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8 & 10 cyl Bristol cars From Type 407 onwards

411 Front Disc Brakes

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Old 19-02-20, 01:26 AM
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Default 411 Front Disc Brakes

The front discs on my car are well worn but still usable. Rather than recondition them does anyone have any experience or knowledge of vented discs and upgraded calipers for 411s. I understand the factory was offering such an upgrade at one stage?
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Old 26-02-20, 12:57 PM
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Peter,

In the absence of any suggestions from closer to home it might be worth your while contacting Alex Mitchell at Spencer Lane-Jones, alex@spencer-lj.com , who do a big brake vented conversion. I don't know whether this involves the modification of any existing bits.

My 410 is pending this conversion. It will out stop many a modern car but the heat can build up to the point that the fluid boils...... somewhat disconcertingly!

Roger Morrall
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Old 26-02-20, 08:29 PM
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Thanks Roger

Spencer Lane Jones have an article out on how to do this conversion which involves a fair bit of machining and the use of Renault discs and calipers.

A 408 in Australia has used Audi solid discs as replacements for the standard bristol discs although they too need machining.

My other alternative is to have my standard discs machined. They are I believe 1/2 inch thick from new. Does any one know how much can be machined off them before they are no longer legal ?
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Old 27-02-20, 12:33 AM
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Peter,
You are right about the thickness of the new ones - I have some from Bristol and they are 12.8 mm, which is quite thin by modern standards, but the Bristol rotors are solid, whereas they are ventillated in most modern cars.

My understanding is that the rules re rotor thickness in Australia are set by each State/Territory.

For modern cars in Victoria I believe they rely on car manufacturers specifications for the minimum thickness, which can vary significantly between different car models. The min thickness is usually stamped on the disc on modern cars, but it is not stamped on the discs I bought from Bristol.

There are different rules for standard equipment and modifications depending on the age of the car. What year was your 411 manufactured?

Last edited by Kevin H; 27-02-20 at 03:33 AM.
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Old 27-02-20, 12:39 AM
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Quote:
Originally Posted by PEU186F View Post
Peter,

My 410 is pending this conversion. It will out stop many a modern car but the heat can build up to the point that the fluid boils...... somewhat disconcertingly!

Roger Morrall
Roger, surely this wouldn't happen in normal road use?
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Old 27-02-20, 12:19 PM
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Peter

S L-J have moved on from the modified Renault approach to an AP conversion. There's a picture on the design and development page on their website, alongside what might be modified Renault. You might be able to sweet talk them into telling you more, I find them very helpful.

Kevin H

Depends on what you mean by normal road use. I have experienced fade on the normal pads on the long drop down from the Prescelly Hills here in Pembrokeshire to our house. This mark you on what is essentially a single track road so no speeding. So I put in "road and track" pads for an Alpine tour and exercised great care. No pad fade but at the end of one long day, after two consecutive passes, the heat struck once we were well into the town. The instructions to the hotel said "straight across the roundabout" and so we did! Normal roads - yes, with ups and downs.

But I did manage to get the 410 up the Stelvio. An achievement, but my advice is don't try it. There is no way back, no way to see what is coming at you, lunatic cyclists and motorcyclists were a nightmare and at the top there's only dirty snow and a load of tatty souvenir stalls. I declined to take the same route out.
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Old 27-02-20, 12:28 PM
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Kevin I spoke to the local brake specialist who confirmed what you said, it should be stamped on the disc. He made the point that being thinner than the minimum does not create a danger. Years ago a friend restored an Austin Healy 3000 with brand new discs but according to the garage who were doing the roadworthy certificate 1/2 inch discs were not satisfactory. Clearly there is confusion about the regulations.

Seems to me if I have my discs machined and they are not marked how can there be a problem. If I stick with standard disc and use the Cooper Craft calipers I should have adequate stopping power.
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Old 29-02-20, 06:40 AM
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Quote:
Originally Posted by peter dowdle View Post
Seems to me if I have my discs machined and they are not marked how can there be a problem. If I stick with standard disc and use the Cooper Craft calipers I should have adequate stopping power.

I was thinking the same thing. When I went to get a roadworthy on my 411, the tester commented to me verbally that the discs were a bit on the thin side, but that wasn't a failure point.

Personally I believe original braking performance on the 411 is adequate providing the system is in good working order.

The main concern if a car has been standing for a long period of time is rust on the skirt of the caliper pistons.
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