C3 corvette rear end

C3 Corvette Restoration Guide: Suspension and Differential Reassembly

In road racingyou get a lot of practice building rear ends. In thirty years of racing with these differentials, we had only one failure. We sheared the ring gear bolts smooth off at the Detroit Grand Prix. We fed almost HP through stock stub axles and spindles, and they never broke. This is one great piece of equipment. See the core value menu for details. The freight back on your old unit is your responsibility. All our differentials come with new ring and pinions, as well as new GM stub axles, and a GM coverTimken bearings, seals, and an Eaton clutch pack. They are shipped complete with fill plug, and are guaranteed to perform perfectly under normal conditions and use for three years. Check stock for used gearsets. Gear sets last longer, differential oil temperatures are reduced, and horsepower loss in the driveline is way down. Specify ratio. Free Freight. GM gear lube only with carbon fiber clutch pack. There are 4 carrier shims, 10 side shims and 10 pinion shims. We will ship freight free within the Continental US in a reusable heavy-duty box. You can use the box to send in your old differential, or you can keep it. Differential Options. Breaking a cast iron rear cover is very rare. These weigh We run a stock cover in our racecar, but if you want a heavy rear cover on your new differential from Duntov, click on this. The physicochemical process used to achieve this finish utilizes high density, non abrasive ceramic media and vibratory finishing equipment. The process removes microscopic surface asperities that are inherent in any machining process. Add for Diff Cooling with drain fitting in the case not shown. If you want to send back your old differential in the fine box we send your new one in, this is the guide we will use to determine its value. When we get your core, we will disassemble, inspect and pay you for everything in there that is good enough to use in one of our differentials. Case with No Damage. This carrier is loaded, meaning it is set up by the factory with new spider gears, heavy duty plates and springs and the new composite clutch pack. If you are building a differential for heavy duty applications, this is a good investment. Free Freight Differential Exploded View. HD Differential Cover This part is not for preventative maintenance. If your stock cover is OK, don't replace it. This thing is bullet proof, but breaking the stock rear cover is almost unheard of. The Grand Sport got along fine with an aluminum rear cover. This one weighs 20 lbs vs. It comes with a gasket and a new breather, but if you don't want to use your old drain plug, you need to order one of those too. Stock Differential Cover These are selected stock covers, sandblasted and painted with Cast Blast, shipped with a gasket and breather.

C3 Corvette 1968-1982 Rear Differential Units - Rebuilt


Eaton cast-iron differential housings were installed on — Sharks. A Dana aluminum differential housing and mounting structure was installed on the — Sharks. A unique stationary crossmember mounting system suspended the castiron housings, and a rubber-bushed mount was used at the front to prevent differential rotation. In the — Shark differential, the major difference was the integral differential cover and support structure. The rear aluminum cover and differential crossmember casting assembly removed a few pounds at the rear. This informative Shark differential photo shows some of the things that Corvette specialists Mid America Motorworks in Effingham, Illinois, can do for you. The right side of the differential has all factory low-horsepower components and strap-type universal joint yoke retainers. On the left, high-strength universal caps are installed with a performance camber control strut rod. Photo Courtesy Mid America Motorworks. Both early and late differentials were a key component of the rear suspension for propelling and maintaining alignment of the rear wheels. You need to determine the application of your C3 in order to decide which differential is best for it. High-performance street Sharks that infrequently enjoy a weekend at autocross events are not going to be an issue if you are using 8- to inch-wide tires and you have less than hp. Smooth driving with good accelerator control gets you around the road course faster and your differential is able to handle the load much easier. One definite note on the differential: Regardless of how easy you are, road racing eventually takes out a high-mileage factory Eaton or Dana differential. All OEM Shark differentials have difficulty withstanding the loads in drag racing. Original Shark tires were rated at about hp or more and were a maximum 8 inches wide. They were not nearly as good as modern tires and provided only a modicum of traction. Today we have sticky wide tires with traction compound on most drag strips. You can be assured differential obliteration is imminent if you have more than hp under the hood. When you surpass hp with sticky tires, the strap-type axle yokes that connect the differential to the axleshafts on your Shark can fail. This reproduction carrier for Eaton differentials is available for a Shark. Eaton made the differentials for GM. This is a heavy-duty replacement with high-tension Posi-Traction springs and the latest carbon-disc Posi-Traction clutch packs. Many of the original Eaton differential carrier assemblies have been used and abused over the past plus years. Although rebuilding is an option for low-mileage units, high-mileage units should be replaced. With all-new components, it delivers equal traction when you launch off the line. The only thing you need to do for years to come is change the fluid.

