Morris Minor Owners Club

All,
Please don’t get me wrong. I’m not trying to promote teflon bushes by any means and judging by the discussion I will strongly consider reverting to poly bushes. I am also sceptical. As LES mentioned, they seemed to have gone to a lot of trouble with the measurements and they certainly didn’t do it for nothing. One thing can be eliminated from the start-it is certainly not a sales gimmick as these bushes are not sold or advertised on a commercial basis,. I only managed to get hold of them through word of mouth from the guy from the spare parts pool here in Germany. He actually knows the manufacturer-Rolf Corbat. (Rolf is regarded as a morris minor expert in Switzerland and having read several articles that he has compiled, he obviously knows what he is on about-very professional.)
(Apparently these bushes are hand carried over the border to avoid paperwork, customs and excise, Switzerland not being an EU member) and are only available at club level and not promoted in any way.
One thing I forgot to post was that it does state on the Swiss Website that these measured temperature values were peaks. It does not however mention how the measurements were carried out or what equipment was used or over what period of time or how the sampling rates were. There is also no trend curve on the results posted. It only mentions thermocouples and there are of course several different types. (We had a similar issue at work some years back with peaks causing premature failures in our hydraulic cylinders. It took ages to get to the bottom of it but that is a different story.) Peaks can be a dangerous thing as I know from my daily (EC&I) routine.
Coming back to the poly bushes, I have noticed there are different coloured bushes available from the various suppliers. What is the difference?-are there different grades and which ones should I purchase if I decide to revert to polyurethane?
I will take your advice and keep a close eye on my chassis legs but after a year and a half of running (4000miles)on the teflon there are no signs of cracking. I can’t really compare the ride with poly bushes as my car had shot rubber bushes when I bought it.
Declan

I haven't seen any mention about the change in function when using teflon bushes. With rubber the bushes are compressed and there is no movement between the pin and the rubber. All rotation is done within the rubber itself. That is why the bushings are not to be compressed until the suspension leg is at its static angle so that there is no pretwist condition. Could be why their rubber bushes failed so early. I believe the poly bushes perform the same way as the rubber ones but probabaly are easier to eliminated the pretwist. Now with nylon, I can't see any possibility of twisting so therefore the pin will be rotating within the nylon. Is this good or bad? I would rather use a larger diameter pin and reduce the thickness of the nylon. Is there any mention of wear on the pin?

I think, as far as I can recall, when I fitted the teflon bushes, that the pin which came with them was only slightly larger than the original pin. The whole thing acted like a plain bearing with little to no play and hardly any friction as the teflon does not compress. I thought it was very well made. The kit had two bushes, new pin, nuts and spring washers-all metric I think. I checked the Swiss website but it doesen't mention anything on sizing.
Declan

Coming back to the poly bushes, I have noticed there are different coloured bushes available from the various suppliers. What is the difference?-are there different grades and which ones should I purchase if I decide to revert to polyurethane?

I believe there are "road" or "performance" versions from some manufacturers, but I found this which made more sense to me:
http://www.superflex.co.uk/hardnessguide.php
I think it's Superlex that have been recommended by "those in the know" (allright, JLH) but it should come up if you do a search as it's been discussed before.

Now with nylon, I can't see any possibility of twisting so therefore the pin will be rotating within the nylon. Is this good or bad? I would rather use a larger diameter pin and reduce the thickness of the nylon. Is there any mention of wear on the pin?

With my nylon eye-bolt bushes the pin was a slide fit (with copper grease) so it does rotate inside the bush, I've not stripped it apart to check for wear since but there's bound to be some after this time. I didn't notice any play when I had the spring load off whilst replacing a bottom trunnion last year though.

Thanks Stig
Declan

I believe the temperature figures especially if they are peak.

Consider the surface speeds of the bush on the pin and then the friction if there is no lubricant. You can make fire by rubbing sticks together, it doesnt take much to get high peak temps with friction.

We used to see signs of burning or over heating on the early bushes we fitted. These were imported from Austrailia because nobody made them in this country. Initially we fitted them without lube but later added lube and there were OK.

My Minor runs with very little compliance in the bushes, about 0.5mm teflon on each bush (makes for more accurate wheel control)