Minitruck Front Axle Disc Brake Conversion For Dummies (FAQ)

[1973Guppie]

Excellent write-up with good educational pics, thumbs up!
I have one Q:

I have a 1980 HJ45 with drums front, and HJ60 knuckles, discs, calipers etc. that I will use for my swap. My Q is; can I reuse the inners and brifields from my HJ45 axle, it has AISIN locking hubs, if that makes the answer easier...? Or do I have to take them apart and use the HJ60 birfields?

Thanks alot!

sorry, but can't help with this one, way over my head! Hopefully someone more knowledgable can post up the right info for you.

Noah

 

[DanS HJ-45]

Excellent write-up with good educational pics, thumbs up!
I have one Q:

I have a 1980 HJ45 with drums front, and HJ60 knuckles, discs, calipers etc. that I will use for my swap. My Q is; can I reuse the inners and brifields from my HJ45 axle, it has AISIN locking hubs, if that makes the answer easier...? Or do I have to take them apart and use the HJ60 birfields?

Thanks alot!

Good question. If I ever get around to disassembling my drum front axle (late model 40) I'll compare the birfs....

Why not just compare them once you've got them apart? If you have to swap the birf onto the 40 series axle, that's no big deal. But I imagine it'll be pretty obvious if you can lay them side by side...

Dan

 

[Christian]

Thanks, both Noah and Dan.

I just wished to know, if the information was readily available, but it seems that that can be my small contribution to this thread!

 

[My71FJ40]

I just wish I would have read this write up over a year ago before I ordered new stock TRE's for my converted front disc 71FJ40. They are the wrong size then what was there. Now I notice I have in and out play in the wheel when its off the ground...indication of worn wheel bearings? So now the fun part of figuring out what exactly is the set up since I bought it this way. I am glad this write up is here for reference...now to just tear into it.

 

[Christian]

Thanks, both Noah and Dan.

I just wished to know, if the information was readily available, but it seems that that can be my small contribution to this thread!

I just finished my conversion, using HJ60 parts, and I compaired the inners and the birfs, and they are identical.

So the conclusion is that late model brum birfs (mine's a 1980) are the same as disc birfs, which also means no grinding needed.

 

[nilepoc]

What size and grade bolt

What size and grade bolt do I need to attach the caliper to the knuckle? Tried google and my ggogle Fu is weak in this search area.

I have almost all the parts to put it back together, except for those bolts.

Thanks for the great writeup.

 

[hedgehog23]

head to Toyota and buy a set of them. not to much money and they would fit proper. not sure what size , but they are fine pitch.

 

[Hugh Heifer]

What size and grade bolt do I need to attach the caliper to the knuckle? Tried google and my ggogle Fu is weak in this search area.

I have almost all the parts to put it back together, except for those bolts.

Thanks for the great writeup.

By memory it was a 12mm finest thread. I do not recall the length.

Sent from technology I can't control using the IH8MUD app.

 

[uberFJ]

M12 X 1.25, 40mm long (caliper to knuckle bolt)

Unrelated - local NAPA didn't have the hoses referenced in post #79, but I did find a good substitute: Raybestos BH38879 (14.5" long)

 

[lelandEOD]

First of all, Noah: thanks for doing this. I've read this thread front to back at least three times since buying my FJ last year. I dumped my front drums and installed a set of Monte Carlo GM calipers and rotors on my truck and have since learned that they are not really suitable for a road going truck. Now, I just picked up a set of mini truck knuckles, hubs, spindles, steering arms, calipers and rotors. The guy I bought the parts off of swapped out the fine spline Asin hubs for a pair of corse splined AVM hubs that look to work with my '73 corse inner axles.

Now that I've got the parts home, I reread this thread and am convinced that I am going to dump the stock mini truck calipers and rotors for FJ60 vented rotors and IFS 4Runner calipers/pads.

I have a few questions I'm hoping you guys can answer for me to save me some hassle and aggravation.

1. I'm ordering a knuckle rebuild kit and need to make sure that the FJ and mini knuckles are the same as far as the rebuild kit is concerned... Or do I need to buy a kit for the mini-truck?

2. I didn't buy the fine spline birfield inner axles and now I'm kind of thinking that if I'm going to do this, I should probably pick up a set of 30 tooth axles since thy are supposedly stonger and will allow me to use the shorter Asin hubs. My question is can the later mini truck axles be dropped in or must the spider gears/diff parts also be swapped out to run the later style axles? I understand that the ball has to be opened up a bit to get the mini truck birf in the axle housing. But, I've not seen mention of the other end of the axle where it mates to the differential. I know I've got 6 spline outer birfs... but since I have yet to disassemble my axle, I don't know what the stock FJ axles look like on the differential end. Does this make sense?

3. Can someone point me to a reference that explains the procedure to center the inner axle in the knuckle? The parts I've bought were completely disassembled so I'm a bit scared of getting the trunnion bearing preload just right using the shims. Rereading this thread I found some mention of having to center the axle somehow and would like to know more about that. I don't even know how to take the shim measurements or even what a SST is!

Thanks, gents.

 

[tyama]

Here ya go...

First of all, Noah: thanks for doing this. I've read this thread front to back at least three times since buying my FJ last year. I dumped my front drums and installed a set of Monte Carlo GM calipers and rotors on my truck and have since learned that they are not really suitable for a road going truck. Now, I just picked up a set of mini truck knuckles, hubs, spindles, steering arms, calipers and rotors. The guy I bought the parts off of swapped out the fine spline Asin hubs for a pair of corse splined AVM hubs that look to work with my '73 corse inner axles.

