Tractor Hop

[Sandman99]

Hey having this issue for a few years ever since I got my tractor a 1977 ? 6100 d manual trans with snow blower on the front.

When I back up in snow the tractor hops!

The only way I can over come this, is to let the clutch out slower than my previous engagement. If its slow enough and when I get going I can let the clutch out all the way with no hopping.

I am running ag tires.

Is this a tire problem or a clutch problem, or something else?

Thanks for any suggestions.

 

[BigG]

Have you tried putting ballast on the back of the tractor? Sounds like the rear of the tractor is too light. You might also load the tires.

 

[MapleLeafFarmer]

if you keep the blower lifted off the ground say 1/2 the depth of the snow you are blowing does it still bounce?

 

[North Idaho Wolfman]

Ballast!
Is it in 4wd?
And when it's hopping is at least on front wheel spinning?

 

[Sandman99]

I have ballast in the rear tires and the blower is off the ground
usually in the hi position witch is about 6 inches when reversing
The tractor is 4 WD I would presume the front tires a slipping some

Thanks

 

[Vigo]

You need to figure out if any tires are slipping during this. IF any tires slip during the hop it could be something like excessive lash in the front driveshaft meaning that if one diff 'unloads' because its tires start to slip, the other end gets a 'running start' taking all the play out of the parts between until sort of 'banging' back into synched movement again. Sort of like 'wheel hop' on a car if you've experienced that. Grip is lost, parts accelerate rapidly with no resistance, and then when the spinning tire slams back down it's pretty harsh. Cycle repeats rapidly, hopping/banging.

It could also be a reflection of your front to rear tire size ratio being off and requiring one set of tires to slip a bit in order to roll while in 4wd, and it is simply not noticed in the forward direction due to differences in tire traction each direction (ags are directional and have different traction forward vs backward on many surfaces) and weight on each set of tires of the tractor when letting the clutch out. For example, if the blower is not 6" lifted when letting the clutch out to go forward, there is much less weight on the front tires. When beginning to roll forward more weight is dynamically transferred away from the front tires as well. When going in reverse with the blower lifted both the static and dynamic weight load on the front tires is higher, magnifying their traction and any side effects of slippage. If the tire size ratio is out of whack you can tell because the 4wd lever will feel a little 'stuck' while rolling along. In a perfect scenario you can actually pull the shifter out of 4wd while rolling and feel no resistance on that lever.

If it were not tire related it would be clutch related, probably oil contamination making the clutch 'chattery' and the effect is worse when the parts are cold. Also possible that the pilot bearing got dramatically worse and is letting the disc wobble 'out of plane' with the flywheel and pressure surfaces, making engagement weird and inconsistent.

So i'd say go try it again and see if tires slip or not. You might also just try leaving the blower dropped and see if it no longer does it in reverse. If so that would suggest it is related to tire slip.

 

[Sandman99]

You need to figure out if any tires are slipping during this. IF any tires slip during the hop it could be something like excessive lash in the front driveshaft meaning that if one diff 'unloads' because its tires start to slip, the other end gets a 'running start' taking all the play out of the parts between until sort of 'banging' back into synched movement again. Sort of like 'wheel hop' on a car if you've experienced that. Grip is lost, parts accelerate rapidly with no resistance, and then when the spinning tire slams back down it's pretty harsh. Cycle repeats rapidly, hopping/banging.

It could also be a reflection of your front to rear tire size ratio being off and requiring one set of tires to slip a bit in order to roll while in 4wd, and it is simply not noticed in the forward direction due to differences in tire traction each direction (ags are directional and have different traction forward vs backward on many surfaces) and weight on each set of tires of the tractor when letting the clutch out. For example, if the blower is not 6" lifted when letting the clutch out to go forward, there is much less weight on the front tires. When beginning to roll forward more weight is dynamically transferred away from the front tires as well. When going in reverse with the blower lifted both the static and dynamic weight load on the front tires is higher, magnifying their traction and any side effects of slippage. If the tire size ratio is out of whack you can tell because the 4wd lever will feel a little 'stuck' while rolling along. In a perfect scenario you can actually pull the shifter out of 4wd while rolling and feel no resistance on that lever.