Rear End & Differential


At this stage, the frame has been inspected, repaired, and finished. All of the light rust damage has been repaired. Any accident damage or rust that has eaten through the frame has been cut out. New parts have been welded into place by a professional Corvette repair shop. This is the perfect time to install refurbished or rebuilt components. Place the frame in a low-traffic and well-lit area so it can be safely reassembled. Placing it on a large piece of non-shag gray or any light color carpet makes it easier to locate dropped parts. The carpet stops parts from bouncing under a table or into a small crevice. Place the frame on four safety stands that are sturdy and protected with pieces of cardboard. Set up several large tables so assembly parts can be laid out in their correct order. This saves a lot of time during the reassembly process when trying to locate the next part to install onto the frame. The front suspension is the perfect place to start reassembling the foundation of your C3. Simply reverse the disassembly procedure discussed in Chapter 6. Tubular upper and lower aftermarket control arms are available from Corvette suppliers such as Van Steel. These parts reduce the unsprung weight of your front suspension and are just as strong as the stamped-steel factory parts. However, if you are just going to use your car for cruising and not racing the factory parts work very well. This is a good time to refurbish or replace the steel control arms. Several well-known Corvette specialty shops offer like-new components at a competitive price that includes a warranty. Each part is cleaned, inspected for cracks, aligned, and powdercoated. New ball joints with rubber or polyurethane bushings are included in the rebuild process. These control arms come ready for installation. In my opinion, this is money well spent. The differential is solidly mounted to the frame and is connected to the engine with a driveshaft. The transverse leaf spring bolts to the differential and is connected to the rear suspension trailing arms. All of these components should be evaluated, inspected, and repaired or replaced as necessary. Now that the frame has been returned to your work area, reconfirm your factory frame measurements. To take the desired measurements, refer to the top right photo on page The frame is light enough for two people to carry it to your work area for assembly. This frame has been carefully placed on four safety stands and four large pieces of cardboard to protect the frame from any scratches. The large gray carpet remnant makes the reassembly process more comfortable and dropped parts are more easily found. Start gathering various bits and pieces, such as small bolts and brake and fuel lines, and place them in your work area. Van Steel uses this square piece of aluminum cut to the proper specification to measure the distance between the two upper control arm brackets.

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To start, it might be helpful to consider the tire patch. Under normal circumstances, this is the only area where your Corvette meets the road. The problem is it changes shape and size dramatically as the car accelerates, brakes and turns. The two rear tire patches provide resistance to the engine torque, and any dissimilarity in the size or effectiveness of the two driven tire patches will dramatically affect handling. Visualize the static tire patch as the contact area of an inflated balloon pressed gently onto a glass topped table. By pushing down slightly harder on the balloon, the contact patch grows, just like the outside tire patch will grow when weight is transferred onto it in a turn. By reducing the pressure slightly on the balloon you will observe a reduction of the contact patch just as the tire patch is reduced when weight is pulled off the inside tire in a turn by weight transfer, braking action or by a rear sway bar or a combination of all three. In road racing, the engineer and driver must manage these dynamic tire patches to maximize the performance potential of the car. In a production based car like the Corvette, it is illegal to make wholesale changes to the suspension attachment points. Weight and the center of gravity 2. Frame stiffness 3. Tire size and brand 4. Ride height and alignment specs 5. Suspension bushing materials 6. Spring rates 7. Shocks 8. Stabilizer bars 9. To understand how the differential affects handling, we need to review how the Corvette Positrac differential works. As you know, both the Eaton and the Dana Corvette differentials use springs to preload the clutch pack that transfers torque to the unloaded tire. The Eaton system uses four coil springs, while the Dana utilizes a conical Belleview spring to preload the clutch pack. In an open differential, as long as the car is moving forward in a stable state, driven by the pinion gear engine powerboth tires are being driven, and the spider gears in the differential are stationary in relation to the side gears. Resistance torque from the tire patches is transferred to the differential by the stub axles. As long as this resistance is equal, the spider gears are stationary within the differential carrier. When this torque is unequal, the engine torque, through the pinion gear, drives only the wheel with the least resistance, which causes the spider gears to spin in relation to the speed differential. On the front axle this difference is accommodated by Ackerman steering geometry that causes the inside tire to turn more sharply than the outside tire. This lean plants the outside tire while lifting the inside, causing the engine torque to drive only the inside wheel, the one with the least resistance. In a high speed-high horsepower situation the inside tire tends to break traction. Bottom line: It turns in great, but you can only put the power down on the unloaded wheel and you end up accomplishing nothing but tattooing the racetrack with a single black stripe. In a locked differential, the spider gears are locked to the side gears at all times, as if they are welded together. You could never use a locked differential on a street driven car, as slow speed tight turns would break the axles in short order. You can use a locked differential on high speed racetracks if you can successfully accommodate the handling problems inherent with this setup. Since nothing can slip inside the differential, either the inside rear tire must be induced to slip, or the front tires are going to slide, or there is going to be a combination of both. Here is where a rear stabilizer will help.

