John deere 6820 problems

[marco]

I've a 6820 and the front axle seems to scrub/ tyres bounce a bit when turning tight. If I turn on and off the 4wd on concrete you can hear it clunk on and off. I reduced the tyre pressure to 22psi (16.9s) and it hasn't cured the problem. Any ideas on what to look for try?

 

[Lofty]

Sonds like it's got the wrong wheels/tyres on it. Has it just started to clonk having been fine before, or is the tractor new to you?

 

[milkloss]

My 6920 does it and I suspect it’s just wind up when you’re turning. Have a loader on mine and I’ve considered putting a switch in to prevent the 4wd coming on when braking whilst working round the yard.

 

[Lofty]

scrub/ tyres bounce a bit when turning tight.

Just re-read you post. Turning in 4WD with any tractor will cause wind up.

 

[nick...]

Could it be wrong oil in diff.i know Deere are specific on the spec of oil.diff locking and not releasing?
Nick...

 

[dowcow]

I know on my Massey there's two different axles that were fitted to this model, and they use different oils depending on who made it. Carraro and Dana I think they were. I think it was Carraro that instead of normal 85w90 it needed 90w105, obviously this would need checking as I'm working on memory here. Noticed very little clunking at the front end since changing it last year. Massey dealer gave me the wrong oil even with the serial numbers, which I just happened to notice before dropping the old oil.

 

[marco]

Ive had the tractor for the last 5 thousand hours. It's coming due for its 7500hr service so I'll drop front axle and hub oil and see what happens. The only other thing I can think of is 4wd clutch pack is dragging abit.

 

[milkloss]

I think you're over thinking it tbh but changing the oil won't hurt

 

[stephen.man]

I've a 6820 and the front axle seems to scrub/ tyres bounce a bit when turning tight. If I turn on and off the 4wd on concrete you can hear it clunk on and off. I reduced the tyre pressure to 22psi (16.9s) and it hasn't cured the problem. Any ideas on what to look for try?

Drop out the oil and refill with LS/90, CURE IT FOR SURE.

 

[stephen.man]

Your limited slip diff has a small set of plates each side built with in diff carrier, friction plates worn. If you have hygard in axle it will rattle like a bag of nails, thats why you want to be using LS 90.

 

[Tractortech]

I've a 6820 and the front axle seems to scrub/ tyres bounce a bit when turning tight. If I turn on and off the 4wd on concrete you can hear it clunk on and off. I reduced the tyre pressure to 22psi (16.9s) and it hasn't cured the problem. Any ideas on what to look for try?

Now Then..
Has it had regular 1500 hour oil changes in the front axle??
I'd change the oil as a start anyway. JD recommend JD Hygard.. I've serviced JD tractors for over 40 years and have no hesitation using it. There's nothing wrong with using a limited slip Diff gear oil either (Morris XEP80/90 for instance)
I had a 6410 some years ago which had missed a few oil changes and was grabbing and making an awful noise when cornering. Changed the oil, quick flash down the road and back,,,,,, different tractor..

 

[Northdowns Martin]

Will try and get a video of my 6534. When the 4wd is engaged by the brake pedal and then released it disengages with extreme violence. We've checked th3 wheel ratios are correct, another suggestion is wrong gear in 4wd gearbox was put in at build point.

 

[nick...]

When was the front axle oil last changed
Nick...

 

[Northdowns Martin]

Just had the convo, June 19, probably only done 250 hrs since.Reason it was charged due to clonking 4WD but I think it’s got worse. Checked what oil was put in, it wasn’t JD hyguard but should have been same spec. Will get some JD oil and try again.

 

[Lofty]

Will try and get a video of my 6534. When the 4wd is engaged by the brake pedal and then released it disengages with extreme violence. We've checked th3 wheel ratios are correct, another suggestion is wrong gear in 4wd gearbox was put in at build point.

More likely that wheels or tyres have been changed since it was new and they don't match what it was built for.
If you speak to Jon Moreton at https://farmerstyre.co.uk/ and give him the serial number of the tractor and the ratio of the plate on the front axle along with the size of tyres, he'll be able to tell you if its within tollerance. JD recommended the front wheels lead between +1.5-4%.
I bought a set of rowcrops for a 6150R that made it clonk out of 4WD. Gave Jon the details and he worked out the lead was over 5%. A change from 85 to 90 ascpect ratio tyres on the rears cured it. It drives smooth as silk on the road now.

 

[Northdowns Martin]

More likely that wheels or tyres have been changed since it was new and they don't match what it was built for.
If you speak to Jon Moreton at https://farmerstyre.co.uk/ and give him the serial number of the tractor and the ratio of the plate on the front axle along with the size of tyres, he'll be able to tell you if its within tollerance. JD recommended the front wheels lead between +1.5-4%.
I bought a set of rowcrops for a 6150R that made it clonk out of 4WD. Gave Jon the details and he worked out the lead was over 5%. A change from 85 to 90 ascpect ratio tyres on the rears cured it. It drives smooth as silk on the road now.

Thank you for contact Lofty. I spoke with Chris at Farmerstyre who was more than helpful. Maths works out we have 4.9% lead which is not ideal. Will now experiment changing tyres with another tractor and altering pressures to see if makes any difference. Change oil in front axle may help as well.