Brake Booster Upgrades BJ71 LHD Dakar build help (2 Viewers)

[DKRBJ71]

Hi, I am new to the forum and Toyotas (had/have Defenders, please don't hate me) but I am entering the Dakar Classic in 2026 with a 1988 Toyota BJ71 (for perhaps obvious reasons to those on this forum that has previously finished 3rd twice in the last 3 years.
I am pulling together key spares and adapting the car (newer FIA spec rollcage / Braid Rally wheels) and I am finding some discontinued as genuine and unsure of aftermarket quality.

One of those is the brake Booster. I can't find anything in search on an upgrade to a later dual diaphragm booster and can only find one genuine single diaphragm unit (at almost $2k!!!!).
The other issue is with the OE master cylinder level cap (I have asked VintageTE if they will ship a cap to UK (awaiting a reply). Perhaps with a newer adaptable dual diaphragm and master cylinder I could future proof it for Rally's.

I have spare diffs/gearbox (and an OE master cylinder).
The only other thing that has failed was the alternator, again unsure of aftermarket quality (tho fairly cheap). OEX recommended this unit OEX Alternator 12V 80A (Hitachi Style) HXA027. Maybe I would also have to upgrade wiring as 80a Vs 25a.

It has the 13BT and is currently fitted with an intercooler and a hybrid tubo and running about 180bhp with lots of instant grunt.
Most of the engine and car was rebuilt from the ground up in 2022 for the 2023 Rally.

Any help or pointers would appreciated re the Brake Booster/master cylinder on my Toyota LC learning curve (It is very robust compared to my defenders, the diffs and props are huge!)

Gratuitous pic from 2025 Rally as an intro.

 

[LuckyDragon88]

Welcome to the madness!

Both the master cylinder and booster are available from cityracerllc.com I haven’t ordered anything from him but am in the market for the same parts as you. I believe he’s one of the vendors on the forum and has good reviews.

Some people have upgraded to an 80 series booster and Mac with good results.

FYI the in forum search function is mediocre, much better to use a search platform IE: google Ih8mud.com 70 series brake booster upgrade

Looking forward to seeing more of your build

 

[hoser]

The OE 80 series dual diaphragm is available again (shown is from Partsouq). Alternatively, there's an aftermarket Seiken unit that is well regarded.

 

[Eurasiaoverland]

I can't really offer any useful info, but I love the idea. A big fan of the B engines here (I'm in the middle of putting a 15B-T into my BJ60). I doubt there are many BJ71s in the UK (I'm originally from there) and would love to see your progress. Take care of that 13B-T as most spare parts are very hard to come by, which you probably know already.

I upgraded the old single diaphragm (and knackered) booster in my BJ60 to a good used HJ61 dual diaphragm booster from Australia, though it took a while and two attempts to find a good one. The 80 Series booster and MC upgrade is probably a far better idea, it'll solve your MC issue too.

With alternators I only use genuine Nippon Denso units. They are hard to find but easy to rebuild as you can mix and match parts. I made myself a 60A alternator from a used Tacoma unit with 80 Series regulator and a pulley I found online. One of the down sides of the 13B-T is that is has no onboard vacuum pump so you need to run the alternator type which greatly narrows down your alternator options. In this case the aftermarket alternator may be the best bet, but I would certainly take a spare.

Mine's not a performance build, but @crave reFleXion has done a mild power build of a 14B-T (basically a 3.7 litre version of the 13B-T with a few updates) in this thread: 14BT Rebuild - https://forum.ih8mud.com/threads/14bt-rebuild.1158362/ and this: Diesel Tech / 24 volts - https://forum.ih8mud.com/forums/diesel-tech-24-volts.24/

Also lots of good info on getting more power out of B engines on the Facebook 15B conversions group.

Looking forward to seeing more.

 

[cruisermatt]

80 booster is a great upgrade. With a 13BT you WILL need a large vacuum reservoir.

 

[DKRBJ71]

Welcome to the madness!

Both the master cylinder and booster are available from cityracerllc.com I haven’t ordered anything from him but am in the market for the same parts as you. I believe he’s one of the vendors on the forum and has good reviews.

Some people have upgraded to an 80 series booster and Mac with good results.

FYI the in forum search function is mediocre, much better to use a search platform IE: google Ih8mud.com 70 series brake booster upgrade

Looking forward to seeing more of your build

Thanks for this I will search on that and check out cityracer.

