How To Fix Weak Trunk Motor From Lifting-Audi A8L

I got the Audi buffers part# 4F5-827-249-B to replace the original ones and they help lifting the trunk without the spring that used to help lifting. Used rivets 1/8″ x 5/16″ from assorted rivets box from Walmart.

The Latest Aluminum case trunk lid motor is 4E0 827 852 H – the H is the key.

08/19/2016

2013-09-25 I figured out a better way of implementing these 2 springs or a single (inner spring) – for 2 springs, I use spring tubing to shrink and hold the inner spring in place so it doesn’t move too much – the second way without the outer spring, just use a 1/2″ plastic drip hose cut out to hold the spring in place – this works every well too.

shrink tubing      shrink tubing

Shrink tubing      drip hose

After so many trials and errors, I found ways that may help old weak A8L trunk motor to lift the trunk lid up.

Make sure the soft close trunk works.

Fix trunk lift with simple spring –

Let’s look at the symptoms –

1. The trunk doesn’t do anything when the latch is activated, but latch the second time then the trunk lifts itself up nicely – just need to adjust the hinges – both left and right for the motor to work – if it needs a push to lift – then it needs springs or clutch tune up.

2. If trunk try to lift but too weak – the passenger side will lift but the driver side doesn’t help – lifts the trunk up a little then slams down – needs springs fix or clutch tune up.

3. The trunk doesn’t seem to turn on the motor at all when latched, push the trunk up a little, then it lifts itself up – need to adjust the hinges – clutch tune up – or springs fix.

There are 2 ways to fix the weak DC motors – I noticed there are 2 types of DC motors up to 2007 A8 and S8 – 176Nm and 163Nm torque.

1. Springs insertion at the driver side back lid stop. This fix only works if the motor and trunk settings (alignment) are still working – which means when you open the trunk at the latch, the passenger side trunk still lifts up then the trunk falls back down because it doesn’t have enough torque to lift the trunk up.

springs added     driver side

outer spring length     outer spring width

inner spring length     outer spring width

2. The clutch tune up fix – DO THIS ON YOUR OWN RISKS – So if the electromagnetic clutch is weak or the surfaces of the mating contact don’t catch fully, the surface slips and the trunk doesn’t open. This procedure was discovered by Luk who fixed his with “colophony – solid pine gum rosin” – he ground the resin and place between the gear and the clutch mating plate. His is still working after 2 months. I bought some solder flux paste instead of the pine gum resin.

If you’re going to open the motor up – make sure to mark 1 white clutch wire with permanent marker so you can put it back correctly. I marked mine with red marker.

sensor position

motor opened     mark white wire

clutch mating surface     gear plate with solder

I bought 2 FEQ trunk struts ($19 each) to try and they did help the trunk to lift up faster 2 seconds – 7 secs from start to finish – 2 secs slower than the new and improved metal case motor – 5 secs.

Need to remove the motor and disassemble it to access the clutch.

How Electromagnetic clutch works

I fixed my clutch by applying some Solder Flux Paste on the surface of the gear plate and the clutch plate.

Trunk Motor

Luk gave me a great idea to try and it seems to work as he said, but I didn’t have the colophony wood – resin, I used the solder flux paste and it did work, but on a stronger torque motor 176Nm and not so well on the 163Nm. This one below is the 176Nm from Paul W.

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