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MysTiK

Fat Tall Front Tire and Mowing Height

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MysTiK
Maybe just a weird idea. What if? Tractor is AC716H = Tire Size & Pressure = Stock Specs. Rear = 23-10.50 X 12 (8 PSI) Front = 16-6.50 X 8 (10 PSI) What if I swap the fronts out for: 18-9.50-8 ?? Or maybe some narrower size would fit better, if available. I dunno; I saw this size for sale, and the mind started working overtime about my ongoing obsession with raising mowing height. Purpose =>> Raise the mowing height + improve deck level + improve belt/pulley angle. About the angle of the deck belt relative to the deck drive pulley: It's not too serious; but the belt gets slightly polished on the lower edge of the pulley. Deck is now max height = approx. 3" mowing height. Actually, it's the rollers that are at max height - and that's what causes the belt/pulley angle issue, where the belt rubs on the lower edge of the drive pulley of the deck. This happens (I think) because, as the rollers go higher, the deck itself (and therefore it's drive pulley) leans forward slightly. So a taller tire on front, would raise the deck at the front MORE than it would raise the deck at the rear; since the rear is farther away from the raised front, and since the front of the deck is fixed, pinned in the hitch. (I had to think about this for a long time to picture how this relative movement would affect things.) So these tires are 3" taller - so the lift on the front end would be something like 1.5" - (maybe "adjustable" w pressure). yes? (And if that's true, then can the stock rear tires be pressure/height adjusted also)? If fatter, taller tires raise the relative front to back "deck level" too much, could a "yoke adjustment" help level the deck - and which way would the yokes have to be turned?? (clockwise or counterclox) I have heard people speak of this as a "rake" adjustment. But nobody seems to really know how this works - at least, I have not heard it said, and there's nothing in any manual I have seen - yet. (please prove me wrong). In my manual, the word "yoke" appears; but no mention of how to use them, or what they actually do. The other concerns - would fat tires affect steering, and would the tires rub on frame or other parts?? Weird question, yes. Weird answers, welcome. Alternative weird ideas also welcome. thx. Graham .

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mtoney
The mower deck should be 1/4 to 1/2 an inch lower in the front that at the rear when measured at the blade tips, with the blades facing fore and aft. Then you set the side to side level at the blade tips with the blades turn to face left and right. Once level side to side and with the proper nose down rake, you have a correctly leveled mower deck. Prior to changing any settings on the mower deck, make sure your tire preasures are equil all the way around. Somewhere around 12-14psi in each tire. You shouldnt need to change tire size beyond what was originaly on the tractor to set up your deck correctly. Guys that run tri ribs on the front do so for better control in field plowing and snow removal. Turfs or the diamon stud tires do just fine otherwise. Your front tires are a standard size for our tractors. The early model B's had the narrow front tires, but the same basic diameter. Same for the rear, they all had the same basic diameter, but different width's, from 6-12 to 23 8.50-12 and 23 10.50-12. 23" diameter, 10.50 wide on a 12in rim ect. Yes fatter tires can make it harder to steer, another reason many put the tri rib tires on, can rub parts when at full lock to one side or the other. The adjustments are in your deck, not the tires beyond correct air presure. The yoke is the two front arms that mount the deck to the front axle. You can adjust them up and down to raise and lower the nose of the mower deck, the adjustments are done on each side and in equil amounts at first. Once you have the "rake" correct, then you turn the blades by hand to face toward the left and right side of the mower dck and check for side to side level. On a simplicity/allis this is done with the deck on the roller and not hanging from the lift chain obviously. It takes some time to get it right, but once its right, its good for a long time unless you hit something. You also dont want to use the mower deck as a place to step on and off the tractor as that can tweak the settings and mess up your nice level deck. If you lived closer, I would set your deck up for you. Mike

