Nearly all Volkswagen cars from the last 40-plus years have the same basic form of rear suspension. It is tough, but nothing is immune to age. Here’s how to give it a straightforward and life- extending overhaul.
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WORDS: JACK GROVER PHOTOS: MARTIN LEWIS
Jack Grover looks at overhauling the rear suspension that Volkswagen has been using pretty much for the last 40 years.
Volkswagen’s fondness for torsion beam suspension goes right back to the first examples of the Beetle, which used transverse torsion beams as a form of front suspension that was simple, rugged and required minimal maintenance. Those factors led to the basic concept being carried over to Volkswagen’s new generation of front wheel drive cars in the 1970s, even if the beam was now at the back and was used in conjunction with conventional coil springs which did most of the actually suspension work. This left the beam to serve mostly as a big anti-roll bar, while also being a compromise between the expense of true independent suspension and the rougher manners of a dead beam setup. Many Volkswagens (and cars from other marques within the VW family) still use variants of the torsion beam to this day.
While the beam itself is all-but immortal, the rear suspension as a whole is still prone to problems that come with age – especially at the age that many Volkswagen models from the 1990s are now reaching. These problems can be simple expiry of rubber parts such as bump stops and bushes, or corrosion getting to steel items such as spring seats. The dampers themselves can wear out too, while springs can sag.
Fortunately, none of these items are hard to replace once the rear beam is off the car and the assembly broken down. And, better yet, getting the beam off is a simple job that is well within the scope of a home mechanic with an average array of tools.
To show how it is done, we have coopted a 1992 VW Corrado VR6 with 130,000 miles on the clock – a model that is gaining momentum as a classic day by day. The rear beam, springs and brakes are shared with the Mk3 Passat, and the likes of the Golf, Polo, Bora and certain Audis of the same era all have rear ends laid out on the same principle. And with Volkswagens being very much about evolution not revolution, there is a lot of scope for upgrading older models with parts from later generations which fit in a straightforward fashion. A rear end overhaul is the perfect time to do such things, so we’ll be looking at that too.
In this case, the work was being done because the Corrado has an MoT advisory for worn trailing arm bushes, a defect that can upset the suspension geometry and thus the handling – not ideal on a V6 sports coupé. As it happened, this job also showed up other issues which could be sorted out along the way.
2 The devil is, predictably, in the detail. The biggest stumbling block is likely to be this brake restrictor valve, which is fixed to a bracket on the beam just inboard of the nearside trailing arm, right in the way of accessing the main securing bolt. The valve has an alloy body, so the chances are that the brake pipe unions and the mild steel bolts securing the valve to the bracket will have seized up. The solution is to do as pictured here – detach the valve and its bracket from the bushed mounting point on the support bracket. Mark the position of the bracket in the slot (although there’s usually a pretty clear imprint) so it can be reassembled correctly. There should be enough movement in the brake lines to move the entire assembly out of the way of the bolt head, but if not, then it will be necessary to cut the brake lines and renew them later.
7 This is also a good time to check the wheelarch and the suspension mounting areas in the body for corrosion, especially if the top plates are in bad condition. Here, after cleaning the inside of the wheelarch, it proves (like many older Volkswagens) to still be in excellent condition with a good layer of original underseal.
1 As you’d expect from such a straightforward arrangement such as this, dropping the rear beam from a Volkswagen is remarkably simple. In essence it requires only removing the brake lines and handbrake cable, then undoing the nuts that secure the bottom of the rear damper struts to the spring seats and the big bolt on each side that secures the beam to the bodyshell brackets – this is the nearside one.
3 With the brake restrictor out the way and the main securing bolts undone, the entire beam assembly can be dropped from the car – having first supported it on a trolley jack of course! Putting a length of wood over the body of the jack to hold up the hubs and keep the beam level makes things a lot easier, although this is still a part of the job that would ideally have two people involved.
6 And here’s a nasty surprise – the spring top plates are seriously rusted and the top bump stops are badly perished. All these items can be bought new and are easy to replace once the rear beam is off and the spring assemblies are apart.
5 With the spring assemblies out of the car and without any load, spring compressors are not strictly required when dismantling them but it is still very strongly recommended! Work from the top down, undoing each securing nut on the threaded section of the strut and removing each component in turn.
4 The spring/damper assemblies can now be removed by undoing the nuts securing them at their top mounts. For some models (like this Corrado), getting access to do this will require removing trim such as a speaker surround. Or at least doing so makes access much easier.
11 The main bushes in the inner end of each trailing arm can be knocked out fairly easily. The new ones (as here) can sometimes be tapped into place with suitably gentle use of a hammer, but you may need to acquire (or make up) a puller to squarely press them into place with sufficient force.
10 And these are the parts that finish off the top of the mounting. From the right, a rubber mounting bush and a dished washer which fit inside the wheelarch, then comes a second rubber mount which goes on the ‘boot- side’ of the wheelarch from inside the car, then the dished washer finished off by a lock nut, the top securing plate and a final locking nut.
9 This is how all the parts go together again in terms of the bits that go up into the wheelarch. The plastic cover goes over the top of the damper strut, then comes the bumpstop, then the spacer washer, then the top rubber bush (it’s usually worth replacing these as well), then the new top plate.
8 It’s also worth checking the exhaust, since the rear section is attached to the car before the rear beam is installed in the factory and so removing and replacing any sections is much easier with the beam off the car. In this case a hole was found in the tailpipe, which was replaced. Access to things such as the fuel filter and the solid brake lines is also greatly improved, so check and change these as necessary too.
14 The second is that a spacer needs to be fitted at the securing point of the handbrake cable, since the Mk4 calipers have a thinner supporting bracket for the cable end. Here a short length of suitable diameter plastic pipe was used to pad out the difference between the securing clip and the concertina boot.
12 A common problem on Mk3 generation Volkswagens (including this Corrado) is that the rear handbrake mechanism seizes up with tedious regularity. The solution is to upgrade to Mk4 Golf rear callipers (here on the left) which have a different mechanism and are made of alloy. These are a bolt- on fit, use the same pads and are very simple to swap while doing work on the rear end.
13 Only two small modifications are needed to fit the Mk4 calipers. The first is that the flexible brake hoses need to be changed for ones with a banjo fitting at the caliper end – these are available over the counter, and changing the flexi hoses while the system is disconnected and you have access is never a bad idea anyway.