It's time to move ahead with Project Shark Attack. While we were runningaround on the Hot Rod Power Tour and the Bloomington Gold show, thecomponents we ordered in Part 2 of this series came pouring in.
Now we can remove some pieces and see if this '79 Corvette is what wethought it would be. The plan is to completely disassemble the rearsuspension and differential. Once all the pieces are cleaned andinspected, they'll be sent out for bead-blasting and powdercoating.
At the start of the project, we checked the underside and sprayed allthe fasteners with P-Blaster rust penetrant, allowing it to soak for along time. The penetrant helps the parts-removal process and sometimesthe flame wrench (torch) isn't necessary. As we disassembled the rearsuspension, the bolts came out easily and had minimum corrosion.
We discovered some interesting things during disassembly. Differentialgear oil was dribbling out from the inner right-side bolt hole of therear-spring retainer plate, which was probably caused by a bolt that wastoo long.
The driver-side axleshaft had a replacement U-joint, and we wondered whysomeone would replace only one. We removed the U-joint and found thereplacement was in worse shape than the originals with at least 124,000miles. It most likely was never greased.
The strut rod stud/shock mounts came out with minimal hammer blows. Thetrailing-arm pivot bolts could be pushed out easily. All the originalrubber suspension bushings were worn, cracked, and ready forreplacement, not surprising after 25 years.
The trailing arms were in fair shape and the spindle bearings sounded OKwhile rotating the spindle. There are a couple of options when it comesto the trailing arms. You can buy completely rebuilt assemblies, partialassemblies with bearing housing available, or rebuild your original one.We decided to rebuild the original trailing arms since we have thespecial tools required for the job. The tools are available fromCorvette Central, but are costly for one-time use.
Once all the subassemblies are removed, put the pieces on a sturdyworkbench. Remove the heavy road grime and greasy buildup beforecomponent disassembly. Use latex or vinyl gloves during disassembly, asdifferential fluid and grease can stay with you for days.
It's important to keep all parts until the job is done. Put the onesyou're replacing in one area to review after disassembly, which makes iteasier to order the additional parts not on the original list. Now thedisassembly of major components can begin, then an evaluation of theircondition after cleaning.
Now that the project is underway and there have been no major surprises,we can consider some upgrades. Replacing the transmission with afive-speed overdrive unit so a 3.70:1 ring-and-pinion can be installedin the differential should liven things up a bit. Until the ODtransmission is installed, the 3.70-ratio will be fun on Saturday nightcruises. The strut-rod assembly will be replaced with Vette Brakes &Products smart struts, which change the strut-rod angle for better rearcamber control. The steel spring will be replaced with a TRW fiberglassmono-spring for ride quality and durability. The U-joints will be BruteForce heavy-duty pieces from Advance Discount Auto Parts. We still don'tknow what brake calipers we'll use, but it isn't an issue until we workon the front suspension.
When installing or removing...
When installing or removing the rear spring, it must be unloaded fromthe trailing arm. Use a C-clamp to prevent the high lift jack fromslipping. The same procedure can be done with a floor jack. Place thefloor jack lifting cup as close to the spring bolt as possible. Thecloser you get to the differential, the harder it is to unload thespring. The axleshafts can be safely removed after spring removal.
It can be difficult to remove...
It can be difficult to remove the strut-rod stud/shock mount from itsserrated press fit in the spindle support without the special tool thatscrews on the stud. The tool is available from Corvette Central (PN582414) for $14.95 and should be in your toolbox. This can be a horriblejob if the strut-rod-bushing inner sleeve is corroded to the mount stud.We used a reciprocating saw to cut the mount stud between the ears ofthe spindle bearing support.
After removing the driveshaft,...
After removing the driveshaft, front differential mount, and the boltsthat retain the differential crossmember, a jack is placed under thedifferential while the crossmember rubber mounts are popped off theframe. These rubber mounts usually release easily, but sometimes ittakes a lot of force. If mounts are tough to release, give the bar aquick pull downward. A quick motion works better than applying extremepressure over a longer period.
Notice the extra washers and...
Notice the extra washers and silicone on the spring-retainer-plate boltthat goes into the differential cover. The inside of the cover waswelded where the spring-retainer bolt went through. A bolt can easilypierce the minimal cast iron in the area. Welding cast iron can bedifficult and minor leakage after repair is common. The welded area willbe sandblasted and cleaned with alcohol before applying J-B Weld epoxy.
First remove the snap ring...
