DDK - Die Deutschen Klassiker

While I was torqueing up my driveshaft bolts today after my 1969 911 engine change, I realised that the LH handbrake is doing nothing (as an aside the car has been away for 18 months and should really have an MoT to check out the basics). The cable tightens up ok, so it's in the rear wheel end.

I don't know anything about the 911 handbrakes and looking at the manual, if I have to take it apart, it's a bit of a faff to take the caliper etc off and have to re-bleed after (mind you the brake fluid should be changed really, it's been in there 5 years).

I will have a look at the adjustment to see if the adjuster is just very loose. Is there anything else that commonly fails in the mechanism?

Now I think about it, I've never had an MoT and don't know if it has worked in my ownership. The single handraked side seems to do a very good job though!

Cheers
Graham

73T
Handbrake performance is great on my 911.
Both side work and are in balance to about 5% looking at the Mot display a few weeks ago.
Adjustment is a faff.
There are 2 main areas.
1
The cable lengths need to be much the same, and this is judged by looking at the cable arm by the handbrake. When ON the arm should be level side to side looking down at it.

The lengths are adjusted using the tube and nuts on each suspension banana arm. This point of adjustment effectively changes the length of the cable by moving the outer sleeve of the cables.
Thirdly, inside the rear hub is a simple mechanism that acts when the cables are pulled tight the 4 small arms of the lever mechanism flatten out, this change opens the drum shoes out to the disc drum.

To get an even side to side brake pressure you achieve this by a bronze adjuster screw that is accessed via a hole in the disc, just large enough to poke a flat blade large screwdriver in to engage on the teeth of the adjuster. You notch this round using the leverage of the driver until the shoes locks on the disc drum. To test this has happened on both sides i put a torque wrench on the drive shaft nut and adjust the bronze wheels until the brakes take the same torque to 'break free'. I then back off the bronze adjuster by 2 teeth.

Pull the h'brake on HARD and off a few times and then apply as you would normally in normal driving. Check the cable arm is level (ish) and check the torque to break the brake free etc.
Iterate a few times till right, unless you are really lucky and get it right first time.

Hope I've said that all correctly.
The Haynes book details it all quite well.

My handbrake was useless so I tried tightening up the cables. It did the square root of fuckall. The proper technique is to loosen them right off and wind on the adjusters until it just drags, then back off the adjuster again and tighten up the cables again. So I did that and now it works.

Thanks both, that is very much like what Mr Haynes says, so I will have a go at that. That'll tell me whether it works at all and if it needs taking apart (argh).

The side that works, seems to work very well.

Hi Graham

I spent a lot of time dismantling, adjusting and readjusting the handbrake on my rally car with very little success. I wanted – a short travel handbrake lever and (if I got it right) to be able to turn the car on the handbrake even on dry tarmac.

I fitted new Expanding Bows x 4 (911 352 090 01) and Compression Springs x 2 (901 352 953 12). I may also have fitted new Compression Spring x 4 (901 352 957 10) What a transformation - the handbrake is superb.

If you are struggling to get it set up right it may be worth trying.

HTH

John

Thanks John. I'm really hoping that the adjuster will do the trick, but something tells me it wont. It's not like the n/s handbrake is weaker, there's just nothing there at all!

I think that is the crunch, working one side, nothing the other rather than out of balance.
If you pull the brake up and check the balance bar under the handbrake itself you might find the bar tilted at a large angle, even 30/45 degrees.

Both cables need to pull the mechanism tight evenly (within reason).

I'm sure the Haynes manual details the procedure?

MoT man always comments how strong my handbrake it on the MoT test.

The amount of pull on each side is the same and the balance bar is well balanced as it were! That's what makes me think there might be a failure in there.

If you can't get both sides tight by the toothed wheel adjuster then I think a full strip might be best so the check the lot.
I've managed to pull the calliper clear by bending the copper pipe, but go the whole hog, brake fluid change too!

Yes agreed Graham. It doesn't look the biggest job. Remove the caliper and disk and hey presto you can see the mechanism.

It may have to wait for the winter as I have a lot of (fun) things competing for my time at the moment! I am guessing that there will be a fault and that it's been there since the car was restored and I took delivery - one of the (hopefully) last snagging things!

I imagine the expanding lever mechanism is flat when the brake handle is pulled up tight.
Easy to fix, just do the cable m6 nut tighter and wind the toothed adjuster back in.
You can adjust everything before the inevitable fight of bleeding 911 brakes!

Just be careful not to pull the handbrake on too tight. If it’s slack on adjustment, the butterfly mechanism can go over centre and lock on. The efficiency is extremely impressive at that point, even more so if you have just been called for a timed run …………..
Ask me how I know …..
JW

ah, that would make it a very slow run!