Darvi MK4/5

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Re: Darvi MK4/5

Postby Dave Robson » Sun Sep 13, 2020 3:31 pm

I too have had a copper (Kunifer) pipe fracture at Cadwell and as Peter says, Ed comes to the rescue!!

The fracture in the copper, in my case, was at the nipple end as was at a notch that had been left by the swageing tool when the nipple was formed. My advice is to check the grip detail on the tool and only use one that has a smooth transition and not sharp grooves. Additionally make sure that the copper pipes are well supported and can't vibrate to generate the fatigue failure.........................come to think of i, that was why the copper feed pipe to the clutch slave cylinder (in the bellhousing) failed at Oulton :( That has now been replaced by a Goodridge flexible :+:

Dave
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Re: Darvi MK4/5

Postby dopdog » Sun Sep 13, 2020 5:29 pm

Dave Robson wrote:I too have had a copper (Kunifer) pipe fracture at Cadwell and as Peter says, Ed comes to the rescue!!

The fracture in the copper, in my case, was at the nipple end as was at a notch that had been left by the swageing tool when the nipple was formed. My advice is to check the grip detail on the tool and only use one that has a smooth transition and not sharp grooves. Additionally make sure that the copper pipes are well supported and can't vibrate to generate the fatigue failure.........................come to think of i, that was why the copper feed pipe to the clutch slave cylinder (in the bellhousing) failed at Oulton :( That has now been replaced by a Goodridge flexible :+:

Dave


Hum interesting, I will have an updated photo for you later in the week :roll:
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Re: Darvi MK4/5

Postby pbove » Sun Sep 13, 2020 8:45 pm

The other issue that you’ve created is that the brake line needs to be broken if you want to remove a hub - which is not great if you have a problem at a race meeting. With braided hose, the calliper can just be removed without breaking the line, so no bleeding is required.
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Re: Darvi MK4/5

Postby Martin Kemp » Sun Sep 13, 2020 10:08 pm

Companies like Hosetecnik can make up custom hoses with whatever fittings and length you need.

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Re: Darvi MK4/5

Postby dopdog » Mon Sep 14, 2020 6:16 am

And so it begins, thank you all for your comments and sorry for my moment of insanity :roll:
IMG_20200914_071236_compress79.jpg
IMG_20200914_071236_compress79.jpg (245.13 KiB) Viewed 250 times
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Re: Darvi MK4/5

Postby pbove » Mon Sep 14, 2020 8:07 am

I've always made my own hoses and had no problems with them at all.....
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Re: Darvi MK4/5

Postby F1300Tony » Mon Sep 14, 2020 4:00 pm

We had a failure of a copper brake line on an old F3 car I was helping with. The pipe was about two seasons old and reasonably tethered inside the chassis. Braided PTFE every time.
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Re: Darvi MK4/5

Postby dopdog » Tue Sep 15, 2020 10:03 am

Normal service has been resumed. Braided hose refitted. Not sure whymy pictures are so big?
IMG_20200915_105909_compress39.jpg
IMG_20200915_105909_compress39.jpg (214.75 KiB) Viewed 164 times
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