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MG Midget and Sprite Technical - Modified wishbone bushes and fulcrum pin

Does anyone know who Ken and Gloria are?
http://www.britcar.net/index.html

On their site they have pics of a 1967 MG midget they restored. In the process, the wishbone bushes and fulcrum pin was modified. I'd like to know how successful that was.

The modification is dated as August 2005.
-------- "they machined new fulcrum pins and A-frame bushings. The latter were partly threaded on one end with a plain bushing on the other. The idea was that this would give more plain bearing surface instead of the threaded surface which would hopefully make the bushings last longer.--- ".

How have they survived? There's only a grease point at one end, and the thread being at only at one end is all there is to control lateral movement in the bush. The rest is smooth. Interesting. How have they lasted?

So who are they? Is there a contact email address?




Lawrence Slater

Gez...idiots

Why stop there... might as well go all in, just hack off the other ends and screw in some rose hymn joints

Shear ?...

Please, everyone knows thats just a fancy word for engeneers throw around to have realavancy and sound smart then the rest of the poer unlearned folk

As im rites??? ...HEEE hawwww there lil youngouns

Prop
Prop and the Blackhole Midget

Whatever prop. :).

The questions are:
Did they last?
Who are they, and is there an email address?
Lawrence Slater

By having a plain pin/bushing, you're actually reducing the bearing surface considerably. I would have thought it would wear faster.
Dave O'Neill2

Not only would the reduced surface area wear faster, but the smooth mating surfaces, after wear, might also result in an ugly "clunk" noise over bumps.



Norm
Norm Kerr

Never seen their website Norm? It's your side of the pond.
Lawrence Slater

Im not 100%, but I think I had a run in with the lady several years ago

They were selling some very dodgy midget parts and trying to make the claim that the parts were SCCA approved

I called her out on it and expressed my concerns about selling dodge homemade parts ...needless to say it was like having a pissed off pousium trapped in the tolit just as your sitting down to drop a duce....the debate didnt end very well as loving close friends

Hahahs

Like I said...im not sure these are the same people But I think Iit was and if it isnt...my apologies for any mis representations

As I recall, she didnt take kindly to being lovingly called ..."chief"

Prop

Prop and the Blackhole Midget

Lawrence vs Prop? Lol! :-)

HE-HAW gets a lesson from the master!

I wish I could give you an answer on those folks but I never heard of them!

I was very surprized to see this design in the front of a stock midget. Was it left over from earlier models that didnt travel at quick speeds?

I tried to save the A arms on the car I was working on, but they were severly rusted together. I put the acetylene torch to the assembly and tried to coax out the lower pin heating and cooling with a water soaked rag. I couldnt get it out. It was all rusted solid.
I noticed that there were stress cracks on the outer
area of the a arms so they had been rusted together a long time and instead of being able to rotate cracked the outer A arm.

We got refubished A arms from Apple hydraulics. I noticed they brazed the bushings in to the A arm holes.

How were they originaly held in?

Im surprized no one hasnt made something better.
I cant believe how much of the front end is considered consumable! All I can say is I filled the new parts with Anti seize before I greased them.

If you plan on keeping your spridget grease the front end. You dont want to have to spend big coin on the A frames!

Steven Devine

"I was very surprized to see this design in the front of a stock midget. Was it left over from earlier models that didnt travel at quick speeds?"

That's exactly what they were Steven.

Alas even regular greasing doesn't hold back the wear. You can stop them siezing, but can't stop the threads eating themselves in the bushes.

We had a long discussion about how to improve on this design last year.

What interests me about what "Ken and Gloria" have done it this.

The pin retains a bit of thread to control lateral movement in the bushes. But as pointed out, the surface area of the remainder of the bush has been reduced and may cause accelerated wear.

However. The bushes are much thicker walled than the regular threaded bushes. Hence there is room to bore them out and inserts "IGUS" type bushes. Sush as here. http://www.igus.co.uk/default.asp?PAGE=iglidur&C=GB&L=en

As long as the frames don't crack having to hold the larger diameter bushes, this might be a good solution.

The remaining thread would still wear though, because all of the thrust would now be handled on far less threads. So it would need some kind of extra easily renewable thrust washer/bearing in there too.
Lawrence Slater

it would be interesting to know how they've lasted. The bearing area is indeed less but it would be possible to make both sides out of much harder stuff than the brazed in threaded bearings. Whether that would help or not I don't know - there is much discussion in the archives.

