[Red89]

Now before I start I am not 100% sure if this will be suitable for a rear disk conversion on Sierra Diffs but for those that arent aware of my setup it is as follows :

Hilux diffs converted to front Hilux disks all round.
CNC dual lever cutting brakes.
38" tyres.

I did some research on AZ and found one upgrade for the stock Sierra MC is one out of a Subaru Forrester, after checking on Ebay I found out theses sell for around $300 - $400 which put me off that idea and so after a bit more research I found that the MC out of a GQ is also a 'bolt on' upgrade. So I checked on ebay and found that there is 2 types, one for drum/disk and one for disk all round and they are sold for around $80 - $100 which suited my inner zook driver much better. The one for 4 wheel disks has a bore of 1 1/16 inch as opposed to the stock Sierra MC with a bore of 7/8 so basically it is the same size/bore as the Forrester one but should be fairly easy to get hold of and a bit cheaper. The steps to fit it up are as below :

1. Unbolt stock Sierra brakelines and remove, be careful of any brake fluid that leaks out. Undo the 2 nuts that hold the Sierra MC on and remove the MC.

2. Now everything I read said it was just a simple matter of reaching in and pulling the plunger out, however the plunger on mine was held in with a spring type clip that couldnt be removed from the engine bay side. So I used a lever to hold down the brake pedal inside the car, to push the plunger out a bit, then I reached inside with some long nose vice grips and unscrewed the bolt from the end with a spanner.

3. I used a 50mm M6 x 1 bolt, ground down and rounded off the head to the same mushroom shape as the bolt I had just removed. I then screwed the new rounded off bolt in place and wound it in about 26 half turns, it took a few test fits to get to this number but basically you want the bolt to be resting against the plunger inside the new MC when it is sitting in place flush up against the booster. I then secured the bolt in place using locktight. My Sierra MC had no gasket but had a rubber o-ring at its base which I transfered over on to the GQ MC.

4. The bolt holes on the GQ MC line up perfectly with the stock Sierra bolts and so you simply push the new MC on and bolt it up. Dont forget to bleed the master cylinder too before you connect the new brakelines. Now I was running completely new brake lines and so it was fairly easy to bend the lines and connect them up to the new outlets on the MC, it may be a bit of a stretch with the stock lines in particular the front line but shouldnt be too hard get a new line made up of need be. Now bleed the brakes at each wheel starting with the wheel furthest from the MC, keep going till you get a nice firm pedal.

Cheers Bevan.

[smiffkid]

well done, let me know how well it works

[Rusho]

smiffkid wrote:

well done, let me know how well it works

X 2 good work

[Boneheimer]

smiffkid wrote:

well done, let me know how well it works

X3 Good to see a fairly cheap MC upgrade, nice job

[Red89]

Boneheimer wrote:

smiffkid wrote:

well done, let me know how well it works

X3 Good to see a fairly cheap MC upgrade, nice job

Took it out on the weekend and it worked like it came from factory with the GQ cylinder in it, very pleased with the result.

[Rusho]

As an educated guess, how do you think it would go as a direct swap in a Sierra with vit LWB calipers and rotors and drum rear??

[Red89]

Seeing as its the same bore as the subi MC and some guys are using those with success, it should be a pretty good swap. I have got a couple of inches of pedal travel before the brakes come on hard which is alot better then what I had before on my old setup with the stock MC.

[Rusho]

Thanks mate. Didn't happen to get a pic of the modded bolt at all?? I got a fair idea of what a ground down domed bolt looks like, just want to make sure it's the same idea that you had

[Red89]

Just read the part where you mentioned a drum rear. I removed everything from the stock booster back, so no residule pressure valve for the rear drums, and I'm not running a proportioning valve. Not sure how it would go with a drum rear, you could perhaps try the smaller GQ MC that is for the drum rear. I picked up my MC from a wrecker for $30, couple dollars worth of bolts, and a bottle of brake fluid, so if youve got $50 to spare if may be worth the effort to find out

This pic was stolen off a Subi write up on Zuwharrie, the stock bolt is on the bottom mine looked basically the same as the top bolt.

[Rusho]

Thanks again, makes sense. I might hold off till I do read disc upgrade and do it all then.

[Boneheimer]

Red89 wrote:

I picked up my MC from a wrecker for $30, couple dollars worth of bolts, and a bottle of brake fluid, so if youve got $50 to spare if may be worth the effort to find out

I'd be lucky to get the master cylinder for less than $50 here, good to hear it works well, I might have to look into it, as well as a ticket over to Perth to pick up a MC, would probably work out cheaper that way

[460cixy]

I'm at a bit of a loss here to work out how this is an up grade going to the larger bore cyl will give better pedal feel as it has a larger displacement how ever in doing that you are pushing harder to do the same job as the smaller 7/8 th cylinder

[Red89]

When I upgraded to 4 wheel Hilux disc brakes the stock MC wouldnt hold enough pressure on the wheels to stop, hence the need to upsize.

[want33s]

GQ master cylinders are getting cheaper every day. I saw a new one on Ebay for $60.
I might end up fitting one to my buggy if the Surf unit isn't up to 4 wheel discs.

[OFFROAD_SOLUTIONS]

that line that runs towards your manifold might hit jas

[SwampmonsteR]

wow this is awesome good Red!! im running a subi master atm in my sierra on lux diffs but im looking at changing it because the fluid bottle is perishing. so the gq upgrade is well worth the swap around?

