One of the kids left a rock next to a new tree my wife had planted, and I nailed it but good. I have dings all over the blades now. I'm not sure at what point a blade becomes "unfixable." I think mine can be fixed, as there are just little dings in them (like an eighth of an inch or smaller) and they still cut fairly well. Just not like when it was new.

I don't have any reason to say that sharpening the blades while mounted is any worse than sharpening them on the bench.. other than wondering how much work it really saves? Is it really that much easier than just taking them off and putting them back on?

How much out of balance does a blade need to be before it begins to cause extra wear on bearings, etc.?

See, I'm way over my head here.. just getting a feel for the water. /w3tcompact/icons/wink.gif

Thanks,
Bob

Hillbilly · Jun 13, 2002

I have never hhhad aa ppproblem(excuse me I have the shakes,just got off my tractor)
No, seriously I never have had a problem.....I can do pretty good free handed.But the way you mentioned sharpening and checking for balance,sounds like a good way.I remember this being discussed one other time.And if I had a problem with balance,I would definately try this approach.

JJT · Jun 13, 2002

I've always used 15/40 year round in the Kubota. I even switched the rider and the push mower over to 15/40.

As for blade sharpening - I'll take mine off, sharpen them on the bench grinder and make sure they are balanced at the beginning and in the middle of the mowing season. Every 4 weeks in between I'll touch them up with a hand help angle grinder. I use an air ratchet, a drop of oil and do not torque the bolts. I've been using the same rider for 20 years and am on my second set of blades, (I average 2 - 3 acres/week from May to October). I've never had a problem with the mower deck. It's 100% original except for the blades, (original drivebelt, bearing/bushings).