TB48 Brake Booster Upgrade to GQ 2.8TD

The Willwood brakes are getting fitted today. The fine print states if the brakes feel 'spongey' after the upgrade, and larger capacity master cylinder may be required (something to do with the change in bias flow to the rears and volumetric capacity?). The recommendation is upgrading from the 2 bolt master cylinder and brake booster in the GQ to the 4 bolt master cylinder and booster out of the 4.8. ( Brunswick don't change the brake booster or master cylinder when they do the upgrade.)

Has anyone done this upgrade, is it a straight swap? Is the 4.8 unit physically larger in size? Where can i source a service kit for the booster as the units are only avail s/h from P.A.P.

The kit includes braided lines as well, however these are already fitted.

The GU Boosters, clutch and brake are non servicable. But, back in the day places like ABS used to repair brake and clutch boosters. I used to do this all the time for work. But that was 20 years ago. Pretty sure there would still be a few places where you could take a booster for repair. Just gotta find them.
As for physical size. I am not sure.

Thanks Mark, was going to throw a 'kit' thru the s/h booster as a precaution. Guys didn't start on my setup today, maybe should not have given them a couple of days! Anyway will see how it pulls up and then decide.

I've been looking at this Hydraulic Brake Booster Upgrade from Mark's 4WD and considering this upgrade with better pads, rotors and braided brake lines (with factory GU III TD42 calipers/rotor size).
https://www.marks4wd.com/mfk20130.html
Not sure if this would fit your GQ though.

Quote:

---

Originally Posted by Cremulator

I've been looking at this Hydraulic Brake Booster Upgrade from Mark's 4WD and considering this upgrade with better pads, rotors and braided brake lines (with factory GU III TD42 calipers/rotor size).
https://www.marks4wd.com/mfk20130.html
Not sure if this would fit your GQ though.

---

This ended up being too custom for what I wanted. Marks don't do a GQ kit anymore or maybe never did. @poindexter has this fitted to his gu ute. It's a lot simpler than the route I have taken and from a YouTube clip I saw it pulled up the patrol 40% shorter, so a worthwhile upgrade for sure

Quote:

---

Originally Posted by PeeBee

This ended up being too custom for what I wanted. Marks don't do a GQ kit anymore or maybe never did. @poindexter has this fitted to his gu ute. It's a lot simpler than the route I have taken and from a YouTube clip I saw it pulled up the patrol 40% shorter, so a worthwhile upgrade for sure

---

Strange, Marks still have the Hydro Brake Booster listed on their web page for the GQ https://www.marks4wd.com/vehicles/nissan/gq

Quote:

---

Originally Posted by Gutsquisher Media

Strange, Marks still have the Hydro Brake Booster listed on their web page for the GQ https://www.marks4wd.com/vehicles/nissan/gq

---

Give them a call. They don't have a kit. They can make one up but you need to leave the vehicle with them so they can get the hoses and fittings correct. I suppose they have to draw a line as to what they carry, and with so many people building custom rigs, maybe the bulk market isn't there. As as example, you can still buy a portal Kit from them for a GQ, but they will resist selling it as it has not undergone second stage manufacturing testing and verification. The GU diff housings are the platform, and we all know they fit the GQ. I was unable to find a VASS engineer in Vic who would take on this testing when I looked at it 5 yrs ago, and shortly afterwards Marks dropped the GQ listing.

OK, kit fitted and clears the rims, however the mechanic says it needs a fair bit of force to get the barge to stop, he was expecting it would be spongy if anything - thinking it may need a larger booster, like the 4.8? The vac assist is working, just not clamping as hard as i/he would have expected. Thoughts? Might have to head to PAP tomorrow for the 4.8 set-up.

Quote:

---

Originally Posted by PeeBee

OK, kit fitted and clears the rims, however the mechanic says it needs a fair bit of force to get the barge to stop, he was expecting it would be spongy if anything - thinking it may need a larger booster, like the 4.8? The vac assist is working, just not clamping as hard as i/he would have expected. Thoughts? Might have to head to PAP tomorrow for the 4.8 set-up.

---

PeeBee. 4.8 Brake stuff is treated like gold ingots at Patrolapart. You'll be paying through your nose for it. It's very sought after gear. I believe they only have refurbished units ...

Sent from my Pixel 3a XL using Tapatalk

Maybe it hasn't been bled properly? Easy to check if the vac is working. Take to vacuum line off and test. Will know pretty quick if there is a change.

A larger master cylinder will allow more line pressure for less effort and the larger booster assists with the increase master volume. It's pretty easy to test brake pressure to see if your at the limits of the gq master. There are also various size masters in the GQ.

GQ brakes are shit when they are at factory tare let alone grossly overweight.