I’ve been eyeing it off too as my next major mod but wondering if it would work with a drum rear setup. I’d be upgrading the front disks, calipers and brake pads to the 4.8 version for maximum bang for buck pedal feel.

 

It should work the same with rear drums. It just allows more pressure in the braking circuit with less pedal effort. I would even suggest that you wouldn’t need the 4.8 calipers with the hydro boost.
I have DBA T2 slotted rotors with ECB Yellowstuff pads and recently fitted stainless braided lines throughout. Also fitted new master cylinder (same as 4.8) but I still feel I need to push the pedal too hard for a good result.

 

My understanding is that the Marks kit also has nation wide engineering approval too.

Off topic a bit, but from what I know there is a mob down south somewhere doing oversize rotor kits for GU's now. Not sure about GQ.

 

You can get a complete 4.8 front upgrade kit including calipers and disks from Roadrunner Off-road when they have their stock.

 

I’m not interested in big rotor & caliper upgrades that mean changing to bigger size rims & tyres etc. I’m hoping for input on hydro boost systems in GUs.
My expectation is that the hydro boost system will make the caliper upgrade unnecessary.

 

I did the hydraulic booster kit conversion from Mark's to my GU III TD42 last weekend. I also fitted the braided lines from them too.
I haven't had a chance to drive it more than about 50 Kilometers but I must say it feels more like braking in a car now than a large 4wd.

The kit was more work than I expected to fit and we really had to work to get it into position with the fuse box between the master cylinder and battery fowling on the extended length of the hydraulic unit (it's about 30-40mm longer than the factory setup).

It does all fit and all components required were supplied with the kit.

 

As I mentioned in the other thread, I'm waiting on one of your typically excellent write-ups but I'll be getting the ball rolling with Marks this morning anyway.
Your comment on how it now brakes like a car is exactly what my expectation is with this mod.

 

Following with interest! Being looking at this since they first came out!

 

Ray, this is interesting coming from a 4.8 owner while many think the 4.8 factory system is the pinnacle in GU brakes..

 

This is a vid that shows more or less what’s involved in doing this mod..

 

I’ve had a very good experience dealing with Marks4WD via email.
They don’t do a kit for the TB45E but they do a kit for the TB48 with ABS so, seeing as the TB48 steering pump is the same as the TB45E and is located in almost the same spot as the TB45E, I asked the sales/tech guy if he could give me the measurements for that hose. He got back to me same day with the precise length & fitting types.
It should fit perfectly for the TB45E so I ordered the kit and it should ship this week.

 

The kit seems reasonably priced considering its machined to fit.

 

Total was $1527 with $30 post. I find that reasonable for what it does and considering anyone with half a notion could fit it at home.

 

Awesome update 😁👍

 

If anyone is wondering, as I initially was, why the ABS kit is different, it’s because the ABS master cylinder has a short rear steel brake line that goes between the master cylinder and a distribution block on the inner guard.
The size of the booster unit pushes the master cylinder 30-40mm forward, as @cremulator mentioned, so the rigid line no longer fits.
Marks supply a short braided line with small banjos to replace it.

 

Whoohoo! It’s in the post so should be here early next week. Rainy weekend forecast so good excuse to spend time in the shed to strip out all the stuff that’s no longer needed.

Really looking forward to seeing what difference this mod makes..

 

“Bleeding the system fitted with the hydro boost is only slightly different from the standard method. Once pressure is applied on the pedal you need to crack the bleeder valve, bleed the fluid through and when the pedal gets low lock the bleeder off like normal. The pedal will come up straight away but the hydraulic cylinder will take a few seconds to return, if you wait 5+ seconds before pressing the pedal again to bleed you will have no problems. If you press the pedal straight away you will get nearly no brake fluid come out of the bleeder.”

Rather than explain to my wife that the bleed process is now slightly different, I went down to Sydney Tools just now, which is only 5 mins down the road, and bought this:

So now I can do it all calmly by myself..

 

They are a very handy tool, not only for brakes.

 

These are the throw away bits. I was expecting the power steering hose to be harder to get out but it’s only a couple of clips and banjos on pump and steering box.
That short brake line is what gets replaced with a slightly longer braided line.

I hate waiting for stuff to arrive..

 

Finally arrived this morning

 

Look forward to the installation writeup.

 

I didn’t really want to start on it until tomorrow morning because we had to go shopping but couldn’t help myself when we got back home so I spent a little while to get the master cylinder bolted on and just sit it in place. Just putting it in is considered the fiddly part because they say you need someone to guide the pushrod fork onto the pedal but I got lucky and lined it up after a couple of dives under the dash.
It pushes hard against the fuse box, which fortunately gives a fair bit, while you push it in but just rubs against it once it’s in place.

Edit: You can see a P clamp in the top left corner of the pic. I did that yesterday because when you’re working in there you don’t feel that you’re leaning on that soft ally AC pipe.
I inadvertently bent it down twice and didn’t want to be 3rd time unlucky so I made a bracket screwed to the inner guard.

 

For those interested in this kind of mod and who might not have searched elsewhere in the forum, here's a link to an interesting discussion back in 2014.

hydraulic brake booster upgrade?

