1984 HJ47 Rear Disc Brakes

[harryb47]

Hi guys,

I’ve got an ‘84 HJ47 with the original factory drum rear brakes/axle/diff. I want to upgrade the brakes to disc so I’m weighing up my options. Here are what I am thinking as options:

1. HZJ75 full Rear axle swap (Mr Landcruiser does this)

2. Take a whole 60 series wheel assembly with disc brakes and chuck them on my 40 axles (does the 60 series housing fit on the 40 knuckle cleanly?) I’d also replace the CV joint and do a full wheel/swivel hub rebuild, new rotors, calipers etc

3. Or are there other easy bolt-up options for rear discs that don’t cost an arm and a leg? Like could I take an 80 series disc brake setup from the rear and put it on my 40 knuckle? Or even a 75 series?

I’m a huge novice so any advice would be great!

Thanks

 

[jimkyser]

Are you doing front brakes or rear brakes, because even though you mention rear brakes a couple of times what you describe in item 2 sounds like front brakes since I don’t recall there being a CV joints/knuckles/etc with the rear axle

 

[harryb47]

Are you doing front brakes or rear brakes, because even though you mention rear brakes a couple of times what you describe in item 2 sounds like front brakes since I don’t recall there being a CV joints/knuckles/etc with the rear axle

Ah yes, apologies. I’ve got disc on the front but drum on the rear

 

[FJ404345]

#2 60 axles are 3" wider then 40 axles if you would like to swap complete

 

[Living in the Past]

If you are in Newcastle Australia the 75 series rear axle with disc brakes is the route I would be looking at. Would have to move spring perches. Probably looking at the brake master and booster from the same vehicle. US never seen a Land Cruiser with rear full floating axle with disc brake until FZJ80. Finding a 75 series like that here would be difficult and expensive. I would starting searching and get a feel for how available they are and how expensive they are.

 

[harryb47]

for

If you are in Newcastle Australia the 75 series rear axle with disc brakes is the route I would be looking at. Would have to move spring perches. Probably looking at the brake master and booster from the same vehicle. US never seen a Land Cruiser with rear full floating axle with disc brake until FZJ80. Finding a 75 series like that here would be difficult and expensive. I would starting searching and get a feel for how available they are and how expensive they are.

That’s great advice - thanks. I was thinking that I could use the 80 series brake booster upgrade and that would be fine with the 75 series rear axle. Would I be correct in thinking that?

Also, the rear diff centres are interchangeable for the 47, 75 and 80 series I believe. Would it be worth swapping my 47 diff centre into the 75 rear axle or leaving the 75 diff centre in mine?

 

[Living in the Past]

That’s great advice - thanks. I was thinking that I could use the 80 series brake booster upgrade and that would be fine with the 75 series rear axle. Would I be correct in thinking that?

Not experienced with a rear disc brake conversion. Believe you want a master cylinder set up for disc brakes on the front and rear axles.

Also, the rear diff centres are interchangeable for the 47, 75 and 80 series I believe. Would it be worth swapping my 47 diff centre into the 75 rear axle or leaving the 75 diff centre in mine?

Just be sure the gear ratios match your front end. Not sure when Toyota switched from 4.11:1 to 4.10:1 or if that would make a big difference if in 2WD on pavement. If either had a limited slip or locker would use that one if in good shape. Would assume in Australia everything is going to be full floaters on the rear axle. Not sure of you build date on the HJ47 but 8/84 the bolt pattern on the driveshafts changed. The pinions on both should be fine spline so might had to change the diff flange on the 70 series. Also not sure when the bolt pattern changed from six lug to five lug. Would not run different lug patterns on the same vehicle. Then might require changing the rear hubs to six lug if that's even possible or running a matching front 70 series axle. If I had a 70 series axle with rear disc I would figure a way to make work. But that's in the US where 40 series also has a semi floating rear axle and no 70 series at all. Australia you have many more options available and would research it and buy parts once. Seen many times someone rushes out and buys a bunch of parts only to find they just don't bolt together without modifying things. Spring perches are a given with any non 40 series.

 

[harryb47]

#2 60 axles are 3" wider then 40 axles if you would like to swap complete

That’s good to know - thanks! Could I just find a wrecking 60 and slap the 60 series rear disc brakes on the hj47?

 

[Living in the Past]

Do not believe any 60 series had disc brakes on the rear axle. The brakes were the same as the 8/80+ 40 series on the rear. Would have relocate the spring perches and still have to covert to disc brakes.