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MG Midget and Sprite Technical - FULCRUM PIN LOWER

is there an easy way to get these out?
Nick Sayle

... only when the cotter pin removes easily, and you can unscrew the FP without finding it's attached by a miracle welding process to the king-pin.

You could try heating the KP to help free it from the FP.

Many take an angle grinder to the KP or the FP (depending on what you want to preserve). You might consider this an easy way(!)

Anyone any better ideas?!

This is one part of the midget I'd love to re-engineer (maybe along the lines of DB).

A
Anthony Cutler

hacksaw (really)

On the other hand, if you are lucky, the tiny wedge pin can be drifted out (after you remove its tiny nut), but don't count on it. Then, if you do get that out, a really large screw driver might be capable of un-threading the fulcrum pin from the A-Pan, but don't count on that either.

Be judicious with heat in this area, because the A-Pan and the threaded pieces (that the fulcrum pin goes in to) are brazed together, and if you melt that, its scrap.

This joint, and the kingpin shimming/reeming process, are the reason why pre-assembled A-Pan/Kingpin assemblies are so widely available from vendors for Spridgets. They make the whole job a very simple "remove and replace" task.

If the parts are fairly new, and have been well oiled throughout their life, the pin should come out. But if everything is worn, it all needs replacing anyway.


Norm
Norm Kerr

It depends. Having just replaced both mine, one side unscrewed easily, the other was a pig. Assuming you have removed the cotter pin, you need to make up a tool, a bit like a big screwdriver blade, to fit snugly in the end of the pin, and as wide as possible, so you can give it some turning force, without breaking bits off the pin, as it is quite brittle. If you then need to, add penetrating fluid, it might take a few days. I finally got it undone with some gentle heat. I had to use some blasphemy as well - it seemed to help.

Jonathan
Jonathan 1972 1275 RWA

If it won't unscrew using Jonathan's methods, then cut through the FP either side of the Kingpin with an angle grinder using thin slitting disk. It is quick, the 3 bits of FP can then be easily removed and can all be done without damaging either the A frame or the KP

Guy
Guy Weller

panic over, job done. now its fully disassembled wire wool sandpaper and re paint time while I wait for all the new bit to arrive. Is there a better material rather than cork that can be used when assembling it?
Nick Sayle

Yeah im a fan of the angle grinder with a thinn disk also...but the experiance of removing has been a huge encourgment to OVER grease the fitting every time the wheel comes off

prop
Prop

Nick,

right or wrong i used a nylon washer instead of the cork...I just took the cork to a good plumbing store and found nylons washer about the same size... no problems so far...It never made any scence to me how the cork would work and not completely disenagrate in a short period of time.
Prop

It all started out looking for a little play and a very slight knock in the off side suspension. The car was handling reasonably well as far as I thought comparing it to my BGT. I took the whole front suspension apart baffled. When I disconnected the top fulcrum from the shock, the arm just dropped under its own weight!! Horrified I took the other side apart and found the same thing! So why was my car nice and tight on the front end? With the springs removed and the wishbone free apart from the lower bushes. They were my shock absorbers! The bushes where so bad as were the pins and this car has 10 months MOT!!! As I had a couple of days for the replacement parts to arrive I decided to clean up the spring pans. All cleaned down to the metal and a few coats of hammerite. Ok I could have just bought new wishbones and pans but I don't believe in that. Took me HOURS!!! New Orange uprated shocks arrived today but I had to respray them red as they clashed with the springs. I salvaged the lower pins and cotters as they came out very easily. One question, is re using the lower fulcrums and cotters a real no no. How tight a fit should the centre of the fulcrum pin have in the lower trunion before the cotter pin is fitted? Jewsons do fibre washers exactly the same dimensions as the stupid cork ones. 12 pence each.


Nick Sayle

Id think it all comes down to the quality of the treads in the wishbone bushings where the F. pins screw into and the F.pins them selfs ...if the threads in the wishbone are toast, then Id al least re-busch to have new threads and then look at the F. pins if there trashed also then Id replace

if the pins came out effortlessly then Id think 1 of 2 things

1. the pins where well maintained and lots of grease applied on a reg. basis... in great shape and can be re-used...OR....

2 the assembly NEVER saw an ounce of grease and is totally worn out and the threads have worn themselfs smooth.

Prop...just my opinion and been along time scence Ive been in that area.
Prop

They where well packed with grease but it looked like copper grease, not sure if thats the right stuff. I have dry assembled the FP and cotter. The threads are very good on the FP and there is little or no wear on the cotter pin slot. The cotter, once the small nut was removed was only finger tight and I was able to simple push it out. I will start to re assemble it all in the morning and reuse the FB and cotter, but I have a feeling I will order new ones. If the rest of the car is anything to go buy the last owner did some serious cowboy (English expression and no offence to CMT viewers) things. So who knows what stresses they have been put under. I mean, there is a trolley jack shaped dent on the sump I had to replace!
Nick Sayle

Nick,
The cotter pin should wedge the FP into the bottom of the kingpin so there is NO movement between the two. Usually this means that the cotter pin is wedged in pretty tight and needs to be drifted out. All of the movement is between the threaded FP and the spring pan bushings. The thread is really just a means of creating an extended surface area for a plain bush - an odd arrangement but it works if kept well greased. Even on new components there is likely to be a little slop but this should be minimal. Annoyingly it is often the spring pan bushes that wear first.

From your description it sounds as if it has all been apart fairly recently and you may not gain anything by replacing individual components unless you replace the whole lot or use one of the improved design spring pans. If you are on a budget then put it all back together and just keep it well greased. (I do mine monthly).

