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MG Midget and Sprite Technical - King Pin Bush Alignment

Hi,

I take it that the hole in the king pin bushes should line up to the grease holes in the stub axle.

If they don't line up am I correct that they have been fitted incorrectly and therefore it is impossible for grease to flow into the bush.

If I am correct has anyone got any experience in removing them and refitting them please.

Many thanks

James


James Paul

Yes, the holes should line up.

You may be able to press them out with a suitably sized socket, hopefully without damage.

The problem with refitting is that the bushes are both reamed at the same time with a stepped reamer. You may have alignment issues.

It might be easier to drill a hole through the side of the bush.
Dave O'Neill 2

I wondered about drilling a hole into the bush but I presume it would have to align with the grease channel in the bush i.e. to enable the grease to flow around the king pin.
Bill Bretherton

If the hole didn’t align with the channel, it should be possible to open up a groove with a Dremel.
Dave O'Neill 2

Yes, good idea Dave. A new hole would seem to be the best solution then.
Bill Bretherton

I guess the other option is new bushes and king pin. Can’t just replace the bush.

The other side is the same.
James Paul

I would say you have 3 options.
Push the bush out with a socket and refit correctly aligned. You may be lucky and it not need reaming. There's a bit of tolerance.
Fit a new bush and get it reamed if necessary. I have rebushed these and fitted new king pins and they didn't need reaming.
Remove the grease nipple and drill through the bush. You may need to fashion a duct to the channel inside again, but there's probably enough clearance for grease to get through to the channel, which then helps spread it evenly through the bore.
GuyW

Hi,

On further inspection there are further issues that are making think I need to replace the whole stub axle.

In the first photo you can see the top of the stub axel as been worn down to the point where you can't see the join between the bush and axle. I can visibly see a difference between the two. Not much but there were no shims or O' rings in one of them.

On the other stub axle I am not sure or not if those holes will affect the inner bearing at all.

All four bushes need replacing as have all been incorrectly fitted.

I am worries about drilling a hole in the bush as the heat might distort the metal or just the pressure alone might do similar damage.

Just annoying there are issues with both of them.







James Paul

Here are the king pins. The surface looks very smooth just these darker patches.

Is this normal or signs of heat stress?

Thanks

James


James Paul

The coloured patches on the kingpins is normal due to the local hardening of the journals. Drilling a hole in the bush for the grease shouldn't generate any significant heat unless your drill is blunt, might benefit from a slight deburr where the drill breaks through inside, not likely to distort the bush either as they're fairly thick walled.
David Billington

the stub axles do look a bit sorry but may not scrap. The dents in the stub axle can just be cleaned up with a fine file so there is no sharp edges. The bearing runs further up so should not be affected. The area where the oil seal sits looks ok.
As regards the top of the stub axle yes it does look worn but providing you can achieve just the tiniest bit of end float when the trunnion top with the thrust washer is installed and bolted up then it should be ok. The swivel axles should turn on the king pin with just a slight resistance.
The king pins look ok.
Just looks generally the a previous owner did not really know what they were doing.
Bob Beaumont

The early hub seals were oil soaked felt, which are more tolerant of pitting on the stub axle. Later (and current replacements) are normal neoprene lip seals which may not like the pitted area on your stub axle, but maybe not run that far up it. The outer part looks OK if that is where the seal lip ends up.
If necessary they are easily fixed with a Speedisleve.
GuyW

In the first picture from the 10.44 post I'm wondering if the stub axle on the left has been ground down a little due possibly to the axle going tight when the top nut is tightened. Dave, Bob, Guy and others may remember I had trouble with this earlier this year when I found the step on the new kingpins wasn't high enough so I had to reduce the thickness of the thrust washers and also added a thicker "shim" I made from a steel washer on one side, Just a thought.
Bill Bretherton

Hi,

Thanks all for your comments.

I decided to knock all four bushes out and they came out reasonably easily after warming the axle.

The second picture shows both the upper bushes. Odd how one is so much shorter in length. If they did grind the stub axle down it doesn't look that much.

I'm wondering if they had trouble driving it all the way in and decided to grind the excess off. It was also upside down so the hole was nowhere near where it should have been.

Anyhow, new bushes, shims, seals, washers,.....

and see how it all fits back together.

Many thanks

James






James Paul

James, is it possible that the stub axles have come from different cars some time in the past? It looks like they have been delt with wrongly, but are different as well!
GuyW

Hi Guy,

There is only one difference between the two in terms of ID.

One ends in A and the other B.

I assumed left and right.

Who knows if they came from other cars. I have zero prehistory info.

Kim Dear sold me the car without anything other than the V5.

I only just realised someone had cut part of the dust cover off.

Sums up this car!


