stripped BX 60" deck blade bolts

[radioman]

My BX24 60 inch mower deck had a couple bolts stripped and spindles threads was ruined. I think i got a little overzealous :ashamed: with the air impact when tightening them since last summer the blades were spinning and not cutting from one of them. I had a bear of a time trying to take them off last weekend when i was about to take blades off to sharpen them. I was able to get the bolts off by reversing/forward many time to get the stripped threads loose enough to back bolt out- but i was nervous about needing a new shaft and rebuild the spindles. Since the dealers were closed over the weekend, i waited till monday to pick up new bolts and yesterday finally worked on it. i had to retap the spindles and if anyone needs to know what tap you need its M12 - 1.25 . got one spindle cleaned easily - but the middle spindle was a bear. took me over an hour to tap it. it must be high speed steel or something as it was really hard to run new thread. used whole quirt can of oil and i was nervous about breaking the tap as it was really twisting as i was turning it when trying to go a tiny 1mm of a turn or so. i had several pieces of metal fragments come out as i air cleaned it out - but it was finally done and i was able to test mow it last night at 9pm jand so far so good

So - lesson learned - if the blades werent holding anymore and not cutting right - its possible the bolts were either worn out or stripped and threads is trashed a little. this time I hand tighten them instead of using impact. Ill still use impact to take them out , but will always hand tighten the bolts.

 

[skipperbrown]

There should be a couple of concave washers you put on the shaft counterpoised after the blade goes on. These act as lock washers to keep the blades/nuts tight and not allow the blades to slip. If you have them, replace them as they are apparently worn out. If you don't have them, get them. These washers are what do the bulk of the holding so you don't have to torque the nuts down to the point of stripping. That must have been a job!

 

[ovrszd]

Good point skipper. That was my question? Should be washers there. The bolt doesn't have to be very tight.

I truly can't remember the last time I sharpened my mower blades. I use these predator blades I get thru JD. They are extremely hard. Replace them when they actually wear thru the serrated lifts and they become ineffective.

Sharpening, if needed, should always be done with something mild like a flapper wheel. A grinding wheel will heat the cutting edge and remove it's temper. Then you get the joyful experience of frequent sharpening.

Glad you got your problem repaired. Much patience was needed I'm sure.

 

[Mowbizz]

Hand that happen to me last year. Just one bolt though. I should check those washers too...this will be my next job between raindrops.
I could not find one of those taps anywhere and finally found that a Grainger store had them and i had to drive 2 hours to get it. Problem solved but not looking forward to this seasons surprises!

 

[Dave M7040]

There should be two stacked spring washers on the wider BX mowers.

The proper term for these washers is "BELLEVILLE WASHERS."

The bolt torque is up to 86 lb ft

Dave M7040

 

[radioman]

There should be two stacked spring washers on the wider BX mowers.

The proper term for these washers is "BELLEVILLE WASHERS."

The bolt torque is up to 86 lb ft

Dave M7040

Mine came with one cupped washers and one none slip washer.good point though... I should replace the cupped washers.. And thanks for proper torque specs. I'm pretty sure that's why I'm having problems last summer. Weak cupped washers plus over tightening. Time to hit online ordering....

 

[Dave M7040]

Mine came with one cupped washers and one none slip washer.good point though... I should replace the cupped washers.. And thanks for proper torque specs. I'm pretty sure that's why I'm having problems last summer. Weak cupped washers plus over tightening. Time to hit online ordering....

Be careful with any mower. Some have reverse thread bolts for the blades.

Re tapping a reverse thread hole is not simple.

Dave M7040

 

[radios1]

you should use tapping fluid, not oil for tapping. many places sell it for threading pipes..

 

[Mowbizz]

Serviced my deck and installed it for the season. No problems with the blade bolts and my bellville washers were in good shape!
Hardest thing was getting a new grease cartridge in my Milwaukee gun...what a pain.
Maybe someone can post the correct way to change the grease cartridges? I must be doing something wrong.
Haha...never mind. Just looked it up on YouTube and I was doing it completely back asswards....didnt know the thing unscrewed from the front...duh.

 

[radioman]

Be careful with any mower. Some have reverse thread bolts for the blades.

Re tapping a reverse thread hole is not simple.

