crash - broken wishbone
 

First off I'm OK :) I'm standing at the side of a road waiting for the RAC which I've just joined. Was a nice day so thought we'd go out do a bit of filming and take some photos. Towards the end Richard was filming me doing some drive bys. Went down the road to turn round came back. All of a sudden crash and my from passenger side wheel is floating about. I thought the wing had come off but no, lower wish bone has torn in two just behind the ball joint.

I'll post some pics went I get back got some video as well but I'm not sure you can see much.

Now I have to call Terry again...

Glad you ok mate.

What happened? Wishbone just gave up the ghost????

There's a triangle metal bit that holds the ball joint its torn straight across where the weld is and over the metal. Looks like a material defect on initial inspection. I'll know more once I get it in the garage and the bits off.

Still waiting for the RAC man at the moment. Lucky I'm not too far from home.

Geeze glad your ok and not gong too fast.

How the hell are you reporting to this site while waiting for the RAC???

Damn, thats not good news, glad you are ok though. I hope you manage to sort it with Marlin, especially if it turns out to be a material defect.

John

The wonders of modern technology......and a long cable :eyebrows:

Glad you are OK Patrick. Scary stuff.....

Robin

he he I've got once of those pocket pc phone things :) (and a long cable :madgrin: ) took forever 3 blocks of wood and a trolly jack to get the car on the truck. Nice bloke though from the towing services.

Here's some photos, lucky there was no one else involved and it was on a very quiet B road:

http://www.msportster.co.uk/data/p_wishbone001.jpg

http://www.msportster.co.uk/data/p_wishbone002.jpg

http://www.msportster.co.uk/data/p_wishbone003.jpg

http://www.msportster.co.uk/data/p_wishbone004.jpg

http://www.msportster.co.uk/data/p_wishbone005.jpg

http://www.msportster.co.uk/data/p_wishbone006.jpg

http://www.msportster.co.uk/data/p_wishbone007.jpg

http://www.msportster.co.uk/data/p_wishbone008.jpg

First thoughts are that the metal plate does look a bit thin for such a job and that I would have thought it a better idea to extend the tubes to just after the central pivot point of the balljoint. I'm certainly no engineer though so could be talking boswollox.

John

Very sorry to hear about the crash but the important thing is that you are ok.

I agree with John that the metal plate doesn't seem that well supported (i.e. cantilevered off the wishbone) and the welding may also have weakened the plate leading to fatigue. Extending the wishbone tubes further out (like they are on the top wishbone) is a good idea.

Are there any signs of fatigue/cracking on the other side?

I wonder if anyone else has had the same problem.

Also, it will be interesting to see what Marlin have got to say on the matter...

Simon

You can't see much but I've put the video up at the bottom of this page:

http://www.msportster.co.uk/videos.asp

I'll have a longer more interesting video to post when I edit it.

That is absolutely incredible!

Thank goodness that you weren't going at speed or on a motorway! It looks like one of those F1 photo's when the wheels come off.
Good to see that your brake pipe styed intact.

Isn't this the part that had changed on Jason's kit (GOO's)? (remember he had to modify his bolt head to fit)

Is there a hint of rust on the crack (photo 4) suggesting that it cracked a while ago?

As others have said, Marlin's response will be interesting. (Might be worth contacting the MOC as well to see if anyone there has heard of this before.)

This would surely be a recall on safety grounds for inspection and replacement?

How does that work in the kit car world??

........probably say it's because you didn't fit the ARB :tape2:

Thanks for all your kind comments guys :) I've posted on the MOC forum too see what they say.

I'm going to take things to bits either after work this week or next weekend see if I can see any more. In the meantime I've posted another thread with the video from before this incident!

Looking closely at the pictures it looks to me like it's been cracked for some time - the area that I've circled looks like it's rusty to me.

http://myweb.tiscali.co.uk/martinclan/images/broke.jpg

Looks like you may be correct there, look how the other end it bent downwards as the wheel will have pushed up pull it off.

The car was making a squeaking noise but I had put that down to the exhaust bracket that was loose.

Just tried to call Marlin and leave a message but their phone number doesn't seem to be working!

(I've put up a new thread with the rest of the video of the day: Click me )

Good news spoke Mark. I'm sending the lower wishbones back to him to inspect and he's replacing all the parts for free that have broken! He's not see one fail there before so I'm hoping it was purely a weak piece of metal or weld.

Some progress which is good.....

I am worrying about mine now, since they are exactly the same construction as yours Patrick. I've noticed, that compared with some older pictures, the damper mounting plates on this type have been extended out towards the ball joint threaded bush,which makes the rest of the wishbone plate very stiff. The line where yours has broken becomes the weakest point.

It will be interesting to see if Mark modifies this area on your replacement parts.

Any other parts bent or damaged?

Peter

Ditto

I'm not sure how best they would be inspected. I think race teams X-ray their parts before use.

