Tuesday, September 6, 2011

Heidt’s Subframe Connector and 4-link Mount Finishing & 9” Rear Axle Inspection

A lot going on the past few weeks, but I have managed to get some good “Boss time” in between diversions and am looking pretty good as the Fall season rapidly approaches.

I spent a few nights tidying up all of the welds securing the 4-link brackets and subframe connectors and sanding the surrounding areas to get everything ready for primer.  At the same time, I decided to scuff clean a few areas on the inside floor of the car where I noticed a few small spots that had lifted where I had primed over some Zero Rust paint.

Once I was satisfied I had properly prepared the bare metal areas around each weld site, I swabbed everything down with generous amounts of PPG DX-330 Acryli-Clean to remove any traces of dirt, grease or wax and, because I was working around so many seams and flanges, I decided to let the solvent dry overnight to make sure I would not have problems with bleed-out once I started priming.

The following day, I got all my paint equipment locked and loaded and prepped the surfaces with a good wipe with a tack rag.  With fresh primer mixed up in my gun, I shot all of the areas with a nice even coat of primer and followed up with a second coat about 20 minutes later.  I am finding I really like the DP-402 catalyst much better than the DP-401, not only because it’s quicker and easier to mix, but because I think the bond strength and resistance to lifting is better and it seems a bit more forgiving to shoot as well.  I think I have been converted…..

With the priming complete, I was happy with the look of the installation and particularly happy to consider the installation a complete success.  Next, it was a simple matter of flipping the car end-for-end in the shop in preparation for the Fall project of replacing the trunk floor panels, taillight panel and repairing the rear axle tunnel.

Since I had a little Labor Day weekend left, I decided to tear down my rear axle housing to see what horrors might exist in that area as I make preparations to complete the 4-link installation.  Much to my surprise, the damage that I expected (and was, in fact evident) was fairly minimal.  As expected, the third member was not the original to the car, but it is a genuine nodular iron “N-case” 9 inch with 31-spline axles, so it appears I have something to work with.  Unmerciful drag launches took their toll on the spring perches as evidenced by the fact that the leaf spring dowel holes were mangled and the perches showed stress cracks at the root of several welds.  Other than that, however, the housing appears to be the original and will be an excellent foundation for the rest of the 4-link rear suspension.  With a fresh Detroit Locker diff and a set of 3.89 gears along with a Daytona pinion support and new bearings and seals and this axle should be just about bulletproof.

Over the next few weeks, I plan to start the slow process of carefully planning the entire trunk floor repair work.  I’m a bit slow on the planning front, but before long, I will be making sparks again with the hope that the work will flow smoothly until the structural work is finally done later this Fall.
A wire cup brush chucked in my drill was the right tool to clean up the weld areas before priming.  However, I started by breezing all the weld edges with my angle grinder to make sure there were no sharp edges.

The 4 link bracket was most challenging to clean up but everything looked good to go after a few hours of work.

Front subframe connector mounts cleaned up well.

When I welded in the front subframe connector mounts, I scorched the primer on the interior floor just above the weld areas.  Here, I scuffed away the scorched primer with the angle grinder and followed it up with a DA sander to blend the edges.

With the spray gun locked and loaded, the priming could begin!  Here's a front subframe connector fully primed.

I love the fact that the 4-link setup looks so inconspicuous when it's all in one color.  Exactly the effect I hope to achieve when the car is completed.

Interior scorched spots are no more.

Rear subframe connector looks nicely integrated.......just like it belonged there.

9-Inch Rear Axle Teardown & Inspection

A genuine 9" nodular iron third member.  Not original to the car based on the date code, but genuine nonetheless.  Something to work with.

Brutal drag race starts have mangled the leaf spring dowel locating holes beyond use.  Fortunately, I will be cutting these off the housing soon.

The opposite side spring perch is equally hosed.

If you look closely at the root of the welds in these two pictures, you will see small stress cracks.  Another sign of a hard life.

Axle housing flanges look excellent.

I am pretty sure the housing itself may be original to the car.  It is in surprisingly good shape considering it's hard life and will be a great foundation to finish the rear suspension.