[C5GTO]

While waiting for the engine to be built and given the anticipated additional 125 HP, I decided to check out the brakes and rear end. After pulling the front calipers, I found the pads to be wearing crooked and thin. This Cobra has Mustang II front suspension and when first built was outfitted with the larger Granada rotors and GM “mid-size” single piston calipers (I believe D52 is the official GM designation). After further inspection, the cause of the angled/crooked pad wear is that the caliper brackets weren’t holding the calipers square to the rotor. Whoever made these aftermarket brackets did a poor job of designing/fabricating them and so off to the scrap bin for them.

Ok, so at a minimum a new set of caliper brackets and pads were required. The brakes had functioned adequately for the 50K miles on the car but as is the emerging theme here, every part failure is an opportunity to upgrade! So I decided to go with the Wilwood D52 bolt-on replacement calipers.



These units provide an upgrade to a double piston caliper and are made from aluminum for less unsprung weight. The piston surface area is about the same as what they are replacing so they won’t clamp any harder but should apply the pressure more evenly over the pads surface. With a new set of properly aligned caliper brackets, these should work very nicely. And yes, they do look better what little you can see of them through the Halibrand style rims.

On to the rear axle which is a 9 inch outfitted with Lincoln Versailles disks. The pads here showed very little wear which tells me I should look at adjusting the brake bias so rear brakes are used more. Now to test the posi differential to see if it is functioning properly. I blocked one tire from turning and spun the driveshaft yoke. The other tire turned just like an open differential works. No resistance was felt at all like you should feel with a minimally working posi unit.

Ok, so the rear axle needs to come apart. It had a slow drip leak from the pumpkin gasket that had been bothering me for many years. Now I had adequate reason to tear it down and fix that as well. After pulling the 9 inch pumpkin, I discovered it had a Ford Traction-lok clutch style posi.





I looked into rebuild kits for this unit, which are available, but the Traction-lok is 50 year old technology and the popular opinion is that the clutch disks wear fairly fast (even with friction modifiers) leaving little to no posi function sooner than preferable. So you guessed it, every part failure is an opportunity to upgrade!

I decided to replace the differential with an Eaton Detroit Trutrac unit (which contrary to its name, is made in Taiwan) that uses helical gears instead of clutches to provide its limited-slip function. Popular opinion on these is that they work great and don’t wear out like the clutch-based units. The ring and pinion looked fine so after replacing the differential roller cups/bearings, I proceeded to reassemble and setup the rear end. I used a LubeLocker brand gasket and so far no leaks or seepage has occurred so hopefully one less oil puddle to wipe up on the garage floor.

Well, if I keep this up, all the major mechanicals in my Cobra will get an upgrade! My pocket book says, “Ouch!” but hopefully it will all be worth it once I get the car back on the road.