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Testing VH44 brake booster...
https://www.ausmini.com/forums/viewtopic.php?f=2&t=44741
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Author:  TasTyger [ Mon Aug 11, 2008 1:13 pm ]
Post subject:  Testing VH44 brake booster...

Hi Guys,

Can anyone give me some guidelines to see what condition a VH44 booster might be in without taking it apart? For example could you hook up the vacuum tube without having the brake lines plumbed in to test the diaphram to see if it was shot or not?

Don't want to go stuffing around with getting everything setup and then finding out it need a complete rebuild although it probably will. It came of a Valiant from a local wreckers 12 months ago. (Though the Valiant hand only been deregistered 12 months before that ...??)

Cheers,

TasTyger

Author:  Mick [ Mon Aug 11, 2008 1:58 pm ]
Post subject: 

It's hard to test it without proving it simply fails...fluid may be leaking into the vacuum housing, pressure may be leaking past the main seals from the hi pressure to lo pressure side under heave load, the smaller vacuum bias diaphragm may also be leaking. It's best to at least pull it down to see if it is leaking fluid before thinking about giving it a go, and it's a brake component...it's a little more important that a fuel pump for instance..

Author:  John Smidt [ Mon Aug 11, 2008 3:40 pm ]
Post subject: 

This is not a definative Test, However, if the booster isfitted to the car, With the engine turned off pump the pedal a few times keep your foot still on the pedal start the engine if the pedal goes down you more than likley have a problem with booster
Regards
John

Author:  Anto [ Mon Aug 11, 2008 4:12 pm ]
Post subject: 

John Smidt wrote:
This is not a definative Test, However, if the booster isfitted to the car, With the engine turned off pump the pedal a few times keep your foot still on the pedal start the engine if the pedal goes down you more than likley have a problem with booster
Regards
John


I always used the test of pumping the brakes with the engine off to get all the pressure out of the booster, then switch on the car (with my foot on the brake). If the booster is working properly, then the pedal will sink slightly as the booster pressurises.

This seems at odds with your method? Or have I got myself mixed up??

Author:  John Smidt [ Mon Aug 11, 2008 4:57 pm ]
Post subject: 

You Are absolutley Correct I am getting a bit old shoul dread if the pedal does not go down then you have a problem with booster,
However With a remote type booster like the VH44 This is not always as acurate as it is with an inline booster
Sorry about the mistake
Regards
John

Author:  kiwiinwgtn [ Mon Aug 11, 2008 7:22 pm ]
Post subject: 

The other problem with them is they corride and crystalise on the inside.

Take it a part they are quite easy once you get into it

You also need to check what bore size the booster is as ther is about 6 sizes and teh one on a mini is a special

Ta

Kiwiinwgtn

Author:  Morris 1100 [ Mon Aug 11, 2008 7:29 pm ]
Post subject: 

There were a couple of sizes fitted to Minis (they were an option on all Minis) but the Cooper S one is the VH44J. :wink:

Author:  John Smidt [ Mon Aug 11, 2008 8:15 pm ]
Post subject: 

Another point to take in to account is that brake fluid is Hygroscopic ( absorbs water) water plus oxygen ( air ) plus a metal = an oxide ( rust or in the case of aluminium, aluminium oxide ) often you can remove a booster in good working order, store it for a period of time and if it still has brake fluid in it will corrode, often turning a good booster into one that is un usable

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