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Posted by: Kaduku Oct 21 2013, 06:38 PM

I have new brakes, rotor, and calipers. Recently had an upgrade to a 19mm brake master cylinder. I now get squeaks when the brakes are warmed up.

Also what are the symptoms of having a non-functioning distributor vacuum advance?

Posted by: pcar916 Oct 21 2013, 06:57 PM

1. Could be your break-in on the new pads/rotors needs to be done again. I'd remove the pads and sand them lightly on a flat surface til new material is showing and the shiny areas are gone. Then scrub them in again. What compound are the pads?

2. Vac. advance would simply make you have less power because the spark wouldn't advance with respect to the rpm. In other words, it'd be more retarded than it should be!

Good luck

Posted by: r_towle Oct 21 2013, 07:10 PM

In the classic thread section here, or on
Www.pmbperformance.com
There is a great article on how to properly bed new brake pads.

Vacuum advance will add some advance ahead of the centrifugal weights.
It's for a cleaner running motor and aids in better emissions.
Without it, the weight will come on a bit later, but you will have full advance at 3 to 3500 rpms, or in that range on a type 4 motor.

You could have a stuck advance mechanism.
Open the distributor and look at the arm that attaches the vacuum advance canister to the advance plates, remove the c-clip
Then remove the canister from the distributor.
See if it moves by hand.
See if it moves by sucking on the vacuum port.
See if it hold a vacuum by sucking, then see if your tongue holds.
You can do all of this with a vacuum pump if you have it.

Another easy issue is the advance plates get very dirty and the 40 year old grease needs to be removed and replaced. It has turned to glue when it gets hot.

There are several threads on how to do this here, with pictures attached for guidance.
Dirty sticky advance plates will make it either stick with no advance or full advance, or somewhere in the middle.
None of that is as designed and it needs to be cleaned...about every 30 years or so.

Rich

Posted by: Kaduku Oct 21 2013, 08:13 PM

Thanks for all for the info.

As far as the brakes, they were nice quiet before the brake master upgrade.

Posted by: Jeff Bowlsby Oct 21 2013, 08:56 PM

Well there you go...the 19mm MC is a downgrade not an upgrade for a stock 914.

Posted by: Eric_Shea Oct 21 2013, 09:16 PM

I doubt it to be either.

It is often misrepresented as an upgrade. It will not improve the braking but, it will improve the feel. It makes the pedal slightly firmer. So slight that I tend to doubt anyone would notice. It also requires more effort... again, so slight I doubt you would notice.

The price is better and they are readily available, not so much as of late with the stock 17mm which will set you back and additional $50 clams.

I "always" recommend an ATE 19mm when in need of a Master Cylinder.

It will change your fluid dynamics so I would suggest you simply re-bed the pads. Sanding is not needed unless you think you've glazed them.

Posted by: Kaduku Oct 21 2013, 09:24 PM

Thanks for the tip. Sounds easy enough!

As far as the 19mm, I wish I stuck with the 17mm because I prefer the feel rather than the stiff feeling of the 19.