Upgrading the Brake Booster on Our 70 Series Land Cruiser – Essential After a GVM Upgrade
When you’re running a fully loaded 70 Series Land Cruiser, especially after a GVM upgrade, braking performance becomes a critical safety factor. The factory brakes on the 70 Series Land Cruiser are not the greatest even within GVM, and once you add bar work, drawers, dual batteries, all your touring gear and then hitch up a trailer, the stopping power struggles even more. That’s why we decided to do a brake booster upgrade on our 76 Series Land Cruiser, and the difference has been nothing short of impressive.
After fitting the JMACX brake booster, we immediately noticed a significant improvement in braking response and pedal feel. It’s one of those upgrades you don’t fully appreciate until you’re in a situation where you really need to stop and stop fast. And trust me, we’ve already had several of those moments where this upgrade likely prevented a serious accident – not our fault obviously.
Why Upgrade the Factory Brake Booster After a GVM Increase?
When you increase your GVM, you’re adding weight and stress to your entire braking system. The factory single diaphragm booster simply isn’t designed for heavy loads above what the 70 Series Land Cruiser was originally engineered for. A dual diaphragm brake booster provides more vacuum assist, improving brake performance under load and giving you confidence when towing or descending steep terrain.
- Factory Toyota Brake Booster
- GVM Increase Registered with Queensland Transport
- JMACX Upgraded Brake Booster
- JMACX Brake Booster Instructions
JMACX Brake Booster: Specs & Real-World Experience
The JMACX brake booster installation was a no brainer for us. It’s the largest vacuum booster (according to JMACX, so take that with a grain of salt) available for the 70 Series Land Cruiser and is fully ADR35 compliant, meaning it meets strict Australian safety standards.
JMACX Brake Booster: Key Specs
- Up to 30% increase in braking power
- Tested on GVM upgrades up to 4200kg with 35” tyres
- Direct bolt-in replacement
- Suits ABS (2012+) and non-ABS (2000–2012)
- Compatible with 76 Wagon, 78 Troopy, 79 Single & Dual Cab
- Works with both VDJ V8 and 1GD 4-cylinder models
JMACX Brake Booster: Price
$595.00 (inc. GST) – via JMACX (there are always specials on these as well).
We had this professionally installed when we did our GVM increase at ARB. Brakes are one area I didn’t want to take chances with, especially with the weight of our setup and if anything was to go wrong from an insurance point of view. Since fitting it, the pedal feel is firmer, and the response is immediate. It’s a confidence booster, especially with our increase in weight well over stock GVM. We only tow a light camper trailer (DOT373) well under 1.6 tonnes, so this was not a big issue for us, but for those towing large vans over 2.5-3 tonnes, this would have a significant impact.
What Does ADR35 Compliance Mean?
ADR35 is the Australian Design Rule for commercial vehicle brake systems. Compliance means the booster has passed rigorous testing for stopping distances, brake balance, fade resistance, and emergency braking under heavy loads. This is critical for vehicles with GVM upgrades because it ensures the component meets legal and safety standards. JMACX provides compliance paperwork and approval numbers for engineering sign-off, which is essential if your vehicle is modified beyond factory specs.
DIY Installation – What You Need to Know
If you’re considering doing a 70 Series Land Cruiser brake booster upgrade and installing this yourself, here’s what you need to know:
- Two People Required – One under the bonnet, one inside the driver’s footwell to bolt the booster to the firewall.
- Remove the Old Booster – Disconnect the master cylinder, vacuum lines, and brake pedal linkage.
- Install the New Booster – It’s a direct bolt-in, but space is tight.
- Reconnect Everything – Ensure all connections are secure.
- Bleed the Brakes – Critical for proper pedal feel and safety.
If you’re not confident, get a professional to do the JMACX brake booster installation, brakes aren’t something to risk. For us it was also about insurance, if we did this ourselves and did something wrong, it would be a massive issue.
Other Brake Booster Options
While we chose JMACX, other brands like Pedders, Bendix, and Terrain Tamer offer similar dual diaphragm boosters. Most claim around 30% braking improvement, so the choice often comes down to cost and availability. From all the research I did, the JMACX brake booster upgrade was significantly cheaper than all the other options and with them being located just down the road from us on the Sunshine Coast, it was a no brainer. But the real takeaway? If you’ve increased your GVM or added significant weight, upgrading your brake booster is essential for safety.
What’s Next? Braided Brake Lines
We haven’t upgraded to braided brake lines yet, but it’s on the list. With more brake pressure going through the system, braided lines help reduce expansion and improve pedal feel even further. We really need to do this at some point as it is highly recommended that braided brake lines are installed when upgrading the booster. In a perfect world we would do a complete brake system overhaul including rotors. Again, this is significant cost, so it something we may do in the future when the budget allows for it.
Final Thoughts
If you’ve done a GVM upgrade or regularly carry heavy loads in your 70 Series Land Cruiser, upgrading your brake booster is one of the smartest safety mods you can make. The difference in braking performance is night and day. You don’t realise how much you need it, until you really need it.
For us, the JMACX booster has already proven its worth in real-world emergency situations. Highly recommended if you’re adding weight to your rig and want peace of mind on the road.
As a note, we paid for our JMACX brake booster and did not receive anything to write this post. This is for information purposes only, so you can see all the upgrades we have done to our 76 Series Land Cruiser and why we chose to do them.
If you would like to read more about our 76 Series Land Cruiser build, you can find all our stories here. To keep up to date on future posts, join the 4WD Adventurer Community here.
If you do have any questions or comments, please leave them below.
Thanks for reading.
The thoughts of Peter
