Axle track question

Just noticed on 6 by 2 rear lift rigid the drive axle tyres have worn funny ,the n.s tyre outer tyre on the outer edge and on o.s of the lorry inner tyre on inner edge ,measuring between the rims from rear lift to drive rims there’s over 10mm difference as in the n.s has more gap between the rims ,this being out of line is more noticeable with the trailer on ,the rear of the lorry looks to be nearer to the middle of the road .

When I stop and line the trailer up in the mirrors as it would look if I was at full speed on straight motorway then get out and look from the rear it’s noticeable .

When rear lift is down the lorry runs straighter than when it’s up .

The rear lift is not adjustable.

The front axle is set parallel.

There is no wear in any bushes.

The side raves measure parallel to the chassis on both body’s .

Is it normal to put up to 8 mm of spaces on the torque arm bolts one side and have none on the other ?

Your thoughts appreciated thanks .

Have any front springs or rear torque rods been changed with after market makes ones? a few millimetres different could be amplified to 10mm by the out side edge of the tyre.

I haven’t measured from the front ,however it does sit down by 1 inch on the n.s.f and I’ve bought a new spring but not put it on yet as not had time to paint it ,I noticed when I bought it the tyres were worn a bit odd and there was a steer track sticker in the window .

Is this a two or four airbag set up for the drive axle? Have you checked that the rim offsets are all the same? ie B 7.5x 22.5 or whatever. If one rim is different and an attempt in the past to align the axle because one wheel was further under the rave (across the vehicle) one side than the other, had meant someone had played around with the torque rod washers, then the axle may have been put be out of line by mistake. This sort of thing is usually a broken centre bolt on a steel spring or two air bag with trailing arm set up. If there is a trailing arm it may be like BPW trailer axles and be adjustable with a wedge at the anchor end.

I came across a Hino double drive six wheeler some years ago which had had the middle axle removed by someone and then refitted with the torque rod ears fitted the wrong side of the chassis mounting bracket. This was causing the propshaft to make a terrible noise when loaded because the sliding joint was bottoming, but the previous person investigating had thought the problem was in the diff.

Is it a factory original build outfit Dan? Also, can you take your hands off the wheel without the vehicle immediately wandering off line. If it’s out by much I would also expect to see feathering of the tag axle tyres

U bolts come loose and spring locating eye sheared off, thus allowing the axle to move backwards one side only, loose u bolts spotted on inpection and tightened with the axle where it was ie out of line?

Seen it on trailers a few times.

cav551:
Is this a two or four airbag set up for the drive axle? Have you checked that the rim offsets are all the same? ie B 7.5x 22.5 or whatever. If one rim is different and an attempt in the past to align the axle because one wheel was further under the rave (across the vehicle) one side than the other, had meant someone had played around with the torque rod washers, then the axle may have been put be out of line by mistake. This sort of thing is usually a broken centre bolt on a steel spring or two air bag with trailing arm set up. If there is a trailing arm it may be like BPW trailer axles and be adjustable with a wedge at the anchor end.

I came across a Hino double drive six wheeler some years ago which had had the middle axle removed by someone and then refitted with the torque rod ears fitted the wrong side of the chassis mounting bracket. This was causing the propshaft to make a terrible noise when loaded because the sliding joint was bottoming, but the previous person investigating had thought the problem was in the diff.

4 bags ,all wheels match from new ,it’s better today after adding a 3rd washer .

Old John:
Is it a factory original build outfit Dan? Also, can you take your hands off the wheel without the vehicle immediately wandering off line. If it’s out by much I would also expect to see feathering of the tag axle tyres

Factory build John ,depending road surface yes can take hands off ,it will ditch very very slightly ,the drivers steer tyre feathers on inner edge very slightly .

Trickydick:
U bolts come loose and spring locating eye sheared off, thus allowing the axle to move backwards one side only, loose u bolts spotted on inpection and tightened with the axle where it was ie out of line?

Seen it on trailers a few times.

Don’t think so there’s not much room for movement on these hendricksons .

This is the Hendrickson HA4 suspension which was a Foden Alpha option. Is this what you have got? Have a look to see if 11 and 25 are displaced.

aus.hendrickson-intl.com/CMSPag … c38b6fba6b

It’s basically the same ,my front side of axle bags are near to the axle and on a different brackets also my roll bar drop links are on the inner side of chassis .

The A frame bushes were prone to wear when fitted to the double drive, rubber suspension models, and that allowed the axles to move laterally, and also radially. It didn’t seem to cause tyre wear issues, but on rough work the tyres didn’t last long anyway.
The A frames have a much easier time of it with your type of suspension and I suppose your problem could have either one cause, or a combination of several.
If all your measurements remain the same regardless of whether you turn left or right, then it must be something that hasn’t been put together properly.
Happy hunting!!

Apart from visual inspection and measuring, I can make three suggestions which may help with diagnosis, one you can do yourself, the others will require a visit to an ATF or a workshop with RBT and shaker plates.

If you chock the front axle, leave the brakes off and use a wheelbrace to check the wheel nuts on axle 2 at 3 and 9 o’clock you may be able to detect any movement. At an ATF if there is significant movement in any bushes it should show up when the axle is braked on the rollers, but it will certainly show up if that axle is put on the shaker plates.

All ATFs are required to make their specialist test lane equipment available for chargeable use by operators.

I can’t help you, but you jogged my memory, whilst following a double drive tipper, let’s say a Leyland Reiver or Buffalo, the rear axles tended to be offset, was this a design fault or deliberate? I could argue it gave more traction.

image.jpeg
image.jpeg
Just made a tool to measure from the chassis ,which shows I have now pulled the axle too far forward on o.s ,however it also shows the axle is not central to the chassis as its 820 mm off on the o.s and 840 mm on the n.s when parallel :cry:

image.jpegiam loaded and have driven forward and back to get any twist off the suspension prior to measuring ,looks like I need some m16 shims

image.jpegjust faced the tool backwards too .

All measurements taken with the Mrs helping ,may be if I re measure tomorrow :open_mouth: it will show that 73 mm is all the way

With the uneven tyre wear, it does seem there is a problem.
But will getting the axle true to the chassis cure it? If the chassis is at all imperfect itll not be a cure will it? Shouldnt you really try to get all three axles true to each other?
Just a thought.

I would measure from a chassis crossmember or check to see if the propshaft centre bearing is in the middle of the chassis. I would then measure from the x member or the drain hole in the bottom of the bearing carrier to the same point, as close as practicable to the wheels, on each side of axle two’s casing. This measurement should be the same. I would also be having a good look at the A frame and its bushes.