Disk brake options

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Roger King
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Location: St Ives, Cambs

Re: Disk brake options

Post by Roger King » Tue Mar 01, 2016 9:28 am

Paul Blore wrote:If you managed to boil the silicon fluid Roger, you were either trying far too hard or something was amiss somewhere. :wink:
The problems occurred in two different cars and the braking systems were working perfectly apart from the fluid. I say the fluid boiled but obviously I didn't look in the reservoir to find it bubbling - but in a new system with no contaminants it had changed colour (slightly brownish). Some kind of denaturing had clearly taken place. The 300SL episode was on an MSA tour in a newly-rebuilt Healey. I had just gone up (a road-closed) Porlock Hill, not particularly fast (it was actually snowing!!), but it was the crawl back down that saw the brakes go. Pedal gradually going further down until nothing left, horrible feeling. Desperate pumping brought a bit back.
Anyhow, I use ATE Super Blue now, never had a problem apart from the colour it turns the reservoirs. For that reason I use BMW bremsflüssigkeit in the MCoupé as I don't want the plastic reservoir to turn blue.

CobStang
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Re: Disk brake options

Post by CobStang » Tue Mar 01, 2016 9:26 pm

Fluid wont boil in the reservoir, it will boil in the caliper and the resultant air/ gas will send the pedal to the floor.
Super DOT 4 is not race only, I have used it for years in my 289.
I run Rover SD1 2600 twin pot front calipers with a solid MGBV8 front disc and Sierra rear discs and calipers.
The front calipers have the same piston area as a Princess 4 pot and I use an MGBV8 pad which also has the same area as the 4 pot. The downsides are - the caliper is heavy and the disc does not cool as well as a vented one, however I have cooling ducts and with the super DOT 4 the fluid will not boil even under track use.
I find the best place to buy Super DOT 4 by the litre is my local Ford dealer. At work we buy 5 litre cans.
Early B.R.A. Warmed 3.9 Rover, 5 sp, 3.07 rear, Fully adjustable front suspension with AVO coilovers, 4 link rear suspension AVO coilovers and Panhard bar, Big 2 pot front calipers, rear discs, servo'd, adjustable front / rear bias, scruffy paint job !

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Roger King
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Posts: 4267
Joined: Mon Mar 19, 2007 10:29 pm
Location: St Ives, Cambs

Re: Disk brake options

Post by Roger King » Tue Mar 01, 2016 10:07 pm

It'll be interesting to see how my car's brakes behave with hard work. As original, they are three-pot cast iron Girling calipers at both front and back, with solid (non-vented) discs. Separate circuits front and rear. I sincerely hope I don't get problems with the rear discs - I have to completely dismantle the driveshaft, hub and bearing assembly to change the disc - in their wisdom AC designed the disc to bolt to the inside of the hub assembly, not the outside.

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