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MG Midget and Sprite Technical - Play in wishbone

Morning :)

As you might have seen, I am changing my springs on my 1972 Midget, and checking my front suspension at the same time... Good idea, as I just discovered that one of my inner pivot on one wishbone is shot, so I will change all of them.

So here is my questions (my springs are out, suspension "hanging" thanks to wood under damper arm) :
- Can I remove only the wishbone, by unscrewing it at the inner pivot and fulcrum pin only ?
- How difficult is the fulcrum pin disassembly/re-assembly (doesn't look nice in the archives...) ?

Thanks!
CH Hamon

It's simple, IF the pivot pin taps out!


If not you'll need a blowlamp and lots of heat.


Good luck.
Steve Smith Kent

Also the fulcrum pin often seizes on the king pin which means it cannot be unscrewed. Plenty of Plus Gas penetrating fluid (or equivalent) needed! In extreme cases where the wishbone threads are worn it needs a new wishbone!
Bob Beaumont

Hum.... I am busy enough lately to not touch this if it doesn't need too :)
Can I just unscrew the inner pivot, and change the rubber without touching the fulcrum pin (leave the wishbone attached to the suspension but not to the shell)? Nothing special to forecast (except to not forget the ARB I guess ?)?
CH Hamon

Yes you can do that Cedric.

But my advice would be to visibly check and feel for wear in all of the moving parts of the front suspension really carefully before starting to dismantle anything. If one part (inner pivots) are worn then you need to know what else might need replacing before attempting to dismantle just that part.
GuyW

A problem can occur when taking out the inner bushes that the bolt is solid on the bushings steel sleeve and the bolt cannot be removed.
I have cut the bolts in the past with a hacksaw blade in a pad saw. Hard and slow work. Did not fancy trying a slitting blade in the tight space.

I would then replace with polyurethane bushings - Super Pro (Australian) are my choice - I have had issues with a British make and poor service.
richard b

Cedric, if the inner fulcrum pins are stuck and will not out, don't spend ages with heat and hammers (potentially causing damage). You can cut through the pivot pin with a hacksaw blade in only a few minutes. Don't ask me how I know this ;-)
Jon
Jonathan Severn

That's exactly for that kind of advises that I post here !
Two came easy, two are stuck, for the reason you mentioned... So hacksaw-time it will be !

(The next tool I will buy is a pillow for me for when I work on the car...)
CH Hamon

"My friend", instead of working and spending his tea-time on his Midget, should better have had cleaned his living room before SWMBO gets home...

CH Hamon

Cedric, I don't think your friend need worry about his living room. It is very clean and tidy, and I am sure that the happy smiling face to greet her will be well appreciated. 😊
GuyW

To avoid making the floor dirty, perhaps next time your 'friend' should place the Midget parts on that handy pink mat.

By the way, if you buy a pillow for working under the Midget, get some safety glasses too, otherwise you might get stuff in your eyes (don't ask...).

Jon
Jonathan Severn

Guy, i did smile: it did the trick ! Or is it because I cooked...? :P

Jon, this is the "gym mat" of the Mrs ! Second most important thing in our flat, after her toothbrush. I would burn in hell for using it...But you did gave me an idea: would be nice to have one to work under the car :) Too late for the glasses, but I definitely agree...(don't ask... :P)

Back to the Midget...
- Any specific product to clean the remaining small rubber pieces and to have a smooth surface for the next bushes?
- And....how to check the fulcrim pin condition ? What to look for ? I do have a slight play around Z axis: i can gently turn the wisbone slightly by +/-5 degrees approx , that the only thing I noticed...

Thanks ! I will now rest my back, my fingers and my eyes.... :)
CH Hamon

Cedric, is the toothbrush an electric one? You will find an electric toothbrush is really good for cleaning small parts, like the awkward corners and shapes of a carburetter body. Better still when used with petrol or a solvent although it might be difficult to difficult to get rid of the petrol flavour before she gets home.

But seriously, I do keep an old electric toothbrush for cleaning small parts like this. I just try to remember not to muddle it with the one in the bathroom.
GuyW

Good call! In case it would happen "accidentally", do you think the smell would leave with a new brush? I think I have seen a pack of them somewhere ;)

CH Hamon

Purée / Punaise / Sacre bleu ! The Old Girl let you know when she doesn't want something... Do you all struggle in silence, or hard just more handy ? I feel lonely struggling... :D

They didn't look old on one side, just seized... It is written "2016", molded on the rubber, despite it can mean a lot of things...

Should I put some copper ease between the pin and the metal insert when re-assembling ? Or I just hope they will last long, before the next battle ? (I can only wear long sleeves to hide my scars for some time...)