James Paul

The top surface of one swivel hub has worn quite a lot. As they should bear against a phospher bronze washer, and that should wear rather than the steel, this looks odd to me. I wonder if the bearing washer on that side has been substituted with something else?
GuyW

There wasn’t one! 🤦🏼
James Paul

Without the washer the stub axle would move up and down on the king pin by several millimeteres. If the previous owner has ground the thickness of the washer off top off the stub axle then it is indeed scrap
Bob Beaumont

James,

If you get someone to do the bushes make sure they have the correct reamer or do the job yourself and rent the reamer on ebay https://www.ebay.co.uk/itm/HIRE-MG-midget-King-Pin-Bushes-Reamer-HIRE/283988305219 . The first time I did mine I did it in a lathe as the tech college had the reamer sizes required. When I next needed to do it I didn't have the kit to do that so took it to Beales in Bath after inquiring if they had the reamer, which they said they did, but last year when checking the journal sizes I found they had ground the kingpin to suit the bushes. I now have the reamer size required and lathe so when I do them I'll be doing them myself.

No amount of grinding of the top of the stubaxle is going to compensate for the lack of a thrust washer.
David Billington

Indeed. A missing thrust washer will give too much clearance, not too little.
Dave O'Neill 2

That's why I thought the pb washer might have been replaced with something else, which had caused the thing to wear like that.
GuyW

James, there's not some sort of spacer stuck inside the trunnion, is there? Otherwise, in the absence of the pb washer, surely the top of the stub axle would be turning and grinding against the trunnion itself, which would account for its appearance.
Bill Bretherton

Hi,

Found a fairly good video on reaming:

https://www.youtube.com/watch?v=q-gdjnCpldI

interesting to see the process.

It still baffles me how the prior owner messes up the installation of the bushes last time by inserting them upside down and not aligning to the grease holes, but somehow managed to ream them perfectly. The king pin fitted very nicely.

Bill - I still think this isn't a sign of wear but because the top bush is shorter in length on one of the stub axles that they used a grinder to cut the top of the bush to make if flush.
James Paul

The guy seemed a bit ham fisted when removing the bushes. He makes a good point about not turning the reamer backwards but I wouldn't be hammering the reamer out like he does as that likely cut into the newly reamed bushes to match each flute on the reamer, rather tighten the tap handle and continue rotating in the cutting direction and pull the reamer out. For fitting the top bush I would fit it from the top of the stubaxle with a washer against the bush so it stops when the bush is flush with the top of the stubaxle, not so easy as he did it from the underside unless you add a washer between the top socket and top of the stubaxle.
David Billington

There's a method described of cutting flutes in an old king pin and using that as a reamer. I think it was on the Chicagolandmg web site. AFAIR a single flute is cut at the top and bottom bearing sections of a kingpin, using a Dremel. The burred edge of this cut is sufficient to do the reaming of the softer bushings in around 10 minutes.

I saved a note of this several years ago with a page link to the chicagoland site but the link isn't working now but it will be on there somewhere.
GuyW

This is what you are looking for.

DIY swivel pin reamer

Technical archive.

https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=97&subjectar=97&thread=2012061600170310845







anamnesis

That's a similar idea, and I see I posted in that thread too, though I had forgotten! But the Chicagoland mg centre was longer ago than that. And I think it only described a single slot ground into in the pin to form the reamer cutting edge.

Unless badly burred during insertion there shouldn't be much to take off when reaming anyway.
GuyW

That video being of an MGB stub axle, it prompted some thoughts.

How long does the bush and fulcrum at the bottom of the king pin last, and how well is thrust controlled? It looks better than the threaded Spridget version. Pity there isn't sufficient meat at the bottom of Spridget k/pins, to ream out and fit a bush and plain pin too. Or is there?


anamnesis

An important factor in how long a fulcrum pin or a king pin will last is if and how it is greased: Intervals, second grease nipple (fulcrum), grease nipples in line with the holes, weather conditions, etc.
I drive summer and winter. I had to change the front suspension after 20.000 miles, there was wear everywhere. I had to remove the fulcrum with a hacksaw.
Since I use a marine grade grease I drove 60.000 miles and I can not feel any wear. The fulcrum turns.
Why a marine grade grease?
The (urea) soap in this blue grease is water resistant.
The "oil" ( in fact a fluorcarbon) in this grease sticks to the metal and can hardly be removed.
I use this fluorcarbon(It is expensive) in my, engines, chain saws and skates! with astonishing results.

Flip



Flip Brühl

Very interesting comments about marine ep grease. Just looked it up. Seems to be an extremely good idea. Is there any reason it wouldn't have been adopted in the past for this use? Was it around when our king Pin / wishbone design was put into production?
anamnesis

Very interesting. The book says LM grease for our use. But EP grease can be used where MP(multi purpose) grease can be used). So why dont we use EP grease? I can only think of pumpability.

EP Grease
Name stands for Extreme Pressure. Under high pressure or shock loading, normal grease can be compressed to the extent that the protective film breaks. If the film breaks, then the greased parts come into physical contact, causing friction and wear. In most all applications, EP grease can be used where any AP or MP grease is called for.