I do like the square on the end of the fulcrum pin. Must make it easier to get in and out.

It still has the problem of moving backwards and forwards as the suspension goes up and down, but again, I'm not sure if that is an issue or not.

It is something I've been thinking about as I get through wishbones rather fast.
Rob Armstrong

you posted as I did Rob.

Remember that long thread last year?

Each time, it needs new bushes, and that means new wishbones too. What's needed is renewables. this design might be adaptable to it.

Lawrence Slater

How many miles say regular driving do these parts last?

I was just surprized to see the bushings fail and crack a part when I tried to remove the bottom pin.

Do the race guys use these parts stock?

Oh yes how expensive new heritage a arms are!
Steven Devine

Depends how often you grease them and the state of the roads too. You can make them last 50000 miles, but you'll have play in them for a lot of those miles.

I've tried to find out where to buy the bushes, but can't find any at all. You have to buy wishbones.

There are some uprated improved ones. Barry King sells them. but essentially they are the same thing. I don't know how long they last.
http://www.spridgetwishbone.co.uk/
Lawrence Slater

The wish bone ends dont leave much room to make the hole much bigger. I cant believe that was never changed during that production run! Crazy!
Steven Devine

Well now's your chance to shine Steven.

Make a beefed up wishbone, that will take a larger metal bush holder, into which you can press a replacable smooth hard plastic bush, that the pin will run/rotate in. You'll also need to devise a way to control the lateral thrust, and do away with the threads. Easy?
Lawrence Slater

"who Ken and Gloria are?"

How did you find them, were you looking for Ken and Barbie?
Arie de Best

I think Ill stick with the antisieze trick. I let you know when my pins need replacement! Ha ha ha!
Steven Devine

No, I know Ken and Barbie personally. lol.
Lawrence Slater

About 25 years ago, I remember seeing/handling a new/prototype wishbone that was fabricated from (square) box section mild steel. I think I was visiting 'C.A.T Spares' in Audnam, Stourbridge at the time. And I believe the wishbone was made by Mr King of Hoddesden (GK Wishbones?). Presumably that is/was Barry's father's company. I can't remember if the wishbone had replaceable bushes, but presumably box section is the way to go if one is to redesign anything. Anybody know anything more . . .?
Andy Hock

Sounds interesting Andy. I wonder why Barry didn't persue that line?

It's not really the wishbones per-se that's the problem, at least for road use anyway. They may flex a bit, but the real issue is having to replace the whole wishbone because the aren't renewable. Hence the double ended greasing, and solid pin in BK's wishbones.

I suppose because of the design, the only way to have renewable bushes is to redesign the whole wishbone ends, so I suppose you might as well make a whole new design of wishbone. Then there is the question of there being a market for them. Which is probably why BK sticks with the traditional design.

So I think the only way this will get done, is people doing it individually for themselves.
Lawrence Slater

It's in the news link on BKs website Andy.

http://www.spridgetwishbone.co.uk/Advertorial.pdf

"Gerry’s fi rst units were fabricated
following the original box tubing
construction; many of his fi rst customers
gave good feedback on the quality of
work, car handling and stability. The only
downfall was the non-original aspect as
many people still preferred the Original
Equipment (OE) part. Even so, many of
these sets were sold nationally and G K
Motors expanded their fabricated units
to include pairs with negative camber
settings of various degrees. Once again
a wide range of replacement wishbones
were on hand as these were popular with
competition drivers.
The lingering interest to manufacture
new reproduction OE wishbones was still
high on the list and the next natural step
of progress. Eventually Gerry managed
to get everything in order to start this
exciting new project. Contact was made
with local tooling companies, but sadly
rejected as a no-go, again due to high
costs and the uncertainty of demand and
manufacturing capacity"
Lawrence Slater

Cant he find a manufacturer in china to make that?

Thats what they would do here in the U.S.!

Lol! :-)
Steven Devine

something else to throw into the pot - as far as I know it's an MOT fail to have a welded wishbone. could be wrong though. I remember a massive thread with much cleverness in it, I'll have to go and read it again.
Rob Armstrong

Rob the thread you want is:

"Lower fulcrums, and Gas grade PTFE".