CH Hamon

Cedric
I put grease on mine to aid disassembly in the future but, actually, the metal inserts aren't meant to rotate around the pins (well not with rubber bushes at least, not sure about poly) but rather the rubber bushes are meant to flex as the wishbones move up and down (as I understand it). So the inserts are not bushes as such but are clamped when the nuts are tightened (or should be). That is why you don't tighten the pin nuts until the car is on its wheels so that the rubber bushes are not stressed at rest. I don't know if that applies to poly bushes.

P.S. I have been known to use bad language when things get diffcult, we probably all do! You sometimes have to walk away, have a cup of tea, then come back and have another go. Never give up, there's always a way.
Bill Bretherton

Cedric
I put grease on mine to aid disassembly in the future but, actually, the metal inserts aren't meant to rotate around the pins (well not with rubber bushes at least, not sure about poly) but rather the rubber bushes are meant to flex as the wishbones move up and down (as I understand it). So the inserts are not bushes as such but are clamped when the nuts are tightened (or should be). That is why you don't tighten the pin nuts until the car is on its wheels so that the rubber bushes are not stressed at rest. I don't know if that applies to poly bushes.
Bill Bretherton

I agree with you Bill, I see it the same way. I was more thinking of copper ease, not to ease rotation and movment, but more to prevent the metal insert to seize on the pin, which then make the disassembly so painful...

I wonder then, if it not less problematic with the polybush: would the metal insert seized on the pin not a problem, and they would come out both together "gently", leaving the polybush in the wishbone alone ?
CH Hamon

Cedric,
don't feel lonely, the idea that these cars are always very easy to maintain and only require a few basic tools is often quite honestly total bollocks.

But I thought you enjoyed the suffering.

Once you have a warehouse full of obscure, one-off use tools, engineering equipment and a stock of old better made parts things will get easier, you could rent a storage unit to keep them all in. :)
Nigel Atkins

Cedric
I don't know about polybushes, maybe someone else will comment. I guess copper ease is ok, whatever you have to hand but put something on.
Bill Bretherton

The Super pro bushes I put on mine came with a sachet of Silicone grease, enough to be liberal all over.
Rob
MG Moneypit

Hi,

Is it normal that the crush tube can't go all the way on the pin ?
If I rotate the tube 180 degrees, it just engage 2 or 3mm before bein stuck on the pin...

Also attached the description of the system, might be interesting towards what we were saying previously.

Cheers,




CH Hamon

No! It seems either the tubes or the pins are badly made and are not completely round. If the car is still mobile bring a tube with you when you call in next week and I can test it using good secondhand pins, I have lots.
David Smith

Hum...They are all on the car now, after a small battle... Not fully screw though, as I still need to put the springs back on, then the car on its tyres before fully screw the pins.

I do wonder if this small interference is not on purpose for polybushes design: they should be no play between the pin and the tube, as the rotation will take place between the tube and the polybush (so the tube should not rotate).
Where is the rotation movment for the rubber bushes ? Are the tube and rubber bushes glued together ?

This how I understand it, but I might mis-interprate it (would not be the first time !)


CH Hamon

Interesting as when I did my rebuild the polybushes I used did not have inserts for the wishbones.

I did have issues with the top trunnion bushes they provided as they were not supplied with washers and spread out when tightened - the supplier was of little help.
I see the kits now include washers.

I binned the trunnion bushes and used 'Superpro' in lieu, which I will use in future for all polybushings.
richard b

There is definitely more engineering and "head scratching" that it looks like in those small kits. I don't know how all those companies develop them: having few cars, testing, disassembling and inspecting... I have my doubts :)

I would not be surprised if at the beginning, when those kits went on the market, they still needed some improvement. And, I would not be surprised again if those improvements were done based on the most accurate and detailed customers feedback...with some coming from here :)

It looks like they thought the polyurethane bushes would be strong enough and not need the "metal" inserts to assist them anymore...and somehow had put them back for some reason :) BL engineers were not bad at all ;)
CH Hamon

I bought a full car set of blue Polybushes. The rear ones worked fine but the front inner wishbone ones crumbled into pieces when I tightened the fulcrum pins and the top trunion ones ballooned as Richard describes. I added some large washers for those which cured that problem.

When I checked the good rear ones were in a pack labelled Polybush (capital P, a registered brand name) but the faulty ones were in a plain unmarked plastic bag. I complained to the supplier who said they were out of stock, but a couple of weeks later they sent me new ones in a correctly marked bag. They were a slightly different shade of blue. I am pretty sure they had initially substituted from a different source though they were listed as an agent for the Polybush brand and wouldn't want Polybush to know!
GuyW

I once tried to fitting some lesser brand of poly bushes to my car. All I remember is they were orange.

