Replacing Rear ARB Drop Links

[Mike Fishwick]

REPLACING REAR ANTI-ROLL BAR DROP LINKS ON A Z3
Mike Fishwick

The rear anti-roll bar on a Z3 – or E36 an Compact 318Ti – is unusual in that the drop links, by which it is attached to the rear suspension arms, are mounted by one of their rubber bushes being pressed onto the end of the bar.

These bushes are a common cause of MoT failure due to their habit of ‘walking’ their way off the ends of the anti-roll bar. After many years this problem was noted in a BMW Service Instruction, and was finally cured from the September 1999 production period by the introduction of a revised drop link manufactured by Boge, whose name is moulded onto the rubber bushes.

Replacement if the drop links is an easy job, but not one to be attempted without a good vice, at least one trolley jack, and some large wooden or concrete blocks.

Usually only one link will have become disconnected at a time, so the other will have to be pulled off after the anti-roll bar has been removed. I find it easier to remove the ARB while the car is standing on its wheels, by jacking the car and supporting it on large blocks of wood, while the front wheels are securely chocked.

First disconnect the lower ends of the drop links, which are secured by 6 mm bolts to brackets on each trailing arm. The bar is pivoted in a pair of rubber bushes secured to the boot floor by a pair of clamps, engaged into a slot at one end and bolted at the other.

Once the bar is loose, it will be found that removal from the car is akin to a Chinese puzzle, and that removal of the spare wheel carrier is necessary. Should your silencer be attached by a clamp to the exhaust pipe, its removal will also make the job easier.

Removal of the drop link from the bar can be a struggle, the best way being to insert a small screwdriver between the rubber bush and the end of the bar, and pour a little lubricant along the screwdriver. Then draw the link off the end of the bar using a small two-legged bearing puller.
On the subject of lubrication, BMW recommend only the use of Rubbing Alcohol, or Surgical Spirit. This is basically alcohol mixed with 10% castor oil, and provides sufficient temporary lubrication before evaporating.

In order that the rubber bushes in the new drop links are not unduly strained when fitted, BMW specify that the links must be fitted at an angle to the bar of 73 to 76 degrees – call it 75 degrees. A cardboard template is very useful for setting this angle.

BMW suggest that the link can be fitted by holding it in a vice, and the bush lubricated, after which the end of the ARB should be pressed into the bush and rotated. This action would defeat a champion sumo wrestler, it being far easier to use the vice as a press.

Assemble the drop link and the ARB in your vice – an assistant is very useful – supporting the outer side of the link on a piece of steel tube, or a suitable socket. If, like me, you paint your suspension, protect the ARB by inserting a piece of wood under the vice jaw.

Tighten the vice until the ARB is held in position, and check the angle of the link and the ARB, then brush some lubricant into the bush and over the end of the bar.

While your assistant holds the ARB in position, tighten the vice until all of the reduced diameter at the end of the bar has entered the bush. Continue for another 3 mm to allow for the inevitable ‘creep back’ as pressure is released from the bush, check the angle again, and remove the link from the vice. If the tapered head at the end of the bar is not fully visible, immediately replace the link in the vice, and press the bar further into the bush.

When both links have been fitted, leave the ARB for a minimum of half an hour before fitting, in order to permit the lubricant to evaporate fully – the longer the better. If, like me, you are an eccentric, this is a good excuse to paint the ARB and drop links, not to mention the entire rear suspension.