James_Douglas Posted October 18, 2021 Author Report Share Posted October 18, 2021 I guess it all depends on what your car comes in at weight wise. My car is like 4500 to 5000 most of the time. Divide that by 120 HP on a good day and... With the BW overdrive I am hopeful that the 4.3 will be ok to live with. The 3.91 has been great in town as I can run in second gear and second OD all day. No shifting in town. But on the larger hills pulling up a grade it struggles. I either need about 30 more HP or numerically higher gears for long grades. I will take some good notes on the ring and pinion work and post it at some point down the line. James Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 18, 2021 Report Share Posted October 18, 2021 I copied this from somewhere a long time ago..Don't know whether it would help you. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 19, 2021 Author Report Share Posted October 19, 2021 Thank you, I have had that chart for 15 years or so. But, if you read my comments you can see that the issue is studs versus bolts and no wiggle room to move the flanges in to account for studs. A rear end swap will do nothing to solve that problem. James 1 Quote Link to comment Share on other sites More sharing options...
wayfarer Posted October 19, 2021 Report Share Posted October 19, 2021 (edited) ...who says that you can't drill and tap the flange for screws? And a sleeve/spacer could be made to hold the wheel whilst inserting bolts. ...or you could buy the Suburban than I have for sale and...... Edited October 19, 2021 by wayfarer Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 21, 2021 Author Report Share Posted October 21, 2021 One could in theory drill and tap an aftermarket axle for lug bolts. The issues are the depth of the flange and the material. When I talked with a couple of the after market axle folks none of them were willing to do it as none of them thought the flanges were deep enough to deal with the fulcrum length of lug bolts. The studs have the flange on the back which distributes the loads over a larger area. I also thought about making a threaded ring of the appropriate steel material for repeated lug screwing but it may get in the way of breaks or other things. Again a lot of engineering after I have spent the money on a rear end and not knowing it will all work before I spend the money. In the end, a $4K custom ring and pinion gear would be a better bet... As an aside, on the rear disc conversion on the '49 I machined a nice little mounting stud that went into one of the removed drum rivet holes and bolts in place. Works nice. James Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 23, 2021 Author Report Share Posted October 23, 2021 Interesting... So, I got my 4.3 to 1 ring and pinion NOS set and they look fine. I wanted to get one more carrier, the thing the ring gear bolts to, as one of mine is bad as I said above and the other is for the 3.3, 3.5 and 3.7 gears. The 3.9, 4.1, 4.3 and 4.5 use a different one. What is interesting is that I called up to my bone yard guy and he is pulling one off of a Limo in the yard and it is 4.3 to 1. What is odd is that a 4.3 does not show up in the Desoto Master Parts Book. It does on the 1946 Chrysler Master Parts book, but not the 1946 to 1948 Chrysler roll up nor the 1954 roll up. *********** The thing today is that my bolts came in from Winters Performance. The ring gear uses a 3/8-24 right hand thread that is about 1 inch long. I called ARP and they said they make a bolt for Winters Performance that is 3/8-24 right hand thread for their fancy rear-ends. I confirmed the length as they make two bolts one a hair longer then 1 inch and one a little shorter. I ordered both and they both come with the ARP washers with the cut side for the curved root of the bolt shaft. I had to order through Pete and Jakes as Winters does not process via CC over the phone or internet. What did bite me in the ass this morning when I has the bolts on the bench is that their shaft is NOT 3.75 but .381 inch...urgggg So, I had to order a 9.7MM (.3818 inch) drill bit and will have to drill the 12 holes in the carrier for the bolts to slip through. So much for getting it done this weekend and I busy for the next week. As a caution to everyone. A factory bolt in my Suburban that was 4.11 failed. When I took it apart a couple of weeks back it only had 4 or 5 bolts holding it on. All the rest had failed or were failing. When I took apart the 3.91 that I have been using the last 6 years the bolts WERE NOT PARTICULARLY TIGHT. Also, I stripped the 3.36 rear-end and their bolts were not very tight. All these rear-ends came from different cars and I can tell by the bend over tabs they had not been touched since the factory. What this means is that these bolts get loose with time and/or the bolt material was not up to the torque needs. In any event, I do not know off the top of my head if the regular rear ends used the 3/8-24RH one inch bolts; but if they do then all are suspect with age. I will swing back when I get the thing together in a couple of weeks and post the result or any issues. James Quote Link to comment Share on other sites More sharing options...
