[Project Toyota 4×4] Transition of the Transmission

Toyota Pickups have a reputation of being nearly indestructible. No matter how many miles you pile on the motor, or service intervals that are laughed at like spam emails asking to send money to the Prince of Arabia, these old Toyotas do not quit. While our favorite 4×4 has kept chugging along, the transmission has been extra noisy and recently gave up 1^st gear. Not the end of the world, but constantly slipping the clutch for a 2^nd gear start gets old pretty quickly.

Fresno Freight

Getting a used transmission is often seen as acceptable, but the likelihood of another three decade old transmission failing was not appealing. This is where Marlin Crawler came into play. Based out of Fresno, California, they’re one of the go-to places for all your classic Toyota 4×4 needs. Marlin is also one of the few places that specializes in rebuilding these old transmissions. While a 9 week lead time to get a hold of a replacement transmission isn’t exactly quick, sometimes the specialists are the only way to go. Thankfully we had other vehicles to drive while the truck was out of commission, otherwise the Uber and Lyft apps were going to be used for a lot more than late nights out on the town.

To our surprise, the transmission arrived a few weeks earlier than anticipated. With things moving ahead of schedule, a new clutch kit was ordered and the show about to begin.

Garage Parts Pile

Unlike the BMWs, the Toyota has plenty of ground clearance, meaning we didn’t even need to put the truck on jack stands. The first order of business was to get the front and rear driveshafts disconnected. To gain more working space, the transmission support was removed and a jack placed on the transmission. Fortunately the exhaust could be left in place due to its simple routing, so one less step to worry about.

Once the driveshafts were out of the way, the fun could begin. Anyone who’s had to remove a transmission still in a vehicle will know that the lower bolts are the easy bit, but the top bolts are a major pain in the rear end (we prefer ours with an LSD…har har). In order to get to these top bolts, it’s necessary to use a 3 foot extension plus a u-joint. To make matters worse, visibility is poor, so an extra set of hands and a flashlight in the engine bay are strongly encouraged. After all the bolts are removed, the last bits preventing the transmission from being removed are the clutch slave cylinder, starter, shift levers, and reverse light wiring. Not tough things to deal with, but certainly items you don’t want to snag while separating the heavy gearbox and transfer case combo from the engine.

Removing the transmission was far from a graceful process. Lots of rocking, rolling, and swearing were involved until we threw in the towel for the evening. Our jack setup was simply not cut out for removing a transmission. So where do you go when you need a specialty tool you’ll probably use once? Yup, Harbor Freight to the rescue. In this case we walked out of the store with a transmission jack. By the following evening, the transmission was finally freed from the truck.

If you’re a Toyota fanboy (or girl), then this is the point to geek out. Our truck has an October, 1985 build date, meaning it’s an early 1986 model year. According to the chart-o-transmissions on Marlin’s website, we needed a replacement G54 transmission. Over the years there have been several variations of transmissions within the Toyota family. A majority of them are cross compatible, so it’s not uncommon to find a different transmission than what left the factory. In our case, an older G52 was the version that came out of the truck. At some point between Microsoft’s IPO and 2017, we’re led to believe the transmission had been previously swapped. A quick call to Marlin brought us good news when they told us that the non-original trans was still eligible for a core deposit.

While the rear of the engine was exposed, we took the liberty to freshen up a few things. The rear main seal was replaced, the flywheel resurfaced, and a new clutch kit installed. A classic example of “while you’re in there.”

Climbing the Mountain

The moment we were all waiting for came when the new transmission was finally unpacked. It was time to swap over the bell housing and transfer case. Assembling all the parts and pieces reminded us how lengthy and heavy this transmission can be. We filled everything up with 75w90 gear oil and the trans jack was called into action once more.

Getting the transmission to cooperate was like asking a six year old to share their Halloween candy. No matter how patient we were trying to guide the transmission into place, it fought us until the very end. Once it was finally settled into its new home, we went about connecting driveshafts and clutch controls.

Back to 1986

Firing up the truck after it’s long nap was fairly uneventful. No strange noises, just the engine slowly warming up. When it came time to move the truck under its own power, immediately evident was the slick shift linkage. On the previous transmission, the shifter bushings were replaced, but nowhere near as tight as the linkage in the newly rebuilt transmission.

The clutch is a little grabby as it bites relatively early in the pedal travel, but flushing the system with fresh fluid and a bleed job should get pedal feel back to normal. Out on the street the transmission is very quiet. More importantly, the ill-tempered 1st gear no longer pops out with a cringe-worthy grinding noise. Off to a good start!

The freeway is where the truck is transformed. As we all know, the power of the truck will never outrun anything more than a Daimler Motor Carriage, but being able to use all five gears makes 75 mph an option instead of a challenge. The bearings in the old transmission were in such poor shape that 3rd and 5th gears were louder than the engine. Not the case anymore, as all the gears are noise free, making highway driving a very tame experience.

To say this “upgrade” is worth the money is probably not a fair assessment, as it was done out of necessity more than anything. Between the transmission, the clutch kit, and other odds and ends, the project was in the $1500 range. A few hundred bucks will come back to us once the old unit gets shipped back to Marlin, but still a costly procedure nonetheless. If you have everything ready to go and set aside a solid weekend with a few friends to help, this is definitely doable for a DIYer. We could have found a known functioning transmission, but at least we know the new trans is guaranteed to work and has a warranty to boot.

No matter how great the transmission might be on the street, 4×4 means this little truck is meant to tackle more than just pavement. About an hour away from us is the Hollister SVRA. Given the mild suspension setup on the Toyota, we’re probably not going to be doing any extreme rock crawling, but that won’t stop us from locking the hubs and making sure the transfer case can pull us through some dirt, gravel, and mud. We’ll also test whether the 31 year old truck can still keep pace with some of the more modern rigs. Sorry new paint job, things are about to get filthy.

–JC

Interested in the parts we used for this job? Check them out below:

Marlin Crawler Rebuilt G54 Transmission

Exedy OEM Clutch Kit