[SD421]

I just picked up these 3.07 gears to swap out my 3.73’s for a more friendly rpm range.
Can someone look at these pics and tell me what you think?

I picked them up for $150 as they were listed in “great condition”.

Thanks, Don

[Formulas]

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

[Schurkey]

Does the "2" represent pinion depth variance?

If not, getting pinion depth right will be a guessing game, which is going to make getting the mesh correct even more difficult.

[SD421]

Originally Posted by Schurkey

Does the "2" represent pinion depth variance?

If not, getting pinion depth right will be a guessing game, which is going to make getting the mesh correct even more difficult.

I haven’t a clue about the 2 stamped on the pinion.

[lust4speed]

Photo #2 looks like the ring gear teeth are galled but I don't see corresponding look on the pinion teeth. Are those teeth as rough textured and pitted as the picture makes them look?

[SD421]

Originally Posted by lust4speed

Photo #2 looks like the ring gear teeth are galled but I don't see corresponding look on the pinion teeth. Are those teeth as rough textured and pitted as the picture makes them look?

Here is a different section of the ring gear and a pic of the backside of the pinion.

[steve25]

What the hell are all the punch marks on the face of that gear?

[AG]

The pinion depth is designated by a 2-digit code for that 12-bolt ranging from 40 to 50. A 45 designates a specific depth (can't remember what it is, have it written down) and numbers below subtract 0.001" per increment and digits above add 0.001" per increment. It can be stamped into the tip of the yoke end. I just checked a 3.07 12-bolt pinion and it is written (grease paint?) on the face of the gear on the bearing side and is a "45".

[Schurkey]

Originally Posted by steve25

What the hell are all the punch marks on the face of that gear?

If it's anything like the similar marks on my Lumina camshafts, it's how they hold the part securely when performing the machining operation(s).

[srmmmm]

Originally Posted by SD421

I just picked up these 3.07 gears to swap out my 3.73’s for a more friendly rpm range.
Can someone look at these pics and tell me what you think?

I picked them up for $150 as they were listed in “great condition”.

Thanks, Don

Not impressed with the tooth face surface in photo#2. The wear pattern is even and covers most of the face indicating proper pinion depth setting, but the pitted surface tells me there were fluid issues from heat, contamination or probably dirt. The 2.73 that just came out of my rear end after 164,000 miles had same wear pattern, but the tooth faces had a polished finish to them.

[geeteeohguy]

Originally Posted by srmmmm

Not impressed with the tooth face surface in photo#2. The wear pattern is even and covers most of the face indicating proper pinion depth setting, but the pitted surface tells me there were fluid issues from heat, contamination or probably dirt. The 2.73 that just came out of my rear end after 164,000 miles had same wear pattern, but the tooth faces had a polished finish to them.

I agree. I've had these opened up with well over 200,000 miles on them, and the gear teeth are as smooth as glass. This is with in-service rear ends on these cars (ones I've owned and customer cars). This looks like rust pitting or contamination. The teeth look rough. Can you feel the surface pits with your fingernail? Or is it just visual.

My opinion: the gears can be used, but may be a bit noisy. They are not 'junk'. You may not even hear them over the exhaust being dumped out of your Tribal Tubes from that tripower 421 you're packing.

[SD421]

Originally Posted by AG

The pinion depth is designated by a 2-digit code for that 12-bolt ranging from 40 to 50. A 45 designates a specific depth (can't remember what it is, have it written down) and numbers below subtract 0.001" per increment and digits above add 0.001" per increment. It can be stamped into the tip of the yoke end. I just checked a 3.07 12-bolt pinion and it is written (grease paint?) on the face of the gear on the bearing side and is a "45".

No stamp on top of pinion but there is a “K8” Stamped on the body and maybe the green mark used to be the code?

[SD421]

Originally Posted by geeteeohguy

I agree. I've had these opened up with well over 200,000 miles on them, and the gear teeth are as smooth as glass. This is with in-service rear ends on these cars (ones I've owned and customer cars). This looks like rust pitting or contamination. The teeth look rough. Can you feel the surface pits with your fingernail? Or is it just visual.

My opinion: the gears can be used, but may be a bit noisy. They are not 'junk'. You may not even hear them over the exhaust being dumped out of your Tribal Tubes from that tripower 421 you're packing.

It’s just Light rust

[694.1]

Buff that light rust with 400 grit.

[AG]

Originally Posted by SD421

No stamp on top of pinion but there is a “K8” Stamped on the body and maybe the green mark used to be the code?

In your third pic where it focuses on the snout of the pinion is where it is supposed to be stamped. If you look straight down onto the face of the gear below the gear is where mine is marked "45". I also have a 2.56 pinion from 1972 and I'll check that one to see where the number is.

[geeteeohguy]

Originally Posted by 694.1

Buff that light rust with 400 grit.

I respectfully disagree. Maybe some 0000 steel wool at most. Never use sandpaper or emery cloth on a gear surface. At least I wouldn't.

[KEN CROCIE]

My first impression is the gears were media blasted to hide defects.

[lust4speed]

Yep. Took out the rust and left the pockets.

[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.

[geeteeohguy]

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.

I missed that looking at the pics. Like a Gilbey's gin bottle....the gears are frosty looking rather than shiny.

IMO, they will work but they will probably be noisy. I don't like ANYTHING bead blasted. I've seen more ruined carbs, engine cases, valve covers, you name it. Once it gets 'frosted' there's no going back.