A Hot Rod T56

The Alternative Six-Speed Swap

Terry O’Donnell Aug 1, 2000 0 Comment(s)

Step By Step

The Weir Hot Rod Products T56 OEM Conversion Kit includes a new 356 T6 aluminum heat-treated bellhousing, a self-adjusting hydraulic throwout bearing, a steel block plate, pressure and bleeding tubes, and new bellhousing and transmission bolts. You will also need to purchase a new 26-spline clutch disc and a 3/4-inch bore clutch master, which can be picked up from McLeod or Wilwood. This kit should be used with a production or “take-out” T56.

When you set the stock T56 bellhousing (left) next to the Weir unit, the differences are obvious. Aside from being constructed from a stronger aluminum than the OE piece, the Weir bellhousing allows the use of a standard flywheel (up to 168-tooth design) and does not require the use of a $200 late-model starter.

For this conversion, we picked up a new standard-style 22- to 28-pound lightened billet-steel flywheel (PN 460222), an 11-inch 2,800- to 3,000-pound pressure plate (PN 360801), and a Dual Performance clutch disc (PN 260871) from McLeod. These clutch parts are designed for serious use. The clutch disc features a standard face on the pressure-plate side for smooth engagement and Kevlar on the flywheel side, which offers greater durability and better heat absorption.

Here’s the Weir throwout bearing close up. Instead of modifying an existing bearing assembly to work with the T56, Weir has machined a completely new push-type hydraulic setup. With the pressure and bleed lines installed by Weir, the assembly comes ready to bolt in.

Here’s how it works: When the clutch pedal is depressed, the throwout-bearing body fills with fluid and the bearing portion of the assembly moves outward. As the bearing moves outward, it will contact and depress the pressure-plate fingers and release the clutch disc.

Once you have all your parts together, the first step is to install the new release-bearing assembly. To secure the bearing and hydraulic lines, Weir includes a bracket within the kit that attaches to the original clutch-fork attachment point (arrow).

After installing the bearing assembly, we installed the new McLeod flywheel. But before you bolt in the flywheel, don’t forget (like we did) to slip in the Weir block plate behind it (arrow). We recommend replacing the flywheel bolts at this time. Remember to torque the bolts to manufacturers’ specs.

With the clutch lined up, the T56 slipped right in without a fight. We used the new bolts supplied to secure the trans to the bellhousing. The ’55 we installed the tranny and Weir kit into had a TCI (Total Cost Involved) adjustable crossmember, so we retained the original T56 tranny mount and everything bolted right up. Chances are your crossmember will need to be modified or a new one made.

The next step is to install the clutch disc and pressure plate. Make sure you use a clutch-alignment tool to get the disc in straight. Also, don’t forget to replace the pilot bearing. With the clutch installed, bolt up the bellhousing with the new bolts supplied in the Weir conversion kit.

Before we hooked up the hydraulic line from the clutch master to the throwout bearing, we bent both of the hard lines toward the rear of the car for additional clearance. If you’re careful, you can bend the lines by hand, though a tube bender is recommended. Bleeding of the clutch is accomplished with the bleeder screw (arrow).

There are few parts that we truly lust after. There are the all-aluminum Donovan big-blocks and the 15-inch Baer brakes or that set of twin turbos, but what we are concerned with in this story is the T56 six-speed transmission. With the countless benefits that can be had with a T56, it’s hard to resist not bolting one in. Unfortunately, there is one major headache involved with the installation—the late-model factory hydraulic-clutch package. Setting up the factory clutch master with its compound angles is anything but easy. So CHP went in search of an alternative. What we found is the T56 OEM Conversion Kit from Weir Hot Rod Products.

Designed to adapt a production T56 transmission to any ’55-’96 Chevy V-8 with a standard bellhousing bolt pattern, the Weir T56 OEM Conversion Kit offers a number of benefits beyond the elimination of the factory hydraulics. Not only does the Weir kit retain your existing standard flywheel and clutch combo, it will also allow you to reuse your block-mounted starter in most cases. The Weir Hot Rod Products T56 kit can reap the T56 benefits while reducing some of the installation hassles and costs.

Before we get to the installation, we will note that some fabrication is necessary for this kit to work. Since the system uses a hydraulic throwout bearing, it will necessitate that you obtain and install a clutch master. This may require a fair amount of creating, fitting, and drilling to attach it to your pedal assembly. Or you may choose to use one of the various pedal assemblies available through companies like Wilwood and Coleman that can make the swap a little easier. (We used a pedal assembly from Coleman that is designed to use the required race-style master cylinder.) Whatever way you choose to go, just remember some fabrication skills are required for this system to work, but this may be an easier alternative to the factory hydraulics.

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