Dissection, More Grinding, More Paint, and Shiny New Parts

Been rolling on the progress on the Mustang. On the word of the shop, I went ahead and ordered myself a new differential. Deciding it was time to quit cutting corners I went for the same one we have in the CP Camaro – a Detorit TrueTrac by Eaton. These are a helical gear type differential and they absolutely rock.

This is a sexy piece of hardware and is a fair bit beefier than the factory Ford Traction Lok unit.

Can’t install without a bearing and shim set, this one complete from Richmond. I decided to take the diff to someone different than the shop that did the rest of the work. He’s done the differential in the Camaro at least twice (we’ve changed gear ratios and differentials a few times) and we’ve never had a problem with his work. Only probably is he’s in Madisonville, but that created an excuse to go shoot some trap and skeet with Todd this weekend, so not all bad there!

I hosed down the old housing and parts with some brake cleaner to make sure they were clean and someone less foul smelling for the ride up there. It was at this point that I realized that the differential shop broke one of the cardinal sins of Ford 9″ rebuilding and did not put the carrier bearing caps back on – they were just floating in the box. These are machined per side and matched specifically. In a panic I tried to see if they’d only fit on one side or the other – nope, they fit both. Inside these housings are a threaded bearing retainer to set preload on the carrier bearings. I was able to mix/match parts until I got these to thread into each side. I’m keeping my fingers crossed that this is correct!!!

I started to strip down the leaf springs for paint, they’re looking a little ratty after being on the car for nearly 12 years!

Barely 10 minutes later a wire wheel in my grinder made quick work of the surface rust and overspray.

It’s funny, when you restore an old car you find all sorts of things that you didn’t expect hidden in various places. In video games they call these “Easter Eggs”. I found one of these stripping the springs down.

Nothing too crazy, but it was neat to see the stenciling on the springs that the spring manufacturer had put on the spring back in the late 90s!

A couple of coats of primer and semi-flat black later and they look halfway decent. I wasn’t super concerned with these being perfect, but I did want to at least knock off some of the rust. I also “reclamped” the spring pack with a sledgehammer since some of the retaining clamps had sprung open slightly. Who knows if it’ll last, but at least it should help a little bit.

In between coats, I decided to dissect the Traction Lok and see what was broke, if anything…

The case comes apart easy after two phillips head screws are removed. It probably came apart too easy actually, but more on that later…

Inside the passenger side of the differential are the spider gears. The center mounted square looking piece is actually suspended on 4 springs – this is what provides the tension on the clutch pack.

Here’s the otherside with the other half of the gear pack removed.

The clutch pack is retained by these little clips which come out easy with a screwdriver.

The clutch hub the lifts out with a little assistance from a screwdriver.

Some goo, but no real signs of damage. The clutches look practically brand new.

Then I pulled the whole clutch pack out… When I had the differential repacked, I remember the guy telling me he “packed in tight”. Now I know how he did it, with extras discs and shims. No wonder the axle hopped in reverse and chirped the inside tire on tight corners! For reference, here’s a picture of a NORMAL clutch pack below:

My diff had too many discs in it. Not to mention, I think this messed with the spring tension, because if diff came apart way too easy.

This is a picture from a thread on how to rebuild a 9″. Of course I found this after the fact, but the case certainly wasn’t under any sort of pressure like this, the screws came out and there was no danger of flying parts… This is a really useful link though: How to Rebuild a Ford 9 Inch.

I didn’t investigate too much further, but I think the decision to get a new differential was the right one!

No more work this weekend. Next weekend is Spring Nationals, so stay tuned for some racing updates!

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