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Do you have to change over the master cylinder when changing from GA drum to GC Disc?

I need to clear this up for gaphil, who is looking at doing this with some of my old struts. Do you even need to change the whole strut? I imagine the mounts on the struts would be different, so I'm expecting to have to change them.
Any info on this would be greatly appreciated, as this is the first Galant I have seen (with my own eyes) with drums, so I've got no idea.

Thanks in advance for any info...

Dave

my gb had drums i used gh siga struts discs and calipers and just used the original master cylinder but from what i can remember u carnt use the standed rims as the calipers hit inside the rims i dont know about gc struts but gh siga u get abit of neg camber

From memory you can swap the GC calliper mounts onto the GA struts so you dont need to change out the whole strut. I'm sure the calliper mounts fit onto the drum brake front struts too. It all bolts up, just not 100% on the flex hoses.
Master cylinder should be ok as well

btw, if there are any leftover struts, I could use them to get the shell on wheels (brakes not required lol)

Thanks very much for the info. I wasn't sure. Certainly just changing the brakes will be quicker.
I'll have a look and let you know how we go with it.

the M/C is different, use the disc one.

Torana68 wrote:the M/C is different, use the disc one.

What he said ....

GA/GB front drum brake MC = 3/4" bore
GA/GB front disc brake MC = 11/16" bore

GC (boosted) MC is different bore again I think ..... maybe 7/8" ?

So can you bolt a GC master cylinder in a GA?

dunno but dont go swapping things unless you do the math on the effects changing the bore will cause, factory isnt dumb stick with the one that goes with the calipers for a start

Here's my problem...
I have GC discs/ Calipers and struts.
I should have a GC master cylinder (but would need rebuilding).
But that's all I have. I don't have GA/GB stuff at all anymore.
So Phil wants to buy my struts to put in his drum braked GA. I want to make sure it's safe, before he does it...

if the rear wheel cylinders are the same size as GC should be ok but if GC uses a pressure valve in the rear this should also have one (usually on the firewall in the rear brake line)

I was speaking to sigmaralliart on the phone tonite about this topic. And he agreed with you 'Torana68', that I should check the sizes of the rear cylinders to see if they match.
Tomorrow, I will get out my workshop manuals and compare sizes between the models.

davetrees wrote: GA/GB front drum brake MC = 3/4" bore
GA/GB front disc brake MC = 11/16" bore

GC (boosted) MC is different bore again I think ..... maybe 7/8" ?

None of my GC's have a booster. I think only the GC 2 door hardtops did. I believe all GD's have them.
Again, I'll consult the books for sizes.

Thanks all for the advice, I will post my findings to see if all agree.

Just as a matter of interest, If you put GH struts on them, what master cylinder do you use?

75wagon wrote: None of my GC's have a booster. I think only the GC 2 door hardtops did. I believe all GD's have them.

My mistake .. I just assumed that GCs as well as GDs had boosted brakes.

Just as a matter of interest, If you put GH struts on them, what master cylinder do you use?

The important thing is the relationship between MC/caliper/wheel cylinder sizes. What struts they are bolted to is irrelevant.

davetrees wrote:The important thing is the relationship between MC/caliper/wheel cylinder sizes. What struts they are bolted to is irrelevant.

Sorry, I left that out, I meant what if you use the GH sigma discs....

Thanks for the help guys, and thanks Dave for setting up the topic!


I had a look in my manual and this is what i found:

GA rear Wheel Cylinder - 20.64mm
GC rear Wheel Cylinder - 19.05mm (same as a GA with front discs)

GA Master Cylinder diameter - 19.05mm
GC Master Cylinder diameter: 17.46mm (same as a GA with front discs)


So if i use GC discs in the front, i should use a GC master cylinder (or a master cylinder from a GA/GB with discs?)

You beat me to it then....

OK I just looked at the GA today and compared it to my GC. The master cylinders are completely different. Would need all the pipe work (brake lines) changed to suit.
Will a GB Disc master cylinder bolt up to the same pipe work as the GA Drum master cylinder?

Does anyone have a pick of the GB disc master cylinder?
I'll be taking photos of the GA drum and the GC disc to post on here on Monday.

What have others done with the master cylinder to convert to disc fronts on the GA? (please add pics).

Dave

75wagon wrote:Will a GB Disc master cylinder bolt up to the same pipe work as the GA Drum master cylinder?

The GB MC is a 11/16" Nabco (no longer available new, I don't think). Note that the front pipe connection has a brass "Y" adapter to split the front brakes L/R

Thanks for the pic Davetrees. It looks the same pattern as Phils GA. My GC has the front brakelines come from the front of the MC not the side. I'm thinking that it would be a lot more difficult to fit the GC MC then worth it.

Yeah they look like a match. Cheers mate


Looks like im scouting for a GB master cylinder then.

i will be doing this soon to! iv got gb disk MC just got to get the rest!
im sik of swerving every time i break blody drums

After Gaphil and I adjusted, flushed and bled hi brakes, it pulls up fine.
Stops good actually.
Dave

discs

davetrees wrote:

75wagon wrote:Will a GB Disc master cylinder bolt up to the same pipe work as the GA Drum master cylinder?

The GB MC is a 11/16" Nabco (no longer available new, I don't think). Note that the front pipe connection has a brass "Y" adapter to split the front brakes L/R

Would any one know if these GA / GB Nabco 11/16" master cylinders are still available or even a kit? I cant find a part number for the master cylinder or kit any where? open to aftermarket brands of the same master cylinder eg PBR?

Regards,Greg.

Does anyone know the part nuber for the GA / GB nabco 11/16" Brake Master cylinder or rebuild kit? Are they
Avail OEM or aftermarket etc?