AU1 3rd brake booster failure:(

**Stav** · 28-10-2007, 08:39 PM

What can I say? What can I say? Tonight while coming home with the family in car my brake pedal went hard and a loud hissing came from my feet at the brake pedal.It was a slow drive with both feet and all of my body weight on the brake pedal to get home. Grr I am mightily disappointed with the au 1 brake boosters .They are the worst brake booster ever made.Probably worse than the low budget cars on the market!!
They are half the size of the au2 booster and made of plastic!! I am going to have to get another one tommorow and may have to cancel work.:(

I may buy an au2 booster and modify the firewall to accept the 4 bolt pattern.The master cylinder is the same and will fit directly back on. When I bought this au1 booster last time I was told by the wreckers that they had never sold an au2 booster but plenty of au1's. I am not a happy chappy at the moment but thankful that I got the famil home safely.If you have an au series 1 I highly recommend you get an au2 booster as these are just too dangerous and if ford get offended well stiff!!

poolkeeper · 28-10-2007, 08:59 PM

yeah au1 brakes are soo crap, Ive had a few scary moments with them myself. Glad you and the family got home safe...

**Stav** · 28-10-2007, 09:08 PM

Since my last post Ive removed the booster and am pulling it apart.It is seized?

**Stav** · 28-10-2007, 09:17 PM

Well I found the problem .It is the same as the last 3 brake boosters.It has a tear in it.The rubber has gone hard and brittle.The au 1 brake booster is not sealed to protect it against water or degreasers.It may even not be resistant to heat.I would take some pics but cant find the camera

**Stav** · 28-10-2007, 09:40 PM

Does anyone know where I can get a brand new pbr brake booster diaphram?

LG · 28-10-2007, 10:05 PM

Stop hammering your car, and stop melting your brake boosters!!! lol

LG · 28-10-2007, 10:06 PM

Nah thats tough luck... Got for the AU2, i've had the specs somewhere. More responsive, better brake pedal feel, and all that jazz.

sly · 28-10-2007, 10:22 PM

Hmmm... maybe that's what's wrong with mine. Pedal is good some days, rock hard others. Have had occasional hissing noise while standing on brake when stopped (checking travel). A cracked diaphragm would also be a source of vacuum leakage? I suspect I have a slight leak somewhere as the ventilation is not as strong as it used to be. I had the whole HVAC out a few months ago to replace a heater core and made sure I sealed it up well while it was out. I suspect the HVAC control system isn't getting enough vacuum and the flaps aren't opening/shutting fully.

I might call the local Ford dealer and Repco tomorrow & see if I can get a diaphragm. Otherwise there is a brake & clutch workshop nearby that is pretty good.

**Stav** · 28-10-2007, 10:59 PM

Quote:

Originally Posted by sly

Hmmm... maybe that's what's wrong with mine. Pedal is good some days, rock hard others. Have had occasional hissing noise while standing on brake when stopped (checking travel). A cracked diaphragm would also be a source of vacuum leakage? I suspect I have a slight leak somewhere as the ventilation is not as strong as it used to be. I had the whole HVAC out a few months ago to replace a heater core and made sure I sealed it up well while it was out. I suspect the HVAC control system isn't getting enough vacuum and the flaps aren't opening/shutting fully.

I might call the local Ford dealer and Repco tomorrow & see if I can get a diaphragm. Otherwise there is a brake & clutch workshop nearby that is pretty good.

Don't delay mate. It sounds like yours is nearing the end as well.

Waggaclint why did my wrecker say that he has never sold an au2 booster? Instead heaps of au1 boosters? Because new or old they're junk. The au 2 booster has a 4 bolt pattern where the au1 is 2 bolt pattern. I have been told the au1 master cylinder will go straight onto au2 booster. The au 2 booster is alot bigger and solid sealed steel.

waggaclint · 28-10-2007, 10:27 PM

Quote:

Originally Posted by Stav

When I bought this au1 booster last time I was told by the wreckers that they had never sold an au2 booster but plenty of au1's.

