[geeteeohguy]

Waiting for Ol' Pinionhead to give the final say on these. Yeah or nay?

[71 Goatman]

Installed one set of used gears in a 68 Firebird for a friend. Horrible gear whine after all that work. Learned my lesson. But once, cry once…..Spend the money get a new set of gears and don’t look back. Certain parts are just fine used, for me a ring and pinion is not one of them.

Just installed a fresh set of 3.73’s in my 71 GTO, went in well and no gear whine whatsoever, Richmond gears.

Just my .02

[SD421]

Could it be residue from the parts being on a shelf inside a bldg in the dirty desert air?
I got these from Frank’s Pontiac Parts. Located in Twenty Nine Palms

[PontiacHO]

Agree with others concerning rough gear surface. If that’s a Chevy style 12 bolt .030 to .035 pinion shim is where I’d start. Backlash at .008. You’ll probably only achieve a decent pattern on one side with used gears.

[Formulas]

OMG clean it up see what you have, spray it with WD40 wipe tooth faces aggressively with a rag / tooth brush to remove loose particles then spray it all down with carb cleaner

No amount of pictures on the internet with people guessing on condition error'ing on the side of caution are going to be able to tell what you will be able to see with your own eyes once cleaned

[Formulabruce]

Originally Posted by b-man

Definitely media blasted to hide defects.

Looks like the ring gear is still dusted with blasting media.

No set of used gears should like like those ones pictured.

Factory / parts counter gear sets were LAPPED after milling. ( only done on high quality sets now a days) The lapping process did NOT leave a smooth surface, it is grit after all. Once lapped, they then Parkerized the set for protection.
When you set up a original set from the 60's and 70's you get a Much wider and fuller gear pattern on the teeth proving the contact amount of the gears. These days you are lucky to get a good football pattern with most replacement gear sets.

[b-man]

Set of used 8.5 GM 3.08 gears I recently purchased here in the classifieds, said to have about 2k miles on them.

[Formulabruce]

look good, and look much newer than that 1970 set.. I just tossed 2 new "us standard" 3.08 sets due to piss poor patterns .

[b-man]

Hopefully they’ll be fairly quiet after setup, replacing the 2.56 open 8.2 with a 3.08 factory posi 8.5 in the near future.

I just don’t spend enough time running the freeway at 75+ enough to justify the 2.56 cogs, most of my driving is at around 50 on our main road through town and in the local canyons. I don’t think my Tri-Power 068 cam 421 really likes being below 2000 rpm 90+ percent of the time, although it does drive nice and smooth.

I’m running 1700 - 1800 at around 50 and I’m thinking at 2000 - 2100 rpm it would be more efficient and would definitely make the car more fun.

[blueghoast]

Originally Posted by SD421

Could it be residue from the parts being on a shelf inside a bldg in the dirty desert air?
I got these from Frank’s Pontiac Parts. Located in Twenty Nine Palms

I'd run them without a second thought.

GT

[Formulabruce]

3.08 is a great ratio. I measure the pinion gear thickness, so no reference number on top is fine with me.
New Posi or used?
New posi units ( Eaton style or the Corp style ) both now have Carbon Fiber clutches. That means NO Synthetic oil , NO synthetic additive.
I have seen people burn up a new posi pretty quick with "the best oil", which isnt what it needs..
Problem is Older posi that needs a set of steel clutches is $$$$ money, as much as buying a while posi carrier.
just some info if you dont know already...

[b-man]

It’s a factory posi in good working condition. The car is just a cruiser that’s not really driven hard with skinny 215/75/14s all around so I’ll roll the dice and run the used posi as-is.

[71 Goatman]

Originally Posted by Formulas

I dont see anything disqualifying i will just say its measurably harder to set up used gears not knowing previous backlash but doable

Agreed, after trying and failing in the past with used gears, only to get nothing but howling I now only purchase new. Replicating the previous backlash is a challange.