C3 Corvette 1968-1982 Rear Differential Units - Rebuilt

Old Corvettes were stout under the hood-who can forget the awesome Tri-power big-blocks, In their day, the old Vettes were a force to be reckoned with on the road course, but the drags were a different story; the Vette was literally a pain in the rear. Excessive camber changes meant that big power and even minimal traction led to vicious wheelhop, soon followed by six broken U-joints and pieces of halfshafts littering the starting line. If the halfshafts somehow survived, the pint-size 8. And even if you could make all those parts live, the Vette IRS was still persona non grata at the drags for Sure, you see a competitive Vette from time to time, but it's probably running a conventional solid rearend and four-link that is far from a bolt-in. But that's about to change. With the growing popularity of street car drags and really quick dual-purpose machines, there are a lot of Vette owners who want to get in on the action without the butchery of a solid axle swap. With a short inch wheelbase and lots of engine setback the front of even a big-block is behind the A-armsa Corvette could be very competitive. Years ago, Tom's figured out how to squeeze a bolt ring-and-pinion and Eaton Posi case into the stock Vette IRS housing, but that was only half the battle. Tom's realized that making the conversion practical and legal meant addressing the entire rear suspension linkage and drive system. Eventually, the company perfected a complete-and virtually bolt-in-setup that utilizes huge, oversized U-joints, halfshafts, and inner and outer drive-axles. Tom's also modified the suspension geometry to minimize camber change. Finally, a safety retention kit consisting of loops and upper retaining links was developed to contain the drive components in the event of failure. The result is a fully NHRA-certified suspension that is virtually bulletproof and has already powered 1,hp, nitrous-equipped Corvettes to subsecond e. In short, "IRS"-at least as it applies to Corvettes-is no longer a dirty word. Read on for a complete audit of Tom's itemized IRS deductions. It's not easy squeezing an inch-od bolt ring gear and all the other oversized parts into a housing originally designed to accept only 8. Making everything fit requires modifying the housing, the housing cover, and even the gears themselves to gain the necessary clearance. Even so, at present the conversion is restricted to four-series cases 3. Special aftermarket thin-flange 3. Expect an all-new Tom's third member casting later this year that'll accept three-series Posi cases and gears. Drive Axles and ShaftsGearing up is only the beginning. Now that the third member is secure, all that torque must be transferred through drive axles, halfshafts, and U-joints. While the stock series U-joints are fairly adequate with correct suspension geometry, the drive axles are marginal, and as for the halfshafts, fergetaboutit-even an second car will pretzel the stockers. Tom's offers beefier U-joints, stout forged-steel drive axles and fatter inch-od thick-wall steel or aluminum halfshafts the best stockers introduced in the '70s were only 3-inch od. The stock inner axles have notoriously poor U-joint support. Most of them retain the U-joint using a flimsy U-bolt, but the stock big-block inner axles that use a U-joint strap retained by straight capscrews are only marginally better. Either way, only a thin Truarc keeps the axle from falling out of the housing.

73 Corvette crossmember and rear end removal.



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