First remove the snap ring that holds the yokes into the differentialhousing. The yokes rest against the pinion shaft, which causes wear andmushrooming of the yoke end where the snap ring goes. The yokes had beenreplaced and the snap rings were intact. Severely worn yokes break thesnap rings, and pieces will float through the differential.
Before removing the ring-and-pinion,...
Before removing the ring-and-pinion, check the ring-gear-to-pinionbacklash. This ring-and-pinion set had .007 backlash. It's possible tochange backlash when changing bearings, so keep a record and set thebacklash to previous settings. Changing the backlash plus or minus .002can cause noise.
It's important to mark the...
It's important to mark the position of the bearing caps to avoidbearing-race distortion. Also mark which side they came from; if youplan to reuse the bearing races, put them with their respective capsafter removal. A shim sets backlash between the bearing race anddifferential housing; place it with the cap and bearing race.
An impact wrench works well...
An impact wrench works well for removing the pinion flange. The outerpinion bearing is under the pinion flange. When the yoke snap ringsbreak apart, the pieces end up underneath the pinion outer bearing. Inmost cases, the flange and outer pinion bearing require removal toretrieve the pieces.
These are the pinion or "spider"...
These are the pinion or "spider" gears. They can be rotated out of thecase after removing the Posi-traction apply plates and springs. ThePosi-traction clutch plates are beneath the larger side gears. Thepinion shaft is pushed out so the plates and pinion gears could beremoved, then pushed back in for photos. You can see the shiny wear bandon the end of the pinion shaft. In most situations, the pinion shaftshould be replaced. As it wears and the case is damaged, the pinionshaft is loose and will break the pinion-shaft retainer bolt.
Use an impact hammer to bend...
Use an impact hammer to bend up the tabs on the differential crossmembermount cushions. Once all the tabs are up, the cushions tap out withoutmuch force. The new cushion taps into place and the tabs are bent over.When reinstalling the crossmember, put a light coat of grease in the cupof the cushions so they don't stick.
This is an unusual situation:...
This is an unusual situation: tapping out the trailing-arm pivot boltswith a long pin punch and small hammer. In many cases, the pivot boltsare seized to the trailing-arm bushing's inner steel sleeve. Whenthey're seized, rust penetrant doesn't work. A reciprocating saw with aneight-blade placed at the shims is the safest solution for removal. Youcan usually remove shims before using the saw. A torch in this area isdangerous because the fiberglass body is close to the frame and a fuelline above the frame.
Remove the spindle flange...
Remove the spindle flange nut to service the spindle bearings. If youdecide to replace just the spindle housing that comes with bearings andspindle, transfer the original flange to the rebuilt assembly. Thecomplete trailing-arm assembly comes with the flange. The spindle has ahole for cotter-pin placement. When tightening the spindle flange nut,do not back off the nut to install the cotter pin. Always go tighter toline up the cotter-pin hole.
Use this tool to safely remove...
Use this tool to safely remove the spindle. The bearing and spindlethermal cycling can tighten up a bearing. Pound on the forcing screwdrive nut hidden inside the 7/8 socket with a 32-ounce ball-peen hammerto loosen the bearings. Pressure is applied with the forcing screw, thenthe hammer shocks the bearing enough to remove the forcing screw. If thehammer technique isn't used on extremely tight bearings, the calipermount used by the removal tool for anchoring will bend or breakdepending on the amount of pressure.
The spindle and rotor assembly...
The spindle and rotor assembly is removed from the spindle supportshowing the broken emergency-brake-shoe return spring. The spring causesa bind in Reverse. It also makes a chirping noise and a popintermittently at low speeds. The grease is minimal and all over thebrake area. The bearing races have a slight red discoloration, almostlike anodizing, which is a warning of impending failure.
An 11/16-inch drill bit works...
An 11/16-inch drill bit works best for removing trailing-arm bushings.The drill bit cuts off the large washer, and you can push the bushingand sleeve out by hand. The trailing-arm bushing is in pretty bad shape,since the rubber is forced out from the center.
The rotors had never been...
The rotors had never been removed from the rear spindles. Use a 3/8-inch drill bit to remove the rivet head. The drill bit is large enough to remove the head of the rivet, leaving the rivet shank to be pushed out. Use a 1/4-inch pin punch to push out the rivets the rest of the way.
This is an OTC ball-joint...
This is an OTC ball-joint press. It works well when disassembling and assembling U-joints. Spray the U-joint cups with rust penetrant before attempting to remove the cups. It also works well when a portable press is required and when replacing C3 and C4 factory-style rear sway-bar bushings.