Maybe this your problem fitting 2nd hand brake parts......keen ya never no were they come from or how they have been used......when it comes to brakes i only eva use new stuff...

**Mechan1k** · 29-10-2007, 08:10 AM

Luckily I haven't had to do a booster on the AUII ... have done a master cylinder though.

Had an issue at a servo recently ... the pedal went hard and car hardly pulled up ... and idle was crap ... I stopped the car to fill up .... I found the vacuum line to the booster had just come off ... put it back on ... right as rain again.

Lucky I guess.

**FTE217** · 29-10-2007, 08:24 AM

Stav go to Brakepro in Parramatta, they'll have all the bits you need.

**Stav** · 29-10-2007, 01:54 PM

I woke up in the morning and went to Bert Bros at Fairfield.I bought a brand new booster and fitted it in 20 minutes.The car is idling alot better.It sounds quieter and most importantly it stops. I promised myself I wont be installing any second hand parts and I am confident it will last longer thn the second hand jobbies. Because it is a work car I did not have time to get an au2 booster and sit around modifying.I got the right part ,went to work and made my daily wage..Got to be happy with that.

sly · 29-10-2007, 02:26 PM

Quote:

Originally Posted by Stav

I got the right part ,went to work and made my daily wage. Got to be happy with that.

I'd be happy too if I'd made my daily wage by 12.54pm...

sly · 29-10-2007, 03:18 PM

Quote:

Originally Posted by Stav

I woke up in the morning and went to Bert Bros at Fairfield.I bought a brand new booster and fitted it in 20 minutes.

If you don't mind me asking, what sort of $'s was it? I've been quoted $250 and $255 so far.

**Stav** · 29-10-2007, 08:29 PM

Around 230 including. Just do it and have piece of mind.If you have time then you may want to try the au2 booster.

GK · 29-10-2007, 08:51 PM

Glad you got it sorted Stav.

GK

sly · 30-10-2007, 12:50 AM

Quote:

Originally Posted by Stav

Around 230 including. Just do it and have piece of mind.If you have time then you may want to try the au2 booster.

Few things on the plate ATM, I'll just whack the direct replacement in. Can't complain, I've got over 320,000k's out of the original. OTOH my engine bay is untouched by degreaser and high-pressure washers...

sly · 06-11-2007, 07:54 PM

Quote:

Originally Posted by Stav

If you have time then you may want to try the au2 booster.

Turned out I had some spare time yesterday so tried a s/h AU2 booster, not sure if it's a good idea. Got it fitted up after a while, and found the pedal sank almost to the floor, probably about 75% of travel before I could feel any braking force. Nice soft pedal compared to the s1 booster, but waaaay different to the Mrs's s3, a little brush on its pedal has the tyres clawing into the tar.

So today I bled the brakes, got some air out of the fronts. Pedal felt firmer after bleeding before I started the car... but once I started testing it was back to maybe 2/3 of travel before biting. Bites nice & hard compared to the old s1 fronts, but still not confidence-inspiring.

So now I have a master cylinder repair kit on order, thinking maybe a dodgy booster had been masking a dodgy m/cyl...

Any other suggestions????

**Mechan1k** · 30-10-2007, 05:57 PM

I'd say Stav is meaning the siren to his car alarm.

The horn is mounted in front of the A/C condensor ... in front of the radiator ... behind the front bumper.

poolkeeper · 30-10-2007, 07:17 PM

Quote:

Originally Posted by Mechan1k

I'd say Stav is meaning the siren to his car alarm.

The horn is mounted in front of the A/C condensor ... in front of the radiator ... behind the front bumper.

oh coolio, whats up with my horn then lol
Im gunna try and suss it out now...

sly · 11-11-2007, 10:49 PM

Found the problem... the pushrod in the s2 booster is shorter than the s1 one by 7mm or so, which translates to a heap of pedal movement just to engage it against the piston in the master cylinder.

7mm of packing later... pure magic!

