Classic Audi Technical Mech/Tech Suspension & Brakes » Bleeding brakes

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Old 04-03-18, 07:29 PM   #1
20vcqdriver
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Default Bleeding brakes

OK so does anyone have a method of bleeding the brake system on a 1986 Cq that works? Since installing the new calipers I have attempted to bleed them but brake pedal is still VERY spongy and twice as much travel as there should be, though now I've done a few miles they at least stop you but the travel is unacceptable. All ideas welcome
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Coupe quattro 1986:-~400bhp + loooong list of mods!
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Old 04-03-18, 07:57 PM   #2
Colin Aitchison
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Sorry for the questions, but my own experience with brake on a coupe is on Ur quattro's, did you fit new front or rear calipers? dose the car have ABS? are you using a self bleed system or second person in the car pumping the pedal? what other brake parts have you changed or modified, servo, master cylinder, brake lines?
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Old 04-03-18, 09:15 PM   #3
Jake Blight
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Had the same problem with my 87 cq prior to getting it back on the road, ended up getting my local garage to sort it. Still not sure what witchcraft they used but it certainly made a difference.

Good luck with it all.
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Old 04-03-18, 09:55 PM   #4
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Strange, I've done it several times over the years using an eezibleed kit without issue...
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Old 05-03-18, 06:51 AM   #5
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Have an accomplice to pump up the pedal and then hold the pressure on whilst you open the nipple and then close (x10 maybe), has always been my preferred way to force air from the system.
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Old 05-03-18, 09:19 AM   #6
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You doing it with the rear suspension supported in it’s normal position?

The rear valve cuts flow to the rear brakes if the suspension is drooping.

I used to have an eazibleed but they leak, I bought a Sealey VS820 which is a much better piece of kit
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Old 05-03-18, 10:27 AM   #7
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Hi 20vcpdriver,
You have had replies from some very wise people, in my own first reply I asked you some questions, Dose the car have ABS, the reason for this is in a Ur quattro with ABS you need to bleed minimum 500ml of brake fluid through each of the 4 brake calipers, the reason for this I an not certain but normally only cars with ABS, the fault you get if you don't bleed 500ml through each caliper is a long brake pedal, normally an air pressure bleeding system is better than second person pumping the brake pedal.
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Old 05-03-18, 10:48 AM   #8
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Quote:
Originally Posted by Duffy3074 View Post
You doing it with the rear suspension supported in its normal position?

The rear valve cuts flow to the rear brakes if the suspension is drooping.

I used to have an eazibleed but they leak, I bought a Sealey VS820 which is a much better piece of kit
There's no such a thing in any Coupe Quattro, because it has independent rear suspension, removing any easy and safe attachment point for bias valve. quattros have brake force regulator, which limits rear brake force according to pressure, not rear height, and it's small cylindrical item attached to brake master cylinder, at least in LHD cars
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Old 05-03-18, 11:01 AM   #9
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Fair enough

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Old 05-03-18, 06:54 PM   #10
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Quote:
Originally Posted by Colin Aitchison View Post
Hi 20vcpdriver,
You have had replies from some very wise people, in my own first reply I asked you some questions, Dose the car have ABS, the reason for this is in a Ur quattro with ABS you need to bleed minimum 500ml of brake fluid through each of the 4 brake calipers, the reason for this I an not certain but normally only cars with ABS, the fault you get if you don't bleed 500ml through each caliper is a long brake pedal, normally an air pressure bleeding system is better than second person pumping the brake pedal.
Thanks for replies everyone Mine does not have ABS, was an option until 1987. I have long pedal and spongy once 'slack' taken up. Only replaced front calipers as part of upgrade (same size piston as Cq).
As already mentioned, I ended up taking it to my local expert last time and witchcraft the only way to describe it as the difference was massive.... Followed the correct sequence as per Haynes manual and used second person on the brake pedal too...Its a weird and annoying issue
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Audi A5 sportback 3.0TDI SLine quattro 2011
Audi A4 2.5TDi Sport cabriolet (163bhp) 2004:- Remapped to 180bhp
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