Dave M7040

yeah -- when i went to the store to get the tap - they had a sizing chart with threads and bolts with labels so i checked the threads with mine bolt i brought in-- its a normal thread not reverse so im good there

 

[radioman]

just an update - one spindle bolt became loose and now its not backing out. i ordered new bellville washers and it should arrrive tues. hopefully they should resolve my issue.

 

[Mowbizz]

just an update - one spindle bolt became loose and now its not backing out. i ordered new bellville washers and it should arrrive tues. hopefully they should resolve my issue.

That is what mine did last year. Bolt would not come out. Finally got it out then went on the tap search.
This season the same bolt was fine.

 

[Henro]

just an update - one spindle bolt became loose and now its not backing out. i ordered new bellville washers and it should arrrive tues. hopefully they should resolve my issue.

I think what happened was you stripped the spindle threads somewhat initially. Then you bought a tap to chase the threads, and restored them somewhat, but not to their original condition.

Apparently this one spindle now has threads that are further damaged. When you chase the threads again the result will be even less strong. The Belleville washers require a certain amount of torque on the bolt to compress them.

The question is: After you chase the threads a second time, will there be enough threads left to hold the bolt at the needed torque?

If not, you may be looking at replacing the spindle. Perhaps a HeliCoil could be used?

Another option might be to drill out the existing threads and tap to the next largest close size, be it SAE or metric.

If whatever you might try fails, nothing is lost, as you will have to replace the spindle anyway if the bolt fails to hold.

Just my take on it.

PS - It will be interesting to see the time shown for this post. It is early afternoon where I am as I type this.

 

[SPYDERLK]

The height of the washer stack is extremely important. Too short and the bolt clamps only the washers leaving the anti spin washer and blade loose. Too long and you have a good clamp but the anti spin washer does not engage the spindle enuf or at all. That can let the spindle turn on the bolt, tightening and wringing it off.

 

[Henro]

The height of the washer stack is extremely important. Too short and the bolt clamps only the washers leaving the anti spin washer and blade loose. Too long and you have a good clamp but the anti spin washer does not engage the spindle enuf or at all. That can let the spindle turn on the bolt, tightening and wringing it off.

In other words, are you saying that if the cup washers are flattened (deformed), the stack will be shorter and therefore the cup washers will not perform their function properly?

Are you also saying that if the spindle/bolt combination slipped on the blade, and then the blade grabbed the bolt for whatever reason, the bolt could experience excessive torque and snap off?

 

[SPYDERLK]

In other words, are you saying that if the cup washers are flattened (deformed), the stack will be shorter and therefore the cup washers will not perform their function properly?

Are you also saying that if the spindle/bolt combination slipped on the blade, and then the blade grabbed the bolt for whatever reason, the bolt could experience excessive torque and snap off?

Actually it is the working/compressed stack height that is important. The anti spin washer has a hex shaped hole to engage the hex on the end of the spindle. You need good engagement but cant go more than the thickness of the washer because it will bottom out on the spindle hex and wont flatten the spring washers fully flat to then actually pinch the blade tightly. (Clamping force is way above the point that flattens the "cup" washers.) I have had to tailor my washer stack with a thin extra washer above the Belleville/spring washers - due to wear I guess.
. . . And yes, without the anti spin washer doing its job, blade slips can act to tighten the bolt and wring it off.

 

[Henro]

Actually it is the working/compressed stack height that is important. The anti spin washer has a hex shaped hole to engage the hex on the end of the spindle. You need good engagement but cant go more than the thickness of the washer because it will bottom out on the spindle hex and wont flatten the spring washers fully flat to then actually pinch the blade tightly. (Clamping force is way above the point that flattens the "cup" washers.) I have had to tailor my washer stack with a thin extra washer above the Belleville/spring washers - due to wear I guess.
. . . And yes, without the anti spin washer doing its job, blade slips can act to tighten the bolt and wring it off.

Are we talking about the same mower? I am out of town so I cannot check mine, but do have this screen shot from a parts manual I downloaded.



Looks like the dust cover is the only thing between the spindle end and the blade surface. On the other side of the blade are the two cup washers, a lock washer, and the bolt goes through the whole works and pulls everything tight against the spindle end.

I see no anti-spin washer. Am I missing the obvious? Would not be the first time.

Looking at this drawing it seems to me the important consideration is the state of the cup washers. Height of the washers would define whether they are satisfactory or need replacement I suppose. But this value is not given...

