[njsteve]

A 3.42 posi out of an 80 Trans Am.

[njsteve]

Here's the link to the online version of the Hemmings Muscle Machines article.
http://www.hemmings.com/magazine/mus...d/3749604.html

[njsteve]

Well it's a little slow around here so I decided to take apart the front suspension on Gramma's car. At 80,000 miles I figured that it was about time. It's always the annoying little stuff that takes the longest...like getting 42 year old cotter pins out. UGH! Or removing the upper control frame nuts and then discovering that the upper control arm won't come off if the engine is there. rolleyes So, I had to tap the knurled bolts back out of the frame so the upper arms could come out.






Here's the pile of greasy old parts:

[njsteve]

And here is the problem for the day. I noticed that the driver's sde lower ball joint nut was really easy to remove (after spending 30 minutes getting the fused cotter pin out). When I turned the spindle to get clearance I noticed that it moved on a strange arc instead of on a normal pivot.

Well here is the reason: the original lower ball joint stud had been loose for who knows how many decades and it completely oblonged the mounting hole.

Does anyone have a spare driver's side second gen Camaro or Firebird spindle they want to get rid of?

[njsteve]

And here's another glitch. It seems that the factory had some issue over the upper control arm bushing nuts coming loose so they tack welded the front driver's side nut on. I have seen this on other 1975 cars. It is only on the front nut of the driver's side.





The passenger side does not have the tack weld but does have a different lock nut on the rear of the stud.

[njsteve]

Well, the plot thickens. After perusing 42 years of old receipts it turns out that the Midas Muffler Shop my brother took the car to, replaced the driver's side spindle about 30 years ago when they did a brake job....and they used a 1978 spindle, and didn't bother to fully tighten the ball joint castle nut. Hence the "D58" date code on the spindle and the noticeably lighter duty casting than the passenger side spindle which is a 329354 spindle dated "G25". So I guess I need a 329353 spindle in case anyone has one sitting on a coffee table somewhere. I believe that this spindle was used on just about every disc brake GM car from 1970 to 1976.

Driver's side 1978 spindle:



Original 1975 passenger spindle:

[The Boss]

Why is Grammy's car wearing out spindles - that's two in 80k miles?

[njsteve]

I think Midas damaged the original spindle's threads back in 1987 and replaced the spindle on our dime. They then neglected to tighten the lower ball joint to spindle nut so the stud then wallowed out the mounting hole of the replacement spindle after 30 years. (Which was only around 5000 miles since 1987).

[Norwood]

I had a 75 Formula and I sure don't remember that nut being welded. I would think that if Midas screwed up the threads on the spindle a much easier fix would be to just run a thread die down the threads

[njsteve]

I've had several people comment so far that they had the same weird welded nut in that same position on various year second gen cars. Anyone ever run across a TSB on this topic?

[njsteve]

Originally Posted by Norwood

I would think that if Midas screwed up the threads on the spindle a much easier fix would be to just run a thread die down the threads

I'm just guessing at the reason but it was there in the work order under parts replaced, along with the rotors and wheel bearings, etc. So maybe a bearing went bad and scored it. (Then again, they were notorious for "making work" and making you pay for it, back then)

[Held for Ransom]

Service bulletin

[njsteve]

WOW! Amazing find! You are some detective, Sir.

Any idea why this was done in the first place? Were they afraid we would tamper with the control arms? - kind of like the tamper-proof idle mixture caps on carburetors in the late 1970s.

[Formulabruce]

We were told it was done in Sub because the QC did Not like the threads, or nuts used on some of the Upper control arm pivot arms. ( more than likely it was substitution nuts ) This was done at Sub Assembly , and Not on the assy Line.

[Held for Ransom]

Originally Posted by njsteve

WOW! Amazing find! You are some detective, Sir.

Any idea why this was done in the first place? Were they afraid we would tamper with the control arms? - kind of like the tamper-proof idle mixture caps on carburetors in the late 1970s.

Started in '74.

[Scarebird]

What size are the front wheels?

This may be a good time to step up to 12" 1LE rotors in front...

[njsteve]

17 inch. I am upgrading the springs with a set made by www.coilsprings.com. They made the springs for my old black 1972 455HO Formula. They build them to spec and can do whatever height drop you want. I ordered a 1" drop on the black car and it was the perfect match to factory height.

[Scarebird]

Excellent. The spindles needed would be far easier to find than 70-73 F units and would fill the wheel better than 11" disc.

[njsteve]

I'm not doing drop spindles. I am ordering springs with a one inch lower installed ride height just to get to a stock ride height. (from prior experience, if you order the factory spec springs, the springs make the car sit like a 4x4).

[Scarebird]

Steve, this would not drop the car at all - the only differences are they use a bigger rotor and the outer bearings, ball joints and tie rods are different. The caliper remains the same as does the dust shield and hoses.