E46 Boot Floor Cracks

[anonymous-user]

corvus said:

Not worth worrying about though unless there are cracks appearing.

My thoughts exactly.

[dr_gn]

corvus said:

I obtained this from the March edition of Total BMW magazine

http://www.redish-motorsport.com/E46M3FloorSubfram...

You might want to take a deep breath before you see the price, especially as you don't have any cracks as yet. They do say that changing the standard subframe bushes for polybushes can help, as the different shape of the polybush puts less stress through the floor.

Not worth worrying about though unless there are cracks appearing.

Yeah, thanks I've got that magazine. I had a good idea of the cost of repairs before I bought the car (I think that figure is top of the tree TBH). I was pretty confident mine wasn't cracked anyway.

ALL I was asking here really was about preventative measures. As I said, if it turns out to be a keeper, the cost of repair is fine.

[jaedba2604]

this thread was getting a bit like a film i once saw, micheal caine, jude law, slueth...if you's get me...

anyways, there's a thread on the m power list, search for sub frame, a chap had his strengthened by an out fit that specialises in it, they injected the epoxy stuff and welded some plates on iirc. i reckon for you lower powered model the injection would be adequate, and it is a diy if you're reasonably handy...

[NelsonR32]

Audi sell the same 2k foam for half the price of BMW and also in a single cartridge format so you can use a standard silicone gun. In theory you can do the foam preventative maintenance repair for about £160 all in for both sides

[dr_gn]

Thanks guys, that's more like it

Presumably the foam/sealant is to form a sandwich between the upper and lower boot floor membranes and stiffen it up/spread the load out a bit? Would be up for DIY no problem.

BMW specify a pretty detailled procedure as a fix, but has anyone here experience of actually doing it?

[dr_gn]

jaedba2604 said:

this thread was getting a bit like a film i once saw, micheal caine, jude law, slueth...if you's get me...

Now I feel old: the version of that film I saw had Michael Caine and Laurence Olivier.

[jaedba2604]

dr_gn said:

Thanks guys, that's more like it

Presumably the foam/sealant is to form a sandwich between the upper and lower boot floor membranes and stiffen it up/spread the load out a bit? Would be up for DIY no problem.

BMW specify a pretty detailled procedure as a fix, but has anyone here experience of actually doing it?

yep, it was something to do with torsional rigidity, you had to leave it for 24 hours to harden off.

if you look on m3cutters you'll see lots of people have had sub frame issues. being cognisant of the fact that people always post problems so it will look worse than it is...

[dr_gn]

jaedba2604 said:

dr_gn said:

Thanks guys, that's more like it

Presumably the foam/sealant is to form a sandwich between the upper and lower boot floor membranes and stiffen it up/spread the load out a bit? Would be up for DIY no problem.

BMW specify a pretty detailled procedure as a fix, but has anyone here experience of actually doing it?

yep, it was something to do with torsional rigidity, you had to leave it for 24 hours to harden off.

if you look on m3cutters you'll see lots of people have had sub frame issues. being cognisant of the fact that people always post problems so it will look worse than it is...

I wonder if you put the foam in, it screws any chance of you adding a welded repair later (if it becomes necessary)?

Some of the welding is from above, inside the cavity.

[jaedba2604]

dr_gn said:

jaedba2604 said:

dr_gn said:

Thanks guys, that's more like it

Presumably the foam/sealant is to form a sandwich between the upper and lower boot floor membranes and stiffen it up/spread the load out a bit? Would be up for DIY no problem.

BMW specify a pretty detailled procedure as a fix, but has anyone here experience of actually doing it?

yep, it was something to do with torsional rigidity, you had to leave it for 24 hours to harden off.

if you look on m3cutters you'll see lots of people have had sub frame issues. being cognisant of the fact that people always post problems so it will look worse than it is...

I wonder if you put the foam in, it screws any chance of you adding a welded repair later (if it becomes necessary)?

Some of the welding is from above, inside the cavity.

don't really know, i think that the plates were welded around the sub frame mounts, not sure where or how.

i suspect that if you've injected and then it goes, you're in write off territory..

[dr_gn]

jaedba2604 said:

dr_gn said:

jaedba2604 said:

dr_gn said:

Thanks guys, that's more like it

Presumably the foam/sealant is to form a sandwich between the upper and lower boot floor membranes and stiffen it up/spread the load out a bit? Would be up for DIY no problem.

BMW specify a pretty detailled procedure as a fix, but has anyone here experience of actually doing it?

yep, it was something to do with torsional rigidity, you had to leave it for 24 hours to harden off.

if you look on m3cutters you'll see lots of people have had sub frame issues. being cognisant of the fact that people always post problems so it will look worse than it is...

