1957 Corvette RestoMod
| C4 Corvette Chassis |
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| 1957 Corvette RestoMod Project - Page 16 Rebuilding the Dana 36 Differential Both the Dana 36 and Dana 44 carriers contain a limited-slip differential (LSD). Called the "case", the LSD transfers power from the engine equally to both wheels. But not entirely equal. Inside the case are spider gears and side gears. And the case also contains clutch packs - and these are what meter the distributed power to each wheel. But when the car is turning, if both wheels turn equally, the inside wheel scrubs the pavement - and tears up your tire tread. The outside wheel always turns more revolutions than the inside wheel on turns. The clutch packs solve this problem. They are designed to not only distribute power, but to also mete out the power so the inside wheel turns the proper number of revolutions - without scrubbing the tire tread. So I needed to disassemble the differential (case) to see if either the gears or clutch packs showed any damage or wear. |
| As page 15 of this project noted, my ring & pinion will be replaced with new gearing that has a 3.54 ratio. The ratio is calculated by dividing the number of pinion teeth into the number of ring gear teeth. Pictured left are etched numbers on the outside of my Dana 36 carrier. The third row of numbers indicates the gear ratio (3.07), then the ring & pinion gear teeth (43-14). The last row is the build date for my Dana 36 - and you can see it definitely comes from a 1995 model year C4. |
| I bought my new ring & pinion online from Just Differentials and made by U.S. Gear. I did not want to buy non-American made gears because of horror stories about steel quality. There are many other online sites, including eBay. Also try Jeep product sites - Jeeps use Dana carriers too. So, the first step is to remove the ring gear from the case (below left). Next, you must use a punch and hammer to remove the locking pin and the center shaft (below middle). Once the center shaft was out, I used the end of an old pry bar to turn the case housing while the gears were held in place by one of the stub axles. The axle was clamped in my bench vise. The right picture below shows how the side gears and thrust washer come out of the case. It takes quite a bit of effort to turn the case housing, so make sure it's held securely. |
| The spider gears and clutch packs come out once the side gears are removed (left). The clutch packs are stacks of grooved plates (right). These grooves counteract each other when the car turns to allow only the correct amount of wheel spin. Clutches are mated to the spider gear by splines. The stub axles are also mated to the spider gear by splines. Just Differentials also has the clutch packs for Dana 36. |
| I also wanted to replace the bearings on the differential. These bearings sit inside cups, and the cups are bolted to the carrier via bearing caps. Two mandatory tools are needed to replace these, and other, bearings: a shop press and a bearing splitter. Below left is the OTC 1123 bearing splitter. As you can see below right, the splitter clamps the underside of the bearing. From there, the splitter's perimeter is supported in the shop press, and the press pushes the bearing seat downward until the bearing pops off. OTC/SPX makes many of the specialty tools used on GM vehicles, but whoa, are they expensive! The 1123 was around $75 from S&J Discount Tools. Chapter 10 of my new book explains in detail how to set up the press and use the splitter. I also explain how to re-assemble the differential - it's not as easy as it looks! |
| Once all re-used and new parts are cleaned and lubricated, time to rebuild the differential. Pictured left are the new clutch packs being installed. The bottom packs are under the lower spider gear inside the case. I came up with a unique way to keep the upper clutch packs and spider gear in place while the side gears were inserted - and it's all explained in Chapter 10. And I used things already in my garage! |
| You can see the center shaft at right partially back in the case. Note the white line on the case housing - the end of the center shaft has one too. The white line was put there at the factory to indicate when the shaft is correctly lined up with the lock pin hole (just above the white line). The shaft has two flat sides near its middle that allow the use of a wrench to align the white line. Make sure you secure the assembly well before hammering in the shaft. |
| The completed differential is picture left. The thrust washers go between the side gears and the case housing - and they are a bear to get re-installed. My new book explains all the tools and procedures I used to make this very scary rebuild easy. From pressing on new bearings, to setting up the backlash, pinion depth, and rotating torque, I used the minimum tools required. I also used many sources of information, and when that didn't work, I used trial and error. Any experience level will benefit from the full explanations and detailed photos found in my book. Chapter 10 is completed NOW! |