Posted in Model A Ford, Transmission

Model-A 5-Speed Conversion – Laine Family

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After driving my Model-A for a while with the stock 3-speed non-synchro transmission, it seemed like the car would be much more compatible with modern-day traffic if it had an overdrive gear. A company in Muncie Indiana, called Auto Restorations makes a kit for installing a Borg-Warner T5 transmission in a Model-A. The kit costs $895, and includes transmission adaptor, driveshaft, brake linkage changes, clutch disk, speedometer cable, etc. Presumably everything you need. After a call to get information (765 288-3291, they don’t have a web site) I ordered a kit.

The only thing you need to know before ordering is how many splines there are on the input shaft, so that you can get the proper clutch disk. The donor transmission comes from a Chevy S10 2WD pickup. These T5 transmissions are unique in that they have the shifter placed further forward than a standard T5. Even though the shifter is further forward, it still is about six inches rear of the original Model-A shifter once the conversion is done. T5 transmissions are synchromesh in all gears and high gear is 0.72:1, a nice 38% reduction of RPMs while cruising. My transmission had the 14-spline input, but some of these T5s have a different spline count. I believe all have a standard 27-spline output. I found a transmission at the local Pull-A-Part for about $70 including tax and the core-charge. They aren’t very difficult to pull out, but I did donate a nice socket to inside the frame of the donor vehicle while I was taking off the cross brace. Here’s what it looks like:

The kit arrived, well packaged, in two boxes. Many of the parts were primed in red oxide. I though that it would have been a nice touch if the supplier had powder-coated them, and I considered doing that myself, but decided instead to paint everything in black prior to installation. In retrospect, I’m glad that I didn’t powder-coat them, since several parts needed to be modified.

Instructions are included, but they are pretty sketchy and in unusual order. I suspect that no word processing was used so that modifying and updating the instructions had long ago ceased. They do include some good pictures and drawings though, that I found to be very helpful. I didn’t have any idea if this was going to be a half-day or week-long job. As it turns out, the latter was the closest guess. If you want to see the instructions that come with the kit, here’s a copy…T5 Installation Instructions.pdf

First thing I did was to modify the transmission. This involves cutting off a tab behind the shifter and drilling a hole below the shifter to accommodate two thick steel plates that bolt to the rear of the transmission. These plates are the new support for the rear control arms connecting to the axle. As was going to be typical in this job, the plate on one side had to be machined to fit the transmission, and the spacers from the kit weren’t quite the right size, so I ended up making new ones. Also, the hole in the T5 needs to be bored to a larger size to work with the kit.

The next step was to start disassembling the car. This involves unbolting the rear spring, brake rods, and shock absorbers from the car so that differential can be lowered and moved back to remove the torque tube. Here’s one step in the instructions: “Go to the back of the transmission and remove six bolts holding the torque tube. At the differential this torque tube should release so it can be taken down. If not, you may have to persuade it.”

Those two sentences turned into hours and hours of work. As it turns out, removing the torque tube at the rear involves pulling the pinion bearings (complete with races) from the differential. After several hours of unsuccessful persuasion, I found a note tacked onto the end of the instructions about how to use a disk and some studs included with the kit to help. Finally, success! Here it is at work:

Once the torque tube is out, the transmission can be removed. It’s not a bad time to also take out the brake linkage since it will all be modified anyway later on. When the transmission is out, the new clutch disk can be installed, using the existing pressure plate. The instructions tell you that you need to get an alignment tool, but they actually included a decent plastic tool for this purpose. The kit also doesn’t mention, but includes a new pilot bushing that slips into the existing flywheel bushing, and extends it out and to the correct diameter for the T5. Forgetting that would be something you would remember for a long time since it would require pulling out everything again. You can see it in this picture.

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