Cure for the death wobble?

Coworker bought a 40U from another guy at the plant, loves it, but he fears using fourth gear, even at low rpm, because the front wheels take of on the "death wobble". He says the tie rod ends appear tight, but the tractor turns considerably sharper to the left than to the right (mirror image of my 2355N). He indicated that one tie rod was adjusted to a notch longer than the other.

I guessed that a PO may have changed tie rods or at least the ends, and got the steering wheel off-center with both rods off, thus resulting in the offset. I do not know if the 40U is centered- we have a 40S which is centered, but my MI is offset to the right.

Should I suggest the other ends of the tie rods, or steering box slop, etc.

PO might have offset them to move the wear spot away from the middle.

Should be set like your MI. Start with checking wheel bearing preload and work your way up all the way up to the steering tube connection checking for wear. Put the tie rods back where they're supposed to be and set the toe in about a quarter inch. He might get it turning the same both ways just by setting the tie rods properly or he may have to drop the Y and move it to where both throws are equal.

Take a look at the diagram below.





Note the left steering arm (Key 4), right steering arm (Key 15), adjustable end with cover (Key 28), tie rod tube (Key 31), and end with dust cover (Key 36).

Reviewed the [b:654c4848f0]SERVICE MANUAL JOHN DEERE 40 SERIES TRACTORS & CRAWLERS SM-2013[/b:654c4848f0] under the [i:654c4848f0]Toe-in Adjustment[/i:654c4848f0] topic on page 170-15-6.

"[b:654c4848f0][i:654c4848f0]Following disassembly of front axle or after replacing any of the steering linkage parts, check toe-in according to following procedure.

With front wheels in the straight ahead position, and the front of the tractor on the floor, measure front wheel tread width at front and rear of wheels at hub height. Proper toe-in is 1/8 to 1/2 inch less in front than in rear. To make necessary adjustment, loosen clamps at inner end of tie rods and set screws at outer ends. Turn each tie rod tube an equal amount until proper toe-in is obtained. Make sure set screws at end of tie rods are pointed away from the axle.

NOTE: Tie rods must be equal in length.

Turn steering wheel to extreme right and left. Steering arms must contact steering arm at each extreme.[/i:654c4848f0][/b:654c4848f0]"

Take a look at the photos below of the adjustable ends on "Audie" our Model 40S.





This is one method of centering the steering on the Model 40S and probably the Model 40U tractors.

Remove the adjustable tie rod ends from both the left and right steering arms.

Turn the steering wheel either to the extreme right or left.

Mark the top of the steering wheel with a small piece of duct tape.

Turn the steering wheel in the opposite direction, counting the number of revolutions, until it stops noting the position of the duct tape.

Divide the number of complete revolutions and any partial revolution by 2.

Turn the steering wheel in the opposite direction the new calculated number and "anchor" the steering wheel.

The steering wheel should be close to center.

Follow the directions above from the service manual.

Take a look at the diagram below.





Note the hex jam nut(Key 3), adjusting screw (Key 4), cover (Key 5), steering shaft (Key 8), and steering gear housing (Key 15).



Reviewed the [b:654c4848f0]SERVICE MANUAL JOHN DEERE 40 SERIES TRACTORS & CRAWLERS SM-2013[/b:654c4848f0] under the [i:654c4848f0]Adjusting Steering Gear Backlash[/i:654c4848f0] topic on page 170-5-5.

"[b:654c4848f0][i:654c4848f0]NOTE: Raise front end of tractor to remove load from front wheels.

Turn wheels so they are in the direct forward position. With adjusting screw lock nut loosened, turn adjusting screw in as far as possible and then back off several turns. Tighten screw until it just bears on steering lever. Tighten the lock nut.

Turn the steering wheel from right to left to check for bind. A slight drag should be felt when wheels pass center of straight ahead position.

When steering wheel is turned to extreme right or left, boss on upper spindle must contact stops on front end support. On adjustable front axle, stops on steering arms must contact stops on axle.

Fill the steering housing with with quantity and weight of oil recommended in Section 30.

Replace grille and hood.[/i:654c4848f0][/b:654c4848f0]"

Take a look at the photo below.



Hope this helps.

Check #23 for being twisted from hitting something .

It just needs a bit of toe & it'll be fine. Unless the
rear pivot pins are very worn causing incorrect
CASTER. I.e the front end is tilted forward or back
too far.

Item #7 the steering box pin as already shown.
The half moon key, the keyway in the worm gear shaft and the clamping keyway in the steering shaft. All three are often worn to bits.

Has tow end of frt tires been checked?

(quoted from post at 15:18:27 05/31/15) Has tow end of frt tires been checked?

Click to expand...

He said this was going to be his first check- he was pretty sure they were toed way too much. He had already taken as much of the play from the steering gear/pin as he could.

I know I have experienced a similar road-gear wobble from a tractor carrying too much rear load with out front weights like a trailer without sufficient tongue weight.