I wonder if you put the foam in, it screws any chance of you adding a welded repair later (if it becomes necessary)?

Some of the welding is from above, inside the cavity.

don't really know, i think that the plates were welded around the sub frame mounts, not sure where or how.

i suspect that if you've injected and then it goes, you're in write off territory..

Ta. This might be useful to some people, its from the E46zone forum, credit "Sam". It is out of date now of course, but outlines what the official BMW angle was on the issue:

http://e46zone.com/Admin/Sam/e46_subframe_tis.pdf

[stevesuk]

I have a late 2001 (registered in 2002) 330 Ci, so I did some investigation in to this.

As the failure figures you posted on the last page seem to suggest, it was more of a problem on older models (323i and 328i) built before the modifications BMW made to the design in February 2000.

I had mine checked by an independent specialist, and all fine at the moment. And to be honest, I think the problem is much rarer with post February 2000 cars.

I found this post from Pistonheads (although from a year ago) that put my mind at rest a bit:

the02shed said:

All of the affected cars are now over 10 years old, so BMW will NOT repair any of them for free anymore.
Yes, it can affect all models ('cept convertibles) but in 15 years I have NEVER seen the problem occur on ANY car later than Feb. 2000 build, when the floors were modified. This despite many internet rumpours, mostly from across the pond. Perhaps there is another problem over there.
That said, we are currently replacing the boot floor of an '03 Touring-though it has a strange history and is actually a pre-production car built in '99, registered later.
The warranty starts from reg date, not build date, so some could still be out there-check carefully!

(from http://www.pistonheads.com/gassing/topic.asp?t=945... )

[jaedba2604]

think maybe smg on the m cars has exacerbated the issue, it's a fierce system!

[anonymous-user]

stevesuk said:

I have a late 2001 (registered in 2002) 330 Ci, so I did some investigation in to this.

As the failure figures you posted on the last page seem to suggest, it was more of a problem on older models (323i and 328i) built before the modifications BMW made to the design in February 2000.

I had mine checked by an independent specialist, and all fine at the moment. And to be honest, I think the problem is much rarer with post February 2000 cars.

I found this post from Pistonheads (although from a year ago) that put my mind at rest a bit:

the02shed said:

All of the affected cars are now over 10 years old, so BMW will NOT repair any of them for free anymore.
Yes, it can affect all models ('cept convertibles) but in 15 years I have NEVER seen the problem occur on ANY car later than Feb. 2000 build, when the floors were modified. This despite many internet rumpours, mostly from across the pond. Perhaps there is another problem over there.
That said, we are currently replacing the boot floor of an '03 Touring-though it has a strange history and is actually a pre-production car built in '99, registered later.
The warranty starts from reg date, not build date, so some could still be out there-check carefully!

(from http://www.pistonheads.com/gassing/topic.asp?t=945... )

This is the point i was trying to get across. It's highly unlikely you'll encounter this problem and if you are concerned then get someone in the know to check it over for peace of mind

[aizvara]

corvus said:

You might want to take a deep breath before you see the price, especially as you don't have any cracks as yet.

£895? That doesn't seem too bad to me. Personally, I'd put that aside at the time of purchase if I were really worried about it happening. I spent nearly that amount last time I took my E46 to have the suspension looked at. And a similar amount replacing the tyres.

St John Smythe said:

It's what I've done with my Alpina and I've nearly got it tip top

Off-topic: how do you find the Alpina compared to your 330ci? How good is the auto/semi auto gearbox (presuming yours is)? I'm thinking about trying to find a B3 saloon to replace mine as I very much like my e46, but would like something with more power, and preferable a suspension more suited to our roads.

[corvus]

aizvara said:

corvus said:

You might want to take a deep breath before you see the price, especially as you don't have any cracks as yet.

£895? That doesn't seem too bad to me. Personally, I'd put that aside at the time of purchase if I were really worried about it happening. I spent nearly that amount last time I took my E46 to have the suspension looked at. And a similar amount replacing the tyres.

It depends. I wouldn't really like having to spend that on a cheap E46 to keep it going when it's a quarter of the price of the car, especially when you are really just trying to make up for a bad design from BMW. I'd rather spend it on something that makes a tangible difference to me like suspension. Although if the car in question is an M3 in good condition, the value of the car would make it worth doing.

[anonymous-user]

aizvara said:

corvus said:

You might want to take a deep breath before you see the price, especially as you don't have any cracks as yet.

£895? That doesn't seem too bad to me. Personally, I'd put that aside at the time of purchase if I were really worried about it happening. I spent nearly that amount last time I took my E46 to have the suspension looked at. And a similar amount replacing the tyres.

