Originally Posted by Bad Luck

After finally completing and installing this swap I have some observations and recommendations to share.

1) If you are stock axle gear ratio I would not recommend this swap unless you do a good amount of 50+mph driving. The rpm drop in 5th gear from the ratio change has resulted in difficulty maintaining speed going up moderate hills between 40-50 mph. Lower rpm means less torque. From a gear ratio perspective it's the equivalent of driving with a true 36 inch tire compared to the stock 265/70R16 when in 5th gear.

2) It has the potential to be quite involved. I used a new Toyota transmission (dumb decision to pull it apart but I'm not that bright). There's several differences between a new R150F and a used one. Mainly in the 5th countergear. Old 5th countergear is two pieces vs new 5th counter gear being 1 piece. 5th gear required the use of an acetylene torch to get the gear hot enough to pull off. Which was quite nerve wrecking as I was trying not to burn the bearing behind the 5th gear. There's a spacer between the 5th gear and the bearing that had to be shortened by about .060 of an inch. Luckily my brother has access to a lathe and removed .040 of an inch off and I used 80 grit sand paper and a lot of time to remove just enough material to get the bearing and retaining clip installed on the 5th gear shaft.

Who I would recommend this for.
If you are regeared for larger tires then this would give you a much more usable 5th gear assuming you have geared appropriately. With the 5th gear ratio change from 0.838 stock to 0.711 it would allow you to regear a couple steps further while maintaining 5th gear rpm's. For example if you regear to 5.23 then 5th gear rpm's will be comparable to 4.30 gearing (ONLY IN 5TH GEAR). In short you can get the advantage of more aggressive gearing for crawling/offroading, but have a usable 5th gear for highway speeds.


Would I do this again? Probably not. It was a lot more involved than any other writeup made it seem. Also very nerve wrecking to be opening up a new transmission and doing this. There was also the risk of having to disassemble the transmission completely to separate the 5th gear shaft completely in order to use a hydraulic press. Also, 5th gear was damaged in the process of removing it. Initial impressions are 5th gear is almost too low of rpm's to use in town driving. If I were running 33's and 4.88 gears then this would be a great mod to do IF I needed to rebuild transmission anyways.

THIS MOD IS NOT FOR THE FAINT OF HEART OR THE BEGINNER WRENCHER

EDIT: To clarify something, after swapping 5th gear you will now have the same gear ratio as our automatic counterparts 4th gear with the torque converter locked up. Automatics may only have 4 gears, but the torque converter makes up for that by being unlocked/locked. Torque converter unlocked adds torque multiplication to the equation for them. My previous 4Runner was an automatic and I was never able to get the torque converter to lock up in 4th gear lower than 44mph so that's probably a good indicator of where I should be shifting from 4th to 5th with my manual transmission and new 5th gear ratio.

Originally Posted by octanejunkie

Nice thread and write up, thank you.

I was considering this, or a 6-speed swap, to gain a better final drive ratio - neither are easy.

If I were to do this I would probably get a donor R150/151 (2-piece 5th gear) and follow a similar procedure and just swap the entire trans next time I need a clutch.

Replying to follow!

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Originally Posted by 96RedRunner

@Bad Luck leading post of the year for 2023, boots on the ground.



"44mph probably a good indicator of where I should be shifting from 4th to 5th new 5th gear ratio."





What are RPM's @44mph in 4th what will they be in 5th @44mph.?

I'm courious where new 5th puts RPM's, does 44mph give the lugging engine like feeling?

I see a possibilty holding 4th longer more MPH could keep you from shifting more often. Dunno

Originally Posted by 96RedRunner

@Bad Luck leading post of the year for 2023, boots on the ground.

"44mph probably a good indicator of where I should be shifting from 4th to 5th new 5th gear ratio."


What are RPM's @44mph in 4th what will they be in 5th @44mph.?
I'm courious where new 5th puts RPM's, does 44mph give the lugging engine like feeling?
I see a possibilty holding 4th longer more MPH could keep you from shifting more often. Dunno

Originally Posted by Bad Luck

I've only driven it twice since reassembling from repairs.

According to grimmjeeper calculator

Originally Posted by 96RedRunner

@Bad Luck , Juice worth the squeeze, I'll take some of that juice.



Holding 4th lil longer rpm's seem good fit in city traffic looking at power band.

May not effect it bad as you think, for the gains @50+ that some bang for buck

learning curve included.

Calc's 33's & 4.56's I need to check that out,