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RayS
Graham, Go to the Simplicity site and download the operators manual for a 990886 manual. It explains all the adjustments in that manual. On page 5, step 10 they call them eye bolts and on a 42" deck that is what is used. On a 48" deck they use an adjustable yoke. Figure 9 is calling it a clevis. It may not be the correct mfg. no. of your deck but the procedure is the same for the 42" and 48" left hand decks. The deck rollers new are 2-1/2" diameter and since the deck rides on those rollers, the only way you are going to get more height of cut is to use taller rollers. If you can find a late model 48" deck that uses gull wing blades. You can get more height of cut. You can buy a set of straight blades and drill the center hole out to 1" diameter with a carbide bit and use them in place of the gull wing blades. Simplicity had three different 48" deck shells. The old style used on the 3300, 3400 and earlier which used a flat stamping in the shell and the old style arbors. Then they had the newer style that had the two piece arbor assembly and a recess in the deck of around 1-3/8" that the shorter newer style arbors mount in. Then they changed the recess in the deck again in the later models. They kept the same arbors but moved the recess up a 1/2" or 5/8". This is when they introduced the gull wing blade. Not sure why they did this. They may have had problems with fatigue in the arbor mounting area of the other deck. Not sure which Mfg. no. but I believe it was 1691219 that they introduced this later style deck. It could have been a little earlier. I do know that the Deutz Ultima had gull wings. I just finished up restoring on from and Ultima for my Sovereign 18. I have a set of gull wing blades for it but I put a set of straight blades on it and you can get 3-5/8" to 3-3/4" cut by doing this. Bill Engle helped me out in alot of emails and pm`s on this restore of the 48" deck and the turbo that I am in the process of restoring now. The Ultima 48" shell and arbors are the same but I had to use Sovereign pulleys because the Ultima was different sizes and I believe they were because of the gear box that runs the deck.

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Brettw
quote:
The mower deck should be 1/4 to 1/2 an inch lower in the front that at the rear when measured at the blade tips,
To my knowledge, exactly the opposite is true. The front leading edge of the blades, when sitting on a flat surface and measured, should be 1/4-1/2" higher than at the rear of the deck. Others may chime in on this, but I believe this is correct. PS Mower should be off and tractor not running when measuring blade heights.:o)

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RayS


Brett, the front of the center blade should be 1/8" to 1/4" higher than the rear of the two side blades. I probably would turn the engine off as well. Just to be safe. I know a guy that use to flip his cutting tool inserts in a Bullard Type L eight spindle maching center with the machine on and spindles turning wide open. Was always scarry watching that take place.

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Brettw
quote:
Brett, the front of the center blade should be 1/8" to 1/4" higher than the rear of the two side blades.
Yes Ray, thanks, that's what it was. I couldn't remember exactly, but knew the 1/4" was one of the numbers. I was referencing more the point that the front of the deck should definitely be higher and not lower than the rear. As for the original question, yes, taller front tires will raise the front of the deck. Whether that is good or not is another question. Unless you can raise the rear enough to keep that 1/8-1/4" difference from front to rear, then I would assume you will effect the quality of the cut. I have also heard that if you do find a way to raise the deck above the 3-1/8" height, to say 4", the vacuum effect is greatly diminished on these decks and again cutting quality is affected. That and 98 more cents may get you a cup of coffee. Somewhere. Cheap.

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Tarheel
Everyone is going to have his or her own ideas about this but I can tell you from seeing it first hand that you probably don't want to exceed the maximum height built into your mower. I knew a guy who felt the same way and wanted his cutting height higher. So he takes the deck to a welder who cut the flat bars that hold the rollers in place and added an inch. Then he added steel to rock the front mounts forward the same. So the man had what he wanted. Just an inch more. Now the wind from the blades causes the tall grass to lay over and it don't get cut. The rest of the cut is pure simplicity for quality but he has a yard full of stick ups when he gets done. That was near 20 years ago and as far as I know that simplicity is still parked. He was to proud to pay someone to reverse what he had done or to buy another deck. There is a thread on here somewhere in which this same idea was bounced around. Al delivered some outstanding input as he had (if I remember correctly) worked with the factory on this idea of more height. He talked about lowering the skirt of the deck shell among other things to try and overcome the problem of loosing lift/leaving grass standing. And again, if I remember correctly, he never was able to make it work. I quit trying because I know Al enough to know he gave it serious thought and effort. But understand my memory isn't what it used to be. I suggest you either ask Al or find the post yourself. It might save you much time and money. Good luck.