 

[DKRBJ71]

80 booster is a great upgrade. With a 13BT you WILL need a large vacuum reservoir.

Can you elaborate? Is there a separate reservoir or do you mean the booster/servo?
I have now found an excellent original alternator as a spare.

 

[DKRBJ71]

Just did the search dive.

For brakes concluded that
80 DD booster + bigger master + HZJ75 calipers (Calipers optional)
Extension to brake rod required (maybe not on early hdj80) of 25mm.
Is this welded or a threaded rod extension (I can’t yet find details of the job)
Does anyone know if the bigger master is just matching a stock hdj80 part and if it needs any mods? Also not found this in threads yet.
I was hoping for a ‘if you want to upgrade tour 70 brake system its these parts with these adjustments!)

Apologies for my need for clarity/ease, First rally is soon so I can't afford much experimentation, reliability is almost more important than outright performance. Right now it is all working well but standard.

 

[cruisermatt]

Just did the search dive.

For brakes concluded that
80 DD booster + bigger master + HZJ75 calipers (Calipers optional)
Extension to brake rod required (maybe not on early hdj80) of 25mm.
Is this welded or a threaded rod extension (I can’t yet find details of the job)
Does anyone know if the bigger master is just matching a stock hdj80 part and if it needs any mods? Also not found this in threads yet.
I was hoping for a ‘if you want to upgrade tour 70 brake system its these parts with these adjustments!)

Apologies for my need for clarity/ease, First rally is soon so I can't afford much experimentation, reliability is almost more important than outright performance. Right now it is all working well but standard.

Can you elaborate? Is there a separate reservoir or do you mean the booster/servo?
I have now found an excellent original alternator as a spare.

I think you might want to familizerize yourself with the search function a bit better as this has all been covered multiple times in this forum section

There is no "one size fits all answer" because everyone's use case, goals, vehicle recquirements, etc are different. You also haven't posted any parameters such as rim size, tire size requirements etc, or what you are actually looking to upgrade, braking performance? part life longevity? Do you have a budget or do you have unlimited money?

your vehicle should already have some sort of vacuum reservoir for the brake booster, but I have found multiple times the 13BT vacuum pump can not generate vacuum fast enough to keep up with the larger diaphrame of the 80 booster if brakes are used in multiple succesions (like 5 or 6 full brakes). With the larger reservoir you have more vacuum ready to go already.

This is what you need for the booster rod:

Extended Brake Clevis for Booster Upgrade

Extended clevis for upgrading to an 80 series booster in your 70 series. Made in USA

cruisermatts.com

 

[jblueridge]

I put a tee in the line and added a blue plastic reservoir from a junk yard.
So I have 3 of them.
Big booster does suck up the vac.

 

[jblueridge]

I used master and booster from a 1990 FJ80.
Bolted right in.
New metal brake lines off master had to be made by me.
Only glitch is the MC and booster are at a slight angle.
80 series firewall must be at an angle to match.
I have to fill reservoir very very full to keep dash warning light off.

 

[DKRBJ71]

Thanks all. I apologise for the rather vague line of questioning, a lot to do in a short time.
The responses have been very helpful and I didn’t mean to come across as complaining.

To answer some Qs, rims are 16” Braid Full Race T Dakar alloys.
Tyres are mainly BFG 255/85R16 KM3s to provide some compliance) alternatives are BFG DKR2+ 245/80R16 if terrain is very rocky.

Goal is reliability and availability of high quality spares to maintain that reliabity and serviceability.

The car is maybe a bit lighter than standard but not much due to the safety kit and reinforcements of running gear.
We are familiar with modding for racing but not familiar with the 70 series.

 

[FJBen]

Hi, I am new to the forum and Toyotas (had/have Defenders, please don't hate me) but I am entering the Dakar Classic in 2026 with a 1988 Toyota BJ71 (for perhaps obvious reasons to those on this forum that has previously finished 3rd twice in the last 3 years.
I am pulling together key spares and adapting the car (newer FIA spec rollcage / Braid Rally wheels) and I am finding some discontinued as genuine and unsure of aftermarket quality.

One of those is the brake Booster. I can't find anything in search on an upgrade to a later dual diaphragm booster and can only find one genuine single diaphragm unit (at almost $2k!!!!).
The other issue is with the OE master cylinder level cap (I have asked VintageTE if they will ship a cap to UK (awaiting a reply). Perhaps with a newer adaptable dual diaphragm and master cylinder I could future proof it for Rally's.

