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rafikdous

Ineffective brake pedal

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Gents, need help. I am stuck

Car is a 1973 T and has been under resto for a while
Brakes were probably done 2 years ago but the car hasn't been used since

The calipers are reco'd and pads are new all around. I am not sure if the MC has been done or not

The brakes, while they stop the car, they are not as sharp or effective as they should be
If I push them real hard, I can lock the front wheels

There is good oil flow out of all the 4 bleeding valves and I double checked that non of the calipers are ceased

What am I missing?

Thanks
Rafik

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New pads need to be bedded before they work properly.

Change the brake fluid as it is 2years old then drive it around carefully for a bit. If road pads it could take a few hundred km. If race or performance ones you can do bedding procedures but if the rotors have been used with a different compound there will be additional time to remove the old transfer layer.

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wet and dry paper on the disc and pads can also help if Glazed or contaminated, also a light bevel on the leading edge of the pads if they don`t have one.

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Hi Rafik

I had the same problem on my 2.4T - Stock standard system and despite going through pretty much everything it was no better

It was very underwhelming and so reading your text I thought I add my 2 cents

Some guys suggest running slightly differnt pads ( check 911s registry ) and you may even try braided lines in case your using the old rubber by any chance

So on those Lake Mountain runs I was always nervous but loved the car

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On 6/5/2018 at 8:41 PM, rafikdous said:

Thanks, will try your suggestions

Are the brakes spongy and unresponsive pedal? 

New piston seals need a few hundred k's to wear in - some shops only do 1 or 2 brake rebuilds at a time on the older cars so you have some brakes while the new ones wear in.

... or reuse 'old' seals that are not cracked or split and already shrunk.

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Stock 911 brakes of this era do have a long pedal. Going up a size in master cyl makes a big difference. Higher pedal pressure but much less throw. 

There is a Merc Benz master cyl that is about 18mm from memory that is a great upgrade and basically bolts on. I have one in my hotrod targa along with project mu street/track pads and this setup is excellent. 

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Everything looks to be in order

No air in the system, all the pistons are moving freely (I removed the pads and had my wife press the pedal)

So I think I just need to drive it for a bit to get everything settled. Problem is the road worth guy is unlikely to pass it as it is

Will see

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I’m guessing the flexible brake lines were replaced at the time of rebuilding? If not that could be the problem. 

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On 6/13/2018 at 9:43 PM, rafikdous said:

Everything looks to be in order

No air in the system, all the pistons are moving freely (I removed the pads and had my wife press the pedal)

So I think I just need to drive it for a bit to get everything settled. Problem is the road worth guy is unlikely to pass it as it is

Will see

Do they test drive them for a roadworthy?

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^ In VIC they use a meter that measures stopping G force and brake pedal pressure in an actual stop. 

Bit of a catch 22 as you need to bed the brakes to pass the test but you can not drive it to bed them before the test if unregistered. 

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They are mongrels to bleed properly. Somehow bubbles remain in the MC. Probably wasnt bled properly when the first brake job was done.

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