R156 swap

[TheBussman]

There are not many manual tundras around, this is probability more useful to the 4runner/tacoma/t100/pickup crowd: i have a 01 tundra 4x4 with a manual transmission. it's been a great truck so far, at 265k miles 1st gear would pop out if you tried to take off quickly or if you were in the middle of a hill climb where you were gaining and loosing traction. everything else with the transmission was fine. i first though to rebuild it (bearings slightly worn and not keeping the shafts in the right place all the time is almost certainly the culprit. but then i started to think about other options. its a r150 just like the other toyota trucks of the time. I think the ratios are fine for a empty truck on flat ground but with a trailer, trying to take off uphill or both 1st gear was a little high for me. shifting from 4 to 5th there is very little change, almost not even worth shifting. There is very little information about the r156 from the 2016 and 2017 4cyl Tacoma available. You would think that there would be alot of people interested in the newest, latest and greatest of the R series transmissions but that is not the case, I even called marlin crawler as I wanted to get there upgrade parts, the person that picked up said he'd never heard of it and he thought they didnt make a manual trans 4cyl. I took a chance and bought the parts anyway.
R150 ratios:

• First Gear: 3.830:1
• Second Gear: 2.062:1
• Third Gear: 1.436:1
• Fourth Gear: 1.00:1
• Fifth Gear: 0.838:1
• Reverse Gear 4.220:1

r156 ratios:

• First Gear: 4.31:1
• Second Gear: 2.33:1
• Third Gear: 1.44:1
• Fourth Gear: 1.00:1
• Fifth Gear: 0.79:1
• Reverse Gear: 4.22:1

5vz shaft left, 2tr shaft right

r156 also has a simplified shift rod setup like the later r151, triple cone syncros for some gears, fully splined 3rd/4th synchro hub. it uses the short input shaft but luckily has the same number of teeth as a long shaft needed for a 5vzfe engine. i found one in a texas junkyard for $600 130k miles they said. the took the drain plug out and then proceeded to drop in in sand.... there was a tiny bit of sand inside the trans, I needed to take it apart anyway to swap the shaft. Everything was throughlly cleaned in the pressure washer cabneit. replaced sevral bearings, installed marlin's chromally thust washer, both billet shift forks and billet bearing retianer, shifter bushings, brand new genuine toyota long input shaft.

The rear case half is slightly different from that of the r150 but swapped right over along with the bell housing.

because the tundra is so much wider then a tacoma it uses a offset shifter the points over to the driver, luckly it swapps over no issue. previous owner of the truck put a clutch in it right before i bought it. looks as though he just put a new disc on a old pressure plate and skipped flywheel resurfacing/replacing there were alot of hot spots engaement was jerky and not smooth, no name clutch disc, throwout and piolt bearing in bad shape.

trans ready to go back in:

 

[TheBussman]

Right after the swap took it on a 5 hour drive to the silver lake sand dunes and drove on the dunes for 3 days. No towing test yet but so far I'm liking the gears. both on the highway and off road. sand climbs with a manual transmission and not very much power are pretty tricky, your bouncing the rev limiter hard at the bottom wishing you could go a little faster and then 3/4 the way to the top its so steep that it just pulls your RPMs down and if things don't go your way you stall. If i try to start and 2nd and down shift 1/2 up i can never do it quick enough to work out. last time I was at the dunes in 2024 at the test hill i could only make it up the easy line on the left side, i was going fast enough to get air on the whoops at the bottom, foot to the floor but still could not make it up the taller and steeper sections. this year with the new trans I was able to make it up any position (not always first try), the conditions are always changing there and I'm not sure if it is easier this year or not. On the highway i think the 5th gear is about perfect, if it was any taller then you would have to downshift at any little grade, i thought about putting in the .69 5th gear from the dyna but I'm glad i didn't.

 

[TheBussman]

Right after the swap took it on a 5 hour drive to the silver lake sand dunes and drove on the dunes for 3 days. No towing test yet but so far I'm liking the gears. . both on the highway and off road. yes go though 1st pretty quickly but the 5vz likes to rev, sand climbs with a manual transmission and not very much power are pretty tricky, your bouncing the rev limiter hard at the bottom wishing you could go faster and then 3/4 the way to the top its so steep that it just pulls your RPMs down and if things don't go your way you stall. If i try to start and 2nd and down shift 1/2 up i can never do it quick enough to work out. last time I was at the dunes in 2024 at the test hill i could only make it up the easy line on the left side. this year with the new trans i was able to make it up any position, the conditions are always changing there and I'm not sure if it is easier this year or not. on the highway i think the 5th gear is about perfect, if it was any taller then you would have to downshift at any little grade, i thought about putting in the .69 5th gear from the dyna but I'm glad i didn't.

View attachment 4179490

anybody that has a pickup/tacoma/4runner/t100, this should work as a good replacement for a r150 if your looking to change up the gearing, the short 2tr input shaft may even work with a 22re/3rz or 3vz.