In the technical archive, last post 09 April 2012.

David Billington discussed the very point you make about welding wishbones.


Lawrence Slater

Lawrence,

The wishbones are rebuildable as many companies used to do it when the cars were more common. The worn bushes were removed and new ones brazed in then they were tapped with a special tap to ensure the threads were coincident. More recently some companies have made pre-tapped bushes which you brazed in using a fulcrum pin to make sure the threads align but I think that's not as good a technique. What I did http://www.metal-arts.co.uk/sprite/frontsuspmods/index.html

Rob,

I think I made mention of welding on a wishbone being an MOT failure. Welding can be used in the construction of wishbones and often is but repairing a cracked wishbone by welding is an MOT failure. Modifying a wishbone by welding may be questionable but I think OK with spridget wishbones. The problem is that some wishbones are heat treated and welding them may cause serious safety issues.
David Billington

Ah, yes. I was waiting for the esteemed Mr Billington to pop by! This topic of fulcrum pins and wishbones has been done to death before, but I can't remember what DB said about load bearing wear on (his) oilite bush design compared to the 'orrible threaded original fulcrum pin design. To me, irrespective of the load bearing discussion, I still can't get my head around the fact that the original design has the fore/aft (lateral?) movement of the fulcrum and king pins (as a result of the fulcrum pin's thread) brought about from vertical wishbone/suspension movement. A horrible design.
Andy Hock

Yup I remember that David. Pity you don't market your design. Could it be done at a cost people would pay?
Lawrence Slater

And do you know any companies that the threaded bushes can be bought from?
Lawrence Slater

The guy that built the "mite" midget made a nice pair of tubular wishbones,

I always enved them... when i was checking the cost To have them 1 off made locally, I kept getting something (i never learned what it was) shoved up my butt just right before the price tag of $1000 to make a pair was blurted out

That would be a great easy part.to manufacture and sell...once you learned how to make Them properly

Prop


Prop and the Blackhole Midget

Found it... the link to how to make tubular wishbones from the guy that built the mite

Btw... if anyone checks locally to see What the cost Iis to have them made and you to get a shafting senstion in your butt cavernjust moments before the price tag is exposed.....let me know what you think that is... to small for 10 foot long snake


Hahaha...its a great artical with lots of extras

Prop

http://the-mite.com/mite9.htm



Prop and the Blackhole Midget

So its an mot fail to weld the a arms but brazing them in is ok? When I first saw what I was looking at I thought it was a hack some One put in there. I couldnt believe that was a stock from the factory!
Has anyone seen the brazefail?
Steven Devine

Those look nice Prop, but he could have made the bushes out of something other than the same old threaded variety. I wonder why he didn't opt for more modern bushes?
Lawrence Slater

I just looked at the mite page again and wondered the same thing. Why go to that effort and still use the standard threaded fulcrum pin. As noted on my page the OE kingpins had the boss through which the fulcrum pin passes ground square but they went out of production in the early 1990s IIRC. Pattern kingpins left the faces as forged so they would need to be machined/ground if used as seating faces. Can someone who has bought kingpins recently confirm if those faces are still as forged and not ground.
David Billington

David,
I bought a pair of kingpins + bushes as a set from MGOC about a year ago. The sides of the boss on the kingpin are machined.
Guy W

Guy,

Thanks for that information. IIRC it was Moss in Bristol that told me the OE (Unipart?) kingpins were going out of production in the early 1990s and all the pattern parts didn't have the facing done at that time. Maybe the pattern suppliers have upped their game or someone is supplying to OE specification again. Would have to check the accuracy of the squareness of the facing to the fulcrum pin bore but that is potentially good news.
David Billington

"but that is potentially good news."

Are you thinking of making modified wishbones commercially, that can take renewable bushes, with side thrust washers on the k/pins then David?
Lawrence Slater

I just looked at my barry kings... it appears one side is machined and the other side is not

I briefly talked to the guy that built the mite about the fulcrum pin Back when I was looking to have a set.of tubulars built ....hehad a change of heart as hindsight is always much better

his opinion was the same here ...redesign with a bushing... I cant remember exactly I want to say we where talking about a rubber/ nython bushing set up as well as a brass bushing set up and do away with the orginal fulcrum pin....basically like the turrion link with the red bushings

Please remeber... this commentary is me remembering back 1.5 years.....so its important to remeber... he to agreed in hindsight that a fulcrum was needing designed

Prop
Prop and the Blackhole Midget

I am not an engineer, so have no way of judging the stresses involved, but it seems to me that a redesigned kingpin wouldn't be that hard to come up with. Instead of the knuckle on the bottom, taking the dreaded horizontal fulcrum pin, the bottom would have a vertical, tapered hole to accept the pin from a conventional lower suspension ball and socket pivot point. I guess it would need machining from a solid billet.

