It pretty much common knowledge that the poor little 56 series four speeds aren't all that strong.
I've owned a couple that have gotten a bit noisy after prolonged abuse. (Albeit behind standard A12's)
I've just tonight finished freshening up a four speed that was rolling around in the boot of my sunny when I bought it. It looks as though someone had tried to hook reverse at 80mph. reverse gear on the countershaft, and the reverse idler pinion had been turning into bevel gears. lol
So using parts from a box with a collapsed rear countershaft bearing, (aquired for a 12pack of beers) I fixed it. (Along with 5 new bearings, at a cost of $67)

So now this box should be all fine and dandy, it got me to thinking. since these are widely thought of as not up to the job, what actually breaks? I mean aside from collapsed bearings from a lack of maintenance.
Many of you must have busted a few over the years. What actually broke?

I broke the gears, chipped the teeth, when running behind an A15.

BUT -- there are two 56-series 4-speeds. The early one is weak.

The last ones used in Sedan/Coupe from 1973 are strong. They have much larger ribbing, larger teeth, improved bearings. They were fitted to all the utes from 1971. They are marked 56A. They seem to last behind A15s.

lots of 56 series gearboxs (i was on my 5th when the 63a went in), when i put the a15 in and was using it as daily driver. best was one which sounded like glass breaking when i went into reverse when i was just about to put a replacement 56 in. im sure one or two of them were 56a's but they also bit the dust within a few months. i really didnt drive too hard either, the a15 has way too much torque for 56's.

also broke the bottom (the bit the bolt goes thru) off one of the rear shocks somehow too. had to renew em..

Smooth case is strong enough unless your doing burnouts and slamming gears, I think most gearbox failures would be the result of 40 years service or poor treatment, not that they are "weak", but it sounds cool to say I have too much power

Good point. The 56-series is not weak -- not fair to say that. You could say it is a lightweight unit designed for engines of 80 lb.ft. or less torque.

I've blown 1st and second gears multiple times I've had my car for just over a year and up to my 8th box including blowing a 5 speed.. Although I do drive like a dumbcun t

eveilism, im still interested how you got a 63a behind the a series... its an l series box how did it get modded?


i only broke 56a's one from low oil the other was rattly from the wreckers i got it from to replace the broken one.

3 a series 1200,s and only the coupe had the failures, ute and sedan boxes went fine with a15s and stuff.

63A for A-series engine is common here. They had some in Japan too. It's a big overweight pig. But migth be good for a supercharged A12.

never seen or heard of 63 a for a series?????? wow so they did exist.

They sure do.
I was fortunate enough to find one myself. (It's currently in the boot of my 1200, waiting for me to give it another birthday)
We have quite a few 60 series 5 speeds here, (Although the price has gone up quite a bit the last few years) but almost no 60 series 4 speeds. (I've heared of them, but not seen one personally)
Before I fitted the 63a, I used to run a 60L five speed. (And had two more 60A five speeds in the shed) And I gave it fvcking death behind my blown A15. It loved it too.
But now all those 60's are sold. so I'm stuck with 56's for my sunny. Which got me curious about what breaks on them.
The guy I got my sunny off has offered me the numbers matching A15 from it just this week. So I'm wondering how long it might last..........