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RayS
I have a friend that runs straight blades on a gull wing deck. He has been doing this for 3 or 4 years without any complaints. I am going to give it a try as well since I have it setup that way. I don`t think a 1/2" is going to make that much of a difference in the lift issues. This is one of the biggest reason why I like the Prestige. You can get a taller cutting height with a shallower deck. I can cut grass between 1" and 4" and the quality of cut isn`t compromised. Simplicity, unlike others has always improved on the quality of there machines. I always thought that the 48" deck was lacking in lift (prefer the 42" to the 48") and never realized how much until I got the Prestige with 50" deck. So is it the roller bar that makes Simplicity great? You can by a roller bar kits for Exmark, Scag and Toro!

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Brettw
Now I have questions. I just sold my Sunstar with a 60" deck. On that deck with the height adjustment all the way up it does cut measurably higher than my Sovereign. I really liked that as it made a big difference. So my multi part question is: Do the 48" Sunstar decks cut as high as the 60"? And if they do, aren't they the same shell as the Sovereign decks? And if so, why can't we get a decent "high" cut on a Sovereign deck but can on a 48" Sunstar deck?

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RayS
I know the shell is the same for the soverign and sunstar. The sunstar has a different bail assembly than Sovereign. They may have a different cutting height. I will check a Sunstar operators manual.

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MysTiK
Thanks for many responses, suggestions, concerns, ideas, and discussion. I expected this thread to be a dud. I don't care if this takes off in any other directions. I love deck discussions, no matter what. So feel free. @Ray - Thanks for proving me wrong. That old manual has the simple info I wanted = basically which way does what with the yoke/clevis/eyebolt adjustors on the front of the bail assembly.




EDIT - this info alone is encouraging. I stared at the yokes, I could see it push/pull the bail; but I could not see, for certain, how things would change. That resulted in some strange configurations and perhaps some undesired Tension, and that tension might be the stuff that causes yoke weld breakage, metal fatigue, etc. , Fearing that, I undid a slight twist I built into the deck for perfect leveling. But now I don't have to worry about what my adjustments are really doing. And with that I can experiment for not only more height; but might also correct the belt/pulley angle. (minor issue). Long story short, I can properly level my deck. I am still interested in tire sizes. The tire I suggested originally was pretty crazy, as it would probably interfere by rubbing, etc. But I think a 1" increase would be a good thing, because it would lift the deck front about a 1/2", since the front of deck, is midway between the fixed points - rollers and yokes. sm01 That would mean perhaps backing off the yokes slightly, which might also mean less tension. (assumes broke yolk metal fatigue might be an issue).

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MysTiK
Deck air currents are pretty amazing; and it's hard to know what's really going on with all that. On the closed side of the deck, it's easy to see grass bending towards the deck. What's amazing, is that I have observed that same bending on the chute side of the deck - where you might expect the grass to be blowing AWAY from the chute. Fascinating to watch - and that means you can minimize overlap on the chute side for better stripes. This is only observable right close to the deck. Away from the deck, it's all opposite, grass blowing away from chute. And yes, there is less vacuum suction, as shell goes higher - but it still works, just not as strong. I have done a lot of mowing at 4" with my Pacer WalkBehind - but it has an infinite rotary crank adjust - and 4" is built into that, it's on the menu, it's within manual specs. Not sure what happens with a Sovy deck - but I want to know. At 3", there is no problem. I would expect 3.5" would be ok also. I like the gullwing swap idea. That would be an easy solution. One other thing - 'high lift' blades. I have a set of these for my Pacer. The sound of the deck goes from WWWRRRRR to VVVOOOOOOMMMMMMM. The suck factor is huge. The clippings are thrown 6 feet in the air - which is hard on breathing if the wind is wrong. They can be handy for spring cleanup, dethatch ops, etc. And they might help if there is a loss of suction due to excessive mowing height. The high lift blades I have, have a "wing" on the blade that's approx 1.25" tall, compare to normal blades at about 1/2" or so. Again, those are on my Pacer mower. I have not tried high lift on my Sovy deck. I have seen some Gators, high lift, w a wing like a comb. Mine are solid wing.

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