How much weight up front?

[Jason280]

Those old fords are heavy tractors for their size. ~30% heavier than your new MX. Do you plan on using the same attachments with the new kubota?

Absolutely, I've used all the same attachments with the L4330....having the bucket up front makes a huge difference.

 

[LD1]

Absolutely, I've used all the same attachments with the L4330....having the bucket up front makes a huge difference.

That's actually quite surprising. The 4330 is a 3500 pound machine with a 75" wheelbase. The 3930 is 5500 pounds and 10" longer. I'm quite surprised it struggles

 

[Midniteoyl]

There is a rule of thumb, but not for our size of tractors: Answers from different OEMs (~100-120lb total weight per HP)

For the Fords, probably start with 400lbs-500lbs on the front and go up from there if needed.

 

[Jason280]

That's actually quite surprising. The 4330 is a 3500 pound machine with a 75" wheelbase. The 3930 is 5500 pounds and 10" longer. I'm quite surprised it struggles

Add in the FEL, and the L4330 is much closer to 5k lbs...plus, it has all the extra weight where it needs it most, out in front of the tractor.

 

[mo1]

There is a rule of thumb, but not for our size of tractors: Answers from different OEMs (~100-120lb total weight per HP)

View attachment 713836

View attachment 713837

For the Fords, probably start with 400lbs-500lbs on the front and go up from there if needed.

The rules of thumb above actually do apply to small tractors as well as larger ones.

The weight split percentages don't change based on size of tractor, you still need about 25% of the total weight on the front axle to be able to steer properly, and if the front axle is driven, you need more weight than that to get much traction out of that driven front axle. That is true if you have a 25 HP compact or a 600 HP center-articulated 4WD tractor.

The tractor weight vs. PTO HP figures are based on getting good performance in pulling heavy drawn and ground-engaging implements. Many compact tractors are much lighter than this as they are largely designed for tasks where minimal ground disturbance and high PTO HP are needed (i.e. mowing.)

Regarding the OP's Fords, a 3910 2WD (I am assuming it's a 2WD as those were more common) without any ballast had 2985 lb on the rear axle and 1695 lb on the front axle according to the University of Nebraska, so it has a 36/57 split without anything on the 3-point. I am not surprised that hanging what may be a thousand pounds or more of harrow off of the 3 point may make it a little light in the front. The scientific way to ballast is to mount the implement and use a truck scale to determine axle weights, and then ballast to bring the front up to "spec." The nonscientific way is to add weight until the front no longer feels "light," particularly with going up a hill with the 3 point raised.