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2009 x728 bouncy/bumpy

5224 Views 32 Replies 16 Participants Last post by  WVdeerehunter
I talked to another owner and found I wasn't alone in my feeling that our x700 series were more bumpy a ride than the x500 series we'd come from. First of all I don't blame the machine for my bumpy yard! But was hoping bigger tires, machine would reduce the feel

It's worst when turning tightly on grass, but some even when on pavement. Kind of a stuttering lurching and bouncing. I'm wondering if related to the hydraulic front wheel motors. Or maybe lateral force on the front tires is making the sidewalls flex. I tried inflating more but didn't help.

I feel like it's bouncier on straight runs if I go medium to fast on slightly bumpy turf (but smooth straight on pavement)

Has anyone else felt this way or better yet found any way to improve it?

I have a bad back and would love to improve this. Bought the suspension seat already...

Thanks for any advice
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Decrease the air pressure in your tires. Not sure if the lurching and bouncing when turning is caused by the full time 4-wheel drive not working correctly or not. Hopefully some more owners will chime in.
Make sure your hydraulic fluid is at the correct level for the front wheel motors and hydraulics. There is some information on other threads where owners had some quirky reactions during turns from the front hydraulic wheel motors. If I remember correctly it was due to low level of hydraulic fluid.
Locking Differential maybe stuck?
Our back yard is pretty bumpy, but with the hard cab on the x728 it rides like its on a cloud, you don't feel any bumps with all of the weight.

This is with a 47'' tiller on the back and 4 suitcase weights on the front and the cab.

Then in the winter a 47'' blower up front and 7 suitcase weights on the back and the cab.

I don't have a mower deck for it and won't put one on it.

I can't begin to tell you how smooth this thing is over bumps, you don't feel any rough ride at all, zero.

My 748 is not bumpy at all.. It was a bit "lurchy" at first... the drive train needs to break in. Also the tires were at LEAST 15PSI over inflated on delivery.

I run my rears at 9.0 PSI and my fronts at 12PSI.
Thanks for the input. (please keep it coming if anyone has anything else!!) I'll check the manual to read about the fluid. Hopefully it's straightforward for a non-mechanic to check...
Looks like the fluid, measured underneath the seat, is JUST at the lower hatch mark. Measured just resting the dipstick on the top of the tube, not screwing it in at all...
It needs weight, add some suitcase weights to the front and back and it will ride alot smoother. The tractor is to light for the power and will cause it to bounce and jurk around.
I'll just up my calorie intake...

No, my lawn stays so spongy; I hate to have it weigh even more. But I see your point.
I don't have an AWD X700 series tractor, but if the hydraulic fluid is at the low end of the hatch marks on your dipstick, that usually means you are down a fair amount. Perhaps someone who owns one can verify this but I believe he should add fluid until it reaches the top of the hatch marks. I am not sure how much fluid it takes to raise it from the bottom to the top of the hatch marks but perhaps one of the other AWD X700 series owners does.
I think it's going to take about a quart.. That's not a "lot" considering how much the system holds.. But it's enough to exacerbate the hurky jerkiness.

You measured the fluid correctly, just make sure it's cold and on level ground. They all are a bit low when delivered, lots of places for air to get trapped in the system and it just needs worked out. Once it's up to the top of the crosshatching you should be fine.

As for adding weight.. I won't argue that weight helps anything, but this is by no means a "light" tractor, the front end of these machines are so heavy I haven't met anyone who can lift mine off the ground :)
I'll pick up 2 quarts... is this the same fluid I'm going to lose when I hook up my deck bypass valve for snow blade?

JD Hyguard Low Viscosity Hydraulic Fluid.

You won't lose much when you do the valve. Also when you go to do the valve, you will probably have to remove the valve (knob and seals and shaft) from the diverter's "body" I wasn't able to turn it to tighten it and had to take it apart and then VERY carefully put it back together making sure not to cut or puncture the seals in the process.

