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 Post subject: brake booster servo 1981s
PostPosted: Wed Jan 04, 2017 6:13 pm 
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Joined: Mon Jan 02, 2017 4:49 pm
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Hi

my car needs a new brake booster servo not the master cylinder installed. Any good ideas to get this part installed as its deep in wing by the bulkhead. It looks daunting to say the least!

Its a 81s


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 Post subject: Re: brake booster servo 1981s
PostPosted: Sun Jan 08, 2017 3:23 pm 
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Location: Stratford-upon-Avon
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You've picked one of more awkward 928 jobs, and harder on the early cars than my S4, since the brake bias valves are connected at master, giving you another couple of awkwardly placed lines to undo. I've not done job myself so can't provide full how-to, but can suggest some tips:

The master and reservoir need to be removed before removing servo.

Use suction pipe/mity-vac to empty as much fluid from reservoir as you can before removal. Even then put a few towels under master and servo to catch any spilt fluid.

You'll be doing some work in footwell. It's possible with seat in, but easier with seat removed. Otherwise move seat all way back and raise car couple of feet on stands so you can kneel by car and reach in. In worst case just jam your head in footwell on your back! In any case remove parcel shelf to help access to the clevis pin at pedal and the four bolts securing old booster.

Of course you will need a proper brake bleed all round after installing the new booster.

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 Post subject: Re: brake booster servo 1981s
PostPosted: Wed Feb 22, 2017 10:27 pm 
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Hi

Brooklands porsche garage in Swanley swapped the booster. They have done an excellent job and im very pleased with the result. Brakes now feel much better.

Now planning to change out my leaking power steering pipes. Any advice?


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 Post subject: Re: brake booster servo 1981s
PostPosted: Thu Feb 23, 2017 12:52 am 
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That's great news on the booster and credit to Brooklands doing a fine job.

On the PS lines do you know which are leaking, and where? It's just that the metal section of return line rarely a problem but is a lot of work to replace. Simpler to cut and replace just rubber section to reservoir.

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 Post subject: Re: brake booster servo 1981s
PostPosted: Thu Feb 23, 2017 12:40 pm 
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Hi

i took 928 to porsche tonbridge and they could see the leak but wanted the car in for proper diagnosis. They also said they had one of the pipes in stock for £256 and the other would have to be refabricated as its no produced by porsche.

At this stage i cant tell what pipe is leaking.

I think Brooklands garage will be having more work in the next few months ☺


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 Post subject: Re: brake booster servo 1981s
PostPosted: Thu Feb 23, 2017 1:01 pm 
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OK Edwall I had heard some PS lines for some years were NLA.

The likelihood is the leak is the high pressure line (pump to rack) which is vulnerable to pinhole leaks. Also potentially very dangerous if ATF is sprayed onto exhaust manifold right next to it if leak is in that area. But it would be good to have more detail. If you can clean everything up, then inspect things after starting engine and giving the rack some exercise.

Apart from the high pressure line, the usual problem is just weeping/leaking where the rubber return and supply lines attach to reservoir. Short term you can just try tightening the clamps little there, but otherwise they are pretty straightforward to replace.

Changing the pressure line is not too bad a job, but if your engine mounts are collapsed it becomes a brutal one as the line runs along crossmember, so really need to have some clearance there to remove/install the line.

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 Post subject: Re: brake booster servo 1981s
PostPosted: Thu Feb 23, 2017 3:24 pm 
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Hi

Do you know where abouts in the engine bay the pipes are? I located the power steering top up reservoir but could not see much else. Guessing i would probably have to get it up on a ramp again and have a good look.

thanks

Ed


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 Post subject: Re: brake booster servo 1981s
PostPosted: Thu Feb 23, 2017 8:01 pm 
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Feel under the PS reservoir. One of the two rubber lines is the supply line - it heads down to the pump after turning couple of right angles. The other is the return line - you'll see it heads down towards left wing, where it's crimped to metal section of line which heads down to rack, via a cooling loop that sits in front of radiator base. Both these lines are low pressure, so more likely to weep than leak dramatically. When you feel under reservoir, how greasy do your fingers get? Should be bone dry there.

The likely suspect is high pressure line. Look between left side shock absorber mount and the exhaust manifold. You'll see a rubber line that comes up out of engine bay, loops over and dives down again, with a metal sleeve (the restrictor) where it turns over. This is high pressure line that comes up from pump, then goes down again to join metal section that runs along cross member before bolting to steering rack. As it's under pressure, any pinhole or crack in the rubber section will see fluid sprayed out.

You can get access to all the lines along their whole length with front of car sitting on axle stands.

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 Post subject: Re: brake booster servo 1981s
PostPosted: Sat Mar 04, 2017 9:30 pm 
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Take your H/P line to "Pirtek" they'll make you one up complete with a universal coupling midway to allow for easy orientation whilst refitting it.., had mine done 5 years ago £45 and no problems at at all.


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 Post subject: Re: brake booster servo 1981s
PostPosted: Sun Mar 12, 2017 10:40 am 
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Hi

was the high pressure line easy to take off?


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 Post subject: Re: brake booster servo 1981s
PostPosted: Mon Mar 13, 2017 12:03 am 
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edwall wrote:
Hi

was the high pressure line easy to take off?


If the engine mounts are in good condition, it's a much easier job than replacing entire return line.

Need to disconnect banjo bolt at pump and at rack (anti-roll bar loosened and swung done to allow access to rack connection). There is one clamp on cross member, and one plastic one inner left wing.

More messy than difficult!

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