FJ40 brake drum compatibility across years (1 Viewer)

[flx]

Which wheel bearing hubs and spindles and birfields did you use? I was assuming those had to change but it sounds like not?

Stock for 10/1973 build date.


I took a maximum of measurements before to commission my garage to do the work, so I was like 80% convinced it should work.

All pictures here are from before the work, so with old drum in place:
My biggest concern was this, the original backing plate already comes very close to the direction ball joint:

And the 1981 FJ45 backing plate are 1cm larger in diameter than the old ones, so the risk was that they contact the ball joint.

Now comes the part that may be hard to explain, the newer flasks/drum are placed more to the exterior (more inside the rim), than the old ones that are closer to the center of the vehicle. The old backing plates actually wrap around the knuckle quite a lot. The newer drum is larger in total but a lot more inside the rim and wrap less around the knuckle.
To measure that as I could not measure on the currently installed backing plate, I measured inside the drum the distance between their mounting surface (that is always the same on the hub) and where they (almost) contact the backing plate. Newer drum has 0.5cm less.

Could also visually see the newer backing plate having less wrap than the old one.

This means the backing plate relative to the direction ball joint is moving like that:

Last point I checked but was not very worried is that the newer drum fit inside the stock rim and is only in contact on the mounting surface:

This is a 16" wheel, not 100% sure it would fit in a 15".


A very last note worthy point as to be here, the newer drum have a double lip around (and same on the backing plate) which probably provide them with a better protection against water ingress. (they also have very very tight tolerances on the fit of those lips)

 

[cruisermatt]

I doubt that will catch on as a common upgrade but neat to know it works.

 

[flx]

I doubt that will catch on as a common upgrade but neat to know it works.

Definitively, I don't think the improvements of the new drum compared to the older ones are worth an upgrade for the sake of an upgrade.

The biggest interest here is that the OEM cylinders for <1976 drums are NLA, aftermarkets exist but only found them in US shops (long wait + $$ shipping), while those >1976 complete drum brakes are easy to get for very cheap or free in non-US market, as a lot people are happy to upgrade to disks. And if in the future there is a need to change the cylinders the OEM ones are still available everywhere for those drums, so an easier long term maintenance.

 

[flx]

To complete this thread, pictures of the 1981 FJ45 drums installed in the front

When I saw them installed with the wheel for the first I was surprised to see that the wheel studs had no extra thread left (stud and nut are flush) while they had before (1st picture front with new drum, 2nd picture rear to show how it was before).

At first I wondered if something was wrong with the installation and couldn't figure what could have caused that as nothing else was changed on the front axle.
In the end the answer is simple... the new drums are wayyyy beefier and the flange side is a lot thicker than on the original drum.

Actually looking at the screw holding the drum in place is very clear (left original drums, right 1981 FJ45 drums).

So I still end up with a slightly wider front axle in the end
Not sure why it is like that... Hard to think it needs to be that thicker for structural rigidity, so is-it to provide the same width than discs?