Steering Shake

[goodo85]

Back in April we fitted a power steering box to my 715. I believe the box came from a mid '70's J10.
Since then, above speeds of around 40mph, if I hit a bump or rough patch in the road the steering goes into a mad death wobble. If I slow right back down it irons out and I am right until the road gets rough again.
Speaking to a couple of people, they seem to think it sounds castor related but I never seemed to have these issues before I converted the steering.
The shackle bushes were replaced about a month before the conversion and I am not running a steering damper.
I am starting to think that it is most likely the box, as there is a bit of movement in the sector shaft. Problem is, being in Australia I had to import this steering box, (I needed it for left hand drive which is hard to get over here) so I can't just go to the wreckers and buy another one. Plus, this one came from a wrecker and if it is the box I would hate to buy another worn out one, as shipping on something this heavy is a killer.

Any ideas? Just wondering if anyone has had issues like this after a similar conversion?
I love the power steering off-road and in tight car parks but I am at the point of going back to the original box because the truck is not driveable the way it is.

[Mikel]

"Death wobble" typically comes from two sources:
- Worn steering components that allow play
- Geometry problems

Given that your truck is not lifted and caster hasn't been affected, I would look for slop in worn components. I would have someone move the steering wheel back and forth while you look for play.

If the steering box itself has a lot of play, you there is a setscrew a the top that can be tightened to remove some of the play. If you do this, I suggest doing a search on the proper way of doing it, as too much of an adjustment can damage the box.

Good luck.

[Don Cavey]

If the steering components are tight, the next thing to check is tire balance. When I drove these trucks I had no steering damper on it. When the original tires wore out, the motor pool put recaps on it. It wobbled immediately. I took it back and was told that they didn't balance them. Through the services over midnight Requision" I procured a new set. The wobble was gone. I really think tire balance is the root of the problem and is agrivated by a worn box, worn or loose wheel bearings, worn tie rod ends etc. Steering dampers just mask the problem. Other than shims, I don't think there is a caster adjustment?

[Barrman]

Tires and worn steering parts. Mine had it bad with NDT tires. I put on XZL's and all gone. Then I had a flat and ran a XL on the front. Severe death wobble above 30 mph. I fixed my tire and all was good again.

[Don Cavey]

Tires and worn steering parts. Mine had it bad with NDT tires. I put on XZL's and all gone. Then I had a flat and ran a XL on the front. Severe death wobble above 30 mph. I fixed my tire and all was good again.

Key word ... "Tire".

[Mikel]

Besides the tires, I had a truck that had pulsating front disks. At certain speeds, every time I hit the brakes, it would start a death wobble.

If all the things mentioned here check OK, a cheap bandaid can be a steering stabilizer. I would *hate* to give up power steering...

[goodo85]

We've already checked the steering the way you mentioned Mikel and there was some movement. I thought there would have to be some way of adjusting it.
I had the same feelings about the steering damper being a 'band-aid' fix too Don. The wheel bearings were done about the same time as the steering.
I have been going to take the tyres for a balance, but since I didn't get a constant wobble at high speeds I thought it might be something else. It can't hurt though, for what it costs. Mine still has the NDT's that were on it when I bought it off the FD, I normally get a small wobble the first time I come up to speed after it has been sitting for a while, but I put that down to the bias ply tyres getting a flat spot and getting out of balance that way.
We put a hydraulic clutch in at the same time as the steering Mikel, The clutch was worn and had no adjustment left, I used to have a lot of trouble when wheeling, - once I got a bit twisted I couldn't get in or out of gear. Totally different truck to drive now, so it would be a shame to lose the power steering. I will look into that adjuster screw.

Thanks for the info guys.

[Don Cavey]

We've already checked the steering the way you mentioned Mikel and there was some movement. I thought there would have to be some way of adjusting it.
I had the same feelings about the steering damper being a 'band-aid' fix too Don. The wheel bearings were done about the same time as the steering.
I have been going to take the tyres for a balance, but since I didn't get a constant wobble at high speeds I thought it might be something else. It can't hurt though, for what it costs. Mine still has the NDT's that were on it when I bought it off the FD, I normally get a small wobble the first time I come up to speed after it has been sitting for a while, but I put that down to the bias ply tyres getting a flat spot and getting out of balance that way.
We put a hydraulic clutch in at the same time as the steering Mikel, The clutch was worn and had no adjustment left, I used to have a lot of trouble when wheeling, - once I got a bit twisted I couldn't get in or out of gear. Totally different truck to drive now, so it would be a shame to lose the power steering. I will look into that adjuster screw.

Thanks for the info guys.

Good on 'ya Mate! Next time I get to Melbourne, if I have time, I should shoot up to NSW and catch up with you!

[goodo85]

Good on 'ya Mate! Next time I get to Melbourne, if I have time, I should shoot up to NSW and catch up with you!

Yeah that'd be good Don. You're welcome any time.

[gonz]

It was a long time ago, I remember a death wobble discussion 3 boards ago dealing with worn washers on the closed knuckle. Barrman would probably remember better than I, I haven't rebuilt a front axle since 1997.