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Double Diaphram Brake Booster

Started by arrimar , Feb 16 2008 12:33 PM

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31 replies to this topic

#1 arrimar

"Have you still got that Torana!"

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Posted 16 February 2008 - 12:33 PM

Hi guys,

I've got an LH torana query regarding the push rod that activates the master cylinder.
I dont think its long enough.

It sticks out the end of the booster 12mm at rest.
Posted Image

The rod length is 156mm.
Posted Image

From the bolt up face at the rear of the master cylinder to the end of the inserted rod is 135mm.
Posted Image

The master cylinder would appear to facilitate 75mm of travel.
I converted the back of this booster to suit LH.
I think originally it was HKTG.
The set up seemed to work fine 17 years ago and it has been overhauled recently.
Could someone measure an LH torana double diaphram push rod please?

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#2 dattoman

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Posted 16 February 2008 - 01:05 PM

Too short
Should be about level with the front can for HK-T-G and LC
Then about 25mm past the front of the can for LJ - H- X

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#3 arrimar

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Posted 16 February 2008 - 01:34 PM

Ok have we got a length that I can use to get one made?

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#4 _rorym_

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Posted 16 February 2008 - 01:53 PM

I have exactly the same problem...also my reaction disc either wasnt fitted on reco or has fallen in..Howard mine is 12mm as well....screwed right out. My overall length of rod is 168mm so it needs to be 180mm less reaction disc...3mm I am guessing. Whats your rod length?
R

Edited by rorym, 16 February 2008 - 01:59 PM.

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#5 arrimar

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Posted 16 February 2008 - 02:01 PM

Ive fired off a PM to Bazza as he had a long one wanting to swap for a short one back in jan 07.

If any body could give us an overall rod length for a double diaphram booster mated to a deep seated big nut master cylinder we could all move on.

My way of thinking says the rod should almost contact the inner of the master cylinder at rest.
That way foot on pedal = Activation of Master Cylinder.

With a short rod there would be opportunity for the rod end to disengage from its locator when the pedal is at rest.

There's no disc in mine and it doesnt show up on the exploded views in the manuals.

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#6 ls2lxhatch

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Posted 16 February 2008 - 03:36 PM

The reaction disc is part # 20 on page 304/344 of the parts catalogue.

What I would like to know is can the reaction disc fall out if the pushrod is removed?

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#7 arrimar

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Posted 16 February 2008 - 04:21 PM

item 15 is between the reaction disc and the push rod then.
How can the disc fall out if its held in item 15?

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#8 dattoman

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Posted 16 February 2008 - 04:27 PM

The reaction disc is help in place by the pushrod on the pics
If the pushrod comes forward the disc can dislodge

You need to have the disc inplace

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#9 _rorym_

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Posted 16 February 2008 - 05:06 PM

They are ...off memory...usually just put in with a dab of grease on the rod face to hold them...when you pull the rod out..they have a tendency to come with it and get knocked off and fall in the booster as you are removing the rod...Datto will confirm or correct...Nothing holds them in...just the pressure of the rod sitting on/pushing on them.
R

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#10 _rorym_

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Posted 16 February 2008 - 05:08 PM

What I would like to know is can the reaction disc fall out if the pushrod is removed?

Only every time. :huh:

R

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#11 ls2lxhatch

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Posted 16 February 2008 - 05:35 PM

This is a picture of my booster. I had it painted and I would like to confirm that they did not loose the reaction disc.

Posted Image

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#12 _rorym_

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Posted 16 February 2008 - 06:04 PM

Stick a screw driver into it...if it is soft and not a metallic DONK!..it is still there..looks like it to me.
R

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#13 arrimar

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Posted 16 February 2008 - 06:19 PM

seriously ...what a shit set up.

imagine....Ive hung your curtains lady. but dont move em or the rail will come off the wall.