If it were not tire related it would be clutch related, probably oil contamination making the clutch 'chattery' and the effect is worse when the parts are cold. Also possible that the pilot bearing got dramatically worse and is letting the disc wobble 'out of plane' with the flywheel and pressure surfaces, making engagement weird and inconsistent.

So i'd say go try it again and see if tires slip or not. You might also just try leaving the blower dropped and see if it no longer does it in reverse. If so that would suggest it is related to tire slip.

Ok all good points I will do some experimenting Interested to see if I can shift out of 4WD when moving

IF it was easy to get to the clutch I would take a look at that but not unless I have to ! Call me chicken!

 

[Dave_eng]

Ok all good points I will do some experimenting Interested to see if I can shift out of 4WD when moving

IF it was easy to get to the clutch I would take a look at that but not unless I have to ! Call me chicken!

My post points out ONE consideration but not the only one
I watched a John Deere engineering video on the subject of tractor hoping.
They demonstrated that hopping starts to occur with a 6% wheel slip.
It happens because of tire sidewall flexing
Tire pressure, especially on the fronts, has a big influence as the hopping is really a harmonic situation like a guitar string.
Here is a link to the video. What you see is the tractor pulling a number of implements where the drawbar load can be controlled.
John deere hop
Here is another video mostly focus on tires.
Tires

Try adjusting tire pressures as it will be the easiest step.

Dave

 

[Vigo]

Ok all good points I will do some experimenting Interested to see if I can shift out of 4WD when moving

IF it was easy to get to the clutch I would take a look at that but not unless I have to ! Call me chicken!

The only thing im gonna call you is someone who read my whole post, that makes you a 'rare bird'

I have run a bunch of tire setups on b6100 and 7100 and that 4wd lever 'tension' thing is a foolproof way to know whether a tire setup is 'unhealthy' due to size mismatch. It will always go into a bind when making sharp turns etc but if that lever loads up even going straight then you know your tire sizes are a bit too far off for comfort. Even if that were the case it may be fixable just with tire pressures.

Let us know what you find out!

 

[jimh406]

I'd try adjusting the clutch. If that doesn't work, I'd try lower RPMs or different higher gear when you start backing up.

 

[6869704x4]

Are the tires OEM size? If not maybe the size ratio is off? The back tires can wore down and change the ratio. On my L45 I can shift on the fly(well, shift on the crawl) no resistance.

 

[mikester]

I would be more suspect of harmonics causing the bounce. In certain snow conditions going through the fields with my rear 3PH blower and loader on the front it can start to hop/bounce back and forth. I have to change my travel and engine speeds.

Even without the blower If I have a loaded bucket I get less hop. It's a big reason why I want to add an accumulator on my loader, stop the crazy harmonics. It's the nature of wheeled machines that have no suspension.

 

[Vigo]

I too want to add some accumulators. I even snagged some old ABS accumulators off old cars for free.. Pretty sure the pressure is already compatible but not sure the bladder material is as it seems a lot of things are safe for either oil or brake fluid but not both.

 

[Sandman99]

Ok an up date

I did try to shift into 2 WD when moving.

It went into 2wd and back to 4WD very easy.
As I remember I get tire hop in loose snow & only when backing up

 

[North Idaho Wolfman]

Throw some ballast on the back and see how it does.

 

[Sandman99]

Throw some ballast on the back and see how it does.

I have ballast in the tires now what increments should I be trying20 pounds or 50

 

[North Idaho Wolfman]

I would get 100lbs on the three point and see what that does for you, sometimes it's just a little to get a big improvement.

 

[Vigo]

Yeah, i would never bother with adding an increment less than 50 lbs if you have a choice, considering the 3pt will lift 500 right from the factory.

You can also try leaving the blower on the ground as you back up. That is likely a similar weight difference on the rear tire contact patch, as to add 100lbs on the 3pt. It may not be a 'solution' but it's a test that doesn't require you to plan or have anything, just to remember to do it.

 

[ken erickson]

For what it’s worth.
I was moving snow , foot to foot and half of dry sandy consistency snow, with my HST L2501, filled R4’s and box blade. When backing up I would get “wheel Hop“ at times. I chalked it up to the nature of the beast (Tractor, no suspension, type and amount of snow as it pushed, transferred snow under the tires). I felt the wheel hop was totally a by product of snow conditions and in no way an issue with the tractor.