News Project Trans Am

Project Trans Am – Month 28, Rear Axle and Oil Pump

Another slow month with the Trans Am. Two of the 4 weekends I was out of town, for only 2 weekends I got a lot done. Here’s an outline of everything that has been happening this past August, 2012.

Rear Axle and Stabilizer Bar

Pretty much the whole month focused around the rear axle. I got new Moser 28 spline axle shafts installed with new c-clips, bearings and axle shaft seals. Before I installed the new axle shafts, I painted the ends of the axle, then proceeded to install the bearings, axle shafts, then put the pinion shaft and a new pinion lock bolt back in the rear differential, followed by installing the maintenance cover with a new gasket lightly coated with gasket sealer. I let it sit for a few hours, then I filled it up with both 80W90 gear oil and GM’s limited slip additive. The wheels turn smooth now,wild how quiet the rear axle is now.


Last weekend I painted the remainder of the rear axle and installed a thicker 3/4″ rear stabilizer bar.

Oil Pump

Per recommendation from the Pontiac How to Rebuild book and my engine builder, I disassembled my oil pump, checked it for any burrs, shavings and grit that could damage the engine then test-fit the pump on my block to make sure the oil pump lines up with the oil galley in the block. Everything checked out. I was lucky that I ordered my pump over 2 years ago, apparently more recent castings are no longer made in the USA and can be a concern both with alignment and cleanliness.

Rear Shocks

Over Labor day weekend I installed the rear shocks. The new shocks are significantly harder and better compared to the set I took off the car. They look good under the car too. I got Edelbrock ISA Classic shocks for the rear this past Spring when Summit Racing had them at 1/3 the price. I also ordered Edelbrock ISA Performer (Not Classic) shocks for the front. I wanted to go with both Performer  shocks front and back but due to the limited availability and later finding out that the shocks were discontinued I decided the mix-match front/rear was better than not having them.

Rear Brakes Started

Over Labor Day weekend I started installing the rear disc brakes.

While I was preparing the rear end for brakes, I discovered that the routing I had designed for the brake lines interfered with the rear stabilizer bar drop links. I ended up having to pull out the stainless steel brake lines I had made and replace them with easy to bend pre-flared with fittings line from NAPA. Wish I did that originally, those stainless steel lines cost me a few bucks, where these pre-flared lines weren’t even $10.

Over the weekend I got as far as installing the rotors and pre-loading the calipers. After doing some research on how to realign the brake piston’s D groove to the 6’0 clock position, I found that both the service manual and folks from the Firebird/Trans Am forums recommended to use organic pads in the rear with semi-metallic pads in the front. I am already using semi-metallic in the front, but I was about to also use semi-metallic in the rear, so now a set of organic rear pads is on order.

From what I understand, the organic pads in the rear help with the brake pedal feel and make it easier for the car to stop. I should stress “stop easier” vs “stop faster”, I would think that semi-metallic pads would make the car stop faster, but knowing how the front and rear brake lines require different brake pressure managed by the proportioning valve it may make sense that the rear brake pad material may dramatically change the proportions that were designed into the proportioning valve. Either way, I’m leaning to the side of caution and ordered organic pads.

What’s Next

Brakes!!! Hopefully the next couple of weekends I will get these brakes done! Following that, I need to paint the inner fender wells,finish assembling the firewall and heater box, install the steering column, dashboard and interior insulation, followed by the remaining assembly of the Pontiac 400 engine (currently only the short block is assembled).