Advice Needed: Thoughts on Trail-Gear FJ40 Knuckle Swap Kit for Disc Brake Swap

[talibraza101]

Hi guys,

I am at my wits' end with trying to get my 1970 FJ40's drum brakes to work. I installed updated 9/71-1975 drum brake hardware and replumbed all the lines, but just can't get them to give me a solid first pedal (they need pumping).

At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear: https://allprooffroad.com/fj40-knuckle-swap.html

If I truly cannot get these drums to work, I'm seriously considering biting the bullet and going 4-wheel disc. Would this kit from Trail-Gear be viable? Does anyone else have any other options in mind? I understand donor axles are the best way to go, but I can't seem to figure out how to find/purchase them. I would ideally like 4-wheel discs.

Thank you!

 

[Pighead]

At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear:

That's an awfully big kit to fix a really small problem. Of course you can make your drum brakes work.

 

[talibraza101]

That's an awfully big kit to fix a really small problem. Of course you can make your drum brakes work.

I feel you man. I'm just at a total loss for what could be wrong with them at the moment. Bled the MC, bled 3 gallons of fluid through quickbleeders until clean, adjusted the shoes outwards until tight, the list goes on. I'm worried there may be some sort of microscopic air leak happening in one of the fittings preventing me from getting a firm pedal, even though I tightened everything down pretty snug. This is my first brake job so my confidence is definitely taking a hit right now

Gonna try expanding the shoes all the way out again and bleeding once more when I get home today. Been hesitant to post my troubles because of how many posts there already are on here!

 

[Jdc1]

Hi guys,

I am at my wits' end with trying to get my 1970 FJ40's drum brakes to work. I installed updated 9/71-1975 drum brake hardware and replumbed all the lines, but just can't get them to give me a solid first pedal (they need pumping).

At any rate, I wanted yall's thoughts on this kit I found on Trail-Gear: https://allprooffroad.com/fj40-knuckle-swap.html

If I truly cannot get these drums to work, I'm seriously considering biting the bullet and going 4-wheel disc. Would this kit from Trail-Gear be viable? Does anyone else have any other options in mind? I understand donor axles are the best way to go, but I can't seem to figure out how to find/purchase them. I would ideally like 4-wheel discs.

Thank you!

Send me your axle housing, Ill build your disc brakes for you.

 

[AZMoonshadow]

I understand the frustration. I made the decision to switch to disc brakes due to the larger tires and faster speeds. I originally wanted to keep stock brakes, but everything played against me. If you do decide to switch, change your master cylinder as well. I installed Man-a-Fre's dual cylinder, and it's been great ever since.

 

[pb4ugo]

That kit is overkill. I would try to find discs sort of locally. Talk to JDC. You can go to the classified section and on top of the thread you can click on "watch" and you will be notified when a new ad is posted. You can post a wanted ad too. You can do the same for your areas in the Clubhouse section too. Reach out to the local groups in the Clubhouse section. On the 2nd page in the classifieds is this add. Maybe see if he'll sell the frt end. It sounds like a weekend road trip. Watch and search marketplace and Craigslist.

For sale Minitruck  Toyota Pickup Axles

Tallassee, AL, US

Toyota truck axles for sale. The front is from a ‘82, the rear is from a ‘87 (IFS width, Approx. 3” wider than the front) According to the data plates from both the trucks I removed them from they are 4:10s. They should be rebuilt before using. $650, obo. Located in Tallassee, Alabama

• cruiserinsanity (+0 /0 /-0)
• Jul 9, 2026
• Updated Tuesday at 11:17 PM
• Views: 110
• Category: Axle / Differential
• 4runner minitruck

$650.00

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I think one of the problems with the drum brake lines is the horseshoe line on the back of the backing plate which creates a high spot and makes it difficult to bleed.

 

[pb4ugo]

If I recall you have a ball and claw frt end. I think you probably need a FJ40 or FJ55 complete frt end.