Chassis vibration

[S_Hoppenbrouwers]

my HZJ 75 (1999) recently started to develop vibration in the chassis. In the beginning it started to be noticeable at 100 km/h and it would be less at 120 km/h. Now it is getting worse (louder) and driving faster than 100 km/h is a real nuisance due to the noise levels.

I had all wheels balanced and revised the right front swivel hub and wheel bearings, as the grease was leaking. The bearings (kingpin and wheel) were well past it. Anyway, it did not make a difference. The left hand side swivel hub is on the to-do list but no grease leaking there.

Other symptoms: the chassis only vibrates on a positive or neutral throttle. No vibration when the engine is driving the car (engine braking). If I drop the clutch on a positive throttle, the vibration continues. If I am engine breaking and drop the clutch at the same speed, no vibration. I would conclude therefore it must be coming from the drivetrain. I checked the forum here but no real clues other than play in the UJs (have not checked that yet).

Anybody any suggestions on how to analyze this?

thanks
Steve

 

[Jimbo4x4]

Yup, sounds very much like the UJ's need either re-greasing or replacing. There are grease nipples on the UJ's, try filling them until it squirts out of the caps and if there's still play in them they'll need replacing.

Jim.

 

[Roger Fairclough]

There are 4 bearings on each UJ, and you must make certain that the grease is getting to all of them. Firstly, clean away all of the old grease and dirt. This includes the nipple itself.Then inject the fresh grease. If you do this quickly, you should get grease to all the bearings. If one bearing stubbornly refuses to exude the fresh grease, you may need to remove the prop-shaft to check each bearing on the workbench.

Also look for indications that a balance weight has been lost.

Roger

 

[S_Hoppenbrouwers]

thanks for your replies, you were right on the money. I took the driveshaft off and sure enough the rear UJ was completely shot. I am now getting the replacement UJs and will let you know if their solves the vibration. Very hopeful it does!

cheers
Steve

 

[roscoFJ73]

Hi Steve,you might want to check the gearbox mount as well. It could be magnifying the UJ problem.

 

[S_Hoppenbrouwers]

hi guys,

I completed the revision of the drive shaft. Replaced both UJs and all vibrations are gone. Runs perfectly again! Thanks for your comments.

cheers

Steven