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LJ master cyl vs LC vs LX


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#1 Baz LJ

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Posted 03 November 2017 - 01:08 PM

hi all

 

trying to get my head around the big nut master cyl differences (trying to buy the correct one for my 72 LJ, secondhand)

 

is this correctt?

 

lc big nut cap has 2 round tops

 

lj cap has  2 square tops

 

lx cap also has same 2 square tops.

 

i understand the date stampings but im looking at a square top capped big nut master cyl, but is stamped 77 on the big nut. Can I use this for my LJ and just change out the big nut to suit my car? 

 

Thanks for any help, new to this



#2 meanmachine72

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Posted 04 November 2017 - 12:20 PM

hi baz
just been through all this

yes LC has the rounded tops on it..dont have a pic of one of them
but have pics of the later 2...


Attached File  DSC00358.JPG   170.34K   5 downloads

Attached File  DSC00360.JPG   364.11K   5 downloads

#3 S pack

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Posted 04 November 2017 - 12:42 PM

hi all

 

trying to get my head around the big nut master cyl differences (trying to buy the correct one for my 72 LJ, secondhand)

 

is this correctt?

 

lc big nut cap has 2 round tops

 

lj cap has  2 square tops

 

lx cap also has same 2 square tops.

 

i understand the date stampings but im looking at a square top capped big nut master cyl, but is stamped 77 on the big nut. Can I use this for my LJ and just change out the big nut to suit my car? 

 

Thanks for any help, new to this

Just a word of warning. The big nut master cyl with the 1977 date code will have the reservoirs reversed compared to pre 1977 master cylinders.

ADR 31 (Hydraulic Braking systems) was applicable from 1 Jan 1977. ADR 31 m/cyl's have the rear brake circuit reservoir at the front (big nut end)  and the front brake circuit is at the rear end closest to the brake booster.


Edited by S pack, 04 November 2017 - 12:48 PM.


#4 Dr Terry

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Posted 13 November 2017 - 03:25 PM

AFAIK the 3 basic styles GM-H 'big nut' master cylinders go like this.

 

The early one with the rounded ends starts at HK & finishes at 7/71 (end of HG).

 

The m/cyl with the 'squarer' ends (top pic in post #2) starts at 7/71 (HQ). This means that the last 6 months of LC (7/71 to 1/72) also got the older style rounded unit. This then fits all Holdens & Toranas prior to 1/77.

 

The larger/wider casting appeared for 1/1/77 (as S pack has said). This was for LX Toranas with a CLX chassis prefix & HX Holdens with a BHX chassis prefix.

 

As far as interchangeability is concerned. The later larger m/cyl will bolt straight on with the pipes swapped, but the early rounded one needs a different length push rod. Aside from that it will bolt on & plumb up as per standard.

 

All of the above excludes the baby Toranas (HB/LC/LJ/TA 4-cylinders)

 

Dr Terry



#5 Liz Clare

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Posted 13 November 2017 - 07:14 PM

AFAIK the 3 basic styles GM-H 'big nut' master cylinders go like this.

 

The early one with the rounded ends starts at HK & finishes at 7/71 (end of HG).

 

The m/cyl with the 'squarer' ends (top pic in post #2) starts at 7/71 (HQ). This means that the last 6 months of LC (7/71 to 1/72) also got the older style rounded unit. This then fits all Holdens & Toranas prior to 1/77.

 

The larger/wider casting appeared for 1/1/77 (as S pack has said). This was for LX Toranas with a CLX chassis prefix & HX Holdens with a BHX chassis prefix.

 

As far as interchangeability is concerned. The later larger m/cyl will bolt straight on with the pipes swapped, but the early rounded one needs a different length push rod. Aside from that it will bolt on & plumb up as per standard.

 

All of the above excludes the baby Toranas (HB/LC/LJ/TA 4-cylinders)

 

Dr Terry

Hi Dr Terry,

 

A very timely thread for me.

 

Just to clarify, my January 72 XU1 should have this type of big nut? I did suspect as much but had trouble getting confirmation from other people, just bought the wrong one too but no time to fit it so I'll wrap it up and try to swap it at some stage. 

 

Attached File  LC round top master cylinder.jpg   73.79K   2 downloads

I got this pic from another thread.

 

Cheers,

 

Liz :)



#6 grumpy xu1

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Posted 13 November 2017 - 07:27 PM

Let's make this a simple question for Liz to Dr Terry, would Liz's 3 week of January lj Adelaide build car get the round lc style master cylinder or the lj style please ?

#7 Bazza

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Posted 13 November 2017 - 08:04 PM

Hi

 

The 3 3/32 wide top disc brake master cylinder (the one with the squarish ends) Part No. 2811647 was introduced with the late LCs. It is the same part number for disc brake fitted 6 cylinder LJs. It follows that this is the correct one for Liz.

