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Adapting A Vintage Engine to a Modern Transmission - Trans-AdaptationLosing The Weak Link In A Vintage Drivetrain From the May, 2012 issue of Rod & Custom By Rob Fortier
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What strange beast lies behind... What strange beast lies behind thy Flathead? Why, a Tremec TKO 500, of course! But not without the aid of Wilcap’s cast-aluminum transmission adapter. To me, the appeal of vintage engines typically ends at the bellhousing surface—I basically have no use for the accompanying tranny. I know, there are plenty of you who are particular to Top Loaders and the like, and there’s absolutely nothing wrong with that. Unless you’re going drag racing or trying to keep up with 65-mph (plus!) traffic on a regular basis, early engines are just fine with early transmissions. Knowing their limitations helps the driver adapt to the particular conditions at hand, but why not do the opposite? Adapting a vintage engine to a modern transmission is the solution I’ve come to live by. Whether it’s via a four-speed automatic overdrive, or as in this case, a five-speed manual, taking a brunt of the load off an old engine—as well as prolonging its life—ultimately takes some of the load off the driver, and in turn, the vehicle itself. I don’t know about you, but buzzing along at 3,000-plus rpm on the freeway and barely doing 55 isn’t time well spent behind the wheel, at least not for me. And in a solid front-axle car or truck with all-wheel drum brakes, winding out Third gear is just another downbeat driving factor I can do without. But, throw in an extra gear or two, and keeping up with traffic—and being able to hear yourself think—is no longer one of those negative aspects. Wilcap, maker of all things... Wilcap, maker of all things that make adapting modern technology to our antiquated engines, manufactures quite the variety of Flathead tranny adapters (left and center); while newcomer QuickTime (right) offers two direct fit adapters for Ford-only applications (no GM/Muncie patterns currently offered). Since all of my recent Chevy inliners got the deserving drivetrain upgrade, I felt the 8BA Flathead going in the ’33 Tudor deserved the same. Weighing all of my options—automatic (C4 or Turbo 350) or manual (S-10/Camaro T-5 or Tremec TKO)—I ultimately decided to “stick” with what I knew best: a TKO 500 five-speed. But the decision making didn’t end there, and as it would turn out, my next one was by far the most difficult choice to make. Upon engaging discussions with my contacts at Tremec, I was ultimately faced with deciding on a particular gear ratio for the TKO 500 I was ordering. Sounds easy enough, right? Well, I thought so myself at first … but I would end up changing my mind, oh, at least three times before coming to a “final” decision. You see, there’s a lot more to manual overdrives than just the addition of a Fifth—or even a Sixth—gear. Not only do you have a choice in how much overdrive you get (0.64, 0.68, or 0.82), you have the option of how much “off-the-line” gear (First), as well. For instance, both the 0.64 and 0.82 overdrives have a 2.87 First, while the 0.68 has a stout 3.27 First. Now if you’re thinking it’s all just a matter of picking the right combo simply based on the transmission data, think again—we’ve still got to factor in a few more very important variables … engine, rearend gear, and rear tire diameter. In my case that equated to a low-revving 8BA Flathead, a Winters 3.86 ring-and-pinion, and a 31.5-inch Coker/Excelsior bias-ply. After quite a few back-and-forth email and phone sessions with my “patient” friends at Tremec, the final-final decision was made to go with the 0.82 TKO 500. With that gear setup, at 76 mph I’d be turning 2,500 rpm (both the 0.64/0.68 ODs would require speeds in excess of 90 mph to attain the same rpm—way too tall for my little Flatty). But I still had one last component to fill in the blank between the five-speed and the Flathead: the adapter. Thanks to Patrick McGuire, owner/proprietor of Wilcap Engineering, that blank was more than filled. McGuire was gracious enough to send me everything he has and/or makes to mate late-model transmissions with all Flathead models. Whether it’s a Turbo 350 or a Muncie, his products are manufactured to exact tolerances, meaning you won’t have to do any jimmy-rigging or head-scratching (he also supplies very descriptive instructions with each kit). So, if you’re tired of winding out that ol’ Flathead of yours just to keep pace with grandma on the freeway, consider a little modern trans-adaptation. I highly recommend it!  When it comes to Flathead...  When it comes to Flathead starter plates, Wilcap utilizes OE items (center)—for their Turbo 350 kit (top), the starter mount is integrated into the machined adapter. H&H offers brand-new, machined aluminum plates (top left), as does QuickTime, though the latter only works with their bellhousings.  The same, but different. Both...  The same, but different. Both transmissions pictured are Tremec TKO 500s; both feature the same internal-rail construction. There are, however, two major differences—the most obvious is the different shifter locations, while the other not-so obvious is the bellhousing patterns (GM on the left; Ford on the right). As mentioned, Wilcap accommodates both; QuickTime only facilitates the Ford pattern.  