69 rear leaf spring u-bolts

[69bigblock4speed]

On a 69 12 bolt rear-does anyone know what the length is for the 2 u-bolts are that go over the rear end tube and help bolt the leaf springs in place?
Also were they natural bare metal , black paint, or black or grey phosphate coming out of Norwood?
The bolts if my research is correct says they are 7/16 with fine threads?

[68camaroz28]

They were phosphate. Interesting question on length as my originals were shorter than later service replacements. I think I show some differences in my build thread.

[69bigblock4speed]

Yes I saw that picture of your u-bolts. You documentaion of that 68 restoration is amazing. I just can not find any info that states how long original u-bolts were.
You mentioned that the color was phosphate? I assume grey ?
With all the research you have done what color were the rear brake drums coming out Norwood on a 69 ? We all know that the rear were painted black, but did yther really paint the drums black too, or were they natural with Black overspray?

[Pacecar]

Drums were black

[68camaroz28]

Yes I saw that picture of your u-bolts. You documentaion of that 68 restoration is amazing. I just can not find any info that states how long original u-bolts were.
You mentioned that the color was phosphate? I assume grey ?
With all the research you have done what color were the rear brake drums coming out Norwood on a 69 ? We all know that the rear were painted black, but did yther really paint the drums black too, or were they natural with Black overspray?

Gray phosphate and as Pacecar stated the drums are painted black. One way to get a view/feel for lenght is look at how much thread of u bolt is out from installed nut. It's not a whole lot. I have car stored away for winter or would try to get you a ball park length.

[68camaroz28]

Look at post 1409 and note only three or so threads below U-bolt nut.
https://www.camaros.net/threads/time-for-another-68-z-28-to-be-restored.182584/page-71#post-1783182217

[69bigblock4speed]

Thank you

[camaronut]

Not to complicate things, but the Camaro Judging Manual says that the U bolts are black.......maybe a black phosphate?  See page 75 where it talks about the rear springs.  I looked this up because I almost took mine off to make them grey phosphate. 

[68camaroz28]

Not to complicate things, but the Camaro Judging Manual says that the U bolts are black.......maybe a black phosphate?  See page 75 where it talks about the rear springs.  I looked this up because I almost took mine off to make them grey phosphate. 

Possibly, but the book states black for just about anything that was phosphate. for technical "Black" is Manganese Phosphate. I used my originals and they were not Manganese Phosphate. Maybe others were or a different supplier.

[69bigblock4speed]

I wish there was a clear answer. I guess if you are going into Legends to be judged Black it is. So is Black- Manganese phosphate or was it Black zinc? Or are these two the same??

[169INDY]

Use this:
https://www.palmettoenterprisesparkerizing.com/
Manganese Phosphate Charcoal (Black)

Also there are a few factors that affect finish appearance: Surface Prep, Time ins solution, Physical composition of material, Temp of solution, Concentration of solution.

With Both Zinc and Manga you can restore ALL manner of GM Factory Hardware without sourcing Expensive Re-seller or replacement hardware. The set up and care and handling of chemical is paramount to effectiveness and personal safety.  This is one of the BEST restoration "Hack" out there and in the 1980 was not known to many restorers. The quality of restorations has come a long way since 1982 Flat Black spray painted Hardware LoL
 Etc.

[69bigblock4speed]

Yes I Agree. We have come along way since the 80's. But what is better, zinc oxide in Black or the Manganese??

[camaronut]

Personally, I think we're getting a little too crazy on this stuff...LOL!

I mean - I get it ...........but geez!!!

[169INDY]

Manganese (Parkerizing) Phosphate Charcoal (Black)

Zinc (Parkerizing) Phosphating Gray

For the Vendor above  I would use the Manganese, "if" you have some other source that is listing the solution as "zinc Oxide" it should render the similar dark charcoal or black results.  I used Don Dorfmans (ASL) Spark Nevada  "Black Oxide" solution back in the Day when I became aware (1985) of the correct blot preparations

[68camaroz28]

https://www.camaros.net/threads/time-for-another-68-z-28-to-be-restored.182584/page-23#post-1677546
dang I'm losing it! I checked my pics and our original u bolts were dark and I did not re-do them or restore. I would call them manganese phosphate. Sorry for the confusion.
https://www.camaros.net/threads/time-for-another-68-z-28-to-be-restored.182584/page-22#post-1668891

[69bigblock4speed]

Thank you for all of your resonses and time. It is final. Black I believe was the color. Now I will decide to go with Black Zinc oxide or the Manganese route. Thanks again.

[68camaroz28]

Thank you for all of your resonses and time. It is final. Black I believe was the color. Now I will decide to go with Black Zinc oxide or the Manganese route. Thanks again.

Everyone I know including myself use the Manganese Phosphate for the black hardware. Not stating its the best, but know many using the Manganese and have good results. Also, you asked about dimensions and that one link I posted from my build thread gives the dimensions.

[Edgemontvillage]

Thank you for all of your resonses and time. It is final. Black I believe was the color. Now I will decide to go with Black Zinc oxide or the Manganese route. Thanks again.

According to the late John Hinkley (John Z) a former GM engineer at the Norwood OH plant during 1969 production who posted on the subject here, GM didn't spec zinc oxide as a finish as it was not cost effective (one exception he noted was for the 5 panhead screws that attach the instrument panel on the 1967 Corvette). Instead GM spec'd manganese phosphate or zinc phosphate. We use both in our shop and when compared side by side, they are different. Zinc oxide is a true black finish and cures/dries to a semi-gloss whereas manganese phosphate, also referred to as black phosphate (used interchangeably in the Legends Judging Manual) dries to a near flat finish (unless well oiled) and depending on the ferrous content of the metal can appear mid gray to black however typically cures/dries to a dark charcoal. If originality is a goal then phosphating is the correct choice.