Broken Subframe and Differential. Dealer won't fix. $9k in damage. Any advice?

[slowman]

Originally Posted by ///My5UV

No, it's usually in 1st gear when the wheels break traction, but due to the road surface and tire condition, instead of just spinning on the ground, they get traction on and off, which causes the tires to hop up and down. So you send sharp shocks of force into the drivetrain and suspension bigger than you get from any normal max-throttle driving. It tears stuff up pretty quickly if you don't recognize the problem and ease off the throttle. The rubber bushings in the diff, trans and engine mounts help absorb some of the shock, along with the rubber driveshaft guibo, but it will find any weak points like bolts that weren't torqued properly.

This is not something you see in normal road racing that you could argue an M3 was kinda meant for. It's also not a fast way to get off the line, so you won't see it often in World Challenge or DTM, even though they have to do a hard launch to start each race.

Are there scenarios where spinning the wheels doesn't cause wheel hop? Are guys doing donuts in parking lots tearing up their rear-ends? What about sliding around on a skid-pad?

Not being argumentative, genuinely curious. I did some reading up and saw some youtubes that showed the suspension components during wheel hop and those shocks looked rough. Got me wondering how much damage kids spinning around were doing.

[Singletrack]

I can't speak for the Dct, but I've never had wheel hop on any of my launches (6mt). Gotta launch on the right service, with the right tire pressure, and correct amount of throttle/engine speed.

[///My5UV]

Originally Posted by slowman

Are there scenarios where spinning the wheels doesn't cause wheel hop? Are guys doing donuts in parking lots tearing up their rear-ends? What about sliding around on a skid-pad?

Not being argumentative, genuinely curious. I did some reading up and saw some youtubes that showed the suspension components during wheel hop and those shocks looked rough. Got me wondering how much damage kids spinning around were doing.

It's a mix of road surface and tire properties. I've experienced it only on cold, wet roads with relatively cold tires. If the tires are just spinning on the ground you're only going to tear up your tires. If you have wheel hop it's like Thor is hammering on the back of the car with his hammer. I saw a video of a open-frame dragster (not top fuel, but that sort of car) with wheel hop and the back end just exploded parts onto the drag strip.

These cars can handle alot, but they just aren't built for drag racing

[Glop]

I don't think I've ever experienced wheel hop...

[husan786]

no im still here. im just waiting for tommorow so i can argue with why the cant cover it. I called bmwna and they sent out a complaint most likely ill just take it to a more relaible service center

[TX]

Originally Posted by husan786

no im still here. im just waiting for tommorow so i can argue with why the cant cover it. I called bmwna and they sent out a complaint most likely ill just take it to a more relaible service center

I thought BMW inspectors/engineers told you it was a no so why would BMW NA issue a complaint against the dealer?

Seems odd.

[dexx]

Originally Posted by gnhm3

I was in total shock. The damage came out to about $9,000 and I think it is ridiculous that they are not covering it. The SA told me if I ever took the car to 8k rpm and I said wtf do you think, its an M3. He then told me its not a warranty problem and it's my fault.

I would have replied with, "All the fucking time, now fix my car"

[dexx]

Originally Posted by Glop

I don't think I've ever experienced wheel hop...

O RLY? Any time it's less than 65F out (i.e. not enough traction for 1st gear) I get wheel hop.

[husan786]

any updates?

[SIIK2NR]

Originally Posted by dexx

O RLY? Any time it's less than 65F out (i.e. not enough traction for 1st gear) I get wheel hop.

You talking about loss of traction or "wheel hop". Totally different.

[///My5UV]

Originally Posted by dexx

O RLY? Any time it's less than 65F out (i.e. not enough traction for 1st gear) I get wheel hop.

If you have EDC, you might try different settings to see if it helps. Or just don't use wide open throttle all the time

[gnhm3]

Originally Posted by husan786

any updates?

BMW failed to cover the costs, and I then proceeded to take the car to my private mechanic. Turns out the differential and subframe were fine. The only damage was a couple of missing bolts and a little damage to the output shaft which I replaced. Total cost was $1200.

BMW really tried to stick it to me this time. This is the last BMW I will be buying.

[Singletrack]

Originally Posted by gnhm3

BMW failed to cover the costs, and I then proceeded to take the car to my private mechanic. Turns out the differential and subframe were fine. The only damage was a couple of missing bolts and a little damage to the output shaft which I replaced. Total cost was $1200.

BMW really tried to stick it to me this time. This is the last BMW I will be buying.

Why do you think that missing bolts are BMW's responsibility?

I can assure you they were on there and torqued properly when it left the factory.

[dexx]

Originally Posted by gnhm3

BMW failed to cover the costs, and I then proceeded to take the car to my private mechanic. Turns out the differential and subframe were fine. The only damage was a couple of missing bolts and a little damage to the output shaft which I replaced. Total cost was $1200.

BMW really tried to stick it to me this time. This is the last BMW I will be buying.

LOL I wondered how it would be possible to destroy the diff and the subframe, basically the strongest parts of the car. My money would be on the axle shafts breaking first, and then of course you're stuck.

What dealership? You should name them for everyone's benefit. You know some other owner may have paid.

[Seattle S65B40]

Originally Posted by Singletrack

Why do you think that missing bolts are BMW's responsibility?

I can assure you they were on there and torqued properly when it left the factory.

plus one. such are the risks of improper modification. Legally speaking, they can use it as a basis to void the warranty, because in most cases they will have direct evidence of the correlation between the mod and the manifest damage.

What I don't understand in OP's case, is why the dealer was charging so much more than it really cost to repair the car?? Sounds like you should be hating the dealer and not BMW.

[IFX]

Originally Posted by Singletrack

Why do you think that missing bolts are BMW's responsibility?

I can assure you they were on there and torqued properly when it left the factory.

mistakes do happen.... who knows.

[Singletrack]

Originally Posted by IFX

mistakes do happen.... who knows.

He has an axle back exhaust. The most popular way to install one is to drop the hangers rather than screw with the rubber bushings/hangers. If you don't reinstall the nuts properly, then this can be the result.

[Singletrack]

Originally Posted by Seattle S65B40

What I don't understand in OP's case, is why the dealer was charging so much more than it really cost to repair the car?? Sounds like you should be hating the dealer and not BMW.

I would agree that based on his account it sounds like the dealer could have handled it better.