View unanswered posts | View active topics It is currently Tue Mar 19, 2024 3:13 am



Reply to topic  [ 8 posts ] 
Master cylinder size 
Author Message
User avatar

Joined: Tue May 10, 2011 2:23 am
Posts: 2816
Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), M/B AMG A35, i30, had Belletts in past, 2 sed, 3 GT's.
Reply with quote
Anybody know the bore size of master cylinder for :

single piston type

dual piston type

ie early and late model master cylinders.

EDIT I think the bore size is 3/4" or 19mm ?? No doubt the 19mm is more Factory accurate.
Not sure if same on both types?

_________________
'72 PR60 Sport


Sat Nov 13, 2021 12:04 am
Profile WWW
User avatar

Joined: Tue May 10, 2011 2:23 am
Posts: 2816
Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), M/B AMG A35, i30, had Belletts in past, 2 sed, 3 GT's.
Reply with quote
any confirmation of bore size ???

_________________
'72 PR60 Sport


Mon Nov 15, 2021 5:54 am
Profile WWW

Joined: Sun Dec 12, 2010 10:04 am
Posts: 385
Location: Boyne Island.Gladstone. Queenland
Car(s): '70 PR91,'69 PR20 x 2,'66 PR20,'65? KR20's x 2,'66 ? PR90,2012 d22 STR Navarra.
Reply with quote
Hi Glenn.
Your correct. Both bores are 3/4". 19.05mm.
The secondary cup on the single master cylinder is the same cup on the secondary piston on the twin.
The secondary piston is the piston at the back of the cylinder and operates the front brakes.
All the other cups are different part numbers. Did notice that the dust boot is the same and the valve
on the front (for the rear brakes) are the same.
PR91W with the remote reservoir is different as well as PA Florian twin. Mabey 7/8". 22.2250mm. Not sure.
PR20 kit K7308X. Primary cup P4344. Secondary cup P4464A. Valve P4346. Valve seat P4599Z. Dust boot P4384.
Hope this will assist you and other owners.

Dave.

_________________
CQGT.
I'm the Dave with the convertible.


Tue Nov 16, 2021 12:39 pm
Profile

Joined: Sun Aug 02, 2009 9:54 am
Posts: 51
Car(s): 2 '68 Belletts, MX5, Hulux Twincab
Reply with quote
Glen, if you google K7308X you should come up with VCCAtas.org.au listing one for sale on their club website.
A.J.


Wed Nov 17, 2021 5:53 am
Profile
User avatar

Joined: Tue May 10, 2011 2:23 am
Posts: 2816
Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), M/B AMG A35, i30, had Belletts in past, 2 sed, 3 GT's.
Reply with quote
CQGT wrote:
Hi Glenn.
Your correct. Both bores are 3/4". 19.05mm.
The secondary cup on the single master cylinder is the same cup on the secondary piston on the twin.
The secondary piston is the piston at the back of the cylinder and operates the front brakes.
All the other cups are different part numbers. Did notice that the dust boot is the same and the valve
on the front (for the rear brakes) are the same.
PR91W with the remote reservoir is different as well as PA Florian twin. Mabey 7/8". 22.2250mm. Not sure.
PR20 kit K7308X. Primary cup P4344. Secondary cup P4464A. Valve P4346. Valve seat P4599Z. Dust boot P4384.
Hope this will assist you and other owners.

Dave.

Thanks for the detailed info Dave. I was lucky when I got the Sport there was a full rebuild kit in the boot for the dual master cylinder (and other things too)
I was wondering if an increase in bore size would 'improve' the brakes. (disk) Was a common upgrade when Peter Brock was doing mods to early commodores.

Something else i saw on YouTube ? or just the web, not sure, was to change the pedal ratio of the brake pedal to get more assistance. The guy moved the hole for the clevis that drives the master cylinder to get a better ratio. It did though mean the firewall for the master cylinder also had to be moved up to align with the new point.
Not sure how practical that is on a Bellett or even if it's advisable.

glenn

_________________
'72 PR60 Sport


Fri Nov 19, 2021 3:56 am
Profile WWW
User avatar

Joined: Mon Nov 15, 2010 3:11 am
Posts: 259
Location: Adelaide
Car(s): 1967 GT Bellett
Reply with quote
Hi Glenn
Have you tried different brake pads
Regards
Flying


Fri Nov 19, 2021 10:07 pm
Profile

Joined: Tue Dec 25, 2018 3:23 pm
Posts: 112
Location: Gawler SA
Car(s): morris cooper s, GTR XU1,PR90
Reply with quote
Glenn,
If you have not already got it fitted, what about adding a power booster?
Cheers
Peter


Sat Nov 20, 2021 12:31 am
Profile
User avatar

Joined: Tue May 10, 2011 2:23 am
Posts: 2816
Location: Melb.
Car(s): '72 Sport Bellett (imported 180912), M/B AMG A35, i30, had Belletts in past, 2 sed, 3 GT's.
Reply with quote
Thanks for replies.....

Like all GT's and the Sport I have had, a Bellett does stop but it needs a bit of 'planning' in heavy traffic.

not tried other pads, the ones in there are near new, but unknown compound. I do have a few worn sets that could be re-done. I'm a bit loathe to fit any pads that may wear the disk much as they are the close end of being unusable after another machining.

I have a VH??? booster exact type unknown, but it needs to be overhauled. Quote i had was about $300. There are Chinese copies on ebay too that some have used with success.

I was just mulling around ideas for now.

_________________
'72 PR60 Sport


Sat Nov 20, 2021 3:29 am
Profile WWW
Display posts from previous:  Sort by  
Reply to topic   [ 8 posts ] 

Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software for PTF.