Given the Sportster has been on the market for 10 years and (so far) mine seems to be the only one that has had this fault I'd put it down to either weak material or a dodgy weld rather than a serious design flaw. However it does expose the weakest point of the design.

Track rod & head lamp casing. Need to take more off the car before I can say for sure.

Gah! Bloody Hell Patrick! :shock:

Glad you're ok, and Marlin have sorted you out with replacement parts. My lower wishbones look like this:

http://www.jason.cundall.dsl.pipex.c...suspension.jpg
http://www.jason.cundall.dsl.pipex.c...uspension2.jpg
http://www.jason.cundall.dsl.pipex.c...upspension.JPG


The only thing that seemt to have changed between Patricks (and the rest of yours) and mine is that the damper mount has moved from the top of the plate to the inside of the wishbone.

That looks substantially stronger in the area where mine broke!

Mark was also talking about the angles of the wishbones and track rods saying that steep angles are bad. He wants a picture of the front of the car with it sitting on the front so he can see what angles things are at.

I think as Simon suggested, if the tubes were longer like the top wishbone, there wouldn't be a problem becasue the ball joint would be welded to the tubes rather than just the thin triangular plate.
Alternatively, an additional plate welded across the bottom of the ball joint socket and the lower edge of the tubes would add strength with only a little addtional weight.

Peter

Wot? Hasn't he seen your website? :D :D

:lol: he's looked but obviously can't find what he wants to see - he watched that video I posted as well.


Sounds like an idea that, one of the directors at work races cars maybe he might know someone who can take a look at it for me :)

A professional second opinion would be a good idea at this stage.
What about the guy that welded your seat belt mounting. He looked pretty clued up.

The question is why has it changed :noidea::noidea:

Robin

Geometry to make the wishbones more parallel or sit the car at a different height? :noidea: :noidea:

The older Ford based cars had bolt on ball joints with a subsantial mounting plate but it must be a least 5 years since the BMW version was introduced?

Your Construction photo number 34 on your website has a good shot of the wishbone when you first installed it.

http://www.msportster.co.uk/data/p_construction34.jpg

http://www.jason.cundall.dsl.pipex.c...suspension.jpg

There's the comparison looks like the tubes go out further, by chance I took this photo earlier in the day (shows our extra steel weld up job on the wing carrier)

http://www.msportster.co.uk/data/p_wishbone010.jpg

Close up 1:1

http://www.msportster.co.uk/data/p_wishbone011.jpg

Moving the spring/shoc mounting will just affect the effective spring rate - the ride height is more adjusted by the adjustable spring plate on the spring. I think there must be another reason.

Certainly it looks like the tubes extend out further on the new design.

I remember talking to someone with a blue Sportster at one of the shows (The car with the BMW instrument cluster fitted) He told me he had had a wishbone fail - albeit after thrashing it around on a track day.

Robin

On thinking about it yeah, wouldn't change the angles of the wishbones just the ride height / adjust-ability. Maybe it lets you adjust the right high more effectively (or its purely to move the stress a bit further back on the plate?

I think I know which one you mean, that was the one with the M engine?

I've been holding back a lot while driving the Sportster for two reasons - its been damp / wet / cold and I've not done any proper set-up yet (because its cold and damp!). So its not like I've been thrashing it about.

I've been trying to find some better pics (close ups of the end of the lower wishbone) but don't seem to have any on my webspace... I can take some tonight if you need them.

It'll give me something to do in the garage, seeing as I seem to have stalled a bit waiting for funds, only to get funds to find that Marlin have shut down for the winter early! :)

Yes please :)

Pics as promised:

http://www.jason.cundall.dsl.pipex.c...kwishbone1.JPG
http://www.jason.cundall.dsl.pipex.c...kwishbone2.JPG
http://www.jason.cundall.dsl.pipex.c...kwishbone3.JPG
http://www.jason.cundall.dsl.pipex.c...kwishbone4.JPG
http://www.jason.cundall.dsl.pipex.c...kwishbone5.JPG

The metal that the end plate the ball joint sits in is approx 6mm thick, and is bent at right angles at the end where the mounting point for the damper is welded on:

http://www.jason.cundall.dsl.pipex.com/lwishbone4.JPG
http://www.jason.cundall.dsl.pipex.com/lwishbone2.JPG

That's great thank you :D I think Mark mentioned the metal the ball joint sits in on my design is 4mm, the bars also come further forward so it must be quite a bit stronger :)

Well those pictures are really interesting, thanks.
The tubes are extended and one now goes to the centre line of the ball joint so no bending forces on that plate.
Also, my end plate is only 4mm thick! Could you check that new ones are 6mm?
So the design has certainly changed for some good reason?

Peter

Did Mark say that the new ones are now thicker?

I think that is John from Warwick but i don't have his email address.
He frequents the MOC forum so hopefully he will see Patrick's post over there.