Help - rear shock mount cracked on De-Dion tube

[Peter Duce]

Not been able to use the Seven (1997 K SS, 15k miles) for the last couple of months as it has been lying a little lower (offside rear) and also has signs of a leaking shock.

 

Finally got around to replacing the shocks yesterday only to find the lower mounting on the De-Dion tube had started to split away. This is about 3 cm outside the welds that hold the retaining head onto the tube for the lower shock mount. (15kb picture I can email if anyone wants to see).

 

Looks as though a crack has started to form and the pressure of driving has gradually made the spilt bigger, to the point where both car sagged and shock started to leak. Taking off the original shock before noticing it, has probably made it worse. Now nothing will locate in the lower mount – not that I would want to drive it like that!

 

I am presuming that the only way to repair is a new De-Dion tube.

 

Anybody experienced this before please?

 

Peter

 

 

 

[Fast Westie]

They all do that Sir! Seriously, I have seen severla posts on this forum about this very problem. I seems to be caused by the fact that the shock mount is welded rather than brased to the De-dion tube.

 

I think some people contacted Caterham directly because it is a know problem, while others just welded it up again.

 

Of course, you don't get this with a Westfie1d teeth.gifteeth.gifteeth.gif (dives for cover)

 

The car in front is a Westfie1d wink.gif

[EFA]

Peter,

 

Go directly to Andy Noble at Caterham - he is a resonable guy and if goodwill is to be given (assuming you are 1st owner of the car) he is the guy to approach.

 

 

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[Peter Duce]

Arnie,

 

Thanks for the advice, but as the 2nd owner .... and a few trackdays, do you think he will be as sympathetic as you may have supposed?

Peter

 

 

[Paul D Jones]

If you live up north I can get it welded for a small fee by a coded welder

 

Paul 01472 590325

[wg_mulholland]

As to the welding/brazing situation- I was dismantling a set of widetrack wishbones today, when I noticed that the lower wishbone is fusion welded, but the upper is brazed. Anyone know if this is normal, or why they ar different? I had another look at the rest of the car too and recon the a-frame is welded too. Weird eh?

[Peter Duce]

Paul,

 

Thanks for the offer, but live in the Sarf (Reading to be precise).

 

However as the split is outside the area of the original braising/welding (actually split the De-Dion tube for about 3 inches) do you reckon it can be welded?

[Paul D Jones]

It sounds like the tube is made from seam welded pipe or tube if your posh the thing to do is drill a hole a litle further down the tube and then cut the split into the hole the stress then has nowhere to go and stops there, the split in the tube can be ground out with a dics cutter grinder, veeed out and root,fill and cap welded a good welder would a able to advise, if you have to pay full price for a welder the going rate for a coded welder is about £80.00 an hour, two hours work or less for the full job, xmas at work is a good time for a cheap job as my job is usualy awash with them doing pipe work mods Steve Rands is one of the top welders in the North and is based out of the said company Birds eye uses at Xmas. He welded my steering coloumb for £20.00 25 minuits work but all the prep was done.

 

hope that helps The best type of welding to use is T.I.G NOT MIG

 

Paul

[Bricol]

I'd be a little concerned about all the additional heat from TIG pulling the tube on cooling, totally mucking up your rear tracking. I would suggest that the best idea os to replace - if it is becoming a known problem, perhaps Caterham should be considering a redesign - sounds like a seamless tube would be the way to go, or a thicker wall.

 

bri

[EFA]

They probably made a batch with thinner wall tube to get the wight of certain weight sensitive models down. Probably fitted at random to other cars.

 

I'd speak to Bruce at Arch and find out the facts on the tube thickness and then buy a new one from Caterham. Spending 2 hours on labour @£80 per hour is ridiculous.

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[Paul D Jones]

Arnie and Peter

 

That is the price they charge Birds eye and other companies I seen enough Quotes and invoices Solid drawn tube tends to be heavier wall thickness TIG welding or stick is the only type of welding by appoved welders that the insurance company will accept for the frige pipwork at work the heat is very local and full penertration to the perent material so the best for the job

If the tube is splitting down the seam weld in the tube probably best with a new tube.

 

Paul

[Peter Duce]

Update:-

 

After talking to Andy Noble on Monday, Caterham were very quick to come back and offer help to me. They were sympathetic but obviously careful about how much help on a 2nd owner 4.5 year old "home built" car. (Distinction being that even in warranty for a home built car only the De -Dion would have been replaced.)

 

After sales have agreed to replace the De-Dion tube for £300 all in - Tube and labour, which represents about 25% saving. Even fitted me in the next few days as well.

 

Advice from everybody seems that this is a fair deal. Would have preferred this money to go towards the 6 speed upgrade, but at least it didn't fail while on the track!

 

Andy Noble even rang back today to see if I was sorted. Handled very professionally.