BJ73 front caliper upgrade

[fullthrottle]

I found an article a while ago and forgot to save it.

Has anyone seen somewhere that you can upgrade the front calipers on a BJ73 with 75 series calipers (4 pot)?

Can you put bigger rotors on plus calipers from another model?

Just thinking ahead to try and stop this old girl after the repower. I am already putting in a dual diaphragm booster and new braided lines.

 

[Hulsty]

Check your vacuum, 80 series booster and HZJ75 calipers and they will be much improved. I do not know of a larger rotor/caliper that works.

 

[LDowney]

Alternate direction for your consideration; hydro-boost.

I used a kit from Mark's for my '86 BJ70 and the brakes perform significantly better than they ever did. I have never encountered a braking situation, since I installed it, where I questioned stopping the truck.

Brake Booster - Hydraulic | Marks 4WD

Shop premium HYDRO Brake BOOSTERS at Marks4WD, the specialist in 4WD Brake Upgrades. Hydraulic brake boosters are the ultimate upgrade for superior braking power.

www.marks4wd.com

The only change to the brake system was the booster. Splicing into the power steering system is the non-trivial aspect.

Also, Mark's does not directly offer a kit for the 70/71/73/74 series Cruisers from the 80s. As I recall, I selected a kit designed for a 4-bolt master without ABS. I then modified the kit (hoses, lengths, splices, fittings) to work with the earlier Cruiser.

 

[fullthrottle]

Hmmmm, very interesting. And so you're still running the rest of the braking system as standard? Calipers, rotors, lines etc

 

[bottombracket]

I’m going to explore the iBooster option from Torfab… But it only works if you’re 12V not 24.

I’m tempted to put it on a 15BFT/43 body/80 frame adventure rig on 37s.

Thread 'Bosch iBooster Brackets for 60/80 Series – Tested in Moab, Ready to Go'

Apr 28, 2026

Hey everyone,

We’ve been developing a Bosch iBooster mounting bracket for Land Cruisers, and I finally got a chance to put it through a proper test.


https://shop.torfab.com/products/torfab-landcruiser-ibooster-adapter

I posted a PDF with instructions in the listing

https://cdn.shopify.com/s/files/1/0...oster-install-instructions-1.pdf?v=1785461270



I installed it in my 80 and...

• torfab
• Replies: 160
• Forum: 80-Series Tech

• 

 

[LDowney]

Hmmmm, very interesting. And so you're still running the rest of the braking system as standard? Calipers, rotors, lines etc

Yes. Also FYI, it has been my experience that the brakes feel the same ... just much more effective with the hydro-boost. Before the install, I was concerned that it might have odd tendencies (such as grabbing or lockup rather than a smooth stop) but I have not encountered any.

The biggest challenge that I encountered were leaks from the new joints. I chased each leak before I started any test drives. After I got the system dry, it has stayed dry. No returning or recurring leaks.

Also of note, the kit that I selected was designed for RHD Cruisers which makes sense since Mark's is based in Australia. Because my BJ70 is LHD, I had to redesign several of the adapters to re-clock the booster correctly to my LHD Cruiser. Your signature line indicates that you are in New Zealand, so this won't be a consideration for you.

Good luck

 

[fullthrottle]

I’m going to explore the iBooster option from Torfab…

Well now, that is some interesting witchcraft right there.
Will have a closer look at that as well.

I'll check with the certifier if this mod is legal in NZ.

Cheers