 

Cheers

 

BazzaAttached File  earlyLJenginebay.jpg   144.14K   3 downloads


Edited by Bazza, 13 November 2017 - 08:14 PM.


#8 Liz Clare

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Posted 13 November 2017 - 08:18 PM

Hi

 

The 3 3/32 wide top disc brake master cylinder (the one with the squarish ends) Part No. 2811647 was introduced with the late LCs. It is the same part number for disc brake fitted 6 cylinder LJs. It follows that this is the correct one for Liz.

 

Cheers

 

Bazzaattachicon.gifearlyLJenginebay.jpg

Thanks Bazza, very much appreciated.

 

Cheers,

 

Liz :)



#9 grumpy xu1

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Posted 13 November 2017 - 08:54 PM

As a side note, notice the "semi" gloss brisbane engine bay with the external regulator reflection on the passenger side inner gaurd ? Hopefully other members will realize that "is" the "correct" factory finish !

#10 Liz Clare

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Posted 13 November 2017 - 09:02 PM

LJ XU1 press launch pic of engine bay from Motor Manual, March 1972 No: 353

 

Attached File  LJ XU1 launch pic from Motor Manual march 1972 No 353 copy.jpg   410.56K   4 downloads

 

Looks like an LC type master cylinder. Just to add to the confusion.

 

Cheers,

 

Liz :)


Edited by Liz Clare, 13 November 2017 - 09:03 PM.


#11 Bazza

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Posted 13 November 2017 - 09:21 PM

As a side note, notice the "semi" gloss brisbane engine bay with the external regulator reflection on the passenger side inner gaurd ? Hopefully other members will realize that "is" the "correct" factory finish !

 

True - Warrigal Black - gloss. The problem arises because it doesn't take many years for the original finish to dull right down and that's how people restored them, thinking that that is the way that they are supposed to be.

 

Cheers

 

Bazza



#12 Bazza

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Posted 13 November 2017 - 09:29 PM

LJ XU1 press launch pic of engine bay from Motor Manual, March 1972 No: 353

 

 

 

Looks like an LC type master cylinder. Just to add to the confusion.

 

Cheers,

 

Liz :)

Hard to explain that one Liz. It doesn't alter the fact that the part number of that one  {2819957) doesn't get a mention in the LJ parts catalogue.However the square ended one (2811647) is in the late LC parts catalogue.

 

Cheers

 

Bazza



#13 Liz Clare

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Posted 13 November 2017 - 09:39 PM

Hard to explain that one Liz. It doesn't alter the fact that the part number of that one  {2819957) doesn't get a mention in the LJ parts catalogue.However the square ended one (2811647) is in the late LC parts catalogue.

 

Cheers

 

Bazza

Yeah, hard for me as a novice, to get a handle on it too. I started buying the old magazines to try and get original pics to use as a reference.

 

I wonder what month of 72 the LJ parts catalogue was printed, maybe that could explain the discrepancy. I've lent mine out to the mechanic so I can't check at the moment. It's all very interesting and a little bit frustrating sometimes too.

 

Cheers,

 

Liz :)



#14 Bazza

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Posted 13 November 2017 - 09:59 PM

Hi

 

There is something really dodgy about that photo. It could be some kind of mock-up or prototype. The brake lines that go to the master aren't right, there doesn't appear to be a juction/brake fail block and the fuel line is in mid air. I don't think that is an LJ heater box either. I wouldn't take any notice of that pic LIz.

 

Cheers

 

Bazza



#15 Liz Clare

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Posted 13 November 2017 - 10:10 PM

Hi

 

There is something really dodgy about that photo. It could be some kind of mock-up or prototype. The brake lines that go to the master aren't right, there doesn't appear to be a juction/brake fail block and the fuel line is in mid air. I don't think that is an LJ heater box either. I wouldn't take any notice of that pic LIz.

 

Cheers

 

Bazza

Oh Geeze! Well spotted. The only thing I noticed myself was the strange heater box.

 

I know that other old photos are dodgy, they didn't have Photoshop but still managed to dodgy-up that GTR to look like an XU1 for the well known brochure so yeah, I will do as you say and stick with the part number for the master cylinder.

 

Thanks again for the guidance :)

 

Cheers,

 

Liz :)

 

Edit: maybe Holden supplied this photo to the magazine rather than it being taken at the launch. Could be another clay model, heater box does look to be made from some strange material.


Edited by Liz Clare, 13 November 2017 - 10:13 PM.


#16 S pack

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Posted 13 November 2017 - 10:26 PM

Yeah, hard for me as a novice, to get a handle on it too. I started buying the old magazines to try and get original pics to use as a reference.

 

I wonder what month of 72 the LJ parts catalogue was printed, maybe that could explain the discrepancy. I've lent mine out to the mechanic so I can't check at the moment. It's all very interesting and a little bit frustrating sometimes too.

