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Audi ur-quattro - Heated Seat Repair - Hawg Ring Lunge

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Before tackling this job, check with a professional trimming company - their rates are often surprisingly low:

• Approved trim suppliers - interior (especially leather) and trim specialists - replacement colour-matched seat cover panels, etc. Leather steering wheel repairs.

The ur-quattro's seats were built - as are many Audi/VW seats - by Recaro. Many cars now have collapsed side bolsters in the driver's seat (look for foam crumbs underneath) and/or failed seat heaters. Another problem is a persistent squeak or wobble caused by frame weld failures at the top corners of the backrest.

First check the cause of failure. The typical failures found in the heated seat system are wire breaks in the seat base and failed seat heater controllers. The controllers often start to click irritatingly because the points inside are dirty - this sometimes leads to them being removed, which of course stops the seat heaters from working. Check that the controllers (right at the top of the auxiliary relay panel in all but the earliest cars) are present - if so, swap them over to check for controller failure. While you have them out, pull the covers off and clean the contacts with a narrow strip of very fine glasspaper or a diamond spatula from, e.g., Maplins.

The seat heater plugs can be disconnected and the resistance measured in situ - two wires go to the backrest element (brown/blue and brown) and two to the seat base element (black base with a coloured stripe and brown/blue). The elements should have roughly the same resistance reading - about 1.5 to 1.7 ohms. Since they are wired in series, a break in either disables the entire seat. From the 1985 Model Year, two other wires go to a thermistor in the seat base - this circuit should read 11k ohms. If this is open-circuit, the seat cover will have to be repaired - the replacement element does not contain a new thermistor. Simple wire breaks at the soldered terminals are common.

The seats are very easy to remove - a 5mm Allen screw and a 10mm nut secure the front of the slider and two screws secure plastic bits at the rear of the runners. Put some newspaper in the rear footwell so you don't get grease on the carpet. Don't forget to unplug the heater cable and, on a digital dash WR, the driver's side seatbelt warning switch.

If you've decided to do it yourself, once the seat is on the bench, check the plastic side panels in good light. Each side is secured by three little dowels pushed into expanding clips. When these dowels are removed, the panels just swing off. Make a careful note of the wire locations in the heater plug, and undo it to release the wires. The assignments should be:

Right hand seat - male connector, with the polarising pin to the left of centre:

Left hand seat - male connector, with the polarising pin to the left of centre:

Remove the rake adjustment knob - it's held on by three tongues and you can reach inside the back of it with a hook and pull them off one by one. Once it's off, remove the adjustment mechanism. The back is held to the base by two circlip type fittings with push-in clips - just pull them off and stretch the arms out over the pins. The seat should now be in two pieces.

Remove the seat cover you're interested in. Unless you're after the backrest squeak, this will usually be the base. The heater repair technique is the same for both.

You'll need good quality side cutters (not the sort you find in 104-part tool kits for under a tenner at Argos) to cut the hog rings that secure the cover to the steel wires passed through the cushions. More of this later. Count the rings you cut and clear out all the fragments. If the side bolsters had collapsed, you'll need a new seat squab. The spare parts diagrams are very confusing; you need 855 881 361C for post-1984 cars - £63 + VAT. Earlier cars had multi-part squabs that are no longer available - the later part can be made to fit.

First check the connections between the wires from the plug and the actual elements and thermistor - it's common for wires to break off at the soldered joints. Repair is then just a matter of stripping and tinning the end of the wire and carefully melting the solder to push it back in. An assistant or a short piece of cardboard tube (often a better conversationalist) can help keep the foam away from the soldering iron.

If there is no obvious external wire break, you will need to order one element - 443 963 555S, £98 + VAT - to replace each broken one. Because of the way the seat is constructed, only Audi's part will fit.

The replacement heater element goes inside the seat cover. Don't be tempted just to lay it on the seat cushion underneath the cover - it will then be underneath a layer of foam in the seat cover and will hardly warm your bum at all.

Lay the cover out, surface facing down and lay the replacement element on top to get the orientation. Note that the wires should come up towards you - not down towards the seat cover surface. Otherwise you'll feel the lump when sitting on the seat and NOTHING is more annoying. You can see that you'll have to cut two slits with a very sharp knife in the cloth backing of the seat cover to thread each arm of the element through - it comes out the other end and the tab is folded over. A ruler is ideal for pushing it through.

You actually cut through the cloth backing and the thin foam layer - the element slides in right behind the old element, which stays in place. Don't even think about removing it. When you replace the seat element (as opposed to the backrest element) you still need the sensor in the old element. Cut the slits at 45 degrees - knife handle sloping outwards from the seat centre - otherwise you'll get a small but very uncomfortable ridge in the seat when reassembled. If you're using a Stanley or Plasplugs knife, be aware that the foam will blunt the blade very quickly - have spare blades to hand. Trim off the old (now unused) supply wires to the seat base element, but be careful to leave the sensor wires intact.

You need two tools for stretching the seat cover back on. Don't be tempted to use cable ties - they're not designed to take intermittent loads and often give way after a year or two.

• The Hook. This is made from a wire coathanger. Take a straightened piece about 18" long and form the smallest hook you can in one end. Make a handle at the other. Don't throw this away after doing this job - it's ideal for replacing the spring clips on the air filter box and retrieving the hydraulic pump belt when you've dropped it down the front of the car.
• The Pliers. We use Mark-Line 12108 - Snap-On YA808 is an alternative, but see below.
• A pack of hog rings - Audi's cheapest spare part. N 015 261 1 is around £10 for a pack of 100 - again, see below.

If you have any problems getting the tools or the rings, try a specialist upholstery factor. Jim Haseltine reported good service from:

Put the cushion on the frame, and start stretching the cover over it. Remember where you cut off the old hog rings? As a check, you should put back the same number you cut out earlier. The replacement procedure is to load a ring into the pliers and hook the top of the 'C' shape into the seat cover wire. If you ever lose a seat cover wire - a motorcycle wheel spoke or even a wire coathanger makes a good substitute. Then get the hook and pick up the wire embedded in the cushion. Then LUNGE - pull the cushion wire up, at the same time as pushing down with the pliers, and hook the cushion wire into the bottom of the hog ring 'C'. Then, with a silly smirk, just squeeze the pliers shut. Takes seconds with practice, and produces a really tight seat.

It's called "The Hawg Ring Lunge".

If you're dismantling the backrest for any reason, it's always a good idea to weld a small fillet of steel into each upper corner of the frame - whether the weld has failed or not - and replace the inner Bowden cable. The way this runs throught the seat leads to it fraying and then snapping, meaning the lever won't lift the catch to allow the seat to swing forward. There are three part numbers for this cable:

Backrest upholstery repairs, replacing the seatback cushion or welding usually requires the removal of the backrest cushion. This is a little tricky because of the headrest supports. First cut all hog rings and pull the cover out of the way. Then unhook the central backrest mesh from the eight springs holding it to the frame. The mesh will then swing upwards, allowing the spread legs at the bottom of the headrest supports (857 881 603A) to be reached with large pliers. Squeeze the legs together and tap gently with a hammer to extract each - this will free both the cover and the cushion.

Re-assembly is easy. As the other guys say - the reverse of dismantling. It's worth considering new sliders (one each of 191 881 213 and 111 881 213-909) to make a really professional job. Well, better than professional, because most dealers wouldn't replace them. For around £1.80 a seat ...

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