Transmission Swaps

[CorollaNut68]

I have finally completed my hybrid transmission, driven and tested it, all seems normal.

There's not much difference in the guts between the earlier and later K40 transmissions. 16 spline vs 19 on the input shaft...placing of the shifter on the tail shaft and there is an access hole in the later case to put the little peanuts in the shifter forks of the longer one

I had the early 16 spline version in the car, just bought new clutch kit when the synchro's went out. Around here, I can't just go find another transmission. I had one in my shop, a later version with 19 spline and shifter further back. It had been broken in half and the output shaft slightly bent (front U-Joint failure at 75 mph) but the guts were still good.

I took them both apart, slid all the gears and stuff from the bent output shaft and put them on the good one. The input shafts are interchangeable so I was able to keep the 16 spline for my new clutch. The only real problem turned out to be finding new shims for the output bearing which were the only things besides the brass cups that were destroyed.

Hopefully I'll get enough miles out of it to start hunting for that spare. :)

[altezzaclub]

Are the ratios the same? I know there were two different 2nd gears in the early boxes, but I don't know if they were related to the spline count.

[CorollaNut68]

Not sure...I just used everything from the later except the forks, input shaft, output shaft and the speedometer gear. Fits in the early case exactly the same. Just by sight, I could tell no difference but I didn't count teeth. I took it out for a bit...downshifts well...punched it hard and did some quick shifts...feels good.

[CorollaNut68]

I checked on it today and yes there is a difference...second gear in the 1100 uses 2.050-1.......1200 is 2.022-1.

Had I not used the countergear from the 1200 trans...it probably would have ground some teeth off..but I would have found that while test fitting it.

 

So the guts are pretty much interchangeable with the cases...if anybody wants the newer version but doesn't want to change the hole in the floor for the shifter, all you have to do (if you still have the old one) is swap tailshaft covers and the shift rods (selector fork rods). and depending on whether you want 16 or 19 spline clutch, you can swap input shafts.

[dannyl]

hey, awesome. thats a problem i was told for my car. other setups means you have to move the shifter back .

you're working on a k40 ? can i id one by the vin? i have a 74 3kc 4 sp. been leaving it be and enjoying the fuel mileage

because they tell me you have that floor/carpet hole reversal problem and parking brake too.

 

if i knew interswap arrangements may be had with case tail and shiftrods etc, i can improve my outlook

for a possible bell housing difference? or no. i like the little screamer now but it could use some accel at highway speed doesnt accel above 60 . its like restrictor plate racing just keeping up

Edited May 6, 2014 by dannyl

[CorollaNut68]

This is really only good for putting the later models guts into the early models. The 74 should have the later version K40, the shifter is about 6 inches or so further back on the housing than the earlier one. You wouldn't need to worry about moving anything, stick with the later version, you can still get some parts for it if needed. (there was a rare 5 speed but I've only seen pictures). The bell housings are part of the main case and not removable.

 

The acceleration problem isn't in the transmission, if it's got a lot of miles on it, it may be compression is low or a number of other things.....good clutch , good compression, tuned up....it should hit 100+ mph stock. Do you have a tachometer in it? 3rd gear in mine runs about even with mph...35mph, tach shows about 3500 rpms) 3500 rpms in fourth is between 55-60 mph but my tire size is slightly off from stock.

 

If you're on my side of the pond, spare transmissions of that age will be tough to find...(after 74 I think they put the starter on the opposite side of the K motors so we can't use the Starlet transmissions and after that it goes to FWD)....you probably trip over K40's everywhere you go on the other side.

[CorollaNut68]

Are the ratios the same? I know there were two different 2nd gears in the early boxes, but I don't know if they were related to the spline count.

and to clarify...when you take everything off of the two models of shafts (33311-Input) the only difference is the spline count for the clutch disc,.....

So you could probably say if it has 19 spline it's also the 2.022:1 ratio. I bet they changed both at the same time. (slightly smoother transition) Fourth gear is part of the input shaft (one piece) and has the same ratio so they can interchange, second (33332) being different ratio, you have to use the matching one piece countergear (33421).

Apparently more is better? They changed a lot of bolts from a coarse thread to a fine thread later too, just to make it interesting.

 

One other slight difference is the number of teeth on the plastic drive gear for the speedo...the gear on the output shaft is the same (5 teeth) but the early uses a keyway and the later uses a ball (33481A)

Edited May 7, 2014 by CorollaNut68