Now that I've got the parts home, I reread this thread and am convinced that I am going to dump the stock mini truck calipers and rotors for FJ60 vented rotors and IFS 4Runner calipers/pads.

I have a few questions I'm hoping you guys can answer for me to save me some hassle and aggravation.

1. I'm ordering a knuckle rebuild kit and need to make sure that the FJ and mini knuckles are the same as far as the rebuild kit is concerned... Or do I need to buy a kit for the mini-truck?

I ordered my set from cruiser outfitters and the fj40/60/55/mini truck disc kits are all the same

2. I didn't buy the fine spline birfield inner axles and now I'm kind of thinking that if I'm going to do this, I should probably pick up a set of 30 tooth axles since thy are supposedly stonger and will allow me to use the shorter Asin hubs. My question is can the later mini truck axles be dropped in or must the spider gears/diff parts also be swapped out to run the later style axles? I understand that the ball has to be opened up a bit to get the mini truck birf in the axle housing. But, I've not seen mention of the other end of the axle where it mates to the differential. I know I've got 6 spline outer birfs... but since I have yet to disassemble my axle, I don't know what the stock FJ axles look like on the differential end. Does this make sense?

If you have a drum axle, you will have to swap out the outer birf with a disc (fine splined) one. You keep the old inner axle.

3. Can someone point me to a reference that explains the procedure to center the inner axle in the knuckle? The parts I've bought were completely disassembled so I'm a bit scared of getting the trunnion bearing preload just right using the shims. Rereading this thread I found some mention of having to center the axle somehow and would like to know more about that. I don't even know how to take the shim measurements or even what a SST is!

The centering is explained in the factory service manual (FSM) hat everyone refers to. You'll need a centering tool that can be borrowed/rented from some folks on this site. Just post up a request. I think i used the old shims in the same arrangement as the old knuckle.
Good luck
ty

Thanks, gents.

 

[FluByU]

bump for the hell of it.......

What he said..........Used this over the weekend to do my 60 disc conversion. Helped out so much figured I would send it on down the line.

 

[Honger]

2. I didn't buy the fine spline birfield inner axles and now I'm kind of thinking that if I'm going to do this, I should probably pick up a set of 30 tooth axles since thy are supposedly stonger and will allow me to use the shorter Asin hubs. My question is can the later mini truck axles be dropped in or must the spider gears/diff parts also be swapped out to run the later style axles? I understand that the ball has to be opened up a bit to get the mini truck birf in the axle housing. But, I've not seen mention of the other end of the axle where it mates to the differential. I know I've got 6 spline outer birfs... but since I have yet to disassemble my axle, I don't know what the stock FJ axles look like on the differential end. Does this make sense?

If you have a drum axle, you will have to swap out the outer birf with a disc (fine splined) one. You keep the old inner axle.

So, @tyama, perhaps you can help me out a bit here. I have a '77 drum axle (build of 12/76). I've checked and I have a fine splined outer birf, not the 6 spline. So can I do the swap without changing the outer birf?

And, props again to @1973Guppie for this thread. It's a fantastic resource! I've been through it several times now.

 

[tyama]

Hiya, it's been a while since I did this, but here's my thoughts. If your birf is the same dimensions as one from a mini truck or later fj 40/55/60, I'd say you're good to go. I'm not sure about this but I'm thinking it should work.

Anyone have any additional thoughts?

Best, Ty

 

[broth9640]

Should work just fine.

 

[FJ40Jim]

Honger,
According to the parts fiche, a 1976-78 non-US drum brake front axle and 76-78 USA disc brake front axle have the same birf joint.

This is a different birf than found on 79-90sumthin Minitruck & Cruiser.

Your best bet is to find a disc brake axle from a 79-90 mintruck or Cruiser and swap the whole thing (if it is 40-series) or swap everything knuckles out, including outer birfs.

 

[broth9640]

I think the mini truck is slightly larger, thus the reason for grinding out the housings a bit to clearance the larger birf. However the stock birf should work, correct?

 

[FJ40Jim]

The mini & cruiser birfs are the same in a given year.
To use a stock 76-78 Cruiser birf requires the 76-78 wheel hub and locking hub, which are different from the common 79-90 Cruiser & mini parts.
It would be best for Honger in the long term to use the knuckles & discs off a 81-later HiLux/40/60/70 series, because the parts are stronger and more readily available.

 

[Honger]

Thanks a bunch Jim.

I'm definitely using an 80-something 60-series knuckle, hub, and disc/caliper. 4x4 Hilux's are hard to find in the yards as are 40's (here in the UAE specifically). Wasn't aware that 70-series were also an option for me. Those ARE available perhaps mores than the 60-series.

To use a stock 76-78 Cruiser birf requires the 76-78 wheel hub and locking hub, which are different from the common 79-90 Cruiser & mini parts.
It would be best for Honger in the long term to use the knuckles & discs off a 81-later HiLux/40/60/70 series, because the parts are stronger and more readily available.

I'm going to hunt down a whole axle assembly so I can take the outer birfs as well. Thanks a bunch for chiming in... and for the parts fiche lookup.

 

[Brad 1979 HJ45]

@Christian im about to do the same as you. 60 series knuckles onto a hj45, do the 40 series TRE match the 60 knuckle arms? What did you do for flexible brake lines?

Have read through this very helpful thread a few times I'm just not sure on the similarities and differences between the different models, that's why I'm asking, everything just seems to be fj60 to fj40. Thanks @1973Guppie for the thread