Spartan mower cut help please

[LittleBittyBigJohn]

I got a used Spartan SRT-XD 72" last year. I like the mower its self. It has the 36hp Vanguard Big Block that really runs well, and Parker pumps and motors, it will scoot. But the cut is very much lacking. I've put new blades on it, new belt, new idler pully, spacers to lower the blades in the deck, and increased the governor by a few hundred RPM. I just can't get the silly thing to cut well. I have to cut so slowly that a 60" running normal speed would be faster than me on the 72. I got it because I keep my whole property mowed. There is probably 9 of over 11 acres that are lawn, the rest is trees and pond. I was hoping this was going to be the mower I kept forever, but if I can't get it to cut well this will be the last summer on it. I may even jump ship this summer, but I just built a house and had to buy a truck.

Do any of you have any ideas on something to improve the cut? I thought about changing spindle pullies or pto drive pully to increase blade RPM but I don't know where to start on that?

The cut basically is uneven throughout the swath. Some areas are cut really well, but there are multiple mohawks of just poorly cut, high, uneven grass. I think the bad areas are on the center of the blades, and better the farther it gets from the center of the blades.

 

[seville009]

Since it seems that you done most of the mechanical changes, maybe it has to do with the deck shell itself. If the deck has large dents, or is caked with mud/debris underneath, the air flow may be affected enough to affect the air flow from the blades.

 

[kozal01]

Have you checked the deck level? The manual should have suggested settings for pitch front to back. My Exmark likes the front of the deck pitched about 1/4" lower in the front. When measuring be sure your tires are at proper PSI then add the equivalent to your body weight on the seat. Deck pitch can really affect the cut quality. Also, you didn't mention if your bagging, side discharge or mulching.

 

[LittleBittyBigJohn]

I forgot about deck level. Yes I adjusted that to around .25-.50 lower in the front. It was pretty bad when I got it. It's definitely in the correct range.

 

[LittleBittyBigJohn]

Since it seems that you done most of the mechanical changes, maybe it has to do with the deck shell itself. If the deck has large dents, or is caked with mud/debris underneath, the air flow may be affected enough to affect the air flow from the blades.

After I got the Spartan I have done a lot of reading different forums and it does seem like the decks are just not very good. It cakes with grass very quickly also.

I really feel like if I can get more vacuum or possibly blade tip speed it would help. Everything I've done has helped just a little, and it's markedly better than when I got it, but nowhere near where it should be for what it costs and that it's marketed as a commercial mower.

One of the extremely stupid things is - if I hit some really tall grass, instead of it bogging down and really cutting, it will just push it over and barely cut it.

 

[seville009]

Tall grass will do that with pretty much any mower. If I run into that, I just mow over that section three or four times in different directions to get it cut down sufficiently.

 

[CloverKnollFarms]

Yikes, my 29HP, 72" Hustler will breeze through tall thick grass. Likely just a poorly designed deck.

 

[RjCorazza]

...
...One of the extremely stupid things is - if I hit some really tall grass, instead of it bogging down and really cutting, it will just push it over and barely cut it.

Not familiar with that mower, but is it possible the blades are slipping on the spindles? My mowers use Bellvue washers, which are domed ever so slightly to keep pressure on the blades.

 

[LittleBittyBigJohn]

Not familiar with that mower, but is it possible the blades are slipping on the spindles? My mowers use Bellvue washers, which are domed ever so slightly to keep pressure on the blades.

I guess it's possible, I don't really know how to test that. I use a piece of wood as a stop between the deck and blade when I tighten the blades on the spindles and they don't slip at that point. So I don't think they are.

I'm pretty confident it's just got a bad deck design I'm just trying to polish the turd as much as possible. I want to like it.

 

[kozal01]

What’s the deck look like under it? Is it baffled? Could it possible have a mulch kit installed?