The steering ball and socket swivels are used on many moderns and it would be an off the shelf and easily replaceable item. It would just need a plate welding to the outer end of the bottom wishbone, drilled to take the 2 or 3 fixing bolts.

Or possibly use a complete lower wishbone unit, but it or the car would likely need some modification. I doubt if the lengths are right! But they are as cheap as chips if Lawrence wants to get one to experiment with!

http://tinyurl.com/kvu3723
Guy W

That's a great idea Guy. I would think the standard Spridget Wishbone would be easy to alter, but getting the kingpin made might be the expensive bit.

Sometime this year I'm going to sort my frontline oilite bushes, so I'll ask how much they would charge to make a king pin the way you describe.
Lawrence Slater

So just curious....

How much movement is needed in the fulcrum joint

It just seems like this would be an easy mkd to figure out

Could we just make a "y" shaped that wod fit over the hole at the bottom of the king and be bolted, sleved, welded, ect ect into place and pin portion be bolted into the new socket area of the wishbone

Granted... its alot of built in shear, but as long as your a fan of disney park E ticket rides...it would make life intresting, if not unpredictable

Im not a big fan of hacking the bottom of the king pin and tapping rose hymn to it

What about somekind of axle shaft U-joint assembly... thats got my imagination at the moment

Prop
Prop and the Blackhole Midget

I guess Andy Phillips might be able to get a good price on my redesigned kingpin idea.

But I still think Lawrwnce's sleeved repair set for the bushes sounds the best, for a simple solution.
Guy W

i have looked at this as i need to replace my a-arms and one side has play in the kingpin, and it also seems to be bent as i cant get it apart.

looked at 'the mite' option but that still uses the kingpin.

My thoughts were to use the ball joints, hub , brakes, stubshaft as a complete assembly from something like a honda jazz.
Then guess what ? no more wheel bearing issues!!!
when i was last in my local scrapyard they had a big box of such assemblies and several looked suitable.

but i will get to the point quite soon where there is nothing original left of my car.. however i have a big box of spare bits i have saved so could build another one...

Andy Phillips (frankenfrog)

Andy...

Arie and I have come to terms, that a midget is no longer a midget when you replace the rear view mirror....its something else at that point

Prop
Prop and the Blackhole Midget

What Does it become, a Ferrari? Lol! Hey look at me! Ive got new king Pins! Ha ha ha!
Steven Devine

Guy,

While on the face of it yours sounds like a good idea, I wonder if it wouldn't put more stress on the shock arm in a stock setup, as the kingpin would be free at the bottom to rock fore and aft. Without triangulation of the top arm, which would be the only thing controlling fore/aft movement of the kingpin, there would be a lot of stress on the upper arm/shock and/or a lot of unwanted movement.
Andrew F

Andrew, as l said, l am not an engineer, but the fore and aft positioning of the bottom of the kingpin is determined by the splay and rigidity of the lower wishbone. In the standard set up this point is compromised by slack, wear and inefficient design of the fulcrum pin and its bushes. This bit would be replaced in my suggestion, with a much more positively locating component.

I think the opposite would be true, it would be a more satisfactory location and put less stress on the upper arm.
Guy W

Maybe I am misunderstanding what you suggest. Are you not suggesting a balljoint as used in most strut and dual wishbone suspension, that allows movement in all directions? Rather than just in a single direction as the standard setup allows (ideally and with no wear of course)?
Andrew F

Yes that's right. And I can see what you are getting at. But if the balljoint itself is securely positioned by the A arm (and that itself is maybe debatable) then it wouldn't impart any more fore and aft movement to the base of the kingpin would it. The bottom would move up and down and the ball joint would pivot through the arc controlled by the bottom wishbone.

