Fitting Rear ARB

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DSC 0186.jpg

The Rear Anti-Roll Bar is a common Suspension feature, fitted to the heavier E30s as standard. This list includes all M20-engined cars, all Cabriolets and all Tourings. It is a common upgrade for all E30 models.

A number of different sizes of ARB were fitted to the E30; you can learn more about anti-roll bars here.

Identification

Identifying your ARB size

Getting your hands on a rear ARB isn't that hard these days. With a variety of E30s rusting in scrapyards or cannibalised for parts, it takes very little time to get the ARB off and back to your place.

The M20 engined cars had 12mm rear ARBs fitted, while Touring models were treated to the chunkier 13.5mm model. However, a number of models including the M3 and 325iX received the thickest of all; a 14.5mm piece of steel.

Working out which one you're holding in your hand isn't easy, since there's no clear markings. The quickest and easiest way is to get your spanners out, and try to fit the jaws of a 12mm, 13mm, 14mm and 15mm spanner around the bar (pictured). If 13mm doesn't fit but 14 does, then you have a 13.5mm bar.

Components

The Anti-Roll Bar isn't exactly sophisticated technology, so there's not many parts needed to get one fitted. However, almost all of these parts will need to be sourced new; only the bar itself is safe to use second-hand.

All E30s should have the mounting points in place for you to fit a rear ARB, but get underneath and check anyway. You are looking for two holes on your trailing arms to bolt the drop link mounts to, as well as two flat plates under the body shell. These plates are at the steel beam that spans the boot floor, just in front of the spare tyre well.

Once you can see where the parts fit, it's time to gather your bits. Remember, buy all bushes, drop links, bolts and bush shells new; it's not worth the hassle or risk of using 20-year-old components here.

No Component Image
1 Rear ARB DSC 0187a.jpg
2 Bush Shells
3 ARB Bushes
4 Brass bolt (M8x16)
5 Drop Links
6 Brass Bolt (M8x43) and nut
7 Drop Link mount (not pictured)

Fitting

1. Get your drop links onto your ARB. This is by far the hardest part of the whole job, so should be done in a wide open space away from your car where no damage can be done. If you are refreshing your drop links on an ARB still attached to the car, good luck.

The drop link has two holes; one with a metal sleeve inside, one without. You need to fit the ARB into the pure rubber hole, using brute force and lubrication. A bench-mounted vice will help, but be careful not to use too much force or you risk tearing the rubber. The use of hammers is strictly prohibited, for the risk of breaking or bending the drop link.

2. Get on your back under the car, and feed the ARB in and through the existing suspension. Take note; the ARB is "handed" - it will only fit one way round. If you look at the long horizontal section, you will see the "long" and "short' straights before the central bend. The long straight point towards the petrol cap, and needs to be fed over the petrol filler pipe.

3. With the bar in place, you can now squeeze the bushes into place. Try to get them as close to the corners as possible. DSC 0189.jpg

4. Now you need to squeeze the shell caps over the bushes. Brute force helps by pushing them up against the floor of the car, but if you're worried about damaging your underseal then use some pliers to pinch the shells into place

5. The tops of the shells are a metal tab that locates into a square hole in the body. The shell then bolts into place at the bottom. It helps to use pliers to pull the shell closed while you tighten the bolt in place.

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6. With the bar itself securely mounted, it's time to sort out the drop links. Twist the drop links until they point downwards. Now, take your drop link mounts and fit them to the bottom of the drop links, secured in place with the long brass bolt.

7. Now you just need to fit the mounts to the trailing arms. This may require jacking up the trailing arm to compress the spring, making it easier to pull your drop link mount into place. If you can, jack up both trailing arms, but make sure the rest of the vehicle is secured on jack stands if you do so. DSC 0191.jpg

8. And that's it! Remove the jacks, put the wheels back onto the ground, and enjoy a firmer cornering feel without being rattled around by stiff springs!