Hey guys, I'm going over my entire brake system, and I'm about to go and buy a new brake master cylinder... I just wanted to know if the non-ABS GU one would be an upgrade? I can't seem to find anything specifically about this, but feel like I've heard it is an upgrade?? :confused: (the GQ one...

www.patrol4x4.com

 

Got it all bolted in before stopping for lunch. You lose a bit of time getting the 4 bolts through from under the dash then having to fix a spanner on them so you can tighten the nuts in the engine bay.
Pressure line from booster to steering box is in place. Brake lines are connected and brake fluid is in. The short braided brake line fits perfectly (see pic).
The long pressure hose that goes to the pump is connected and hanging down under the engine. I’ll make a couple of brackets rather than zip tie it. The fluid return hose also connected but not yet spliced into the return cooler circuit.

So far nothing has been difficult or required special tools. I haven’t needed help with anything up to this point. It’s really a very well designed kit.

 

Interesting read on the link you posted. One question that came up a bit was with regards to the engineering side of things when you upgrade from original. Is this Marks4wd unit legal in that sense or are you going to have to get it signed off with an engineer??

 

If it’s installed with only the components supplied in the kit and according to the fitting instructions, Marks say it’s just a question of contacting an engineer to get it all inspected.
It’s something I’ll look at further down the track..

 

Here’s the fitting on the steering pump. You need to feed the 2.2m of hose (for the TB45/TB48 install) from the unit across to the other side. I also ran the low pressure return line underneath to join up with the pipe that goes to the fluid cooler. ZD and TD42 installs are much easier with the pump on the right side.
I could have directed the hose from the pump straight down but I had to lose a bit of the length somewhere so I gave it a slight curve which will also help absorb mouvement.
i have it P clamped to the side of the chassis rail.

Steering fluid is in now as well but I need to bleed that when I start it.
I’ll do the final pedal adjustment and brake bleed tomorrow so it should hopefully be running after lunch.

 

Very tidy. Mine has ABS. 😖

 

That short braided line in the pic above is only for ABS models.
How does yours make vacuum? Is there a vacuum pump on that Chev engine?

 

I’ve had the conversion since 2011/2012 🤔 and I’ve never wondered about it, trouble about things that work. I’ll have a look tomorrow. 🤔

 

Good work so far. Looking forward to the drive report

 

Took it for a quick run around the block. It’s an entirely different feeling to the doughy vacuum system. The pedal has absolutely no “soft” feel about it and very little play. I even went back into the shed and put a bit more free play in the pedal but haven’t driven it again since.

There‘s no question the brakes are much more responsive with less pedal pressure. It’s just the application of that pressure that’s a lot different because of the way the pedal feels. I’m sure I’ll get used to it in no time.

I bled the brakes by myself with that vacuum tool and it works quite well. You just need to have something to hold the receiving jar upright so you don’t suck fluid into the tool.

The steering was easy and quick to bleed. I emptied what I could from the system and replaced it with the Nulon synthetic trans fluid I use for my trans.

So, in summary, anyone with average mechanical ability can do this mod on their own. I’m a 76 year old grandad and I had no problem at all

 

That pic shows that it’s getting near time to change that serpentine belt. It’s starting to show fine cracks in the hardened rubber.

 

Can’t be worn out, only 10 years and 100000km old. 🤔😉🤣🤣

 

Final job is to trim the fuse box cover to get around the reservoir.

 

Last month I fitted the Marks 4WD Adaptors hydraulic brake booster and braided brake lines.
This incident was one of the deciding factors:

I'll skip the whole removal and installation, but flag some points that may be helpful for others fitting this unit.
The kit comes with everything required and is pretty straightforward to install. Having said that, the unit is about 30mm-40mm longer than the factory booster so it is challenging to fit with the fuse box in the engine bay.
It took two of us a whole day to remove and fit the booster and replace all brake lines with the braided ones.
The only thing that required some modification was the bracket that holds the fuel filter, as one of the hard lines from the master cylinder fouled on it due to the extended length of the hydraulic unit.
Before:

After:

Here are pics of trying to fit it with the fuse box:

And this is the part of the bracket we had to modify to clear the brake line:

So I will say the difference is amazing!
Instead of slowing you down like you were coming to the end of a theme park ride, as the factory brakes do, it now responds more like a car. The brake pedal has a firm feel with little give in it, and it now takes less pressure to get a response.

A friend of mine runs a garage that performs roadworthy inspections. They use a machine to measure braking performance as part of that test, so I arranged a before and after to see the difference it made on my car. It has a sensor to also measure pedal force.

(Note: on Marks 4WD Adaptors website, they have test results braking from 100km/h using a 79 series dual cab LandCruiser weighing 3780kg)
Braking Distance – Standard factory vacuum – 98 metres
Braking Distance – Marks4wd Hydraulic booster – 58 metres

So this is the result of my experience, and I made sure nothing changed between tests (this is with an unloaded car, no passengers, no spare wheel, front tyre pressure 33 PSI, rear tyre pressure 35 PSI running 10+ year old 285/75R16 tyres with roughly 5mm tread, standard rotors and callipers)

You can see that the distance was reduced slightly, but the pedal effort was greatly reduced. During the hydraulic adaptor test, pedal application had to be backed off as the wheels started to lock up (no ABS). With the factory set up, there was absolutely no way that you would be able to lock the wheels on my car.

I am very pleased with this modification and I don't feel like I will require any heavy-duty pads to further improve the performance as it may just induce locking the wheels more easily.