I've just submitted a new How2 for replacing the outer bush in the rear upper control arms without having to remove the arm from the car. Here's a copy of it in case anyone is doing this job this w/e and would like to know how to do it, whilst the How2 is awaiting moderator approval.
Following a poll in a thread I started, most people said that it was only the outer bush in the Upper Control Arm (from now on referred to as UCA) that was worn, and that the inner one was fine. This means that it's often not necessary to go to the cost of buying new arms, and perhaps more importantly, you can save yourself the hassle of acessing the inner nut/bolt, which is quite fiddly to do. I got the idea from an episode of Wheeler Dealers, where Edd China used a threaded rod and bolts to remove a bush on a Fiat Dino, and I decided to build myself a similar tool. The cost was around £7 in total, and I then realised I had inadvertently built myself something very very similar to bush removal tools sold on ebay for £35-£40.
What you can buy on ebay:
VectraB Bush Remover.jpg
The replacement bushes can be bought on ebay (Vauxhall don't sell just the bush, only the whole arm), and there are lots of different prices, ranging from £5 each to £20 each. Alternatively you can pay circa £120 for two Powerflex polyurethane outer bushes.
Replacement outer bush
Threaded rod (use M12 size or bigger)*
Several nuts and thick metal washers, same size as the rod
Silicone lubricant spray (rubber-friendly)
E20 socket, preferably 1/2" size
Pliers or mole grips
Strong steel tube wide enough for the bush to fit into*
Wheel chocks (or something else that will stop the wheels moving whilst one corner of the car is in the air and the handbrake is off)
(* The tube you use needs to be made of strong steel in order to withstand the considerable force that will be applied to it. Aluminium, or thin steel, will not be strong enough and will start to buckle or crumple. For this same reason, the minimum size of threaded rod to use is M12 – larger will be even better as long as it's not too large to fit through the hole in the bushes).
Put the gearlever into gear and apply the handbrake.
Jack up the rear wheel on the side you will be working on and remove the wheel.
Put an axle stand under the car and transfer the weight of the car from the jack to the axle stand.
Chock at least two of the wheels that are on the ground.
Turn off the handbrake.
Spray some silicone lubricant to the bolt that holds the UCA to the hub assembly and also to the outer bush on the UCA. This gives it time to take effect while you do other steps in the process.
Using the mole grips or large pliers, remove one end (any end) of the slim spring that holds the handbrake cable to the caliper (see photo below).
With the spring undone, use the molegrips to disengage the handbrake cable from the caliper.
Fit the 21mm spanner over the nut that holds the UCA to the hub and use the E20 socket and a wrench to hold the corresponding bolt head. Counter-holding one of these tools, use the other one to undo the nut/bolt. I found it easier to hold the nut stationary and turn the bolt.
Remove the bolt and nut. Push the end of the UCA upwards and away from the hub.
Unclip the cabling from the UCA and make sure it isn't under tension.
You will now find that the handbrake cable is somewhat in the way of the arm, and later on it will prevent the bush removal tool from being positioned correctly, so ease the handbrake cable downwards over the end of the UCA and push the UCA upwards away from the cable.
Insert the threaded rod through the hole in the centre of the bush in the outer end of the UCA. On one end of the rod, put 2 or 3 of the thick washers onto the rod, followed by 2 or 3 of the nuts. Over the other end, slide the metal cylinder, followed by washers big enough not to go into the cylinder (in my photos this big washer changes part way through, as the original one started to bend under pressure). Next, insert the smaller thick washers and a bolt. You should end up with something like the photo below.
Using one of the spanners, counter-hold the end nut on one end of the rod, and on the end where there is just one nut, use another spanner to turn the nut clockwise, i.e. tighten it.
There are large forces involved here, so do it slowly and keep an eye out for any component of the tool that may start to buckle or give way.
The aim is to reduce the distance between the two sets of nuts on the rod by pushing the bush out of the UCA and into the metal tube. The bush may be very reluctant to move at first, but it will become easier as soon as it moves a little.
Once the bush comes out of the arm, undo the nut(s) at one end of the threaded rod and remove the washers so that you can then remove the rod and components from the UCA.
Old and new bushes:
To test if the bush you've removed was indeed worn out, hold the outer metal section firmly in your hand and then try to move the inner metal sleeve – if you can move it then the rubber is worn and has become too soft.
Clean the hole in the UCA where the bush has just been removed from, so as to remove any grit or dust that will impede the new bush. Spray some silicone lubricant into the hole and also around the outside of the new bush. Push the new bush into the hole in the UCA as far as it will go by hand (which will be a few millimetres). Make sure the bush is lined up straight with the hole rather than at an angle.
Insert the threaded rod through the hole in the new bush, this time with the three nuts on the rod being at the same end as the bush is going in from – so that the nuts will be pushing the bush – and some washers between the nuts and the bush.
At the other end of the threaded rod, insert the steel tube, followed by whatever you're using as washers, then the nut.
Counter-hold the last of the three nuts while you tighten the nut at the other end – the end you want to pull the bush towards.
Keep slowly turning the single nut until the new bush has been pulled fully into the UCA and is protruding the same amount at each side of the UCA.
Undo the nuts on the threaded rod so that you can remove all the washers etc from the new bush.
Now it's just a case of reassembling everything you removed or disconnected. Firstly pull the UCA downwards at its free end and push the handbrake cable up over the end of the UCA.
Now line up the hole in the new bush with the hole in the hub assembly that the retaining bolt goes through. You might need to raise the hub assembly with the jack to get it high enough, and you can also tilt the inner sleeve in the bush to get it at the correct angle to meet the hole in the hub.
Insert the bolt through its hole in the hub assembly and turn it using the E20 socket to screw it through the hole and into the bush. Once the end of the bolt clears the bush, fit the nut to the end of it and tighten them together.
Reconnect the end of the handbrake cable to the caliper, and the reattach the spring as well.
Reclip the cabling to the UCA.
Refit the road wheel and its bolts, raise the car using the jack, remove the axle stand, remove the chocks from the wheels and gently lower the car to the ground.