After hours of swearing and getting nowhere they went in the bin and I put rubber ones back in!

Malcolm


For mine none used sleeves. That was 20 years ago so I suspect the design has been improved to include a smooth surface for the bush to turn on. I suspect that Cedric is right and the sleeve is engineered to prevent it rotating on the fulcrum pin. Engineered - may mean distorted slightly by squashing!
GuyW

Personally I prefer the rubber bushes. I had cause to replace the cork seals on the king pin a few months back. I took the opportunity to check the bushes which had been in there since I rebuilt the car in 2009. The upper trunnion bushes were still servicable but I took the opportunity to replace them(suitably lubed with copper slip) The inner wishbone ones were still in good condition and were not replaced. The car had done roughly 25000 miles. I am not at all certain that some of these aftermarket upgrades have been properly evaluated. Its different if the car is used in competition where stability is required but then it probably only does a few hundred miles at most. Regular road use I think presents a greater challenge.
Bob Beaumont

My original bushes were genuine 'Polybushes'

R.
richard b

I admit i went almost straight to "polybush", without really checking feedback and advises (i.e. asking here before hand :) )

I did 130miles this weekend, with the new springs (9.0" 369lb.ft) and the new bushes (and no ARB!), and the car does feel really different ! Was not really spirited driving, as i had my "favorite" passenger, but the feeling is totally different... You do feel much more the road through the steering, and the car is more stable. But... I am also happy with my choices (based on your feedback): harder and more informative, but more would be too hard for me... (I am a Citroen driver too :D)

Still need to test with 5/8 ARB and a bit more "cornering speed" to see :) Then i can send my head for more BHP :p
CH Hamon

Cedic,
perhaps a good thing you changed those tyres(?).

Try these for your new ARB and handling, if you don't like them I will buy them from you at half-price - yes I know I am too good to you.

Midget Ball Jointed ARB link kit H160 - http://www.mgocspares.co.uk/acatalog/MGOC_SPARES_Front_suspension_650.html
Nigel Atkins

Cedric I'll pay 10% more than what Nigel has offered ;)
Chris Madge

Tuff luck Chris, my offer was in imperial measure which will appeal to Cedric's new learning.
Nigel Atkins

Nigel you have to price your offer in Guineas....
David Smith

The imperial negociation did make me laugh :)

But if I buy these great ARB link, they will last, and I will have nothing to complain about, right ? I will not come here and ask for help anymore, true ? Do you really want this to happen ? Do you ?

:(
CH Hamon

If you install the ball-jointed links you will be removing some of the compliance provided by the rubber bushings in the standard links. I'd say that makes it all the more important that you reinforce the chassis rails to prevent the brackets being torn out - unless you have already done this :-)
Jonathan Severn

Cedric, since you may struggle to buy petrol for your car within 10 years, or may not be allowed to use it, perhaps the rubber mounted links are all that you need pay for as they should last long enough.
GuyW

Sorry to disappoint you: they are already in and drying :) Rubber, but repainted to avoid rust, all this to try to push them to 20 years of lifetime: that is my bet of petrol affordable for normal people ;)
(or everybody will have electric cars, plastic will be banned, so demand in petrol will crash and we will be able to keep on going ! :))

CH Hamon

Modern art installation, I expect if your name was Damien Hirst that would be worth at least a million £.
David Billington

I don't know what the life of the rubber in standard drop links is now but apparently the originals were very long lasting, but when I made the mistake of replacing mine the replacements had very short lived rubber in them.

Going back a bit in the thread, Cedric would think if I offered him guineas he'd be getting furry animals, or get them mixed up with the Oirish currency of guinness.
Nigel Atkins

Thanks David ! Next time I need to hang them in the kitchen due to lack of place, I will tell my girlfriend she just can't understand the artist inside me... :p Hope I will managed to be rich before my death...Or at least it will not give her idea to do so!

Nigel, of course I understood Guiness. I thought it was a way to call it in "real English". I would be alright with good ales from the good book from micro-brewery from Midlands :) Almost like this now... :D
CH Hamon

Guiness is about as far from being real ale and a microbrewery as you can get - fabulous marketing though only ever bettered by a few American fizzy water products (and perhaps a certain MG specialist).

I am into real ale stouts now and have had a number of different ones but some are still too much stout taste for me.

In the late 70s and very early 80s when real ale was still being revived I used to very occasionally have to have bottled Guinness, it was a different brew then in a bottle (not the double fizz stuff) and it was horrible, two bottles and I got a headache and aftertaste the next morning.
Nigel Atkins

This thread was discussed between 10/09/2020 and 23/09/2020

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