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Metro Balljoints - part nos

PostPosted: Mon Feb 24, 2020 11:12 am
by ACourtney
Questions about the Metro balljoints have appeared in the Facebook page several times now, but the problem with FB is that the answers disappear into the mists of time.
So to avoid having to keep repeating the same answer again and again I thought that I should deposit the information here so that I can provide a link to it in the future.

As most Midas Gold owners will know, the balljoints were uprated on the Mk2 -post 84- Metro, an upgrade that appears to have come in with the Metro Turbo at the end of 1983.
The Rover Metro/100 had a different front upright design with the lower balljoint being changed to one fitted to the lower wishbone. However, it used the same upper balljoint as the Mk2.

The Mk1 - Pre-84- Metro had the same size taper fitting on the balljoint as the Mini, with the small end being around 12.7mm (1/2" ?) in diameter.
Image20200227_155133 by Alistair Courtney, on Flickr

These are the part numbers that I know of:

Mk1 1980-84
Rover – GSJ189, GSJ207, GSJ268, FAM9220
Borg & Beck BBJ5150
FAI – SS170

The Mk2 -post 84- had a thicker taper fitting, with the small end being around 14mm in diameter.
Image20200227_154830 by Alistair Courtney, on Flickr

MK2 1984-1990 + Rover Metro/100 1990-97 Upper balljoint
Rover – GSJ257, GSJ 269, NAM5308, RBG000020
Borg & Beck BBJ5151

These are the part numbers that I am aware of. If any Midas owner has used balljoints from other OEM part brands then please post them below.

One question that shouldn't really be asked is can I use a post-84 balljoint with a pre-83 arm, or vice-versa. The front upright was unchanged so either type of balljoint could be fitted.
In the case of the later balljoint in the earlier arm, the taper will go into the hole about halfway and you will only have a few threads showing. I would hope that would be enough to put anyone off the idea.
I have come across a car where an earlier balljoint had been fitted to a later arm. In this case, the end of the taper stood out by around 4mm and the giveaway was that three washers had been used to allow the nut to pull the taper up tight into the arm. Even then the taper was not a tight fit and it wasn't necessary to use a splitter to separate the balljoint from the arm.

Another part of the question is how can you tell which you have fitted to your car, without dismantling the front suspension first?
The answer may be that you can't, at least not without taking one of the nuts off a balljoint to see if you can measure the end of the taper - see diameters above.
The upper and lower arms obviously had the different taper sizes machined into the ends to match the different balljoints, so they would have had different part numbers. However, the foundry numbers which were cast onto the arms were unchanged, i.e. the foundry was producing the same blank arm forging pre- and post-84, the difference only came when they machined the taper.
The lower arms also had a raised date stamp, which was formed in the recess of the arm. You may be lucky enough to find that this has survived the ravages of time, but the chances are that it has been eroded by rust and may no longer be legible.
So really the best answer is to use a balljoint splitter, take them apart and measure them.

Another word of caution - it is not unknown for Midas Golds to have a mixture of pre- and post-84 balljoints, where perhaps the owner had replaced damaged upper, or lower arms, during the build. This isn't ideal, but as long as the balljoints are in good condition and the tapers are correct for the arms then it shouldn't be an issue. I've only ever heard of balljoints failing due to wear in the ball and never due to a breakage in the taper.

Re: Metro Balljoints - part nos

PostPosted: Tue Feb 25, 2020 9:27 pm
by benofbrum
I my red convertible, I had a top joint snap at the taper when driving rather rapidly around a roundabout. It was the taper pin that broke off. A most helpful farmer went off to fetch his "telehoist" and returned shortly afterwards with a bloody big tractor with lifting forks fitted. He went under the car from the side and lifted it high in the air and chugged back a short distance to his farm , preceded by a WPC walking ahead. He arranged to have it repaired by a local mechanic and rang a spares shop to have a new ball joint delivered. I was given a lift to Huntingdon railway station and came home by train.
Tony Moss gave me a lift back the following week to collect it and I had to fight the steering all the way home. It was happy going left or right, but did not want to go straight on. On later inspection back home, I discovered that a later ball joint had bee fitted (partway) into what was obviously an earlier top arm. It got me home, but definitely not to be recommended.

Re: Metro Balljoints - part nos

PostPosted: Thu Jul 23, 2020 9:24 pm
by Geoff Butcher
I also have Motaquip VSJ473 for the later larger type

Re: Metro Balljoints - part nos

PostPosted: Thu Jul 30, 2020 10:51 am
by Geoff Butcher
To add to the confusion, my garage have just got some BBJ5150, which appear above as pre -84 and so should have the small taper, but they are 14+mm at the small end, i.e. the later large type...