Front Subframe Bolt
 

Sigh. Same as ever with a used car, you end up spending time fixing all the bodges the previous owner (or their "specialist") has left you with.

I had the front of the car up in the air yesterday to give the brakes a once-over and purely by accident I stuck my finger up the tube that one of the front subframe bolts sits in and the the bolt wobbled about :yikes: I tried tightening it but it just span round and round. Same thing when I tried to remove it. I loosened all the other subframe bolts to give some wriggle room and with a bit of encouragement it dropped out. The first ¼" of the thread was completely mashed :rolleyes: Judging by the oxidation on the bolt it's been like that for a long time. Someone must have cross-threaded it and then just left it in the hope that nobody would notice.

It'll be no problem to buy a new bolt but the thread in the chassis is damaged too - I tried installing the bolt from the other side to check, and it wouldn't go. The design of the subframe means I can't easily get a tap in there to clean out the thread, so my main question here is: how far can I drop the subframe without running into other problems ? Seeing as the engine is attached to it I'm guessing "not much" :(

Also, looking on the ETK HERE, I don't seem to have item 3, "reinforcement plate", or even anywhere obvious that it would attach to. Has anyone got a photo of the underside of an E53 (2001, 4.4i) that shows what's supposed to be there ? I have no undershield or anything below the engine.

FWIW I also discovered that the driver's side CV boot is split, and the passenger side one has been replaced, but is held on with zip ties instead of the correct metal clamps. More jobs on the list...

Steve.

By subframe, do you mean item 1 in your link, the front axle support? I haven't dropped one myself, perhaps Weasel or Killcrap could comment as BMW techs.

If you can't clean out the threads easily, can you just drill it and put a bolt and nut in?

Item 3 is called a reinforcement plate, but I always called it an underbody tray. It has been posted here that BMW advised not to drive without it in place, but I can't imagine it providing much stiffening, it seems more like an insulation item than a strength item.

Check this article for good photos of the underbody tray on a 4.4

http://www.xoutpost.com/articles/x5/...lvetronic.html

Good luck, sounds like you have some small jobs to do!

Yes, I meant item #1. The exact bolt in question is this one:

http://www.sundayjumper.com/e53_front_subframe.jpg

Passenger side for me, driver's side for you. Not that it really makes any difference !

Not sure that I can drill it and put a bolt through. I suspect that it's a captive thread in the chassis rail and putting a long bolt right through could squash the chassis rail. It'll only be a few turns of the thread that are damaged, if I can clean them out I'm sure it'll be fine.

That's a good link for pics of the underbody tray. I definitely don't have one of those :(

Maybe your car was in an accident and improperly repaired. In any case, I would not drive the car without the reinforcement plate.

Have you seen where it's fitted ? It's attached to, and within the bounds of, the subframe. You'd need to have a MAJOR smash to damage it, enough to bend the subframe too, and there's no sign of any damage anywhere else. More likely it was removed for access last year when the steering rack was replaced, and somehow forgotten when they reassembled.

Anyway, I've been driving it for two months, and the previous owner was driving it for I-don't-know-how-long like this and nothing bad has happened. I'll definitely get a replacement from a breakers but for now I'm not going to sweat it.

The "stiffening plate" was actually the subject of a recent post. I've taken mine off temporarily to chase a leak, and I wanted to know if anyone else has. One other guy volunteered that he did.

I'm not sure where you would even get a new plate from. Junkyard?

Yeah, I remember reading the thread and being a bit confused as there was nothing like what you described fitted to my car :)

I'll try a few breakers and see how much they want. I'd rather go to a yard and remove it myself but there's none close enough to me to make the travelling time & fuel worthwhile.

The reinforcement plate bolts MUST be replaced after each torquing due to the fact that they are STRETCHED by the 2 stage torquing process, 41 ft/lbs and then an additional 90 degrees of rotation, if i recall the tq spec correctly.

Update - a s/h plate cost me £40 delivered. Not too bad I guess. Fitted it today but not driven the car yet to see if it makes any difference. I'm not expecting much.