The same, but different. Both...  The same, but different. Both transmissions pictured are Tremec TKO 500s; both feature the same internal-rail construction. There are, however, two major differences—the most obvious is the different shifter locations, while the other not-so obvious is the bellhousing patterns (GM on the left; Ford on the right). As mentioned, Wilcap accommodates both; QuickTime only facilitates the Ford pattern.  Oh, yeah, there is one more...  Oh, yeah, there is one more difference—the input shaft and its retainer plate are different sizes on each model; the OD of the retainer is wider and the input splines are shallower on the Ford version.  Oh, yeah, there is one more...  Oh, yeah, there is one more difference—the input shaft and its retainer plate are different sizes on each model; the OD of the retainer is wider and the input splines are shallower on the Ford version.  To help facilitate my adaptation...  To help facilitate my adaptation session, Mac’s Custom Tie-Downs supplied me with their new Pivot Plate engine hoist attachment (with accompanying Flathead plate adapter). The Pivot does just what its name suggests—“pivots” to aid in positioning the engine when installing/removing from a vehicle, or in this case, when mating with a transmission.  First order of business: resolve...  First order of business: resolve my clutch issue. When the engine was built, a Ford 10-spline clutch disc was installed; the GM-style TKO has a 26-spline input shaft. Simple enough—just swap discs, right?  The engine had also been “fully”...  The engine had also been “fully” balanced, but fortunately, H&H marked the pressure plate and flywheel—so in essence, it was just a simple swap. The 26-spline disc was obtained from Speedway Motors.  The engine had also been “fully”...  The engine had also been “fully” balanced, but fortunately, H&H marked the pressure plate and flywheel—so in essence, it was just a simple swap. The 26-spline disc was obtained from Speedway Motors.  Now, with the clutch all sorted...  Now, with the clutch all sorted out, I wanted to do a dry run to ensure that the input shaft not only meshed with the clutch disc, but that its snout fit inside the pilot bearing. All systems were a go from here.  Unsure whether or not the...  Unsure whether or not the input shaft protruded too far, I took a couple quick measurements just to verify. Again, another green light.  Unsure whether or not the...  Unsure whether or not the input shaft protruded too far, I took a couple quick measurements just to verify. Again, another green light.  One last round of test-fits—this...  One last round of test-fits—this time, with the Wilcap BH 59A-350 adapter on both the transmission and the OE cast-iron (8BA truck/Merc style) Ford bellhousing. Wilcap suggests that bellhousing and adapter be installed onto the engine first followed by the trans.  One last round of test-fits—this...  One last round of test-fits—this time, with the Wilcap BH 59A-350 adapter on both the transmission and the OE cast-iron (8BA truck/Merc style) Ford bellhousing. Wilcap suggests that bellhousing and adapter be installed onto the engine first followed by the trans.  Wilcap supplies mechanical...  Wilcap supplies mechanical clutch forks and throwout bearings, but if you so desire, hydraulic kits are available (McCleod). I chose to go the mechanical route, even though my body will probably hate me for it down the road!  Wilcap supplies mechanical...  Wilcap supplies mechanical clutch forks and throwout bearings, but if you so desire, hydraulic kits are available (McCleod). I chose to go the mechanical route, even though my body will probably hate me for it down the road!  Not wanting to ruin a perfectly...  Not wanting to ruin a perfectly good clutch fork, I had Mike at H&H hone it out rather than attempting to press it on myself (with a hammer and piece of wood) …  The adapter sleeve Wilcap...  The adapter sleeve Wilcap supplies for the throwout bearing may also need to be pressed on. With the trans adapter bolted to the tranny, I’ve assembled the cross-shaft/fork/T-O just for illustration purposes, as it’s nearly impossible to show the assembly once it’s actually in place.  The adapter sleeve Wilcap...  The adapter sleeve Wilcap supplies for the throwout bearing may also need to be pressed on. With the trans adapter bolted to the tranny, I’ve assembled the cross-shaft/fork/T-O just for illustration purposes, as it’s nearly impossible to show the assembly once it’s actually in place.  After reversing my “illustration”...  After reversing my “illustration” assembly, I could finally mate the TKO with the Flathead. Using a floor jack supporting the transmission and a driveshaft yoke to coerce the input shaft, the mating process went like butter.  Prior to installing the five-speed,...  Prior to installing the five-speed, for reference I mocked up Wilcap’s 292-350 BHA adapter with an OE stamped-steel passenger car bellhousing. This setup uses the stamped clutch fork shown earlier.  Finally, using the “borrowed”...  Finally, using the “borrowed” Ford TKO 500, here’s what you’d be looking like using the QuickTime adapter. As stated, at the time this was written, the company had no applications for GM/Muncie-style transmissions, only Ford.
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