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Replacing the drop arm ball joint

Les Henson

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This is usually a real swine of a job. 95% of the time it goes wrong or gets unbelieveably difficult, and there's nothing much you can do about it except suffer! Failure of the ball joint is usually because the rubber gaiter on it gets split - allowing water in and the grease out - resulting in the ball seat corroding and causing excessive play. If the ball joint has been worn for some considerable time, you might be wise to just replace the whole arm, rather than mess around - sometimes the corrosion extends into the seating in the arm, and a repair isn't possible. Fortunately, this job went as planned, and it was quite easy - however this is a first, and I have had to use gas welding equipment to remove the inner ball seat in the past.

Anyway: this is the problem, fitted to 2.5 N/A and TD 90/110's - the joint is available as a kit, rather than later ones, which are a ready-made track rod end (TRE).


This is the repair kit (about £7)


Remove the split pin, 19mm castellated nut and washer. Then strike the steering damper/steering link rod bracket here. The joint should pop apart.


Bend back the large tab washer and then undo the large nut that holds the drop arm to the steering box shaft.


Now the hard bit - the drop arm has to come off the shaft, and usually a big puller is needed to do this. There are two lugs on the drop arm, and I have a long chrome vanadium bar with a tapered end on it. From inside the engine bay the rod reaches down to the top of the drop arm on the lugs, and then I belt it hard on alternate sides until the arm lets go. There's no other way to remove the arm apart from these two methods, using heat will damage the steering box seals, but if you are going to replace the whole arm then you can cut best of the way through it and then crack it with a chisel.

Anyway - after about 10 minutes, the arm comes loose. With the rubber boot removed, the corrosion can easily be seen.


Remove the circlip and the guts of the joint will come out with the exception of the top ball seat.


In this picture you can see the ball seat still in place (and usually seized in)


From the top of the arm, there's a thin lip which I place a hardened steel rod on and knock with a hammer on opposite sides. After a while, and a bit of care, the seat starts to move.


Once out, the seat damage is usually pretty bad.


Carefully clean the arm inside and out - use a small wire brush in an electric drill to remove rust and other dirt. Make sure that the circlip slot is cleaned as well - if the circlip isn't in properly, the joint will fall aprt after a short while.


Place the new seat in (make sure it's the right way round). Use a 19mm socket to press it in the housing nice and square.


Check that the seat is all the way in.


Dunk the ball end in grease and put it in next.


Then the bottom seat - grease will toothpaste out as you push it home.


Now put the drop arm in a vice as shown, place the spring in the centre, and the thin rubber O-ring around the inside lip - this acts as a seal when the disc and circlip are fitted.


Fill the space 2/3 with more grease.


Place the disc on top of the spring - chamfered edge on the inside. Press it down against the spring with a rod or 3/8" extension bar, and then fit the new circlip, making sure it's in the slot all the way round. (this is quite a fiddly job, as the spring is quite powerful, and keeping the disc level at the same time is hard.


Turn the arm over, add more grease, place the rubber boot on, the spring retainer on the bottom, and the small steel clip ring on the top. The arm can now be fitted back on the vehicle.


A new nut, washer, and circlip comes with the repair kit. Replace the arm back on the vehicle reverse of taking it off. Don't forget to bend the tab washer back over the nut.


Like I said at the beginning - this can be very difficult to do, and sometimes there's no way the arm will come off. It's not unusual to have to fit the repair kit with the arm still on the vehicle, and this just makes it all the more difficult.

Les. :)

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Nice posting Les.

I had my drop arm changed recently by a LR German dealership. They said they had big problems getting the old one off. If they did use heat would a steering box seal failure generally happen straight away?

Cheers, Paul.

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sometimes there's no way the arm will come off. It's not unusual to have to fit the repair kit with the arm still on the vehicle, and this just makes it all the more difficult.

Les. :)

I can confirm that. I can also confirm that some cheaper kits do not leave an adequate lip to drift the old part out, further frustrating the job.

FWIW I have fitted three now, two cheap ones and a genuine one. I don't imagine I will have to do it again but if I did it would be with another genuine one. The rubber fits properly and prevents grit getting in - and I would have a sporting chance of drifting it out if I had to. :)


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I think that if you applied enough heat to make a difference to the removal of the drop arm - you will have damaged the seal as well. The outer seal is neoprene, but the inner one is a high pressure hydraulic type seal. I wouldn't take a chance on using heat. I have fitted a seal kit to a steering box, and apart from it being a very awkward job to do (you have to remove that bluddy arm!), it didn't work anyway, and the box had to be replaced in the end.

Les. :)

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nice one les, i've done this job several times, both on and off the truck.

if you 'modify' the old ball/shaft component slightly, using a bench grinder, you can use it as a drift to knock the old seat out....

and you can use a mastic gun to clamp the whole arangement together whilst fitting the circlip.

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How compatible are drop arms?

The RR / Disco drop arm uses a modifed TRE which completely removes the need for removing the arm from the box.

Can you swap the defender style for a RR style? Would certain;y make life easier in the future...

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I had so much trouble getting the arm off (two broken LR OE removal tools and still stuck) that I replaced the box with a Disco one - it having the TRE ball joint.

I used a steering rod from a RR with a clamp on mount for the damper (both from QT services) - and have never looked back.

The TRE's are better quality than the original ball joints and seem to last longer. When it does go, it's an everso easy job to change - even more everso than Les makes this look.

Nice article Les.


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I did mine in situ, but this made it impossible to see what was going on when attempting to drift the upper race out of the arm. The solution was to measure the hole with vernier calipers, find a socket exactly the right size to catch on the lip and whack it with a hammer. I suppose I could have done it by trial and error, but this way gave me confidence that the socket was bearing on the lip rather than the sides of the hole.

fwiw, I found that the socket had to be between 20.02 and 22.45mm diameter. If you're modifying an old ball/shaft component to do the job I suppose it would need to be the same size.

I also used a screw jack to press a small deep socket into the cover so I could insert the circlip. Worked fine after a few attempts...

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It's a lot easier to change the ball joint with the arm off the vehicle. In the past, I've undone the droparm retaining nut a little and then manouvred the vehicle around the yard, from lock to lock, to loosen the arm.

I use a Gen part ball joint kit, but mod the base plate to take a grease nipple - it means that the ball joint lasts a LOT longer.


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