JD 42" lawn tractor lurches

[eriebar]

My lawn tractor lurches when putting it in gear, no matter how slowly I release the clutch. What could be causing this?

 

[bertsmobile1]

There is a spring that adjusts the balance between the brake & clutch
Jack the rear up and adjust is so the brake comes off just before the wheels start to spin .
There is also a pedal return spring which may need replacing .
The brake is not progressive like your car brakes .
It is either on 100% or off 100% as it locks the layshaft which causes the wheels to turn in opposite directions which is the same as the P position on an automatic gear box in a car

 

[Rivets]

I’ve also found that a bad or worn drive belt will cause this. When was it last changed?