4720 Front Axle Question

[Cranky]

Is the bolt in the picture the only thing keeping the front axle attached to the tractor?

How tight should it be?

Sorry for the stupid questions, but I found it was only finger tight this morning. I haven't been able to find any info about it and have had scary thoughts of the front axle falling off while I was brush hogging or worse -- driving down the road moving the tractor about 2 miles.

Thanks!

 

[jd110]

That bolt adjusts the end play of the front axle. You want to jack up the tractor so the axle is hanging free. Then turn the bolt in until it just removes any forward and backward play. THen turn the nut under the head of the bolt down tight to keep the bolt from coming loose. You don't want the bolt adjusted too tight or the axle wont be able to pivot smoothly when running over uneven ground.

 

[Cranky]

Thanks jd110!!

 

[jgayman]

Is the bolt in the picture the only thing keeping the front axle attached to the tractor?

How tight should it be?

Sorry for the stupid questions, but I found it was only finger tight this morning. I haven't been able to find any info about it and have had scary thoughts of the front axle falling off while I was brush hogging or worse -- driving down the road moving the tractor about 2 miles.

Thanks!

View attachment 516125

The adjustment procedure for this bolt is detailed in the Owner's Manual.

Adjusting Front Axle Thrust Bolt Torque
NOTE: Adjust bolt torque at the required service interval to prevent excessive forward and rearward movement of the front axle.

1. Park machine safely. (See Parking Safely in the Safety section.)

2. Raise front axle off ground to take machine weight off the front axle.

3. Loosen jam nut (A).

4. Tighten bolt (B) to 32 N•m (24 lb-ft). Do not overtighten.

5. Tighten back the jam nut.

6. Lower front axle back to ground.

 

[Spanner]

And grease that front bushing regularly. The fitting is visible in your pic. There was a Serial No. break and not all front trunnion bushes are greasable. Yours is.

The rear trunnion bushing is surrounding the MFWD driveshaft input. The front bushing is in that casting you show and which is secured by 2 bolts each side through the chassis frame. Look for them from the side.

So the axle is secured front and back. As the others have said: that bolt is just to adjust free-play slop.

:wrench:

 

[Cranky]

Thanks jgayman and Spanner!

I will be certain to adjust bolt torque and grease the bushing before I use the tractor again.

 

[Red Horse]

And grease that front bushing regularly. The fitting is visible in your pic. There was a Serial No. break and not all front trunnion bushes are greasable. Yours is.

The rear trunnion bushing is surrounding the MFWD driveshaft input. The front bushing is in that casting you show and which is secured by 2 bolts each side through the chassis frame. Look for them from the side.

So the axle is secured front and back. As the others have said: that bolt is just to adjust free-play slop.

:wrench:

Well thanks for that info about the serial no. break. I'm not home now so I will check mine tomorrow-I saw that grease fitting in picture and said.."what grease fitting!??"

 

[wcarm]

I was trying to adjust my front axle thrust bolt today (J Deere 4720) per the Operator's Manual (axle hanging free), and the bolt would not tighten i.e., would not make the torque wrench click at about 20 lb/ft, until I tightened it it all the way down on the jam nut. I am sure it is supposed to tighten up before it touches the jam nut?

Tomorrow, I plan to back it out some and see how the axle moves. What would be a symptom if I have it too tight? Axle won't move up and down?

I googled and found one J Deere manual that said to, after tightening the thrust bolt to spec (22.12 lb.-ft), "oscillate axle from stop to stop 3 times. Check torque". I guess I will try that.

All ideas appreciated.

 

[beenthere]

Don't follow, but is the jam nut loose while you adjust the bolt?

 

[Cranky]

My understanding is the jam nut should be tightened first to about half of the thrust bolt spec (11 lb.-ft).

The thrust bolt should then be tightened against the jam nut.

Someone will probably correct me if I am wrong.