In the standard arrangement the fulcrum pin is usually so slack in the wishbone bushes that the kingpin will pivot fore and aft at the top anyway. And the wishbone itself would twist and distort as well, if the top suspension arm would allow it. I am pretty sure the standard design it isn't intended that the bottom fulcrum design should support the kingpin from tilting fore and aft. The top lever arm seeks to provides that, which is why the common adaptation to stiffen it up is to add an extra triangulation in some form at the top.
Guy W

Guy,

Andy's point is that if you adopt a ball joint at the bottom of the kingpin, then you must replace the lever arm at the top with a fully triangulated arm, otherwise you will have very little to control fore-aft location of the wheel (the king pin will be free to rotate at the bottom, and a lever arm provides not enough control at the top, by itself).


Norm
Norm Kerr

I am clearly being a bit slow to grasp this one!

The ball joint at the bottom is attached to the end of the lower wishbone and as such can only move through an arc in the vertical plane. It cannot move out, away from the car and it cannot move forwards or backwards along the axis of the car.

Yes the ball then swivels, but from a fixed point (or rather from a fixed arc) So if the kingpin were not attached at the top end it could thrash around in all directions. But it is fixed at the top.

I don't believe that the normal arrangement gives any more support to the kingpin, and in fact because of the design I think it gives rather less. There is always slop at the fulcrum point which allows the bottom of the kingpin to deflect along the axis of the car, imparting a twisting leverage to the upper suspension arm.
Guy W

picture from http://www.britishracecar.com/ChuckPitt-Spridget.htm
replaced king pins with ball joints, and triangulated top arm.



Andy Phillips (frankenfrog)

Wouldn't it be nice, if that was on sale as a kit, and at a reasonable price.
Lawrence Slater

Guy,

I presume in your idea that the bottom of the kingpin is still cranked and the ball joint fits through where the fulcrum pin is but downward. If that is the case then the offset between the ball axis and the kingpin axis will result in the kingpin being twisted under braking loads and that would have to be resisted by the upper trunnion which it isn't designed to take likely leading to something breaking (under braking). In order for it to work the ball axis would have to be coincident with the kingpin axis but worse case if the bushes seized it might still twist the top off the kingpin. The current trunnion arrangement takes the twisting loads well. I think the best way is a redesigned trunnion with tophat bushes. I think I have mentioned before that years ago I met a guy that had done a number of conversion using spitfire lower trunnion parts and they're cheap on ebay.
David Billington

Ah yes David, I see that.
Looking at the modern ones I have noticed I see that the axis of the bottom one doesn't "aim" directly at the axis of the top one. They are sort of angled and I think that the axis of each ptobably intersects at the centre of the hub. Presumably for just the reason you state. I think you can see that on the photo that Andy has posted.

Front steering and suspension geometry is much more complex that one realises. Even on a bog standard 1952 designed set up like the Sprite!
Guy W

Well still no feedback on Ken and Gloria.

I guess we'll never know, how their re-designed fulcrum and bushes lasted.

And just as I posted that, BINGO. I found an email address for them. I email them and ask.
Lawrence Slater

Hi I remember the box section you mention Andy Hock I did show the advert on here a while back those wishbones were very popular with the track and performance Midget owners mainly because of their strength and the diferent camber we made them with but not so with the restoration guys and also the stockists hence why my dad brought out the pressed OE replacement BUT all you budding engineers I believe the jigs and tooling are still in the benches and would not be difficult to reproduce so there is a business opportunity there for somebody,as you all probably know my dad will be stopping producing wishbones this year he is 75 in the summer so we will be looking for someone to take it all on I am sure it would suit an MG related engineering shop I will try to find a picture of the box section ones and load on here later. thanks Barry
bp king

Thank you for your reply, Barry. Interesting to read that you might still have the jigs and tooling for the box section wishbones. I'd always assumed that you, personally, were now running the (pressed steel) production and that dad provided the moral and technical support - I'm sorry to hear that he is retiring in the summer, but I guess he deserves a rest! Spridget wishbone manufacture/supply is, to say the least, a niche market. Barry, presuming that you are not going to take over the reins, I do hope that a suitable buyer (who has a long term interest) takes over. Regards to you and dad.
Andy Hock

I'd like to see someone take it on and introduce easily renewable bushes into them.
Lawrence Slater

This thread was discussed between 20/06/2013 and 30/06/2013

MG Midget and Sprite Technical index

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