King Pins and Bearings

Have a read of Brian Rainbow’s article in issue 9 December 2011. I followed his advice and fitted Torrington bearings to my TA2446. I then had to get the right shims to recover the float to 4 to 6 thou. I used one additional Torrington shim and then had a gap of 12 thou on one side and 16 on the other. I had bought a set of steel shim sheets, so I cut some bits out and clamped them between the old brass thrust washers and filed a pair of annular shims from 8 thou and 12 thou pieces.

My main issue was that the king-pins on my TA were not a sliding fit in the bushes, they were rock solid, plus there were some very dodgy cotter pins. I removed the cotter pins with a hammer and drove the king-pins out as well. I bought a set of king- pins from Amsteer and cotters from Roger Furneaux. Points here are, if you speak to John Davis from Vintage and Collectors Spares, he will advise that the original bushes had steel backings and brass faces. The new ones are just brass. Also, the original king-pins had an oil gallery in the centre of the pin. Finally, Roger’s cotters are easier to fit and remove without a hammer.

The pictures show how to ream the bushes to get the correct fit. I have just reamed the existing ones on the car, I still have the new set on the shelf. So, apologies for no advice or experience on replacing the bushes. They appeared to have been replaced with the addition of some less than standard thrust washers.

This is a picture of the reamer and pilot guide in use. Just ream from either end. I used 3 in 1 oil to lubricate the cutter.

My main problem was finding an expanding reamer for non-ferrous metal with a pilot guide of the correct size. I got the last one from a supplier in Edinburgh but it came with an incorrect collar. Mick Pay very kindly made me the correct one for a donation to Cancer Research. The size is 18.25mm to 19.84 mm. 19.05mm is ¾ inch so the range spans the kingpin diameter.

When using the reamer, make microscopic adjustments and test for fit between cuts. There is only a slight adjustment between too tight and too large. If you take too large a cut you will get a rippled finish with straight cut reamers, compared to the spiral ones so again make small adjustments.

This sliding collar floats on the pilot rod and the taper needs to be pushed up to the end of the opposite bush to centre the reamer.

As did Brian, I got a large gap (25 +15 thou) and thus excessive float on the king pin with the standard brass thrust washers, so I headed for the Torrington ones.

Once you have got the axle apart there are a variety of options for reassembling the components.

Points to note:

Stub Axles are marked LH and RH. The axles are threaded so that when the wheel rolls forward it tightens the nut. Left-hand side is a left-hand thread and the Right-hand side is a right-hand thread.

The axle itself has an identity cast into it and this lettering should face the rear of the car. Do not trust this and check the geometry of the king pin holes. There is a series of seven existing articles on steering by Eric Worpe that are essential reading. Check the castor angle to confirm the orientation. Put a rod in the axle and the king pin leans back at the top. Same logic as a supermarket trolley that the wheels will align to where you point it. This picture is from Eric’s article.

Fitting and removing the cotters: Do not hit them with a hammer before you are completely satisfied that they do not need to be removed in the near future. Eric Worpe recommends seating them with a hammer – “they should be hammered home and only then should the nut be tightened”. Roger Furneaux advises against. Eric’s article explains his point of view so I hit mine lightly.

Roger Furneaux’s have nuts both ends. One end of Roger’s cotter provides the steering stop at the rear, the other a means for removal. Picture of the steering stop below. Note also the slight downward angle on the stub axle.

The nut at the rear of the cotter and the one on the swivel form the steering lock stop.

The nut at the front is used for removal. Take the nut off and put some washers underneath and then tighten it back down. This has the effect of withdrawing the cotter. Keep adding washers until it comes free. Makes sure the cotter can pass through the washers! A sharp tap from the rear may start it once there is some tension on it.

Yes, I do have the only available pilot reamer but I have learnt to my cost that loaned tools invariably do not get returned. I could not find anywhere to get the work done and I was lucky to be able to purchase the tool and do it myself.

If you want your king-pins re-bushed and reamed and the stub axles crack-detected, then I can arrange the work for you with a local engineering company in Stroud who at present have my engine.

I purchased a pair of swivel/stub axles from Tim Patchett on the basis that I had crack detected my originals with no cracks, but I was dismayed at the quality of the machining on the radius of the originals and there were many machining marks that could propagate fatigue cracks.

I bought a set of bushes and kingpins from Amsteer. I also had a set of 1950s kingpins from John Davis. The 1950s ones are slightly larger than the Amsteer ones so I have used the smaller ones.

I pulled the bushes in with washers, a flat plate and a threaded rod. I did not need to take the old ones out but would have used a small socket as a plunger and a large one as a receptacle and pulled them out with a smaller threaded rod as the one I have does not go through a 3/8 inch socket drive.

You can pull the bush in from the outer end, but I pulled it from the middle to avoid any possibility of distortion.

Tim Parrott
tp(at)tpss.co.uk

Ed’s note: The seven articles by Eric Worpe, mentioned by Tim are as follows:

CHASSIS – is it true? – Issue 19 (August 2013)

FRONT AXLE GEOMETRY – Issue 20 (October 2013)

FRONT SPRINGS – Issue 21 (December 2013)

KING PINS – Issue 22 (February 2014)

TRACK ROD AND DRAG LINK ENDSIssue 23 (April 2014)

TYRES AND TRACKINGIssue 25 (August 2014)

THE BISHOPS CAM STEERING BOX – Issue 26 (October 2014)

One thought on “King Pins and Bearings

  1. Eric Worpe says:

    Hi Tim, Thanks for an illuminating article. May I clarify my comments about hammering home the cotter pins. This advice applies only to standard cotter pins with just one threaded end. I also recommended cotter pins made from hardened steel, as these resisted deformation by rucking as its flat tapered section scrapes across the edge of the king pin’s locating flat. Roger’s cotter pins were made to the original pattern with threaded sections either end and used a low carbon steel. A tight cotter pin is essential to clamp the king pin securely, tightening the cotter using just the nut seemed less than adequate.
    Regards, Eric.

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