broken wish bone - crash

[h_m_cumming]

Re: broken wish bone - crash

Hi Patrick, any update on your new wishbones. Are the new ones different to the old?

[Patrick]

Re: broken wish bone - crash

Hi Huge,

I'm still waiting for parts from Marlin. Terry emailed me today saying they've unpacked a few things back at their old place, but need to get some bit laser cut and then assembled. So will probably be another 2 to 3 weeks.

In the mean time I'm half way through an engine rebuild - which is keeping me busy!

I'll post some links to pics once I get the new ones.

Thanks, Patrick

[donsayers]

Re: broken wish bone - crash

Don puts his engineering hat on.
Looking at the pictures, I can only say that I am horrified. I thought that the SVA was supposed to have put an end to this sort of thing.

The design of the failed wishbone is definately to blame. there is a sress concentration where the wishbone tubes end and there is a weld at that point, which probably introduced more stress concentrations in the form of irregularities in the weld and inclusions.

From the photo it would appear from the rust that the crack had been forming for some time. The engineering word is fatigue: repeated reversed stresses leading to failure.

I will stick my neck out and say that I am not impressed with the design of the wishbone component and would very strongly recommend the immediate replacement of any wishbones made to the same design.

[Peterx]

Re: broken wish bone - crash

Don,
interesing to see your engineering analysis. Patrick had only had the car on the road a few weeks before this happened.
Terry at Marlin has agreed to replace anybodies wishbones who are concerned about their safety. As Patrick says above there are a few of us waiting for replacement parts which have been delayed by Marlin's factory move.
It will be interesting to see what the new design looks like.
cheers

Peter

[Patrick]

Re: broken wish bone - crash

These messages were posted by Terry@Marlin on the www.madabout-kitcars.com forum:

----------------------------------

Hello builders

Thought we would have clarify the situation over one paragraph in our newsletter which refers to the new Sportster front suspension upgrade components.

This upgrade was brought about in order to reduce the number of different ball joints that were used on the Sportsters front suspension arms. In the past there were two types used now there is only the one, i.e. the same ball joint is now used both on the top and bottom of the upright.

The ball joint we have now decided to use is much more easy to obtain, less expensive, but most of all it looks better ;-)

We are very happy to offer a safety check if any of you are at all worried about the wishbone/suspension components supplied in your kit. We will freely replace any of those components any hint of faultiness :-)

Kind Regards
Terry & Mark
Reply With Quote

-------------------------------

Additionally regarding the mudguard stays:

Calling all builders

We have experienced some breakages on our front mud guard stays made using a light tubular material. As a result of we have decided to offer a free replacement service, (we do need the tubular mud guard stays returned to us in order that we can re-supply stays that our made to the correct fitting pattern).

We think there may still be a few of these old parts being used so this is just pre-cautionary note ............ check.

Best Wishes
Terry & Mark

------------------------------

I've posted pictures of the break on my mud guard stays here:

http://www.madabout-kitcars.com/forum/showthread.php?t=270&page=21

Patrick

[Patrick]

Re: broken wish bone - crash

I'm back on the road again now with new wish bones, however I've just heard from another build who's wishbone is bent.

I highly recommend all BMW Sportster owners with Pre-2008 cars on the old design wishbones check their lower wishbones regularly!

You can see pictures of the new design here:

http://www.msportster.co.uk/detail.asp?cat=6&offset=48

Thanks, Patrick
www.msportster.co.uk

[lizbillings]

Re: broken wish bone - crash

Hi Patrick. Glad to hear you are back in action with your sportster. Will you make Stoneleigh? Be interesting to talk to you about wishbones etc and see the car. Regards Liz

[Patrick]

Re: broken wish bone - crash

Hi Liz, thanks I will be at Stoneleigh this year. Looking forward to it as it will be the first time I can go with the Sportster.

I've put a FAQ item up on my website summarising the issues: http://www.msportster.co.uk/faq.asp?FAQ=22 I've tried to be neutral and fair to Marlin.

I'm wondering if it is worth putting a note into pitstop to make others aware to double check their wishbones.

Thanks, Patrick

[Mike]

Re: broken wish bone - crash

I am surprised the MOC club has not made a much bigger issue of this. The failure of this part is life threatening. Can I urge the clubs stewards to pick up on this before someone gets injured.....or worse.
Mike