[douglasgiersch]

*Warning Possible Noob question*
So have a 1l with brake troubles, the wheel cylinders are pretty well all siezed and will be replaced also thing the MC is a bit crook to so would replace that, looked at the 1.3 upgrade with the booster but firewall mods didnt really excite me to much, Will the GQ bolt pattern be the same as the 1l? and would it suit stock 1l drums,
Only on 205'S at the moment. and bigger tyres arent in the bugdget for a while but would like to pull up safely. Or is there a more suitable upgrade for the drum system on 1l, excluding disks. Thanks

[Red89]

SwampmonsteR wrote:

wow this is awesome good Red!! im running a subi master atm in my sierra on lux diffs but im looking at changing it because the fluid bottle is perishing. so the gq upgrade is well worth the swap around?

Without a doubt, it was well worth it for me. In theory it may 'take more effort' to push the pedal but that certainly doesnt translate over into my real life experience. I have an inch or so of travel before full stopping pressure happens and another inch or so before lockup happens which requires no more effort then the 4 to 5 inches of travel required with the Sierra MC. If youre already running the subi one I think it should be a straight bolt on replacement, just check the plunger depth to make sure its not holding the brakes on.

douglasgiersch wrote:

*Warning Possible Noob question*
So have a 1l with brake troubles, the wheel cylinders are pretty well all siezed and will be replaced also thing the MC is a bit crook to so would replace that, looked at the 1.3 upgrade with the booster but firewall mods didnt really excite me to much, Will the GQ bolt pattern be the same as the 1l? and would it suit stock 1l drums,
Only on 205'S at the moment. and bigger tyres arent in the bugdget for a while but would like to pull up safely. Or is there a more suitable upgrade for the drum system on 1l, excluding disks. Thanks

If a 1.3 MC fits it then the GQ MC will fit, I couldnt safely recommend it as an upgrade for a 1lt as I dont know enough about the 1lt.

[sideways]

douglasgiersch wrote:

*Warning Possible Noob question*
So have a 1l with brake troubles, the wheel cylinders are pretty well all siezed and will be replaced also thing the MC is a bit crook to so would replace that, looked at the 1.3 upgrade with the booster but firewall mods didnt really excite me to much, Will the GQ bolt pattern be the same as the 1l? and would it suit stock 1l drums,
Only on 205'S at the moment. and bigger tyres arent in the bugdget for a while but would like to pull up safely. Or is there a more suitable upgrade for the drum system on 1l, excluding disks. Thanks

Installing a GQ master cylinder wont make your brakes perform better, it has a larger diameter bore so it can displace more fluid in order to "fill" larger brakes. If you were to install one on a 1l (no idea if it will fit) it would result in an incredibly short pedal travel and more effort being needed to get the same result. Basically, it would be a downgrade.

The hubs/brakes from later Sierras (disc front, self adjusting larger rear drums) will bolt onto a early 1l. Not only is this relatively cheap, it's quite easy and very effective. It seems you don't want discs though? If not, the best thing you could do is overhaul your current braking system and get good at adjusting it.

IMO the only good thing about the early 1ls drums is that if you are stuck and don't have lockers, you can adjust the wheel(s) that are spinning until they're tight enough that drive is sent the other wheel... but then they probably wont work anyway because they would likely be wet.

My 1ls drums are extremely tempremental and try and kill me almost on a daily basis. Sometimes it'l pull hard to the right, other to the left. It very rarely stops in a straight line. After I go through water (relatively often) the brakes take hours to return to their original selves.

I dislike my drum brakes.

Thanks

Hayden

[douglasgiersch]

Thanks Hayden, Dont not want disk but once the funds roll in i will be going WT diffs and didnt want to fork out to much on a set of diffs only under the car fro2 12 months or so, but i guess if i could get a front disk in working order for 150 bucks would be viable. Because i need new wheel cylinders for the drums and thats roughly 90 bucks. Need to replace the master cylinder anyway so i thought if it was semidecent/simple upradge for the right price sounded good, i understand the larger diameter bore meaning more fuild/pressure but didnt think about shorter/harder pedal stroke

[sideways]

douglasgiersch wrote:

Thanks Hayden, Dont not want disk but once the funds roll in i will be going WT diffs and didnt want to fork out to much on a set of diffs only under the car fro2 12 months or so, but i guess if i could get a front disk in working order for 150 bucks would be viable. Because i need new wheel cylinders for the drums and thats roughly 90 bucks. Need to replace the master cylinder anyway so i thought if it was semidecent/simple upradge for the right price sounded good, i understand the larger diameter bore meaning more fuild/pressure but didnt think about shorter/harder pedal stroke

Well if you're going to go WT diffs later and are staying on 205s, I'd just overhaul your current ones and get good at adjusting them. When mine was on 205s it could lock them up on tarmac at pretty decent speeds but after I started dunking them in water on a regular basis they went to shit, now with the 30s on I'd hate to have to rely on them for an emergency stop, they'd probably just spear me off the road into a tree or something. A disc conversion is certainly on the cards!

Thanks

Hayden

[douglasgiersch]

All pads and drums are good just the master and wheel cylinder need replaceing so hopefully they pull up fine for a while,
Thanks for the help mate.

[jono165]

I believe there is 2 options for this upgrade depending on if you have rear disk conversion or not. So you can either get a GQ patrol Disc/Drum MC or a Disc/Disc MC

[Boone]

Hey guys im considering GQ diffs in my Sierra, has here done this and can share advice?

[watermouse]

Boone wrote:

Hey guys im considering GQ diffs in my Sierra, has here done this and can share advice?

Theres already a really good thread about this..

http://www.auszookers.com/forum/viewtopic.php?f=5&t=50577

[monley]

Hey Red any chance you could measure the length of the GQ mc from the mounting flange to the of the mc?

[Red89]

Will do tommorow

[Red89]

If you still need it, 152mm from mounting face to tip