 

Cheers,

 

Liz :)

The first edition of the LJ parts cat was Feb '72.



#17 S pack

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Posted 13 November 2017 - 10:32 PM

Hi

 

There is something really dodgy about that photo. It could be some kind of mock-up or prototype. The brake lines that go to the master aren't right, there doesn't appear to be a juction/brake fail block and the fuel line is in mid air. I don't think that is an LJ heater box either. I wouldn't take any notice of that pic LIz.

 

Cheers

 

Bazza

The Chassis number appears to be LC201**A


Edited by S pack, 13 November 2017 - 10:40 PM.


#18 dattoman

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Posted 13 November 2017 - 11:05 PM

Thus the booster part #'s would have changed with the change in pushrod



#19 Liz Clare

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Posted 14 November 2017 - 06:13 AM

The first edition of the LJ parts cat was Feb '72.

Thanks Dave, makes sense seeing as the LJ started production Feb 72.

 

The Chassis number appears to be LC201**A

Very well spotted. I did try to zoom in as I thought I could see a number but couldn't make it out.

 

Cheers,

 

Liz :)



#20 Dr Terry

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Posted 14 November 2017 - 06:55 AM

Yes, you need to be careful with press release & sales brochure shots, because many of these cars are built months before the official release date & are often made using previous models altered with a few bits added.

A famous one is the HX LE brochure. It has many HJ pics because the pilot car was actually an HJ.

This one could be the same; LC m/cyl, LC heater box !! What about the carby fuel lines ? Are they 186 XU1 style. I always forget, were the LC fuel pipes used for early LJ, or were the LJ style fitted to late LC ? What I mean is where rubber hoses were replaced by tailored steel pipes.

Getting back to the square-ended m/cyl, the simple fact is that the LJ style including the booster with the different pushrod, was introduced in HQ production in July 1971 & this carried over to LC production, so by Aug/Sept 71 the rounded m/cyl was no longer used. In similar fashion to the Opel M20, it too was gone by that time. So, if you had a pic of an LJ XU1 with an Opel box fitted, we know it can't be correct, unless it was an export special or similar.

The lack of the brake pressure differential switch block, this makes it a very early 1971 at the latest !

Dr Terry

#21 S pack

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Posted 14 November 2017 - 07:51 AM

Chassis # LC 201**A would be around October 1970 which fits perfectly with there being no brake fail switch junction block.



#22 S pack

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Posted 14 November 2017 - 07:56 AM

The only thing I noticed myself was the strange heater box.

 

Thanks again for the guidance :)

 

Cheers,

 

Liz :)

 

Edit: maybe Holden supplied this photo to the magazine rather than it being taken at the launch. Could be another clay model, heater box does look to be made from some strange material.

Nothing wrong with the heater box Liz. The shadows on the top of the box make it look different however it is a normal garden variety LC heater box.



#23 Liz Clare

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Posted 14 November 2017 - 08:09 AM

Nothing wrong with the heater box Liz. The shadows on the top of the box make it look different however it is a normal garden variety LC heater box.

Thanks for the correction, Dave. There's so much I don't know..even though in some ways I feel like I've learned a lot on these Forums.

 

Cheers,

 

Liz :)



#24 Liz Clare

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Posted 14 November 2017 - 08:39 AM

Yes, you need to be careful with press release & sales brochure shots, because many of these cars are built months before the official release date & are often made using previous models altered with a few bits added.

A famous one is the HX LE brochure. It has many HJ pics because the pilot car was actually an HJ.

This one could be the same; LC m/cyl, LC heater box !! What about the carby fuel lines ? Are they 186 XU1 style. I always forget, were the LC fuel pipes used for early LJ, or were the LJ style fitted to late LC ? What I mean is where rubber hoses were replaced by tailored steel pipes.

Getting back to the square-ended m/cyl, the simple fact is that the LJ style including the booster with the different pushrod, was introduced in HQ production in July 1971 & this carried over to LC production, so by Aug/Sept 71 the rounded m/cyl was no longer used. In similar fashion to the Opel M20, it too was gone by that time. So, if you had a pic of an LJ XU1 with an Opel box fitted, we know it can't be correct, unless it was an export special or similar.

The lack of the brake pressure differential switch block, this makes it a very early 1971 at the latest !

Dr Terry

Good to know that about the press release images, Dr Terry. It's just near to impossible getting primary sources of information on these cars.

 

Cheers,

 

Liz :)



#25 grumpy xu1

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Posted 14 November 2017 - 04:47 PM

LJ XU1 press launch pic of engine bay from Motor Manual, March 1972 No: 353
 
attachicon.gifLJ XU1 launch pic from Motor Manual march 1972 No 353 copy.jpg
 
Looks like an LC type master cylinder. Just to add to the confusion.
 
Cheers,
 
Liz :)


The vacuum advance is on carb number 2 aswell ?




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