Ripped E46 convertible subframe - well worth checking.

[Martin W]

About 3 months ago I began to get an annoying clicking noise coming from the rear of my 2003 E46 M3 convertible whenever I applied even the slightest power. I wondered if the springs were shot so had them checked at my local independant but whilst in there the real cause of the noise was discovered - a split boot pan; more disturbingly, mine was the second one they'd discovered in 2 days. They advised me that this was a known fault and that BMW would likely repair the damage free of charge even though the car was outside of warranty. When looking at the damage from the underside of the car, the visible split was about 3 inches long running from back to front just to the left of the rear differential and disappeared vertically up behind the boot. I took the car into my local BMW mainline dealer and they put it straight up on the ramps. They took some photos and said they would send them to BMW's Head Office to try to gain approval to repair the damage. About a week later I got a 'phone call and approval was given as a 'good will' gesture; I was advised that the brake lines may need replacing and I would have to pay for that if so, but everything else would be covered. When I enquired why I'd have to pay for the brake lines they made it clear that the car was not under warranty and they were legally under no obligation to fix it but would do so anyway. They also advised that they wanted the car straight away as they didn't want the subframe to twist. A new reinforced rear floor pan was ordered (which is about the same size as the bonnet of the car) and the whole rear end of the car was disassembled. The car was then placed in jig brackets and the floor was cut out. Apparently it took very little persuasion to come out, the welding had come away in places; the noise I had been hearing was the boot pan clicking as it repeatedly passed it's moorings in the frame. The new floor was welded in, painted, treated and the car reassembled and given a 4 wheel alignment. The entire job took about 5 weeks to complete (although there was about a weeks wait for the jig brackets to become available so they could be hired in) with the total cost of the work coming in somewhere between £3,000 and £4,000.

I don't know exactly what qualifies a car to be accepted for this repair as a 'good will' gesture, but I have heard that it should be less than 10 years old, be completely standard at the rear end (including bushes and springs etc) and not have been subject to power upgrades. BMW have been great with me and I really appreciate their efforts; the car is driving phenominally now and it didn't cost me a penny to have this repair done. I have no idea what I'd have done if I had had to fund the repair myself! It appears that there are repair kits out there on the market for this very problem at a fraction of the cost, but I can't help thinking that if these provided a really good, effective solution to this problem, then presumably BMW would have done something similar - but they didn't; they went a lot further and I'm very pleased and grateful they did. I would recommend that all owners take a look at their cars to make sure that they are not suffering from this issue as this could be extremely costly and/or affect resale if ignored. Whilst the convertible M3 appears to be the most susceptible to this, I appears that it is not unheard of for the coupe to suffer from this also.

Edited by Martin W on Monday 24th August 15:05

[n boost]

Its becoming quite a popular subject at the moment and from what ive read, bmw have a legal duty to fix this as it is a structural problem and shouldn't be happening.
My local Indy told me they have seen about 5 e46 m3'swith cracks in them!
BTW...did u end up paying for the brake lines?, and if yes how much did they charge you?

[anonymous-user]

See also here: http://www.mtorque.co.uk/ubbthreads/ubbthreads.php...

[Martin W]

n boost said:

Its becoming quite a popular subject at the moment and from what ive read, bmw have a legal duty to fix this as it is a structural problem and shouldn't be happening.
My local Indy told me they have seen about 5 e46 m3'swith cracks in them!
BTW...did u end up paying for the brake lines?, and if yes how much did they charge you?

No, all costs for the repair were covered in the end. I did have to insure the courtesy car that I was provided with but that was a diesel and I saved more in petrol money than it cost to insure!

[Martin W]

Greg66 said:

See also here: http://www.mtorque.co.uk/ubbthreads/ubbthreads.php...

The 2003 convertible referred to by the original poster in that thread was mine; the coupe was in the day before.

[NickXX]

I have a friend who had the same sort of work done on an e46 328 coupe. IIRC, it was a 1999 model. All work done as a goodwill gesture and took about the same amount of time.

Well worth checking the boot floor from the top side to check for any distortions.

[Martin W]

NickXX said:

I have a friend who had the same sort of work done on an e46 328 coupe. IIRC, it was a 1999 model. All work done as a goodwill gesture and took about the same amount of time.

Well worth checking the boot floor from the top side to check for any distortions.

It's a worth while check but because the boot is double skinned, it isn't necessarily conclusive; mine was split on the underside but if you looked inside the boot with all the matting stripped out it looked fine.