front end alignment question

"There is supposed to be no discernible camber or castor movement in the kingpins,"

Thanks.  This is one of the pieces of info I've  been looking for.

Could you have a broken spring main  leaf,..... if its under the wrapper , ( 2nd leaf ), some times its a bit hard to detect. ...........

Check both springs............(left and right )

Also check the U Bolts to make sure the axle has not moved (broken centre bolt sort of thing ) ..............

........................Billy........................

Hi Billy,

The springs are fairly new. There is a vertical line and they haven't moved. I did suspect a broken center? bolt and have discounted that.

Having said that, I think I have traced it to a toe out issue.   Unfortunately, I made an adjustment while driving and don't have an original reference.  Anyway, the toe is now set up as per the specs.

The hardest part is being able to take measurements around the body.   I use a simple jig to 'virtually' bring the wheels angles forward of the bus and measure across the front.







 

   Mate......if you did make an adjustment..... then the wear started .......it could be classified 
as self inflicted injuries..........
However, if it was a toe out issue,    one might also think both tyres could be 
effected ....(maybe)............

................Billy.............

yeah nah.

It was wearing before.  It was an attempt to stop it on the road last week. Trouble is, I still don't know what/when the cause was.
Went down to Port Fairy at Christmas, and over the Spur in about Nov and through NSW prior.  It became noticeable coming home after PF.

Fair point about both tyres.  There might still be something wrong on one side.

          Ah   haaaa ........
So it seems the problem has been around for a while.............
It looks like you may need to start from scratch...........
(are you really sure a main leaf is not broken at the eye??????????).

.................Billy..................

SB VAM BLP VAL Bedford front axle are known to wear in the I beam king pin eye
No load don’t show up worn & only move when loaded on the ground
Very slight but over the height of true it is a couple degrees out

Jumbo,

Do you mean in the eye bush?  And do you know if it results in a positive or negative camber?

thanks
Jon

Bit of an update.

Following on from Jumbo's comment. I went a bit further and pulled the stubs and king pins.

The bushes were worn on both, however, the passengers axle eye was worn too.  Managed to find bushes and a 10 thou oversize king pin. Reamed the axle eye today. Bushes already fitted and reamed in the stubs.

Had someone coaching me on the bushes. ...   but  geez, you have to be careful with the reamer!!

Still not completely sure about the tyre wear cause. Next is to have the  (newish) front passenger spring hot reset as it's sunk a little compared to the drivers. Then a full alignment.

Reamer



Axle eye showing the oval after a couple of light cuts



King pin in the hole.  (no cotter pin holding - just cooled down in the freezer with a little blast of map gas)

 

From my limited knowledge about things like this

Toe out causes unusual things including wear on tyres

Add to this worn bushes and things get really strange

I have a Mack a bit like this waiting on time from me
Funny thing is it steers perfect with a trailer on, yet is like a cat on ice when bob tail

I guess all Im saying quite badly is things in this department are very complex

Paul