2011 bmw g 650 gs fork failure

Question from an interested lurker;

Is it much more cost effective to cast these parts than to just machine them out of a billet?

Yes, if you're making thousands of them.

Yes unless you are cranking out a prototype or two. Casting cost efficencies come on pretty quickly. You need to amortize the cost of the 'mold'. It doesn't take too many produced to do this.

The issue is that many forks have this leading lug design but none fail like BMW and none need to be machined from billet either.

Probably been mentioned but it seems to me many other designs have the axle lug further up the tube, allowing for a more gradual transition both top and bottom.

These seem (to my instincts) to be located too close to the bottom of the tube, causing the lower part of the axle lug transition to be sharper and possibly creating a stress concentration.

Much more; you have a little more upfront costs to create the tooling for casting but then your price per part cost is quite low, upwards to 50-70% lower than a cnc'd part. Casting is not bad if the quality control and the design specs are in order, but as pointed out by others it can take a long time to find the source of the issue when eating with casting.

Not bad? For years now, firearm receivers have been made of investment castings. The process is good enough if the care is in and the engineering well done.

Right, I think Bill Ruger was the first to use the process so widely.

I think you are right about Ruger but now many other apps are using investment casting in high stress situations. The Japanese seem to be casting masters.

Exactly! The process is excellent when great engineering, great materials and great processes are in place! At work we are currently having parts made out of composite materials in an injection molding process; just 2 years ago these parts we cnc made.
By looking at the failure in the picture I think we can all agree that thugs improvements could be make in the process and design.

BMW Motorrad disagrees.

Hi, been thinking of purchasing 650gs or serato, but having come across various threads i cannot believe that fork failiure such as this can occur on a new machine. Does anyone know if the same thing has happened to a serato or gs650se (800 twin), as they both appear to have the same diameter forks 41mm?

I have a 1994 ttr250 and that has 42 mm diameter forks on a bike weighing approximately 125kg. Does not make sense!!!

What progress, if any has AW made? Wish her well.

It is the size and strength of the leading axle mounting lugs which are in question not the fork tube diameter

The F650GS twin fork lowers are believed to be different to the single but I have not checked the Part No's.

The bottom line is that a set of damper rod forks on a machine like a Sertao means that it is well behind the ball game

Yes ok thanks for the prompt reply.

As to AW, she withdrew from the thread months ago w/o notice that she was going to do so.

Some here speculated that she got a settlement which prevented her from discussing things further, but we really do not know. For all the info we have, that may have occurred or maybe she got a new bike, the forks failed on that too and she bought the farm.

AW claimed insurance & so it is up to the Insurance Co to take up the case with BMW so there is no settlement with BMW

I understand she will ride another make & model but will definitely be back on 2 wheels & is getting on with life as she should

We have no idea how that evolved. The insurance company can get an offer which binds its policyholder to behaviors such as non-disclosure.

We can either believe that BMW never paid a cent on any of these claims or the payment / settlement was accompanied by a non-disclosure of that payment.

Which do you believe?

As to AW's status, either you know something or you are just spouting hot air about she moving on and continuing to ride. So which is it?

It is as I have stated, AW claimed insurance, It is for the Insurance Co to decide on action re BMW & that would be unlikely

AW could look at an injury claim but the injuries/likely payout would not cover legals so that is not viable

AW was looking at her next machine purchase & it was not a BMW

Re other failures on the earlier F650GS there were settled cases in the EU with non disclosure agreements but none we are aware of outside of the EU. In each case where BMW was informed of the failures they denied knowing of other failures,

It was the NHTSA preliminary investigation which caused a change in BMW's position where they stated they were aware of a small number of failures and claimed the failures were the result of accidents not the cause.

When I first saw the pictures of the failure way back, it strongly reminded me of a brittle fracture of a high strength aluminum casting caused by over-aging (too much time at an elevated temperature).

Been there seen that on other aluminum parts. In that case the alloy was 7075. There was no ductility whatsoever.

MN MechEngr (retired)

A little OT, but regarding what BMW may or may not have known: Last year I was in the market for a new bike, and had whittled it down to the Yamaha SuperTenere and the BMW Adventure GS. About the same price over here in the EU. At any rate, I know all about the rear drive failures on the Beemers, but wanted to get the dealer's impressions and had they been fixed yet... wasn't expecting much, because I'm not entirely a mental defective. Dealer deadpans, what are you talking about? I don't know of any systemic rear drive failure issues on any Beemer. Now how about that test ride?? I laughed and told him not to be a moron, and rode off to buy the Super Tenere. Which is a bulletproof Yamaha, and a bulletproof bike. So far, anyway!

Outright liars, those folks, just remember that when shopping.

Funnily enough, I had a conversation yesterday with a mate who has had a BMW 1200LT since new...think it is about a 98 model...he has had years of grief with BMW trying to rectify a mapping/fueling issue with this bike, which is apparently well documented and recorded, and BMW continue to deny there is a problem. Made me think of this thread...seems fairly common for BMW to simply deny there is an issue.