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Overdrive Conversion Fit For A Classic Truck - Five-Speed Fever! - TechAn Overdrive Conversion Fit For A Classic Truck From the January, 2011 issue of Custom Classic Trucks By Ryan Manson
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Fuel economy and gas mileage are two terms that are impossible for truck enthusiasts to ignore these days. With the current trends in the price of oil, those of us driving gas guzzling or otherwise unfriendly fuel, consumers are going to get hit the hardest. There are numerous ways to increase the fuel efficiency of your truck, from updating that old Quadrajet to a modern EFI system, to changing the gears in your rearend. But one of the easiest and perhaps cheapest ways to go is to install an overdrive transmission. For those of you running a Muncie or similar manual trans behind a small-block Chevy, dropping in an overdrive manual trans such as a T5 or a Tremec TKO can't get any easier. And while a brand-new overdrive five- or six-speed gearbox may not be the cheapest way to reduce engine speed and gain fuel efficiency, there are junkyards filled with a great alternative, the T5. Originally manufactured by Borg-Warner Automotive, the T5 transmission originally appeared in the early 1980s. These early T5s are classified as non-World Class (NWC) and are rated for slightly less power than their later World Class (WC) counterparts, which appeared by the end of the decade in the Mustang, Camaro, Firebird, and even some Jeep lines. Since it is the only American-made transmission to span more than 20 years, there is now a good supply of T5 transmissions, both WC and non-WC, in salvage yards across the country. Given their relative abundance, they have become a very popular option within the hot rod crowd when it comes to an economic overdrive manual trans. With five fully synchronized forward gears, overdrive, an internal shift-rail mechanism, and the ability to handle more than 300 lb-ft of torque, the T5 is also one of the most versatile manual transmissions available. During the past ten years or so, supported by a strong aftermarket industry supplying adapters to a vast number of vintage engines, the T5 has continued to increase in popularity. Add to that the compact size and lightweight of the T5 and you have a transmission that seems almost tailored for use in a classic truck. Here's our stock Camaro transmission... Here's our stock Camaro transmission with the S-10 tailshaft in the background. Note the drastic difference in shifter positions between the two. One of the problems with the later WC T5s is shifter placement. While the Muncie, T10, and other vintage boxes placed the shifter relatively close to the bellhousing, the WC T5 places the shifter way back on the tailshaft, too far back for most early trucks. This often causes interference with stock bench seats, among other things. The S-10 truck T5, however, has the shifter in a more appropriate location, about 10 inches closer to the bellhousing. While not as strong as the WC trans, the NWC S-10 transmission would be fine in a mild truck with, say, a Flathead or inline-six. But with the T5 trans, you can have your cake and eat it too. Because the T5 transmission has been produced in such large quantities and in such a wide variety of models, there are a few different variations of the original design and, luckily for us, the parts needed to relocate the shifter position are interchangeable. This is great news, but requires either finding the correct two transmissions or a good WC trans and a few parts it takes to make the conversion possible. A few years back, I became the proud owner of a '52 Ford F-1 pickup project and began putting the drivetrain together for it. An old Chrysler Hemi engine from a previous project, along with a Camaro T5 transmission was bolted together and slid between the framerails. Taking a few rough measurements, it quickly became clear that the shifter location on the Camaro trans was going to be located too far rearward for the truck cab. A call to Julian Nieto at 4C's Transmission in Whittier, California, located an S-10 tailshaft with the forward-mounted shifter location, along with the necessary shifter shaft. These swaps will not only move the shifter forward about 10 inches, but will also center and level the transmission mount. Julian also installed a new rear seal in the tailshaft to ensure the final assembly would be leak-free.  The first step in the swap...  The first step in the swap is to remove the old Camaro tailshaft. Start by shifting the transmission into Neutral before removing the shift lever and assembly from the tailshaft. Next, the offset lever roll pin must be driven out to free the shifter shaft. Now, the eight 15mm bolts that secure the tailshaft to the trans case can be removed. The Camaro tailshaft features an offset transmission mount (arrow) that is positioned at a 45-degree angle, which is not ideal for mounting the trans to an aftermarket, bolt-in transmission crossmember like the one we'll be using.  With the tailshaft assembly...  With the tailshaft assembly free, it can be slid off the output shaft and the case cover can be removed, exposing the transmission internals.  At this point, the transmission...  At this point, the transmission can be inspected for any wear to the gears, blocking rings, synchros, and the shift forks.  All the contact surfaces look...  All the contact surfaces look pretty good, so the trans is ready to be reassembled with the new tailshaft.  Before the case cover can...  Before the case cover can be installed, however, the Camaro shifter shaft needs to be replaced with the shorter S-10 unit. This requires driving a roll pin out of the selector arm assembly to free the shifter shaft.  