Broken ring gear

Frank Miller

Frank Miller

Well-known member
A friend asked me to help him rebuild his rear end after he broke a tooth on the ring gear. I have not seen it yet but would like to know some things to look for to figure out what happened. I cannot see how these gears just break by themselves. Parts are not cheap and we only want to do this once. I usually only check in here in the morning so if you hear nothing right away that's why.
 
Spinning a tire on ice,then hitting solid pavement will break ring gears.It's probably not something he just did,but somebody cracked it 50-60 years ago and it finally gave way.I took one out of a truck that the owner had been driving for years with no problem.One day it just made a clunk,and lots of crashes after that.We took it apart and found one whole tooth broken off.After washing the parts we realized there was just a little section of fresh break,the rest of the break was aged with oil soaking.
 
This one Frank is talking about above was a club member who broke it in the parking lot at the N.E. Meet in Lake George when we where leaving for home. The car was parked on a slight hill and when he went to go it went "BANG" locked the wheels and stalled the motor - every one stop and looked up when it happen. The rear end locked up but we were able to free it by backing in reverse. Loaded it on a club members trailer for the return trip home. I understand that it is now all apart waiting for parts. Keith
 
Keith said:
This one Frank is talking about above was a club member who broke it in the parking lot at the N.E. Meet in Lake George when we where leaving for home. The car was parked on a slight hill and when he went to go it went "BANG" locked the wheels and stalled the motor - every one stop and looked up when it happen. The rear end locked up but we were able to free it by backing in reverse. Loaded it on a club members trailer for the return trip home. I understand that it is now all apart waiting for parts. Keith
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For great help putting it back together look up Tom Endy's 64 page instructions. Fantastic help.
Al
 
Get and follow those instructions. It is far from simply changing parts. Those things that seal the banjo housing are not just gaskets, they are shims. Good luck.
 
Perhaps some other piece broke loose (like a bit of safety wire?) and wedged itself in the ring gear, causing the tooth to break when the car was put in motion? My advice is to tear the whole thing completely apart and inspect everything. Replace the pinion gear along with the ring gear as a set. Check the spider gears and replace them if in question (though they tend not to have much wear as there is normally not that much relative motion between the spider and axle gears) Put in all new seals and bearings. It's a pretty big job so you'd want to do it right the first time.
 
Having actively played with antique cars for about 60 years, I have seen ring gear teeth break off after many years of faithful use. Metal fatigue is usually the culprit. As mentioned above, there was an old oily shadow around where the tooth had been cracked before it finally let go. Metal fatigue results from many years of use where the piece is subjected to hard use. Metal fatigue is not limited to just the ring gear, but all of the stressed parts of the automobile.
 
The transverse rear spring on a Model A Ford can easily bounce the rear wheels off the road when going over a speed bump, railroad tracks, or on a rutted road. During the brief period the wheels are clear of the pavement if you have your foot on the gas the engine will speed up and the drive shaft with the pinion gear on the end will speed up several times the speed of the car and so will the rear wheels. When the wheels reconnect with the pavement something has to give and since there are only a few teeth engaged between the ring and pinion and it can break the teeth off either or both.


When in high school some friends and I were traveling down the road in a 1928 Model A at about 45 MPH when we went over some very rough rail road tracks. The driver kept his foot on the gas and it cleaned off all the teeth on the pinion gear. Moral to the story, take your foot off the gas when going over rail road tracks or speed bumps.


Tom Endy
 
I had a part of a tooth broken on a ring gear along with bad (loose and sloppy) pinion bearings. I believe the bad bearings let the pinion move and get out of alignment with the ring gear causing the damage.
 
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