Bill

 

[SPYDERLK]

Actually it is the working/compressed stack height that is important. The anti spin washer has a hex shaped hole to engage the hex on the end of the spindle. You need good engagement but cant go more than the thickness of the washer because it will bottom out on the spindle hex and wont flatten the spring washers fully flat to then actually pinch the blade tightly. (Clamping force is way above the point that flattens the "cup" washers.) I have had to tailor my washer stack with a thin extra washer above the Belleville/spring washers - due to wear I guess.
. . . And yes, without the anti spin washer doing its job, blade slips can act to tighten the bolt and wring it off.

Are we talking about the same mower? I am out of town so I cannot check mine, but do have this screen shot from a parts manual I downloaded.

View attachment 604775

Looks like the dust cover is the only thing between the spindle end and the blade surface. On the other side of the blade are the two cup washers, a lock washer, and the bolt goes through the whole works and pulls everything tight against the spindle end.

I see no anti-spin washer. Am I missing the obvious? Would not be the first time.

Looking at this drawing it seems to me the important consideration is the state of the cup washers. Height of the washers would define whether they are satisfactory or need replacement I suppose. But this value is not given...

Bill

:thumbsup: Thanks for the diagram!

Part # 120 is what I am calling the anti spin washer. - - By its internal hex it "keys" to the spindle tip. Since the bolt screws into the spindle, any slip of the blade must be isolated from the bolt lest the slip force spin the bolt tighter and tighter. That washer provides this isolation.

The cup/spring/belleville washers spread the clamp force nicely on the blade but they operate totally flat. Older, well used cup washers dont spread the clamp force quite as well, but its the flat thickness of them in their position that is most important. Their spring force is trivial compared to the force applied by the bolt. That force must come directly to bear as a pinch on the blade before the anti spin washer and bolt bottom against the spindle nose.​

 

[Henro]

The cup/spring/belleville washers spread the clamp force nicely on the blade but they operate totally flat. Older, well used cup washers dont spread the clamp force quite as well, but its the flat thickness of them in their position that is most important. Their spring force is trivial compared to the force applied by the bolt. That force must come directly to bear as a pinch on the blade before the anti spin washer and bolt bottom against the spindle nose.

At the risk of beating this horse more than anyone would like...and since the conclusion by Radioman that he caused the thread damage by over torquing the bolts is likely true, I suppose there is no damage in talking about the mechanical set up a bit more.

I assume the spindle has a hex shape only towards the end, and the part where the blade fits is circular. If so, if one were to put the anti spin washer on the shaft end, there would be a certain space between the dust cover and the anti spin washer, when the anti spin washer hit the end of the hex portion of the shaft. The question becomes: Is this space greater than the height of the blade plus two compressed cup washers, or not?

Spyderlk, you mention you feel the pressure applied by the bolt pushing on the anti spin washer far exceeds the pressure exerted by the cup washers themselves. This could only be true if the cup washers were fully compressed and essentially acting just as flat washers would. If so, then why have them to begin with?

My guess is that the system is designed to operate with the cup washers NOT fully compressed, so that a blade will slip if it strikes something hard in the ground, thereby reducing the mechanical shock felt by the spindle somewhat.

Without looking back, I believe Radioman also mentioned there was only one cup washer on his spindles when two are specified. If so, there would be more of a tendency for his blades to slip than if two cup washers were in place.

I guess what I am thinking is that the anti spin washer probably bottoms out on the spindle end BEFORE the cup washers are fully compressed. And that the cup washers serve as a bit of a shock reliever if the blade impacts a solid object like a rock.

This has become a learning experience for me and perhaps others as well. Appreciate you thoughts on my conclusions Spyderlk.

Thanks to Radioman for starting this thread. Hope to see a success report soon!

Bill

 

[aczlan]

Re: stripped BX 60" deck blade bolts

I assume the spindle has a hex shape only towards the end, and the part where the blade fits is circular. If so, if one were to put the anti spin washer on the shaft end, there would be a certain space between the dust cover and the anti spin washer, when the anti spin washer hit the end of the hex portion of the shaft. The question becomes: Is this space greater than the height of the blade plus two compressed cup washers, or not?

As I recall, the hex on the ends of the spindles on our bx2660 is somewhere between 1/2"and 3/4" tall.
Slightly taller than the hex washer and the two bellevue washers when compressed.

Aaron Z