Brake Boosters explained

[cheesygrinner]

My mechanic has just been putting in a reconditioned brake booster in my WB van. He is going to take another look on Friday as he didn't have time to finish the job completely yesterday.

When the brakes are applied via the pedal, it has the feeling of a notch in the actuation about 2/3 of the travel of the pedal.

Any ideas to what this might be? The issue wasn't there prior to new booster fitment? Just trying to troubleshoot it.

[RodneyHZ253]

HQ..double prong adjustable straight shaft..
HQ..double prong non adjustable straight shaft..
HJ..double prong non adjustable straight shaft..
all 6 cylinder and v8 are the same interchangeable boosters in hq and hj.

HX..HZ..bent shaft single circle mount to pedal 6 cylinder and 8 cylinder drum brake rear..
HX..HZ..double diaphragm disc brake rear booster..

WB..bent shaft same as hx hz but booster will not take early pbr master..
WB STATESMAN..double diaphram for disc rear..master cylinder looks the same as wb commercial but is not interchangeable with drum rear.

6 that i can think of..

HQ HJ does not interchange with HX HZ and vice versa because of the pedals and the shafts..angle of push isnt right and brakes wont work properly..
wb will interchange with HX HZ and vice versa but wb has metric brake lines to the master cylinder..

sorry to steal your post adam but you were too slow and it was raining here so i just went and did it...

Thanks oz your information is very helpful when sorting out replacement brake boaster for yellow van

[ozbox]

no worries roddo...

[mook]

My mechanic has just been putting in a reconditioned brake booster in my WB van. He is going to take another look on Friday as he didn't have time to finish the job completely yesterday.

When the brakes are applied via the pedal, it has the feeling of a notch in the actuation about 2/3 of the travel of the pedal.

Any ideas to what this might be? The issue wasn't there prior to new booster fitment? Just trying to troubleshoot it.

Sort of a side note to anyone tinkering with the WB's, as I discovered yesterday the slave cylinder fittings for the brake lines are imperial, but at the other end it's metric. So the imperial fitting will go into the metric hole but be loose and the metric fitting won't fit the imperial hole. Only a minor trap a discovered after 3 hours of swearing under the van.

[ambientgoat]

If I have a HJ van, do I need to put a HJ booster in it? Or can I install a HZ booster and matching HZ brake pedal?

[panoz78]

Hz booster HZ pedal

[Big Rob]

Good info here... I didn't realise there were so many different ones.

[SLR_dave]

Sort of a side note to anyone tinkering with the WB's, as I discovered yesterday the slave cylinder fittings for the brake lines are imperial, but at the other end it's metric. So the imperial fitting will go into the metric hole but be loose and the metric fitting won't fit the imperial hole. Only a minor trap a discovered after 3 hours of swearing under the van.

Interesting subject. May I add a further side note to that, when I went to get the brake line over the rear axle re-made cause it was mangled, my local brake shop did it pretty inexpensively in new bunge, but the fittings they provided had metric flats, (This was to go on an HX).

They reckoned they could not get fittings with imperial flats anymore, but said the thread on the fittings they supplied was the same. Anyway, whilst the thread fitted, the flats are metric. I really don't like any mix of metric and imperial on a restored car personally. so I will redo that job later. I didn't measure the thread, but it matched the new wheel cylinders and also the old ones which had fittings with imperial flats.

Anyway iif it really is true brake shops cant get fittings with imperial flats anymore, maybe its worth saving the old fittings if they are in good nick. P.S. The recent series of Sidchrome spanners have that little notch in the open end side. I've found these heaps better for cracking those tight semi seized 20 year old fittings without distorting the flats than the previous style. (Having two notched 3/8th spanners even better.) Drop of penetrene a few hours before, and they come off like new.

[wbute]

Flare nut spammers are what you are meant to use for fittings like brake lines.
You should be able to get imperial fittings.

[Dr Terry]

Flare nut spammers are what you are meant to use for fittings like brake lines.
You should be able to get imperial fittings.

What SLR_dave has said is 100% correct.

AFAIK pipe nuts with a 3/8" hex have not been available for over 15-20 years, but you can still buy them with metric threads. Confusing, isn't it ? Put simply, you can still purchase a full range of pipe nuts & fittings with imperial threads, but they have metric hex sizes.

In other words all pipe nuts with either 10mm or 3/8" threads are both manufactured from the same 10mm hex bar stock.

Rear axle brake pipes for WB (or early Commodore) are quite unique in that they have a 3/8" UNF nut at one end to suit the imperial wheel cylinders & a 10mm x 1 metric nut at the other to fit into the junction block integral with the rear axle to chassis brake hose.

You would need very good eyesight to be able to distinguish between a 3/8" hex & a 10mm hex without a spanner or vernier calipers. Even the most anal restorer (or concours judge) would not bother with such a minute difference. Also, a remade brake pipe utilising brand new pipe nuts looks a lot nicer than one made using old rusted or rounded nuts.

OK, you would need to 'infect' your old Holden imperial toolkit with the occasional metric spanner but I'm sure there are other areas on a WB that require metric tools. A set of good quality flare nut spanners (both SAE & metric) is a good investment & a must for any serious restorer.

Dr Terry