A little fun yesterday - ring gear bolts came out!

[James_Douglas]

Yesterday coming home from a car show a very loud bang followed by a very loud "thump, thump, thump..." happened.

It took a hour to do a 15 minute trip at 20 MPH.

I had thought a rear wheel axle bearing had gone bad. Turns out that two of the 12 ring gear bolts failed. The steel bend over retainer came out with two bolts.

Why? who know. The car is 5000 pounds and with six people in the car and running along at 70 MPH...It just failed.

The ring and pinion looks not too good. The bolts got in between the ring and pinion.

This is for a Large Wheel Base Desoto (LWB) and is the same as the Big Chrysler 8, the Town and County, and all the Chrysler, Desoto, Dodge, and Plymouth Limo's and Taxi's.

Anyone out there have a 4.11 ring and pinion in good shape for the LWB chassis ?

Thanks, James

[TodFitch]

Ouch! I hope that it was not raining too bad during that too. It poured at my house just after I returned home.

I don't have a DeSoto parts book, but the 1930s long wheel base Plymouths used part 308282 which is the same number as used on the later 1930 30-U Plymouths through the P1 and P2. P3 and up non-long wheel base Plymouths used part 663481. It might be that your car uses the same bolt as my 1933, but I don't have spares... And I don't have a cross to a modern equivalent.

[JerseyHarold]

Did you try looking in Section 18 of the parts book (standard parts)? It gives the specs on various fasteners and may make it easier to track down a replacement.

[desoto1939]

According to my Mopar parts book:

for Desoto

1937 - 40 With overdrive 4.3 ring gear and pinion set 865690 new # 1192395

1937-42 without OD Std trans 4.1 664392 new # 1192394

Also Dodge 46-50 Std Trans without Fluid Drive 664392 or 1192394

1942 Ply also

Chrylser 37-40 without oD same numbers

Check Ebay for these I see them on there sometimes

Rich HArtung

desoto1939@aol.com

[TodFitch]

Did you try looking in Section 18 of the parts book (standard parts)? It gives the specs on various fasteners and may make it easier to track down a replacement.

The part numbers in the "standard parts" section range from 100021 through 193460. All of the numbers posted on this thread are well outside that range. So these were not standard fasteners but ones specifically designed for the application.

[Gary Manes]

James,

Some screw sizes have not been made in years. The parts books will show the size. Go to a good fastener shop and see what they have.

I had fits trying to find the screws for the exterior door handles. Went to my neighborhood shop, and the owner told me immediately that those screws had not been made since 1962. He is an older fella, and knows his merchandise.

Which brings me to the machine shop approach. You may have to have some made--that is if the running gear, etc. is salvageable.

Maybe I was lucky but the last time I was looking for some rearend parts there were several for sale on e-bay. As a last restort, check with the salvage yard in South Dakota that specializes in old Mopars. Can't remember the name of the company, but they have expanded into other makes more recently, but originally were MOPAR only. The problem was their prices.

They have just about everything, but you will have to pay for it. I'll try to recall the name of the yard, and post it later for you.

[Gary Manes]

James,

There could be a number of possible sources for rearend parts for you, but I can just about guarantee these folks have what you may need.

One of the few things I recall is that even for the big rearend there were at least two ratios available--one low and one for cruising. Keep that in mind as you are shopping for replacement parts.

www.mooresautosalvage.com

[James_Douglas]

I have two extra rear ends. One a 3.91 and one a 3.36. I cleaned up the 3.91 and am putting it in. Desoto used a 3.91 during the first few months of production of the Suburban. I think that went to 4.11 because of the weight. I will take my time, assuming the 3.91 works and find a new set of gears for the 4.11. Mine are about shot. Then I will have the old pumkin rebuilt. I will get a set of ARP bolts for the ring gear during the rebuild. If too long, I will put them into my lathe and cut them down.

I will know by this evening if the 3.91 is working. Wish me luck.

James

[TodFitch]

I have two extra rear ends. One a 3.91 and one a 3.36. I cleaned up the 3.91 and am putting it in. Desoto used a 3.91 during the first few months of production of the Suburban. I think that went to 4.11 because of the weight. I will take my time, assuming the 3.91 works and find a new set of gears for the 4.11. Mine are about shot. Then I will have the old pumkin rebuilt. I will get a set of ARP bolts for the ring gear during the rebuild. If too long, I will put them into my lathe and cut them down.

I will know by this evening if the 3.91 is working. Wish me luck.

James

I think you are careful and thoughtful about how you approach technical issues on cars. Seems like that mitigates the need for luck.

Regarding bolts for attaching the ring gear: The 1920s and 30s automotive trade magazine made a big deal about how ring gears should be riveted in place rather than bolted. The reason given was that the shank on a rivet expanded as the head was set and that took out all clearance between the fastener (rivet) and the holes in the ring gear and carrier. My take away from that is that the shanks on bolts used to hold the ring gear in place are probably manufactured to much closer diameter tolerances than generic bolts. Since the numbers for those bolts are not in the standard parts list it makes sense that they are different from generic bolts in some way and I'm guessing that it is a combination of hardness and close tolerances on shank diameter.

[desoto1939]

here is some ring gear info

Rich HArtung