I got bad news today!

[CalG]

Certainly not! Any slop in suspensions will cause breakage faster due to impact/shock loading. The suspension appears to have poorly made bushings in the aluminum uprights. Either bad material or bad tolerances.

This is not true. Any mechanism that can prolong the transfer of forces during impact can only serve to DECREASE the shock /impact loading.

Its velocity over time and distance. Do the math.

There are rubber bushings in all our automitive suspension as well, Only that the compliance rate (rubber hardness) is so high we can't move the wheels by hand. Rubber just the same!
Racers replace the rubber parts with metal on metal, and pay the price with noise, stress related failures and high maintenance. (Half racers go half way and use "firmer" polyurethane bushings)

Not a good trade for something that is supposed to be fun ;-)

 

[Hersheyfarm]

This is not true. Any mechanism that can prolong the transfer of forces during impact can only serve to DECREASE the shock /impact loading.

Its velocity over time and distance. Do the math.

There are rubber bushings in all our automitive suspension as well, Only that the compliance rate (rubber hardness) is so high we can' move the wheels by hand. Rubber just the same!
Racers replace the rubber parts with metal on metal, and pay the price with noise, stress related failures and high maintenance. (Half racers go half way and use "firmer" polyurethane bushings)

Not a good trade for something that is supposed to be fun ;-)

Right. You can make a 'rubber' ibeam that can support and elephant.Or a ball of rubber that can be squished flat by a pound. The issue here is a wheel placing torque to ground will flare out during acceleration alone, causing each rear tire to want to 'steer' away from each other.

 

[DIXIEDOG]

The problem is, for us 1100 owners at least, is there is no alternative.They have a very unique product with the cab.

Very true....it's a very expensive piece of equipment too. It's disappointing that nothing can be done to remedy the slop. I know if it was my $$ I'd be upset over it to say the least. Hopefully enough chatter comes up that will force Kubota to do the right thing and start replacing parts.

 

[PapaPerk]

This is not true. Any mechanism that can prolong the transfer of forces during impact can only serve to DECREASE the shock /impact loading. Its velocity over time and distance. Do the math. There are rubber bushings in all our automitive suspension as well, Only that the compliance rate (rubber hardness) is so high we can't move the wheels by hand. Rubber just the same! Racers replace the rubber parts with metal on metal, and pay the price with noise, stress related failures and high maintenance. (Half racers go half way and use "firmer" polyurethane bushings) Not a good trade for something that is supposed to be fun ;-)

The suspension should not have slop in it! Vehicle suspension with bushings have no slop. If they do they break.

You are confusing slop with dampening. The Kubota has way too much slop (excess multiple degrees of freedom).

When you can move a suspension/drivetrain system with your bare hands and it flops around there's a problem!

And believe me I know the math!!

 

[Tailrotor]

Calg

Rubber bushing hardness is measured in Shore not compliance rate. It would be a number such as 1 2,3,4 and so on this number will determine the rate at which it crushes at and the spring back or return to its original shape and how long it will stay that way.

So the harder the shore # the less slop you have and the rubber will wear better overtime. Now if you referring to compliance rate as the theory or dynamic rubber and it's ability to flex and the rate of change that's another subject altogether.

But for all intense purposes rubber bushing will be measured in shore.

 

[rapracing]

Well I got the machine back yesterday.

The dealer said they "did not" do anything in the front. I thought he had told me on the phone they put shims in to keep it from moving front to rear but I guess not. He said the rep did not want to do anything that is the way the want it. I took it for a ride last evening on a bit of a rough road. Traveling 5-8MPH and it thumps just like it did before. I am 99% sure that is in the front end.

They did however put shims in the rear where the pins go through the hub. He said that took all the movement out of the rear wheel (will jack it up a little later today and check that). He said it was "nylon" bushings in the hub. Not sure if I read on hear or the other forum but supposedly they are rubber? I don't know if they changed them to nylon or what happened there.

I guess I am still not sure what I should do. The old machine shows some signs of wear and tear but less that 400 hours. I guess I could but a little money in it and have a good machine for a whole lot less money.

 

[PapaPerk]

Well I got the machine back yesterday.