This is the selector arm assembly...  This is the selector arm assembly that attaches to the shifter shaft and actuates the shift forks. Notice the disassembled assembly in the foreground? That's not good. If the pin were to have fallen into the transmission case during regular operation, the gearbox would be a box of frag. Needless to say, we replaced the old assembly, which is installed on the shift shaft.  Here's the roll pin that secures...  Here's the roll pin that secures the selector arm assembly to the shifter shaft. Make sure it drives through the shaft and is secure. Also, note the relation between the selector arm assembly and the interlock plate and the two selector plates.  One very costly mistake that...  One very costly mistake that is seen with some regularity is the removal of the Fifth/Reverse shift lever pivot pin mistaken for a filler plug. If the pivot pin is removed without first removing the snap ring, the snap ring will break off into the transmission case, often unbeknownst to the mechanic, causing detrimental failure to the transmission internals. With parts in hand, I headed back to the shop, where in a single evening I had the tailshafts swapped out, the internals of the transmission inspected, and the entire assembly back between the framerails of the F-1 in preparation for the crossmember and motor mounts to be installed. When the time comes for the trans to be installed permanently, it will be filled with Synthetic ATF and 12 ounces of Lucas Oil. But for now, the shifter falls just under the dash and clears the stock seat assembly and enables the use of a stock-looking early Ford shifter, all with the performance and reliability of a modern day, overdrive transmission. Inspecting the internals
Since the case cover was removed to install the shorter S-10 shifter shaft, it's as good a time as any to inspect the transmission internals. Visually inspect all parts except O-rings and oil seals, which should be replaced with new parts. Draining the oil out of the trans is necessary to thoroughly inspect the internals of the transmission and makes the mess slightly more ruly. Be sure to inspect the trans oil for metal shavings or other indications of unnecessary contact or wear and inspect the internals and case as well. Check the gear tooth contact patterns and compare with the diagram shown. Parts with contact patterns shown in the accept column are good to go. Those in the reject column will wind up being wall art. The gear and spline teeth also need to be inspected for chipping and compared to the diagram shown. Small burrs, nicks, or chips that fall under the repair column can be blend-repaired using a high-speed, handheld grinding tool. The repair should be blended into the surrounding area, removing as little material as possible and leaving a smooth contour, devoid of any sharp edges. The gear teeth also need to be inspected for contact patterns and replaced as needed. The spline teeth will not show such wear, but may show signs of step wear, which warrants replacement. Inspect the clutch teeth as well for rounding. Face rounding will cause the clutch to jump out of gear. Clutch teeth with rounding on the end are usable, but will result in hard shifting. Burrs, nicks, or chips can be repaired in the same manner as gear teeth.  The offset lever is installed...  The offset lever is installed on the shifter shaft with the ball and spring between it and the detent guide plate. The last thing to do is to install the roll pin, bolt the tailshaft securely to the transmission case, and torque the bolts to 23 lb-ft.  With the assembly finished,...  With the assembly finished, the shifter lever assembly can be installed before running the transmission through all the gears. It's very important to make sure everything works perfectly before the transmission is installed in the vehicle. If it doesn't work on the bench, it definitely won't work in the truck!  Here's the assembled transmission...  Here's the assembled transmission installed behind the early Hemi in our '52 Ford F-1 pickup chassis.  With the internals inspected...  With the internals inspected and checking out, and the S-10 shift shaft installed in the case cover, it's time to reassemble the transmission. A bead of clear RTV silicone is applied to the transmission case after thoroughly cleaning the surface.  Before installing the case...  Before installing the case cover, the two synchros and the Fifth/Reverse shift lever must be in the Neutral position. The case cover is then slid into position with care taken that the shift forks engage the synchros properly. Among the ten bolts that fasten the case cover to the transmission assembly are two that index the case cover to the transmission case (shown here). Install these two first before installing the rest of the bolts. These fasteners are then torqued to 10 lb-ft.  A bead of clear RTV silicone...  A bead of clear RTV silicone is also applied to the mating surface of the S-10 tailshaft prior to it being mated to the transmission case.  Under the offset lever is...  Under the offset lever is a ball and spring that rides on the detent guide. This is what gives the shifter a positive feel when running through the gears and needs to be installed before the tailshaft is mated to the trans case. A bit of grease holds the ball in place while the assembly is slid together.
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The Thinker??? - Haul Monitor
Ryan talks about the friendly badgering that goes on around the shop and overcoming obstacles that seemly pop up out of nowhere during a project....
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