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Lower A arm failure


yankeedoodoo

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This is interesting. When I had my Birkin the American owners were always having problems with lower wishbone failure yet AFAIK it was never a problem in the UK and certainly never a problem on mine despite the hammering it got on some of Irelands back roads.

 

ON the car with the wishbone that failed did it have std Caterham spec springs and dampers? This seemed to be one issue which may have contributed to the failure on the Birkin.

 

I can`t believe the roads in California are any worse than the ones in NI

 

Simon Bell - Caterham 7 Duratec R

I`ve seen the future.....and it`s powered by duratec Check out the website here

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i had a failure in my left one last year, the spherical rotating bit became loose in the frame/shaft it was mounted in. didn't notice / feel anything but was led to believe that had it not been discovered what you're talking about could've happened to me.

 

what age is the car in question? mine is May 2001, and this occurred at about 12K miles ☹️

 

A-frame is now replaced

 

Steve B

Big Black Beast^3 USA 2005: How the West Was Driven

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I was in the car when it happened.

 

We were doing approx 30 mph when we braked moderatly ahead of a dip in the road. Before we hit the dip, at about 15mph, the left lower wishbone collapsed, and we skidded to a halt about 100 ft further down the road.

 

The rear arm snapped straight off, leaving the bush in place in its frame mounting with a approx 1 cm of wishbone tubing protuding from the bush/wishbone weld.

 

The front wishbone tubing encasing the front bush opened up and released from the bush, which was left in place on the front end of the car.

 

I cannot tell if the front or the rear arm failed first.

 

Once the failure was complete, the entire front wheel assembly rotated 180 degrees counterclockwise, probably due to the torque induced during braking, and snapped off the stock Bilstein shock.

 

The rest of the car's travel to a full stop occured on the fender, marking our progress with a green streak on the road.

 

The upper wishbone was left intact since the upper balljoint pivoted in the threading normally used to adjust camber.

 

During the rotation, the lower wishbone said hello to the aluminium skin and more or less shredded it.

 

There were no personal injuries, and we were extremely lucky since I had been test driving the car at speed on the highway just 30 minutes earlier.

 

As far as I could see on site, the tubular framing was not warped. Since the (aluminum) oil pan took a part of the impact when the car went down, we must check that the pan is OK and that the engine mounts survived the shock.

 

I'd like to emphasise that there was no extreme driving involved in this.

We were driving in a residential area to pinpoint a weak spot in the mapping when the collapse occured. The tires were stock Avons (ZV1?) on Catehram's 16" wheels, which guarantees that no excessive forces were in play since they are quite slippery.

 

After I have talked to Caterham USA, and if the owner agrees, I'll post pictures of the incident on the California Caterham Club site.

 

Until then, I've removed the link I mailed yankeedoodoo from the site.

 

/Magnus F.

 

Edited by - magnusfeuer on 28 Feb 2005 03:17:51

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Brad, how can you wreck your car when the most important track day of the year is coming up 😬 But seriously, good to hear you and Magnus are O.K. (and the car still in repairable shape...)

 

This does not sound like the problem Simon mentioned that several Birkins had a while ago. In their case it was apparently incorrect spring/shock setup that made it bottom out and bend/buckle the a-arm at the shock attachment point. Not such a complete rupture.

 

The failure Magnus describes sounds really weird. Right in the middle of the tube? I would really like to see the pics....

 

Gert

 

P.S.: Better don't imagine that happened on one of our mountain blats *eek*

 

PPS: Oops, just read "Duratec SV"....that is not your car anyway, isn't it?

 

Edited by - Slomove on 28 Feb 2005 03:54:30

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Glad the result wasn't more serious 😬

 

Eagerly await the photo's - I think I'll give my front suspension a detailed check - just in case 😬

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

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Interesting (and a little un-nerving).

 

By the sounds of it, the failure in the rear leg wasn't "in the middle of the tube." 1cm from the weld may be within the heat affected zone of the weld.

 

Was the failure of the bush housing on the front adjacent to the weld with the 'leg' of the wishbone?

 

All speculation at this point, but my hunch would be that the front failed first, and then as the rear tube bent backwards it snapped perhaps due to embrittlement from the weld.

 

Are the SV wishbones of the same design as those on the standard car (but longer)? Anyone know offhand how much longer the wishbones on an SV might be than on a standard car?

 

Dave

 

 

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It looks to me that the front failed first. The rear break is bright metal, whereas the front looks quite corroded and "Nasty" *thumbdown*

 

It's likely to be an isolated event, but I intend to give my front end a good close look with a bright lamp and magnifying glass *thumbup*

 

Have you had any official response?

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

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I don't like how corroded the inside of the front bushing tube looks. Especially the fact that there is surface rust visible on the surfaces of the split as if maybe it's been partially split for some time.

 

Also, what's all the crud visible in the shot of the other end of the split bushing tube (in the UnpublisedPhotos file)? Was that picked up as the car dragged to a stop?

 

Very relieved no one was hurt. Hope you'll keep us informed of what you hear from Caterham/Caterham USA.

 

Dave

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Tony,

 

I actually think it was the rear that failed first.

 

If you look at the front tubing, it seems like it has been twisted off its bush. This would happen if the rear mount snapped and then the entire wishbone rotated as the rear end was pushed upward by the weight by the car. The rotating action then twisted off the front mounting.

 

The crud inside the front mount was asphalt picked up during our skidding.

 

/Magnus F.

 

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