I have seen some old threads where the repo pinions split. There was talk about where the keyway was machined (not in the valley between the teeth, and the parts being over hardened.
Glenn Chaffin had done much of the investigation / root cause on the bad ones, if he or anyone that knows could chime in as to if / when they were fixed and how to identify them, I would appreciate it.
I'm running a set from Langs that I got about three years ago and the bolt holes were in the correct location relative t the teeth on the ring gear and the keyway was incorrect position. I've got about 2K miles on them so far. What you have to watch out for is the new drive shaft. Check the location of the ujoint pin hole. If it isn't right, let them know and send it back.
Yes, they're OK now. It was a batch around 2007 from Mark Auto that was faulty - or maybe some were good, the pinion key had a random location relative the teeth and that means they're mostly in a wrong position..
The batches since then have been good.
Here's an example from the bad batch, the edges of the keyway are between teeth:
Here's a good pinion - the keyway edges are both under a tooth = more material in between that keeps it from breaking:
One of the improperly cut pinion gears was installed in my touring in 2007 when my rear axle was rebuilt. In 2010 that gear broke in half when I was pulling away from a stop sign on a hill. It was the repro rocky mountain brakes that save my wife and I from getting hurt. The next pinion gear was cut correctly as I made sure when I fixed that rear axle.
Today you need to watch out for the axle shafts. I had a repro break that was installed in 2012. One broke in half and the other was heavily worn. Both had less than two thousand miles on them.
Since driveshafts were mentioned above I'd like to add something. The new repro shafts are still slightly undersized as well as the universal locking pin hole being off. I purchased one of those from Lang's and they took it back with no problem. Great supplier! I use them almost exclusively
John Regan made an initial run of driveshafts that are truly made to Ford specs. The shaft is perfect in every respect, everything fits as it should. A NOS Ford script universal joint slips on and fits perfectly. I don't want to speak for John here but he may end up making more of these. If he does your driveshaft problems are over. I'm sure Lang's is tired of getting the other problem shafts back and having to contact their supplier to get reimbursed.
Way back, I think Mark Auto Company in Layton, N.J. made them.
Not a Ford made Factory part???
Can you say "SPURIOUS"?.........Sure you can!
not being what it purports to be; false or fake.
"separating authentic and spurious claims"
synonyms: bogus, fake, false, counterfeit, forged, fraudulent, sham, artificial, imitation, simulated, feigned, deceptive, misleading, specious; More
"an attempt to be excused due to some spurious medical condition"
(of a line of reasoning) apparently but not actually valid.
"this spurious reasoning results in nonsense"
(of offspring) illegitimate.
I used one in a friend's car and it split at under 100 miles. It was marked "MARK USA".
When did that happen? Yesterday? 5 years ago? Trying to get an idea on the quality of the current offerings.
Sorry I did not give a date. I did this about 3 years ago, but he did not drive it until now when the pinion broke. The one I just ordered was not a "Mark's" and I assume it is better. Also, Stan Howe recommended making sure the woodruff key is not too tall as that can cause problems as well.