The dealer said they "did not" do anything in the front. I thought he had told me on the phone they put shims in to keep it from moving front to rear but I guess not. He said the rep did not want to do anything that is the way the want it. I took it for a ride last evening on a bit of a rough road. Traveling 5-8MPH and it thumps just like it did before. I am 99% sure that is in the front end.

They did however put shims in the rear where the pins go through the hub. He said that took all the movement out of the rear wheel (will jack it up a little later today and check that). He said it was "nylon" bushings in the hub. Not sure if I read on hear or the other forum but supposedly they are rubber? I don't know if they changed them to nylon or what happened there.

I guess I am still not sure what I should do. The old machine shows some signs of wear and tear but less that 400 hours. I guess I could but a little money in it and have a good machine for a whole lot less money.

Yes if the upright bushings are rubber that could be a big issue. For this machine it should be nylon. Please let us know if rear end has slop in it now.

 

[rapracing]

Yes if the upright bushings are rubber that could be a big issue. For this machine she should be nylon. Please let us know if rear end has slop in it now.

I was just out and jacked it up. The play seems to be gone, at least for now. I am still confused as to whether it is rubber or nylon. On the net tractor talk forum there is a guy who tore his machine down to see what was in there. That is where I heard it was rubber. The dealer had told me it was rubber as well. Yesterday he said nylon. I said to him "rubber or nylon" and he said "no, no it's nylon". From my understanding of what he told me, they put a spacer between the a-arm and the bushing on the pin to take away the play. I'm not sure if that's good or bad though. He said it was a steel washer the thickness to tighten it up. If that is in there spinning on the pin it is going to wear the bushing, whether it is rubber or nylon, at least I would think???

ETA: I think I am going to try pulling a pin out and see exactly what they did put in it. I'll try to do that sometime today.

 

[CalG]

Calg

Rubber bushing hardness is measured in Shore not compliance rate. It would be a number such as 1 2,3,4 and so on this number will determine the rate at which it crushes at and the spring back or return to its original shape and how long it will stay that way.

So the harder the shore # the less slop you have and the rubber will wear better overtime. Now if you referring to compliance rate as the theory or dynamic rubber and it's ability to flex and the rate of change that's another subject altogether.

But for all intense purposes rubber bushing will be measured in shore.

Only Shore scale anymore? Has the Durometer scale been made obsolete?? This will be big news in the o-ring industry....

It doesn't really matter what the units of measure are, compliance is NOT a unit, it is a quality. Double the hardness (Shore value) but also double the loading, and you have exactly the same "quality" of compliance. Force per unit area and all that ;-)



How Many X Models - Page 3 - Net Tractor Talk ...................... read post 54

Seems like the entire issue is a matter of opinion. At least by the above account.

And just for comparison. Automotive practice for the driven axles on independent suspension is to set static toe in NEGATIVE,(i.e. toe OUT) or at zero. That way, when transmitting power, Toe goes positive. With good results.

There are some rather well thought out systems of links, arms and bushings to achieve the desired aspects of comfort and control.

Rubber is a very good suspension material when used to it's best qualities. Seems like there are a few qualities of this RTV that don't impress anyone, but no one has really described the fault.

It's like the medical system, good at treating the symptoms, but not so good at fixing the cause.

 

[PapaPerk]

Only Shore scale anymore? Has the Durometer scale been made obsolete?? This will be big news in the o-ring industry....

It doesn't really matter what the units of measure are, compliance is NOT a unit, it is a quality. Double the hardness (Shore value) but also double the loading, and you have exactly the same "quality" of compliance. Force per unit area and all that ;-)

How Many X Models - Page 3 - Net Tractor Talk ...................... read post 54

Seems like the entire issue is a matter of opinion. At least by the above account.

And just for comparison. Automotive practice for the driven axles on independent suspension is to set static toe in NEGATIVE,(i.e. toe OUT) or at zero. That way, when transmitting power, Toe goes positive. With good results.

There are some rather well thought out systems of links, arms and bushings to achieve the desired aspects of comfort and control.

Rubber is a very good suspension material when used to it's best qualities. Seems like there are a few qualities of this RTV that don't impress anyone, but no one has really described the fault.

It's like the medical system, good at treating the symptoms, but not so good at fixing the cause.

The rubber is too soft for a bushing on the a-arm mounts. That's the problem with rubber. It should be nylon because it lasts longer and does not flex.

When you make rubber bushings for suspension they are reinforced with steel innards.