Say what you will about the old Stovebolts and straight axles, some Advance Design pickups simply weren’t destined for small-blocks and Mustang IIs. It’s really kind of refreshing to see a nicely done, subtly lowered 1947-1953 Chevy pickup still riding on parallel leafs and an I-beam with a hopped-up straight-six under the hood.
Those devout inliners aren’t all sticklers for originality when it comes to the remaining two-thirds of the driveline, however. The limitations of the torque tube when it comes to lowering the suspension is one thing that automatically leads to an open-drive swap—but equally a concern is the limitation of the factory gearing that really puts the early Chevy trucks at odds trying to keep pace with today’s freeway traffic. Fortunately, the 216/235 engine family affords the ability to drop the granny-geared top shifters for more modern transmissions: the popular T-5/Tremec conversion or the automatic route with a TH350 (or an overdrive with the properly set up engine). Combine that with a 10/12-bolt or 9-inch rearend, and now that old six can breathe a hell of a lot easier on the highway.
Whether you go the auto or manual route, there are plenty of options when it comes to mounting the transmission in the chassis. Jimenez Brothers Customs (JBC) just developed an all-new, adjustable transmission crossmember that not only is very straightforward to install, but allows for precise driveline placement while providing a super strong, worry-free mounting point for that modern gearbox.
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Now, in the process of incorporating the new drivetrain components, in most situations you end up losing the integral bellhousing side mounts. Seeing as the engine attaches to the frame at the very front, and the transmission now locates at the very rear, a weak point has been created where the bellhousing and block meet. JBC addressed that as well by developing a side-mount kit for the 216/235s. The brackets require welding, as that allows the installer to set the engine higher or lower than stock, if needed—but since the kit uses boxing plates for the frame, a proficient welder (both person and machine) is required for the job anyway. Furthermore, the tube center portion of the trans crossmember will need to be welded to the brackets as well.
We grabbed one of the first trans crossmembers JBC finished up to install in a bare 1947-1953 chassis to accommodate a 235/T-5 using JBC’s straight-six side-mount kit. Having the cab off allows the crossmember installation to be completely bolt-in; JBC also offers a bracket configuration designed specifically for “cab on” installations, which attaches to the side of the framerail rather than the upper/lower lips, but is still vertically adjustable.
JBC offers adjustable crossmember kits for the earlier (pre-1947) and later (1955-up) Chevys as well as Ford F-1/F-100s. Because of the universal nature, other makes and models will also apply depending on framerail height. Give JBC a call for more info.
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Image may be NSFW. Clik here to view.1 Jimenez Brothers Customs’ new adjustable transmission crossmember is available for a variety of makes/models of truck (and car) chassis: we’ll be installing their 1947-1953 Chevy version with the “cab off” brackets (brackets, shown, are available for installation with cab mounted).Image may be NSFW. Clik here to view.2 And to compensate for the load stress in the absence of the stock bellhousing side-mounting crossmember, we’ll move the engine mounts back from below the timing cover to the side of the block with JBC’s 216/235 bracket kit (which includes frame boxing plates, not shown here).Image may be NSFW. Clik here to view.3 The stock front crossmember serves a number of purposes: along with radiator core support base, it also mounts the inline-six engine. That portion will not only remain, it will also temporarily mount the 235 engine we’re using while we set up the new side brackets and trans crossmember.Image may be NSFW. Clik here to view.4 The stock bellhousing mount crossmember, however, will be removed.
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Image may be NSFW. Clik here to view.5 First, the bulk of the crossmember was set free with a plasma cutter; the remaining portions riveted to the framerails were cut loose with an air chisel.Image may be NSFW. Clik here to view.6 JBC’s side mounts for the 216/235, unlike the 1954-later factory type, allow a wide option of placement locations, from stock height (based off the front mount location, which we will use), or higher/lower depending on your drivetrain and chassis needs.Image may be NSFW. Clik here to view.7 The 235, with its S-10 T5 attached via GM cast-iron bellhousing (with what some refer to as the “Muncie pattern”), was installed into the chassis using a new rubber front mount.Image may be NSFW. Clik here to view.8 Once the driveline angle was initially set (based off the frame sitting at 0 degrees) with the engine mounted securely in the front cradle, the transmission tailshaft was supported on a jackstand.
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Image may be NSFW. Clik here to view.9 Despite having a semi-tight workspace with the engine between the ‘rails, the boxing plates were fit and tack-welded in.Image may be NSFW. Clik here to view.10 If, for whatever reasons down the road, a Mustang II frontend is installed, the job will be that much easier having the boxing plates welded in (just the frame-side brackets would need to be trimmed off).
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Image may be NSFW. Clik here to view.11 With the block plates bolted tightly in place, the remaining portions of the bracket are assembled with the biscuit mount to determine how much needs to be trimmed off the frame-side bracket, as they’re supplied oversize.
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Image may be NSFW. Clik here to view.12 Once cut to size and fitted properly (parallel, not offset), each side is tack-welded together while still assembled.Image may be NSFW. Clik here to view.13 After the transmission crossmember has been installed, the engine brackets will be removed and fully welded up.Image may be NSFW. Clik here to view.14 The center portion of the crossmember is also supplied longer than needed for this application; before installing, it needs to be measured between the frame with the brackets set in place and then cut to size.Image may be NSFW. Clik here to view.15 There are a few different ways in which the crossmember can be fit and installed; we chose to do so with the T5 left in place (with new tranny mount installed), where we set the driveline angle.Image may be NSFW. Clik here to view.16 With the mounting hardware semi-snug, but not tight, the crossmember is squared up in the frame, and then the transmission tailshaft centered.Image may be NSFW. Clik here to view.17 Once everything is set, the hardware is tightened up to place the frame brackets where they need to be so that the holes can be transferred and drilled into the framerails. We simply measured the bracket hole locations from the inside of the ‘rail and transferred that to the outside for drilling.Image may be NSFW. Clik here to view.18 As mentioned in the story, having the cab mounted would dictate that instead of bolting on, the side brackets would need to be welded in place, as the floor prohibits access for drilling.Image may be NSFW. Clik here to view.19 With our holes drilled and all supplied hardware installed, everything was tightened down securely.Image may be NSFW. Clik here to view.20 The tube center still needs to be secured, however, as it’s free to rotate within the brackets no matter how tight they’re bolted down.Image may be NSFW. Clik here to view.21 With the transmission centered (if there’s any side-to-side movement), the side brackets are then welded in place.Image may be NSFW. Clik here to view.22 Save for finishing up the welds on the engine mount brackets, the old inline-six and its modern gearbox are set to go and power this old Chevy in its next shot at life on the road thanks to JBC.
