DDK - Die Deutschen Klassiker

Afternoon all,

Last winter I went through my 68 912 brakes with new MC, rebuilt calipers (by me), new brake lines, new pads etc. Discs are in good shape and true.

I have always felt that the brake pedal had a long travel before engaging, the brakes pulled up well enough as witnessed by my lad face planting into the headrest one day. Just felt that I would like the pedal higher and firmer. The factory owners manual refers to 30-50% of total travel before the brakes will bite. I feel I'm beyond that.

I have been chasing through the usual suspects of hysteresis, brake push rod adjustment etc but to no avail.

I went down to the assembly today to look for slop or breakages and have decided the bushings will be replaced as there is some movement on the brake pedal shaft and crumbly remains of bushings.

My question of you is whether worn out bushings will allow excess brake pedal travel or if this is a red herring?

The bushes will be done regardless just interested in opinion/experience/fact.

Matt

For what it’s worth, there’s an updated set of pedal bushings, got mine from a guy on here.

If the pedal assembly is the same as the 911 unit then you can adjust the amount of free play before the brakes bite. This is done on the MC rod, its on a thread with a locking nut, making the rod longer will reduce the free play. Bushing will obviously help remove slop too.

Kind Regards

Part 44 is your friend.


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Thanks gents,

I have a bushing set in hand as this was on the list anyway.

I am aware of the mc push rod adjustment and don't feel it is that but it will be adjusted as part of this process as well.

Might well get stuck in this evening.

Matt

Do not go too far with adjusting pedal bite position with that rod. You can reach a point where the hydraulics will slowly build up pressure after a few actions and the brakes will bind and even lock on.
I've been through all this on my 73T 911.
My pedal travels about 30mm before the pads are 'on' and a further 10mm until the brakes are really hard on.

Just saying do not try to get a pedal position that would shame a modern car. Follow the manual.

Beware also of damaging the brake light switch if it is a separate micro-switch on the assembly when adjusting the rod. They are expensive!

Bit of an update for future reference.

I replaced the bushings with bronze numbers, NB RHD cars need two extra bushings for the accelerator linkage similar to those on the bell crank at the gearbox. Equally RHD cars have brackets on either side of the footwell so is a little more time consuming than LHD cars.

Pedal movement definitely improved and it was certainly needed although I didn't have binding or stickiness in the pedals.

Pedal travel didn't seem to be massively impacted by the bushings so I guess that answers my question. On the subject of brake rod adjustment. Max gap on my car was 6mm down at the fulcrum which translated to around 30mm travel at the rubber pedal pad.

When adjusted to 1mm at the fulcrum there is about 5mm at the pedal before I hear the click as it engages in the pocket of the MC.

I also replaced my calipers bleed screws with Goodridge speed bleeders, 7x1mm at the front and 10x1mm at the rear (x4 of course).

I think the speed bleeders were a bigger factor in enabling me to do a one man bleed and get a decent pedal feel.

Road test next.

Matt