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#14 _rorym_

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Posted 16 February 2008 - 06:27 PM

Howard..How long is the rod overall?
R

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#15 arrimar

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Posted 16 February 2008 - 06:33 PM

rory^see my first post second pic

156mm ...and it wont adjust too easily

I reckon if the disc is 6mm or 10mm thick Im happy

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#16 _rorym_

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Posted 16 February 2008 - 08:56 PM

Shit missed that...
Mine is 167 about as I said...I got mine to screw out...about 9mm I reckon...but its still only 12mm on the face..add the disc...thats what I am short. Will check at the brake place if new ones come in different lengths.
R

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#17 _rorym_

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Posted 16 February 2008 - 09:22 PM

Problem solved...Let me charge the batteries for the camera and I will explain.

OK...I measured everything and the rod goes into the M/C by 12mm off the face....all seems right...then tried depressing the brake pedal...it goes in about 40mm before you feel...and you can feel it...engaging the booster...
So...Howard..the tip DOES screw out..bitch is tight but it does come out.

Then I found a bolt the same thread...easy!!

Tomorrow will trim the bolt to be about 15mm longer than the end pin and screw it in.

Problem solvered!! :spoton:

R

Edited by rorym, 16 February 2008 - 09:33 PM.

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#18 arrimar

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Posted 17 February 2008 - 10:02 AM

My first intention also R.

I had a reply from an ebay seller with a long rod booster, 175mm.

How deep is your M/Cyl as measured in post #1- pic #3?

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#19 _rorym_

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Posted 17 February 2008 - 10:21 AM

Rod goes into master cyl about 12mm from bolt up face. Internal face..less reaction disc out to bolt up face is 155mm. Overall its 167 screwed right out and if Dattos right then its still wrong with only 12mm showing. Its 13mm short.
R

Edited by rorym, 17 February 2008 - 10:22 AM.

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#20 _debbiedavid_

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Posted 17 February 2008 - 11:42 AM

This info might help
My brake guy showed me how to check the rod length adjustment.

1. With the booster removed from the car put in place the rod and position the booster assembly 90 degrees to its normal position so that the rod is vertical and sticking out the top. You will now notice that the weight of the booster pressing on the rear rod will cause the rod to push further out, you need to take the weight off so that it returns to its rest position.
2. Place the master cylinder onto the booster studs (do not put nuts on), now push the booster downwards and as the rod comes into contact with the piston in the master it will raise it off the booster. Ideally the master will move off the booster as you start to depress it down, otherwise adjust rod length until it does. Also if the rod is too long then the master wont come to rest against the booster face when you first place it on.
Cheers Dave

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#21 _rorym_

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Posted 17 February 2008 - 12:19 PM

Think I will just stick with the 25mm out the front Dave...Not pulling the bloody thing off again! :huh:

R

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#22 _rorym_

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Posted 17 February 2008 - 12:20 PM

My first intention also R.

I had a reply from an ebay seller with a long rod booster, 175mm.

How deep is your M/Cyl as measured in post #1- pic #3?

Done the mod...looks fine...Now 175mm ...22mm out the front...plus I need to add the reaction disc. :spoton:

R

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#23 arrimar

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Posted 17 February 2008 - 02:07 PM

Back to basics.

Step 1: Ensure rubber disc is fitted.
Posted Image

Step 2: Measure depth of booster from rubber disc to bolt up face
Posted Image

Step 3: Stand Master Cylinder on end, insert rod and measure from bolt up face to tip of rod
Posted Image

Step 4: Adjust rod to match depth of booster
Posted Image

Step 5: Fit Master Cylinder , admire your new shiny bits
Posted Image

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#24 _rorym_

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Posted 17 February 2008 - 02:30 PM

So how far out does it protrude now?...I do remember the 25mm thing...even though the depth into the master was 12mm...I think there is take up with the piston in the M/C...

Datto?

R

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#25 _rorym_

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Posted 17 February 2008 - 02:46 PM

Forget that bit.....Just re-measured mine 4 times!!..doing it your way...150mm to face...25mm into the master..rod is 175mm so I will need to wind it in the thickness of the rubber bit. Whew!! :huh: