ZD326 blade stops turning when in high grass

[tallyho8]

My ZD326 was laid up for a couple of weeks while I repaired the fuel gauge and with the hot weather and lots of rain we have been having my grass grew rapidly and was a lot higher and thicker than usual. I also have a mulcher on it which makes it even harder to cut tall grass. I bought 2 new cup washers for the blade and torqued it to 95# but one of the blades will slip and make a terrible racket when it gets in the tall grass. Anybody have a cure for this?

 

[LittleBill21]

what a dumb design, the blades aren't keyed?, I would torque the cup washer to blade at the proper torque, then I would weld the cup washer to the blade itself. Ridiculous design.

 

[m7040]

This can happen when the washers or the cup covering the spindle are worn thinner from being loose and then the torque applied to the spindle bolt will not give the full pressure on the blade

 

[tallyho8]

I can understand not having the blade in a fixed position unable to slip, because if it was not able to slip if hit a chunk of concrete, it could bend the shaft or cause other major damage. It acts like a clutch on a pto but it should hold a lot tighter than it is doing. I did install new cupped washers. By my understanding, the cup covering the spindle is just a thin sheet metal dust cover and does not spin with the blade and the blade should mount tightly even if you leave the cup off. The bolt holds the cup washers tight against the shaft with the splined insert going through the blade and unto the splined shaft.

There is nothing stopping the washers from turning with the blade so welding the blade to the washers would not accomplish anything. Now welding the blade to the insert would lock it up and if you did not hit anything to bend the shaft would work except you would have to buy new inserts for the blades when you change blades which I do on a regular basis.

 

[thclimer]

Just for reference here is a picture of the setup tallyho8 is describing:

Is your lock washer #4 in good shape?

 

[oldnslo]

If the blades have spline that fits on the spindle it sounds like the splines are worn or the blade was not installed properly on the splines. Slipping splines would make a lot of noise until the splines are ground away.

 

[RjCorazza]

Assuming the op has the bellview washers oriented correctly, I would be inclined to torque the bolts a little more. Perhaps add a 3rd washer and increase the bolt torque if there is enough thread (I've never added a 3rd washer).
I don't use a torque wrench on the blade bolts for my zd326 or zd1211, but I'm sure I keep them tighter than 98 ft/lbs.
I take the blades off to sharpen every 2 weeks or so, and have never had a problem with them.

 

[mikester]

Try some new OEM blades and a new OEM belt on it. Check and adjust the belt tension.

I think the spec torque is 85ft.lbs. If you use an impact gun to tighten or you have over torqued you might have stripped some threads inside the spindle.

I'm suspicious you might have broken something on/in the spindle since you say you are hearing a racket when it slips. You might need to pull the spindle to see what's going on.

 

[tallyho8]

I wire brushed my blade down where the washers connect to it and I tightened the bolt to 110# and tried it out and it is working ok now. My old torque wrench might not be too accurate anymore. Time will tell if this works.

 

[90cummins]

Just the other day I removed my blades off my ZD1211 (I agree stupid overly complex design) to sharpen & balance. When I reinstalled them the right side blade screw would spin the shaft while trying to torque to 80 lbft & I’ve had them of many times with no issues. I removed it and checked assembly, it was proper & clean so I tried again to torque & once again it slipped so off with two blades to swap assembly’s with same results.
Had to touch it with the impact slightly before it would reach torque.
On my machine the cupped washers were assembled opposite from the drawing above.
When I removed them for the first time a couple years ago it was obvious due to witness marks how I received to machine so I reassembled the same way.
I just checked my shop manual & it is the same as thclimer.
Looks like I need to turn them around before damage is done.
Thanks for the post.
90cummins

 

[Brown Dog]

Sounds like the 2 coned spring washers have flattened out
OR
you don’t have the components assembled correctly.

 

[tallyho8]

Now that my blades are on tight, I have a new problem. I started to cut grass yesterday and the same blade was loose again. I had only cut for about 5 minutes. I drove it to my shop to work on it, turned the key off and it kept running. I looked for wires to pull to kill it and couldn't find any that killed it. I took the key switch off and unplugged it but it kept on running. I sat back and tried to think of a solution to kill it. After about 5 minutes, it started missing out and sounded like it was running out of fuel although the tank was almost full. Then it killed.

I waited a few minutes then hit the starter and it started right up. I turned off the key and it killed and has worked fine since. Anyone know what could have made it refuse to kill?

 

[Brown Dog]

98ft lbs on those small 10mm threads sure seems excessive

Is ZD326/331 the same setup as ZD1211 in the pic illustration in post #5 ?

 

[Midniteoyl]

If you havent yet, try new bolts. Those may be too stretched.

 

[4570Man]

what a dumb design, the blades aren't keyed?, I would torque the cup washer to blade at the proper torque, then I would weld the cup washer to the blade itself. Ridiculous design.

Basically all zero turns along with virtually all other riding mowers use round hole blades. I don’t know what bases for comparison you’re using to say it’s a terrible design. I would venture to say the Kubota zero turn is the strongest design on the market. Kubota has a shaft drive deck. Basically all the others use a drive belt that slips under high load. The Kubota uses a double belt to drive the blades that’s last upwards of 1k hours. Virtually all the others use a single belt that only last a few hundred hours. The Kubota blades use a splined washer on the blade that’s better than just a regular bolt that virtually all the other zero turns use.

 

[4570Man]

98ft lbs on those small 10mm threads sure seems excessive

Is ZD326/331 the same setup as ZD1211 in the pic illustration in post #5 ?

The illustration in post 5 says 98-117 newton meters. If I translated right the top end of that chart at 117 is 86 foot pounds.

 

[4570Man]

Assuming the op has the bellview washers oriented correctly, I would be inclined to torque the bolts a little more. Perhaps add a 3rd washer and increase the bolt torque if there is enough thread (I've never added a 3rd washer).
I don't use a torque wrench on the blade bolts for my zd326 or zd1211, but I'm sure I keep them tighter than 98 ft/lbs.
I take the blades off to sharpen every 2 weeks or so, and have never had a problem with them.

You’re way over doing it with in excess of 100 ft pounds on a 10mm bolt. The blade bolts are self tightening anyway. I only put mine on snug and they never slip.

 

[LittleBill21]

Basically all zero turns along with virtually all other riding mowers use round hole blades. I don’t know what bases for comparison you’re using to say it’s a terrible design. I would venture to say the Kubota zero turn is the strongest design on the market. Kubota has a shaft drive deck. Basically all the others use a drive belt that slips under high load. The Kubota uses a double belt to drive the blades that’s last upwards of 1k hours. Virtually all the others use a single belt that only last a few hundred hours. The Kubota blades use a splined washer on the blade that’s better than just a regular bolt that virtually all the other zero turns use.

virtually all? I have personally seen it once, I have worked on maybe 50 different riders over my years, and all of the ones I worked on had a star variant stamped blade which is what kept it in place on the on the spindle from slipping, that said I have not worked on more industrial machines, usually lower end consumer grade stuff.

I have multiple machines on a single belt at close to 1k hour with no wear, so not sure I agree there at all

 

[Midniteoyl]

Basically all zero turns along with virtually all other riding mowers use round hole blades. I don’t know what bases for comparison you’re using to say it’s a terrible design. I would venture to say the Kubota zero turn is the strongest design on the market. Kubota has a shaft drive deck. Basically all the others use a drive belt that slips under high load. The Kubota uses a double belt to drive the blades that’s last upwards of 1k hours. Virtually all the others use a single belt that only last a few hundred hours. The Kubota blades use a splined washer on the blade that’s better than just a regular bolt that virtually all the other zero turns use.

Never had a round hole blade that didnt also have pin holes. My ZT uses pin holes.

 

[ROUSTABOUT]

Never had a round hole blade that didnt also have pin holes. My ZT uses pin holes.

Heavy duty commercial has round holes. I kept sharp blades handy and changed 66 blades a week. Basically half the mowers every other day. Kept a few new blades to replace ones too worn. They'd wear in two on the back side where they turned up. I welded some of those back and used them again.