You "could" pull the whole selective control valve away from the frame(I didn't try that).
Topping off the hydraulic fluid didn't make a noticeable difference, unfortunately.

One of the main reasons I upgraded from x500 to x700 series was hopefully to get a smoother ride (partly by adding the SE seat). But even with the better seat, my opinion is that it's rougher ride than the x534. but it's been so many months since I sold that; never got to drive them both the same day to compare, to be fair.

Are there any suspension components that need to be checked? My perception is that it's pretty smooth on pavement or going really slowly, but if I speed up much at all on grass, once it starts bouncing/lurching it just feeds on itself and grows. But if I slow down and restart more gradually I get past it. Hard to be 100% sure but it feels like a component of lurching in the forward-back direction, not just up-down bumpiness.

If I turn really tightly on pavement it does it a little. Not sure if it's lateral force on the front wheel side walls making the tires wobble or inconsistent turning of the front hydraulic motors....

I'm not expecting a luxury car ride, but this is enough to throw my (weak) back out sometimes after mowing. I know this post sounds a bit neurotic. But I'm hoping it'll sound like someone else's experience... I wish I had another x700 to drive on my lawn to see if it's "just in my head/lawn" and it's just how the machine is :( Not what I was hoping for for the price. (But otherwise love the machine so far; love the 60" 7iron deck. way better than the one on the x500 series I had)
I understand the description - the self-pepetuating bounce. That sounds like your tire pressures are way too high.

What are your tire pressures? 90% of the ride is in the rear tire pressures. Try setting the rears by sight versus pressure like you do on an ag tractor. Have someone sit on the seat and then drop the rear pressures until you get a SLIGHT bulge in the sidewall. Then try it. I wouldn't be surprised if you end up in the 7-8 psi range.

If you feel any scrubbing or scuffing from the front end, then increase the pressures in the rear a little. But I don't think you will have any overun issues (speed of front drive versus rear). I'd run the fronts at @ 10 psi.
Hey brentj,

Good luck tracking this down. Just a couple points of reference for you to consider. I upgraded from a 445 to my x728 almost exactly a year ago. I did not notice any significant difference in bounciness between those two. I also did not notice any jutters in corners, a pleasant surprise at how well the apportioning valving for the front drive system works. I spent a couple hours yesterday attending to my couple acres of leaves which means I was often transporting a full Trac-Vac across the lawn at a higher speed than I normally mow. Again, I did not notice extra bounciness. Among my trees I do have two large swamp maples that run their roots across the surface, and that makes for a bumpy ride under them. I always have to slow down when mowing under them, but that hasn't changed for the last 20 years through a 317, the 445, and the still new x728.

I'm sure you are doing a good job at diagnosing this, but is it possible that your forward pedal is more sensitive than was on your x500, so that once a bouncing starts, your foot begins bouncing on the pedal and causing or exagerating the speed lurches?

Finally, I am envious of your SE seat, but if you think it might be the cause of your problem, I'd be happy to sacrifice trade my standard for yours:fing32: Ok, guess not.
Thanks for the advice. I set them all to the middle of the range listed in the manual (without me sitting on it)

I'll have to experiment more I guess.
Ask your john deere dealer if you could borrow some weights, mine rides like a limo.

You don't feel any bumps, none.

Tell him to duplicate the weight I have.

A curtiss hard cab, three point, pto.

Now with a 647 tiller on the back 4 suitcase weights on the front.

Now with a 47'' two stage blower on the front, 6 suitcase weights on the back.

I'm 69 and have a tender back, this x728 drives and rides better then any car I have ever had, put the weight on it.

Hey brentj,

I'm sure you are doing a good job at diagnosing this, but is it possible that your forward pedal is more sensitive than was on your x500, so that once a bouncing starts, your foot begins bouncing on the pedal and causing or exagerating the speed lurches?
Good thought Jere, I hadn't thought of that yet!:fing32:
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