Toyota manual transmissions are made of tough stuff, and they usually shift well and come in a small lightweight package. But as with anything on a wheeling truck, time can take its toll, and the same is true for the five-speed in our '86 Toy pickup commonly referred to as Clampy. Clampy has been through the wringer in recent years and a repower was the next step in this little truck's life. However more power wasn't going to mix well with the old trans. In fact it wasn't even the original unit, but a weaker early model that shifted more like stirring soup than selecting gears. Even though it hadn't completely broken, with the current 60 horses under the hood a future power upgrade was definitely going to be that little gearbox's noose.
We had a plan to repower the truck with a late-model Toyota engine (you'll see that story in a future issue), and while at Marlin Crawler preparing for the swap we began discussing our options for transmission upgrades. Marlin Crawler has been doing dual transfer-case kits for years, but they also specialize in rebuilding Toyota transmissions. Our bench racing resulted in the assembly of an R-series transmission which is commonly found behind the V-6 engines and the turbocharged four-cylinder. These transmissions can take serious power numbers and are often used in high-horsepower racing Toyotas.
Our new transmission is an...
Our new transmission is an R150F out of a V-6-powered Toyota. However it has some additional upgrades. In standard form the R150F is considered 40 percent stronger than a W56. The W56 Clampy originally had is about 30 percent stronger than the current G54 transmission because of the helical-cut gears. Thus our new trans would be at least 70 percent stronger. Our R150F was outfitted with a Marlin Crawler exclusive-conversion bellhousing to bolt up to the Tacoma four-cylinder.
In some previous life the...
In some previous life the original W56 five-speed was replaced with a G54 from an '84-'88 carbureted truck. The G54 is recognized by the forward shift lever (the second shifter back from the bellhousing) that shifts the transfer case. Behind the G54 is a dual transfer case for added gearing and a lower crawl ratio. As the miles creeped around 200,000, the G54 became a sloppy mess, and though it could have been reused with our new Tacoma four-cylinder, an upgrade would add security with the higher torque numbers.
Inside the transmission there...
Inside the transmission there are many specs that set the R150 transmission apart from the early Toyota manuals. This larger countershaft is more rigid and supported by larger bearings.
Master transmission builder...
Master transmission builder Angelo Ferrari also installed a First gear out of an R151F transmission from a turbocharged four-cylinder truck into the R150 case, giving us a 4.3:1 First. Even though our older G54 has a slightly lower 4.45:1 First, the new transmission has a larger input shaft and front counter bearings and First gear is larger than previous versions and Fifth gear is mounted closer to the center plate for added strength and rigidity.
Keeping all the shafts in...
Keeping all the shafts in the transmission firmly located is the secret to a strong and long-lasting gearbox. The Marlin-built R-series transmissions use a heavy-duty rear thrust-bearing retainer and a new thrust washer made of chromoly to take the abuse of off-roading and to support the larger First gear.
The R150F transmission would...
The R150F transmission would normally require an adapter to bolt to the earlier geardriven transfer cases, but ours was outfitted with a tailhousing from an R151F transmission from a turbo truck. The R151F is hard to find, but the tailhousing negates the adapter requirement and shortens the overall transmission and transfer-case package.
The turbo tailhousing required...
The turbo tailhousing required a 23-spline coupler between the transmission and transfer case versus the 21-spline found in G and W series transmissions. The 23-spline coupler is made by Marlin with a few upgrades over the stock coupler. However, the Marlin piece has a 2-degree bevel cut on the gear clutch of the synchro to keep it from popping out of low range unlike some other couplers on the market.
Clampy uses a BudBuilt crossmember...
Clampy uses a BudBuilt crossmember which can also be sourced through Marlin Crawler. These crossmembers tuck the geartrain up nice and tight and have a skidplate that protects all the vital parts from rock rash.