EP grease has in its components, solid lubricants (graphite and/or molybdenum disulfide) to provide protection under heavy loadings. Besides the normal protective film provided by the lubricant, EP grease contains solid lubricants that bond to the surface of the metal and adds a sub-layer that prevents metal to metal contact. This insures in the end, that there is no friction and wear when the lubricant film gets too thin/breaks.

https://fuelandfriction.com/weekend-warrior/ap-grease-mp-grease-ep-grease/

anamnesis

Surely it was just a case of the cheapest the manufacturer and its dealerships could get away with using - or to be more charitable, the standard grease was considered more than good enough if routine maintenance wa observed.
Nigel Atkins

Quality of the grease is only half the story. Especially with the fulcrum pins, the action of the suspension turning the threaded pin back and forth pulls road grit into the bushes and that is what causes the wear. Pumping grease through at regular and frequent intervals carries the grit out again. When greasing, it is not sufficient to just pump a little in, you really need to keep replenishing until fresh clean grease begins to come out, even if by then you have half a cup full oozing from behind the cork seals.
GuyW

The front suspension started life in the A30 in the early 50's and the recommended lubricant was EP 140 oil rather than grease. This was carried over to the Frogeye. The oiling intervals were 1000 miles for every nipple (excluding the steering rack). At some point it changed to LM grease (Later Mk11 Sprite?)and the intervals increased to 3000 miles. I suspect this was because the performance of modern greases had improved and to reduce servicing intervals.
Of course mileages back then were not that high, I recall 6000 PA on average?? So this would have meant oiling every 2 months which probably would keep the system in decent order. I grease mine a 3/4 times depending on how its used.
My pal's modern plus4 Morgan with its sliding pillar suspension has to be lubricated every 1000 miles even now!
Bob Beaumont

Guy mentioned the felt seals for the hub bearing.

This is s genuine Rover seal from the 1990s, which has both felt and neoprene.

I'm not sure if I've seen a hub seal that is only felt, but the early timing cover seals were.





Dave O'Neill 2

Dave I think Guy was referring to the fulcrum pins not the hub bearing seal.

Trev
T Mason

And with only 1 grease nipple at the ends of the fulcrum pin (as standard) pumping fresh grease to purge out the old wont guarantee you will get it all out.
Chris Madge

Trev

It was in reference to the wear/pitting on the stub axle.

"The early hub seals were oil soaked felt, which are more tolerant of pitting on the stub axle. Later (and current replacements) are normal neoprene lip seals which may not like the pitted area on your stub axle, but maybe not run that far up it. The outer part looks OK if that is where the seal lip ends up.
If necessary they are easily fixed with a Speedisleve."
Dave O'Neill 2

Sorry Dave, I had forgotten Guy posted that earlier.

Trev
T Mason

Yes, I was meaning the hub bearing inner seal. I removed some which I think were just felt, not dual felt/ neoprene like the one Dave shows. But those dual ones look good.

Chris,the solution is to put an extra grease nipple in the blanking cap at the other end of the fulcrum pin.

The cork washers on the fulcrum pin on my car weren't very effective at keeping out road dirt. Perhaps I need to find cleaner roads to drive on! But slices of closed-cell pipe insulation work pretty well. Cut slightly oversize (length) they compress into position to give a better seal. If fitted when assembling the fulcrum pin you can leave the slices intact but one can add them later by splitting the insulation and "springing" it into place. I added them over the cork ones, trimming the fit with a Stanley blade.
GuyW

So in view of this here's something that might be of interest

https://tinyurl.com/yxodaot4
GuyW

Hi Guy,

I have found a local engineering company that has been around for decades that the local Jaguar restoration company recommends.

Think I’ll take the stub axles, king pins and new bushes there first to see what they charge. I’m sure they’ll do a better job than I will, especially if the Jag guys use them.

Thanks though

James
James Paul

James, there is an MG centre near me (in Yate) which is the original Bristol MG centre re-located. They fitted and reamed my kingpin bushes for £40 although I had to look away when the guy was hammering in the bushes - looked a bit neanderthal. But they seem ok and the holes line up!
Bill Bretherton

Hi Bill,

That is really good to know, many thanks! 😊
James Paul

Bill,
I assume thats the guys that had the shop in Staplehill and a garage nearby - the shop closed about the time Moss arrived in Bristol ISTR - many years ago.

I used them quite a bit for parts and they did a couple of sets of stub axles for 'B's I was working on.
Not sure but i think it was either two brothers or BIW's - possibly Bob the mechanic ? If its still them I found them very helpful guys.

R.
richard b

Our local engineering guru - Steve Kiel - made some seals for the fulcrum pin from leather. Modern cork is really bad compared to cork supplied at the time the cars were current.
The leather seals need to be soaked in engine oil for a few days before installation.
He made 2 dies one for each size of fulcrum seal and cut them from old leather belts of varying thicknesses.

He also reckons that if you have 2 grease nipples on the fulcrum pin, the groove in the fulcrum pin should be blocked at the midway point to ensure the grease lubricates both ends of the fulcrum pin.

Rob
MG Moneypit

Richard, yes the same company although the shop is before I moved here. I used to sometimes cycle/ drive past the garage on my way to work. I think it's now run by the son/ relative of a former owner plus a youngish mechanic. There was a panel beater called Barry who worked part time for them and who had originally worked in Staple Hill I think. I was going to get him to do some panel beating but I think he's fully retired now.
Bill Bretherton

This thread was discussed between 03/10/2020 and 10/10/2020

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.