What's that noise?

[stevepritch]

Took a little drive out this morning, started off as it normally does.. 5 minutes down the road applied the brakes and there was an unusual metallic clunk, but car stopped. Moved forward braked and again the clunk. Not sure exactly where it was coming from, seemed to be middle to rear under the car. Got us home and up on ramps.. Could not see anything. Off to the garage and up on the ramp. Loose bolts on the prop.. They were tightened, but still a clunk on the back. Rear wheels off and a closer look. Off side rear caliper lost a bolt, hence the clunk when braking. Made a new bolt from from a suitable substitute, bit of a die, bit of a saw, bit of a grind. Fitted, tightened and checks all around. Back on the road, big smile.

[David]

Re: What's that noise?

Well done

[copperleaves11]

Re: What's that noise?

I'd be inclined to check all bolts if you find brake caliper bolts missing.

[stevepritch]

Re: What's that noise?

Went round it all, found nothing else of concern. Will be looking for some bolts for the prop, the existing appear to be a little too 'custom'.

[greyV8pete]

Re: What's that noise?

Make sure you use high tensile for those applications. Also for prop shaft flanges you need bolts (with a plain diameter locating in both the flanges), not set screws (which are threaded all along). Please get a new H/T bolt for the caliper. H/T threads are rolled so the grain runs around the thread form profile. Running a die down to increase the thread length cuts through the grain and weakens the bolt. Peter.

[stevepritch]

Re: What's that noise?

Thanks Peter.
It was a HT bolt that was re-threaded, and a shoulder was left on. However I have been in touch with BMW for new bolts.
Certainly looking for some decent bolts for the prop.