What caused the "scratches" along this pinion gear surface? I can feel them with my finger nail. Also, what is the cause of the rusty looking area on the aft end of the gear faces? This gears twin is listed on eBay.
Here's my take. The scratches on the outside diameter are from the gear blanking process back in the day. As well as the vertical lines seen in the picture. Gears are hobbed and this is the remnants. Ford in my opinion have very low or little quality control back in the day plus the metal wasn't the best.
The pinion gear out of my diff looked the same.
Would this be a little used gear since the vertical lines are not worn smooth?
The area with the "scratches" (actually rough machine tool marks) is actually never in contact with anything. So it does not wear.
Guess I wasn't clear, the marks I am asking about are the vertical ones on the gear surfaces not the horizontal ones on the gear edges.
That is a miter gear. It is not made on a gear hob. That is normal for the day and the material is very good stuff. T rear ends do not have the pinion supported like the later v-8 rear ends. The fact that they live as long as they do shows how good the material is. A gear hob makes very nice gears as does a gear shaper. But a miter is a different cat. Scott
So is this a good gear and the marks just artifacts from the mfg process?
Yes, I think so. Usually the pinion gears holds up well, but ring gears are rarely any good out of an unknown used rear axle. Thus, if you have to change out the ring gear, you may want a new pinion anyway since you don't want to mix gears with different wear - and new ring gears are sold in sets with a pinion.
Jim, that is an excellent pinion gear. I would much rather use that one than any of the new reproduction gears available. If you go down Roger's suggested track and fit a new pinion and ring gear, can I have your old one?
Roger is correct that the vendors do sell ring gears with new pinions. However, they are not a matched set like you get with later hypoid gear sets, so they do not necessarily need to be fitted together. Indeed, Chaffin's offer a range of different pinion gears to mate to existing ring gears.
It is advisable to fit new gears as a pair, to give yourself the best chance of having a reasonably quiet rear end. But I would have no hesitation mating your pinion up to a new ring gear.
Hope this helps.
Allan from down under
This is what you call a marriage. After all these
years you now have a matched set. Most likely got
that way in its "first days" I doubt very much,
machining perfect matched sets was'nt on their mind,
volume production was. Look at it this way, your
great grandchild will never find a computor control for a 100yr old Crown vic will they?
Nice gear. Most likely it will have a Ford script on the back side. Those lines you are concerned about are just the factory machine marks. Don't worry about them.
Looking at the wear pattern on that gear indicates that it is a very good used gear.
Pinion gears are harder than ring gears and good used pinion gears are easy to find.
Finding a good used ring gear is the challenge, however if you find one, and you set up your axle correctly, it may be noisy when first run, but should quiet down significantly in 5-10 miles of use. If it does not, then it is probably as quiet as it will ever be. If any rear axle noise gets louder, then there is a possibility you may have done something wrong, or have another issue in the rear end or drive train.
A miter gear is a gear that is meant to mesh with another gear of the same number of teeth and with shaft centerlines at 90 degrees to each other. Bevel gears are used in a pair where each gear has a different number of teeth. Model T's use bevel gears. (Yes, it's a fine point.)
Yes Jerry but I was keeping the can of worms smaller. Most folks are not up to speed with the different types of gears or how they are made.
Thanks for keeping me straight. Scott