The main problem with the original design is that only the end of the FP nearest the grease nipple ever gets properly greased as it spews out around the cork washers. It is an easy modification to drill and tap the blanking plug on the opposite end of the FP and add another grease nipple so that both ends get greased. I use slices of dense foam pipe insulation in place of the cork washers as it has some squishyness and achieves a better seal to keep out road dirt.

When you reassemble check for vertical movement of the hub carrier on the kingpin - you may find that this needs to be adjusted (shims under the top trunnion)

Guy
Guy Weller

agree it's OK to re-use parts that are still in good nick. Theree is actually no need for the cotter to be mega-tightened against the pin, if you have the two flat surfaces mating correctly then a single light tap with a hammer and nip the nut up gently will give you the result you've already experienced, I.E. it can be disassembled later! Use bearing grease e.g. Castrol LM not coppaslip.
David Smith

The fulcrum pin is very hard steel so wears less than the softer bushings. That said, they can corrode; look at the thread and if there is any corrosion I'd replace. On the first side I did, I re-fitted the old f-pin to a new wishbone (the PO supplied it with the car), and it was a very tight fit to re-assemble. However, I think this is correct - you have to almost ream it into the bushing, 1/2 a turn in then back off 1/4 turn. I used the same metal tool i'd made to unscrew the pin. When its fully in, it will be a real snug fit, and when you add the kingpin, there will be no play at all. When I did the other side, I used a new f-pin, as the old was corroded, but the wishbone bushings seemed ok. The f-pin went in easily, but when all was re-assembled, there was a very slight (but acceptable) amount of play, noticeable at the top of the kingpin.

Jonathan
Jonathan 1972 1275 RWA

Never had one so tight it had to be reamed in - but maybe there is a lot of variation. At the other extreme I have wound PTFE tape around the threads of the FP to reduce the slackness. And when I stripped it down some 5000 miles later the PTFE was still in place so it did its job.
Guy Weller

PTFE! good call. that reminds me! the washing machine hose is leaking.
Nick Sayle

I used the thicker PTFE tape supplied for gas fitting but I guess more turns of the standard thin stuff would do the same thing.

Guy
Guy Weller

cleaning suspension parts is a pain in the bum! I have spent hours and hours with a wire brush and various cleaning fluids. I ended up using Mr Muscle oven cleaner. Its amazing!!


Nick Sayle

Guy. I probably meant 'tapping' rather than 'reaming'. The method is mentioned in this article which I found invaluable.

http://www.mgcars.org.uk/midgetspriteclub/MascNew/TechTips/Suspension.html

The PTFE tip sounds good so long as it doesn't break up over time and prevent grease reaching the threads.

Jonathan
Jonathan 1972 1275 RWA

Jonathan - Yes I gathered that is what you meant. Interesting that the article says that this is normally necessary. I stand corrected as I have only ever found them to be relatively slack, even with "new" (reconditioned) wishbones. If they were that tight one couldn't then use the PTFE idea. I do think that adding the extra grease nipple is a worthwhile job whilst the thing is in bits.
Guy Weller

I have just come on to the forum to find info an this very job and here it is only 3 days old!!!
Near side was OK but offside will not turn at all - well it will with the steering wheel but is heavy - hence the take apart. The cotter pin is out but the rest is solid so it looks as of a replacement set up is reqd.

If any body else has to do this job - good luck.

I recommend very regular greasing - took one nipple off and the grease was solid..
Dave
Dave Price

A fault at the Lower Fulcrum pin is unlikely itself to make for heavy steering. Sounds more like seized king pin bushes or incorrectly adjusted top trunnion.
Guy Weller

Guy
Siezed it is. I got the wishbone and king pin assy off but thats about as far as I can go. A crow bar can just make it turn but it will not drift off the pin. Is it worth cutting the fulcrum pin besides the king pin assy and swapping the lot or struggle on?
ALSO there is a bit of play between the fulcrum pin and wishbone - does that mean a new wishbone as the pin is screwed in and not bushed???

I love this car but I wish the PO had greased the effing thing!!!!!!!!!

Dave - 2 hrs in the garage away from election tripe - Price
Dave Price

Dave,
Do I understand correctly that you can (just) turn the hub carrier on the kingpin, but it won't drift off the kingpin?

If it will turn, even a little then it should with some persistence come off the pin. I would try soaking some penetrating oil down the kingpin. You could make a reservoir around the top of the pin with plasticene or putty, fill that with penetrating oil and leave it standing overnight. Or put some into a grease gun and pump it in via the grease nipples. After this work the swivel hub to and fro until it gradually should come free.

Guy
Guy Weller

Guy - after soaking and teasing !!! the king pin and hub carrier are now separate. I have cut the lower bolt in two and managed to get the end with the slot in out - the other I will cut a slot with the dremmel and screw out. Is the centre part of the bolt unthreaded and therefore drift out post wd 40 application?
Dave
Dave Price

Yes Dave, the centre piece is unthreaded and should drift out - assuming that you have removed the cotter pin first.

Good to hear you got the kingpin disassembled!

Guy
Guy Weller

Cotter pin came out before removal from car so its just soak and hit. Had the hub carrier spayed in oven cleaner and have just wahed off in the kitchen sink with fairy liqued- the wife wass 'surprised' but the mother in law ( who lives with us) said 'its a hobby - keeps him quiet'
Dave Price

Mr Muscle rules!!
Nick Sayle

Guy,
I soaked the king pin in WD 40 - then put into an oven at 200 C for 30 mins - it just drifted right out - all I got to do is wait for the parts to arrive from Moss and stick it back together - Thanks for the input
Dave Price

This thread was discussed between 28/04/2010 and 14/05/2010

MG Midget and Sprite Technical index

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