I have spare diffs/gearbox (and an OE master cylinder).
The only other thing that has failed was the alternator, again unsure of aftermarket quality (tho fairly cheap). OEX recommended this unit OEX Alternator 12V 80A (Hitachi Style) HXA027. Maybe I would also have to upgrade wiring as 80a Vs 25a.

It has the 13BT and is currently fitted with an intercooler and a hybrid tubo and running about 180bhp with lots of instant grunt.
Most of the engine and car was rebuilt from the ground up in 2022 for the 2023 Rally.

Any help or pointers would appreciated re the Brake Booster/master cylinder on my Toyota LC learning curve (It is very robust compared to my defenders, the diffs and props are huge!)

Gratuitous pic from 2025 Rally as an intro.

View attachment 3935287

Would love to see more pictures of this cruiser! Any other mods to the engine?

Any engine pictures? Looks like the intercooler is sitting out front


Very cool build, hope we can help

 

[DKRBJ71]

Would love to see more pictures of this cruiser! Any other mods to the engine?

Any engine pictures? Looks like the intercooler is sitting out front


Very cool build, hope we can help

Thanks, it has already been a help.

The engjne was rebuilt with as many OE parts as possible, the turbo was modified to a hybrid using some elements from the 4.2TD 80 so it spins up very quickly and makes a bit more power from that. The chap I purchased it from had the intercooler fitted, it makes a big difference, sits on top of the engine at the back, the bonnet had to be cut out and a new carbon bulge has been fitted.

No other tuning on the motor, It makes more torque and about 170bhp. It pulls strongly right off tickover.

We are looking to make up some more progressive leafs and match them to the Oram remote reservoir rally shocks, we are fitting a new FIA spec roll cage and changing the wheels to the Braids, making some new internal wheel carriers and storage.

Currently tidying up the engine bay hoses and making a new intercooler header tank (my friend runs Allisport here in the UK and makes radiators/intercoolers/airboxes and stuff for motorsport and 4x4s and objected to the chequerplate tank!)

I guess this is the wrong place for photo’s of the car/build?
Happy to post up as we finish if not or post in a more appropriate location but here is a screenshot from a video Juraj (the 2025 Dakar driver) made showing engine before rhe 2025 Dakar. The carbon bulge hadn’t been finished at this point but was for the race.

It finished 3rd overall in classic in 23 and 24 with Paulo Bedeschi, Juraj dropped from 3rd to 25th on the last day in 25 but he won a stage. He will race an 80 this year to build a new ‘story’. This will be my first Dakar and my first cruiser. I am told it is good in the dunes

 

[DKRBJ71]

If interested (but in Croatian and English) if you search Nas Dakar! In youtube Juraj made a video of his 2025 Dakar race in the car. Lots of footage of the car, including during stages. He is a lovely guy and works hard for his sponsors!

 

[AirheadNut]

Sweet build! One of the issues with putting together a “here’s what you need” for swapping in an 80-series dual diaphragm booster is the vast array of options and variations of the 70-series. For instance, when I did the conversion in my LJ78 I didn’t need to extend the pushrod, it fit perfectly with all stock hardware, contrary to the common experience here.

Rather than bend new hard lines for mine, I took off the factory hard lines from the MC to the junction on the inner fender and replaced them with braided stainless AN hoses and adapters.

 

[cruiseroutfit]

Both the master cylinder and booster are available from cityracerllc.com I haven’t ordered anything from him but am in the market for the same parts as you. I believe he’s one of the vendors on the forum and has good reviews.

Roger has the BJ71/74 master (47201-60350) avail? Link?

While there are maaaaaaaaany different OEM and aftermarket master cylinders and booster combos that can be fitted, the original 47201-60350 with correct line orientation and heat shield bungs is NLA.

 

[DKRBJ71]

Changed headlights today for what we call an MoT to complete the import process. I took a couple a pic of the current bay and the progress on the new tank for the intercooler.
Not finished yet. The cooler uses an electric water pump.
We have some tidying up to do in the bay as mentioned.
I do have a spare MC in good condition and rhe brakes seem ok, not amazing but not terrible either. Clutch is heavy even compared to a defender. Might have to investigate that and options.