**Stav** · 13-11-2007, 06:02 PM

Quote:

Originally Posted by sly

Found the problem... the pushrod in the s2 booster is shorter than the s1 one by 7mm or so, which translates to a heap of pedal movement just to engage it against the piston in the master cylinder.

7mm of packing later... pure magic!

How did you get it to 7mm?

GK · 13-11-2007, 07:09 PM

Come on Sly, you've got all us S1 owners hanging on a thread; now please spill the beans! LOL!

GK

StealthAu · 11-11-2007, 10:56 PM

So whats involved in fitting the series 2 booster?

sly · 14-11-2007, 06:30 PM

Quote:

Originally Posted by stockoau

So whats involved in fitting the series 2 booster?

You need to drill 4 new holes in the firewall. The S1 booster has only 2 holes. The key is to make a good template for the bolt pattern of the S2 booster with the bolt holes in the right places relative to the piston. The piston fits the hole in the S1 firewall OK. And you need to line the template up right on the firewall to get the fluid reservoir at the same angle. The top pair of holes line up horizontally (as do the bottom ones) where the S1 holes are offset from horizontal.

Apart from that, you can disconnect the booster from the brake pedal easily enough if your fingers are strong enough to manipulate the R-clip, just take note of where the spacers/washers go to put it back together. If your car is non-ABS like mine you can get the master cylinder off the booster by just undoing the 2 nuts on the flange and unclipping the brake pipes from the firewall. My LPG lockoff was in the road so I had to move it too. There is some flex in the pipes so you can carefully move the m/cyl to the side to remove the booster.

If you have ABS you might have to disconnect the brake pipes from the master cylinder, not sure. If you have to disconnect the pipes do so with the master cylinder firmly bolted to the booster, the flare nuts bind up. I broke 1 flare nut spanner (13mm) then rounded off 2 of the 3 heads getting the m/cyl off to put a repair kit through it. Had to get a small Stillson (20mm??) in the end to get the flare nuts off.

Anyway it's not too hard to do this, then see my other reply above about the spacer... measure the depth of the cavity in the m/cyl piston, the length of the pushrod from the seal in the booster (maybe screw the adjusting screw all the way in first) and cut a soft metal spacer to fit the difference.

GK · 14-11-2007, 07:48 PM

Thanks for all that Sly. If you pull it apart again, do a "how to" with some digital pics. That would be a helpful resource.

Cheers,

GK

sly · 14-11-2007, 02:36 PM

Sorry, been @ work... :togo:

The primary piston in the master cylinder is hollow, the pushrod fits inside it and acts on the bottom end. The pushrod on the booster I got didn't reach the bottom of the cavity by 7mm. As the booster attaches near the top of the brake pedal, this 7mm shortfall translates to some 30-40mm of pedal pad movement before the pushrod contacts the piston. It feels like a shipload more though.

The pushrod has an adjustment screw in the end to fine-tune the clearance to the piston, but mine was already close to fully extended. I just cut a small piece of metal rod the same diameter as the pushrod (best to be a soft metal), inserted it into the cavity of the piston (which is a little over 30mm deep) and remounted the master cylinder taking care not to let the spacer fall out. A day or so after doing this I realised that I should have screwed the adjusting screw right in and made the spacer longer accordingly.

I regard this as a hack and very much a temporary workaround. I'm not sure whether there is any freeplay between pushrod and piston which would give potential for the spacer to bind & lock the brakes on. From the look of the system there shouldn't be, it seems the spacer will always be lightly wedged between the pushrod & piston. I was just doing this on a Sunday so couldn't source a S2 master cylinder at the time to see if it would fit.

I'm surprised that I had a problem, I've seen other posts here suggesting that the only issue with fitting a S2 booster is the need to drill the 4 holes in the firewall...

**Stav** · 14-11-2007, 05:47 PM

I suggested it but never got round to doing it because time is a luxury my business couldn't afford at the time.The wagon had to keep on the road.

sly · 14-11-2007, 06:08 PM

It wasn't a shot at you Stav, I think it's touched on in the BA Brakes sticky, sounded like someone had already done it.