St John Smythe said:

It's what I've done with my Alpina and I've nearly got it tip top

Off-topic: how do you find the Alpina compared to your 330ci? How good is the auto/semi auto gearbox (presuming yours is)? I'm thinking about trying to find a B3 saloon to replace mine as I very much like my e46, but would like something with more power, and preferable a suspension more suited to our roads.

The 330ci I had was a great car but the B3 is in a different league IMO! In fact it's probably my most favourite car that I've owned.

My 330 was Steptronic and I couldn't get on with the gearbox at all (reason I sold it to be honest) but the Switchtronic in the Alpina is excellent. 'Manual' gear changes are much faster plus the buttons on the steering wheel are much more fun to use. In normal auto mode Alpina have developed it to take advantage of the torque of the engine so it can be a bit reluctant to change down. There is a marked difference between driving about town in auto mode and then driving it through some twisties in manual mode. It's a bit of a jekyll and hyde car

Power wise they are not far off 300bhp so noticeably quicker than a 330ci. Running costs are pretty much the same. Yes, suspension can be pricey but the brakes on my car for example are standard 330. Cost of a service will be the same as a 330. I like the rarity of the car and it gets a lot of comments and people (even petrolheads) don't know much about them. At the same time it's quite understated when compared to an M3.

A few of us are off to the Alps this summer and I can't wait to get the B3 over there (via an autobahn of course). If you need any more advice then drop me a mail.

[aizvara]

corvus said:

It depends. I wouldn't really like having to spend that on a cheap E46 to keep it going when it's a quarter of the price of the car, especially when you are really just trying to make up for a bad design from BMW. I'd rather spend it on something that makes a tangible difference to me like suspension. Although if the car in question is an M3 in good condition, the value of the car would make it worth doing.

True. Although the bad design part actually might help if BMW will fix it for you (there is that possibly apocryphal tale that they'll repair subframe cracks in ten year or younger cars). Many older, formerly expensive, cars have faults that will cost a fortune if they break. Probably best to be aware of these things, but not let worry ruin any enjoyment you might otherwise get out of the car.

St John Smythe said:

The 330ci I had was a great car but the B3 is in a different league IMO! In fact it's probably my most favourite car that I've owned.

My 330 was Steptronic and I couldn't get on with the gearbox at all (reason I sold it to be honest) but the Switchtronic in the Alpina is excellent. 'Manual' gear changes are much faster plus the buttons on the steering wheel are much more fun to use. In normal auto mode Alpina have developed it to take advantage of the torque of the engine so it can be a bit reluctant to change down. There is a marked difference between driving about town in auto mode and then driving it through some twisties in manual mode. It's a bit of a jekyll and hyde car

Power wise they are not far off 300bhp so noticeably quicker than a 330ci. Running costs are pretty much the same. Yes, suspension can be pricey but the brakes on my car for example are standard 330. Cost of a service will be the same as a 330. I like the rarity of the car and it gets a lot of comments and people (even petrolheads) don't know much about them. At the same time it's quite understated when compared to an M3.

A few of us are off to the Alps this summer and I can't wait to get the B3 over there (via an autobahn of course). If you need any more advice then drop me a mail.

Thanks for taking the time to post! The problem is that you've pretty much said exactly what I wanted to hear and I'm now dangerously tempted. Off to the classifieds!

[kev b]

I have a 328Ci auto build date Aug 99, I had been driving around smugly thinking that as my car is auto it was immune to cracks. I had checked the area thoroughly at Christmas after seeing three examples of cracking in my brothers MOT station. Six weeks ago I was trying to find the source of a knocking noise when as a last resort I checked the o/s rear subframe mounting, there were two cracks 30mm long. Three weeks later when I found time to remove the subframe the area looked like a smashed eggshell, in only 400 miles the damage had spread significantly. Incidentally the car has only covered 80,000miles and is driven fairly gently. Subsequent research has revealed that rear subframe mounting point weakness is also found on E30 E36 Z3 and M Coupe, this issue should have been resolved years ago and I am not impressed with the cynical way BMW has treated this matter.

[Blair357ci]

It happens to all age, I don't know what changes were made post 2000 but they didn't work!

Here's my 01 325 coupe

The telltale sign is not just the crack but the rusty spot welds

[dr_gn]

Just got back from Sytner BMW to exchange the water pump. Had a chat to the service manager while I was there, and he reckoned they'd only had 2 or 3 in for repair (1 saloon), the others coupes. They repaired them with the foam method in the BMW bulletin. He confirmed the 10 year cut off, but was a bit vague about the necessity to have a full BMWSH. I got the impresion that it was not a pre-requisite to getting it done under some form of manufacturer's agreement.

He also offered to put mine on the ramp and have a quick look, so with some trepidation I accepted. He said it all looked fine, and if it hadn't gone at 69k it probably wouldn't.

Apparently the epoxy foam repair kit is still available from BMW.