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1978 Toyota Chinook (Hilux Pickup) L43 to W50 and W50 to W55 Transmission Swap


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After searching all around the internet and coming up empty handed (or only finding posts written by people with little care for clarity), I decided to register for an account and make a write-up about the ability to swap various transmissions into a 1978 Toyota Chinook (Hilux pickup truck).

 

INITIAL SWAP FROM L43 TO W50:

 

My Chinook initially had a L43 4spd transmission that I decided needed to go.  So I swapped to a W50 5sp transmission.  Going from L43 to W50 was a breeze except that the cross member needed two additional holes to be drilled and tapped to allow the transmission cross member to be supported at slightly different locations relative to the stock L43 cross member.  Also, the floor of the vehicle had to be cut just a little to accommodate the ~2-3" relocation of the W50 shifter that was closer to the rear of the vehicle (by 2-3").    The W50 and L43 had the exact same bellhousing, same transmission mount location, same clutch fork, same release bearing.  **Note that the W50 transmission has a 5 bolt shift tower assembly that is unique to that transmission and no other.  So if you do this swap from L43 to W50, then be sure to get the 5-bolt shift tower and matching shifter lever!

 

SWAP FROM W50 TO W55:

After a while, my W50 developed a rattle noise that I believe was a failing input shaft bearing.  So I decided to buy a fully rebuilt W55 (no rebuilt W50 was available).  The W55 has a transmission mount location that is 1.75" further to the rear of the vehicle than the W50 and L43.  So this required some further creative cutting and drilling/tapping of the cross member to achieve support (see photo4 below).  The length of the W55 is the exact same as the L43 and W50 so absolutely no driveline modifications were required.  The clutch slave cyl could be reused between all three transmissions. The bellhousing for the W55 requires a 22R bellhousing because it connects to the transmission with 9 bolts.  The bellhousing connection to the engine block is the same for the 20R and the 22R.    **Note that the W50 and L43 clutch fork is DIFFERENT than the one used in the W55 (the release bearing is totally different).  So make sure you use the bigger clutch fork for the W55 if you decide to try this swap.

 

Photos:

Photo1: W55 (left) comparison to W50 (right).  Same overall length of each transmission.

Photo2: W55 clutch fork and release bearing.

Photo3: Modified cross member.  Note the cutouts on R and L side to accommodate 1.75" difference in mount location.

Photo4: W50 trans mount measurement from output shaft collar.

Photo5: W55 trans mount measurement from output shaft collar.

 

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Temp4.JPG

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Temp2.JPG

Edited by deejay1272
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Great information. Thank you for posting it. Many of our members do have earlier Toyota RV's with the same chassis as the Chinook and this info might help them. There is also a Chinook group on IO groups. 

https://groups.io/g/toyotachinook

Unfortunately when it got transferred from the Yahoo group I wasn't able to save all the conversations because transmission changes were discussed many times there. I would love it if you would post there too. 

Linda S

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A former member here claims the W58 is an almost even swap for the L43. New crossmember and slight relocation of the shift hole is all that is needed. He also had several Chinooks. His 1978 is the vehicle he did the swap with.

on a side note, the L43 is about “bulletproof “ as you can get. I personally see no advantage to going to the 5 speed. IMHO

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Hi Everyone,

 

After I swapped my transmission, I'm seeing a pretty large error in my speedometer.  I swapped in the W55 transmission from an early 90's 2WD Toyota that must've had a different gear ratio at the differential.  I understand that the '78 Chinooks have a 4.1 differential (please confirm?) so what speedometer gear do I need to exchange in order to address my speedometer issues?

 

(Note that I'm running stock wheels/tires, so no changes there to impact speedometer reading)

 

EDIT: This thread has extensive descriptions of various Toyota part numbers for speedometer gears.  It appears that the L43 to W50 swap required no changes in the speedo gear while the W50 to W55 swap requires Toyota PN 33403-29115 for a 33T speedo gear that mates up with the 11T W55 output shaft gear.  You can confirm the number of teeth on your output shaft gear by removing the speedometer gear and looking at the white plastic gear where it will have two numbers: one for the number of teeth on the speedometer gear (the higher number) and another for the number of teeth on the output shaft gear (lower number).

Edited by deejay1272
..
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47 minutes ago, deejay1272 said:

Hi Everyone,

 

After I swapped my transmission, I'm seeing a pretty large error in my speedometer.  I swapped in the W55 transmission from an early 90's 2WD Toyota that must've had a different gear ratio at the differential.  I understand that the '78 Chinooks have a 4.1 differential (please confirm?) so what speedometer gear do I need to exchange in order to address my speedometer issues?

 

(Note that I'm running stock wheels/tires, so no changes there to impact speedometer reading)

4.10 is correct. When I upgraded my rear axle, I didn’t worry about speedometer accuracy. I use my old Garmin gps unit and set it to digital speedometer. Much more accurate and easy to read.

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  • 1 month later...

UPDATE: After several weeks of puttering around in my Chinook with 5 sp transmission and I can unequivocally say that I have no regrets in terms of my decision to swap from 4sp to 5sp transmission.  The 4sp L43 that I had would cause the engine RPMs to get excessively high at freeway speeds.  That's not a terrible issue if you're open to a non-optimal fuel economy situation, but the associated engine noise was a real problem.  To me, cruising on the freeway and having a conversation with your passenger should not be mutually exclusive.  The 5sp keeps engine RPMs at a reasonable level until around 70 mph is achieved (at which point the 20R is reaching near its top speed anyway).  As a sidebar, I also installed roofing butyl tape (same thing as Dynamat, but much, much cheaper at the hardware store) to further reduce road noise.  Applying butyl table to the under-side of the hood and in the wheel wells seems to make a big difference.  Someday I'll disassemble the dash and add more back there too.

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