Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing New Kigpins needed?Help /advice please.

Hi Cain

There's an awful lot of plain sliding PTFE bearings available out there!

From a tribology perspective a material’s softness is not the overriding criteria. There are many factors involved. Just look at how soft white metal main bearings are.

Both Oilon and Delrin are very good bearing materials in the right application. Have used both before. Oilon I think is an oil loaded nylon 6 which is very hydroscopic (more than the orig Devol bearings) and there might be a seizing risk . Delrin is less so depending on the grade.

I agree with Cain re unfilled PTFE, it would probably not have the inherent strength unless it had some fibre filler mixed in, although its lubricity would be fine. If you went with a filled PEEK grade for example the FC30 this has 10% each of PTFE, Carbon Fibre and Graphite. This is an incredibly good bearing material and is used extensively in high end automotive applications and in the oil and gas industry. It machines well and can be reamed.

Ok. PTFE’s suitability is not looking good then. I did have a slight niggle about its tendency to cold flow without the filler

."If you went with a filled PEEK grade"

What does he word "filled" mean? I am an accountant not an engineer.

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The problem I have with Devol is that I honed the stub axle tube rather than ream the bush to achieve a resultant fit. Fortunately I have a new set of Devol's given to Me by one of My Aussie friends. Also the Devol's don't seem to wear. They are a UK product - Scotland I think. It is too bad the Factory Workers did not follow Bill Beck's advice as to clearance etc. My experience is they work OK. Actually Bronze is OK. But Bronze need an expensive reamer and I use a Sunnen Hone to finish them. In the UK this is not a problem as there are plenty of mechanics familiar with Morgan. But in the Pacific NW with about 150 Morgans, most of them old, it is not so easy.

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Filled, as with any Plastics means that a % of the plastic has a filler material to enhance its base properties. The most common fillers are short strand glass fibre, talc, Fluoroploymers and a host of other materials, chopped carbon fibre is also used to enhance the strength of the plastic but this is only usually used in plastics which are expensive as the carbon fibre is an expensive product itself. A lot of automotive mouldings are glass filled Nylons, polypropylene etc.

Roger, before I retired, I did some work with a company that cast bronze powder with PTFE. It was one of those products which was looking for an application but I don't think it got further than the development trials.

I used to get the advisory on the last few MoT's but the car handled well enough to rule out needing new king pins and bushes.

Old MoT garage closed down and new garage passes car no problems. The Authorized Tester sees the old MoT ticket and explained that VOSA through its big computer works out if a garage has an abnormally high pass rate its letting dodgy motors through, if has an abnormally low rate, its perhaps failing cars unnecessarily to get the repair work.

A pass and advise however, tells the computer that the tester is really being thorough but not trying to line his own pockets. Had some really daft ones on the tin tops "Engine covers fitted" "Sump guard fitted" etc

Just had a quick look thanks Edgar. Impressive material but I bet it would be a job to get hold of.

I don’t think the Devol bushes are available any longer which is a pity although I see that Devlon S still features on James Walker website, somebody may know different?

There are several producers of PEEK rod stock shape, Quadrant in the UK should stock it in FC30 form, not sure what the minimum quantity would be. Its expensive stuff.