748 problem with shuddering

[wilnis]

Hi-I have a 748 with 7iron deck that I love, 360 hours and only a broken deck hanger (my fault) but it has an annoying feature. If i drive up a very slight slope it will shudder to the point it almost hops. Only at slow speeds, it I accelerate a little it seems to go away.
My dealer poo-poos this as a non problem but I'm curious as to why. I changed the transmission fluid correctly at 50hours, 250 hours and the level is at the top of the cross hatch on the dip stick. Any thoughts would be appreciated. Thanks. Bill

 

[Kish318420]

Is mower in use, when this happens or just driving? When you accelerate is it engine (RPM) or foot pedal (ground speed)? When you changed fluid did you use JD or other party, Low, Reg, or High viscosity. You left information out, so we have to do the spatter approach.

 

[Spanner]

More questions:

X748??

What do you mean by "Slow speeds" ? Is that slow engine speed and you accelerate by increasing revs? Or is that slow ground speed while engine revs are high?

Are you on grass or hard surface when this occurs?

Are you in 2WD, 4WD or do you have the later Hydrostatic Front Axle?

 

[wilnis]

Hi-ground speed is slow, just starting out, going around bushes, trees, etc, but does it more going in straight line. Mower blade speed at full throttle, JD low viscosity fluid used at direction of dealer, mower deck in operation on grass surfaces (I have not tried it on hard surfaces such as blacktop drive). It is hydraulic(hydrostatic) 4wd and I have no manual control over that as far as I know. As the ground speed increases the shuddering decreases. X748 special edition machine. Any other things I left out, tell me and I will add them. Bill

 

[Spanner]

Is there any difference whether the blades are running, or not?

 

[wilnis]

not that I can tell, at slow speeds, with or without the blades running. I've noticed it more with the blades running and the mower at slow speeds because when I'm not cutting, I'm not usually going slow.

 

[ccsial]

I suspect you have the newer model with full time 4WD. I know several people with these units that have had some jerking under various conditions.

 

[wilnis]

ccsial-Thanks for that information, that has been my speculation as it has been flawless otherwise and this symptom is more of an annoyance than a problem. Thanks again. Bill

 

[Spanner]

Yes. The full-time 4WD was established in Post #4. The only one I have seen with "Jerky" drive was an early one. It had an issue in the front axle hydrostat and the whole axle was replaced under warranty. The axle was returned to the factory for analysis so we never got to pull it apart.
Sorry I can't be more help. If you can live with it, carry on. If it is of concern, invoke your warranty and discuss with your dealer. Get the "Fault" logged with JD DTAC so you can get some resolution if necessary.