28-11-2017, 01:55 PM
A technical question for the engineers.
The A7 has a flanged bush in the bottom of the stub axle to take the king pin (phosphor bronze?). Between that and the axle beam eye there is a thrust washer. The Big 7 is similar except no flange on the lower bush so the thrust washer runs directly on the stub axle and beam axle eyes. The big 7 beam has a recessed area around the bottom of the eye into which the thrust washer partly sits. Big 7 king pin is 5/8 inch dia.
I would obviously like the least possible wear to the stub and beam axle faces. Washers can easily be replaced
The big question is what should the thrust washer be made from????
There is information that they should be hardened steel.
The ones that came with my last set of KP and bushes were a tuffnol type material!
The A30/A35 Austin swivel pins (also the 5/8 inch dia. like the big 7 king pin) also have thrust washers and are same size apart from being 1 1/4 OD instead of smaller (I recon 1 1/8 for the big 7 beam and stub spot faces but easy enough to turn down the OD by mounting them on a bolt in a drill and filing the edges).
Bull Motif can supply the A30/35 thrusts but theirs are made in brass.
I am sure I read somewhere that hard and soft metal rubbing together then perversely the HARD metal will wear away quicker?
So - hardened steel, brass, phosphor bronze, Nylatron, tuffnol, ?, ?. What and why?
The last time I did the king pins I put a thin washer in the big 7 beam recess with araldite so the thrust was wearing against the washer and not the beam (washer could be replaced eventually). I will also araldite a thin washer onto the stub axle lower eye.
Dennis
The A7 has a flanged bush in the bottom of the stub axle to take the king pin (phosphor bronze?). Between that and the axle beam eye there is a thrust washer. The Big 7 is similar except no flange on the lower bush so the thrust washer runs directly on the stub axle and beam axle eyes. The big 7 beam has a recessed area around the bottom of the eye into which the thrust washer partly sits. Big 7 king pin is 5/8 inch dia.
I would obviously like the least possible wear to the stub and beam axle faces. Washers can easily be replaced
The big question is what should the thrust washer be made from????
There is information that they should be hardened steel.
The ones that came with my last set of KP and bushes were a tuffnol type material!
The A30/A35 Austin swivel pins (also the 5/8 inch dia. like the big 7 king pin) also have thrust washers and are same size apart from being 1 1/4 OD instead of smaller (I recon 1 1/8 for the big 7 beam and stub spot faces but easy enough to turn down the OD by mounting them on a bolt in a drill and filing the edges).
Bull Motif can supply the A30/35 thrusts but theirs are made in brass.
I am sure I read somewhere that hard and soft metal rubbing together then perversely the HARD metal will wear away quicker?
So - hardened steel, brass, phosphor bronze, Nylatron, tuffnol, ?, ?. What and why?
The last time I did the king pins I put a thin washer in the big 7 beam recess with araldite so the thrust was wearing against the washer and not the beam (washer could be replaced eventually). I will also araldite a thin washer onto the stub axle lower eye.
Dennis