Sniper Posted October 23, 2021 Report Share Posted October 23, 2021 One other possibility, however remote, was that they weren't properly torqued at the factory. 1 Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 24, 2021 Author Report Share Posted October 24, 2021 23 hours ago, Sniper said: One other possibility, however remote, was that they weren't properly torqued at the factory. On three different cars... The rear-end pumkins were in fact made by Dana. I do not know if Dana made the entire rear-end and just delivered them or if they delivered parts like full pumpkins and Desoto assembled the rear-ends. In any case, I suggest that people may want to check the ring gear bolts at their next opportunity. If the ring gear shifts even a very little bit...it will toss off the ring and pinion mess. The MOPAR service books state that "as little as .002" will cause the rear-end to make noise and wear prematurely. James Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 24, 2021 Report Share Posted October 24, 2021 When I was doing the R&P on my 1992 Dodge Dakota the instructions said to use red loctite on the bolts holding the ring to the carrier. Other directions were to use an arkansas stone to plane around the bolt holes before mounting, also to check carrier runout. Need to go to my other computer to post pics. Quote Link to comment Share on other sites More sharing options...
Sniper Posted October 24, 2021 Report Share Posted October 24, 2021 7 minutes ago, James_Douglas said: On three different cars... I know, but the implication here is that the factory did something wrong. If those bolts are loosening up then somebody did something wrong. Either under torqued compared to specification, improper torque specification to begin with, design issues, materials choices, who knows. So I did some digging, based on my 51 Plymouth. FSM calls for 35-40 ft/lbs. Parts manual says it's a 3/8-24, no grade given, nut is cadmium plated. Generic max torque specs would be 35 ft/lbs for grade 5, 49 ft/lbs for grade 8. So that is in the ball park. Guess that is why aviation uses safety wire, lol. https://www.aircraftspruce.com/catalog/hapages/drillnutsnas509.php Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 24, 2021 Report Share Posted October 24, 2021 Back on my laptop.. here's a link with same problem..https://www.pirate4x4.com/threads/ring-gear-bolts.791979/ I also found when I was torqueing my carrier caps and following the manual, there is a BIG difference between dry engineering torque specs and already lubricated bolt specs. Kept shaking my head at 100 ft/lbs in the book...the bolts were stopping at 60..glad I didn't snap them.. Here's pics of me honing the bolt holes..shiny crescent was high. Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 24, 2021 Report Share Posted October 24, 2021 Also with bolt holes on my Dakota new carrier, there were 2 sets of Ring gear holes. One for large bolts and one for smaller. Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 24, 2021 Report Share Posted October 24, 2021 Reduced Torque with Lubricated Bolts (engineeringtoolbox.com) and Bolt Torque Chart (repairengineering.com) Quote Link to comment Share on other sites More sharing options...
JBNeal Posted October 24, 2021 Report Share Posted October 24, 2021 Something I have seen from alloy bolts of this vintage is their threads can distort, which can account for the small variations in bolt length over time and load cycles. This distortion, in effect, stretches the bolt, so that it has yielded but not failed. As the bolts continue to yield from loading, the possibility for failure increases. As alloy technology has improved over the decades, the frequency of these types of failures has declined. However, in recent years, fracture failure frequency has increased because of quality issues from foreign sourced fasteners *cough*CHINA*cough* So if it's not one thing, it's another 1 Quote Link to comment Share on other sites More sharing options...
Sniper Posted October 24, 2021 Report Share Posted October 24, 2021 ARP to the rescue I guess. https://arp-bolts.com/kits/bulk.php?PL=1&M=2&W=*&D=3&P=7&WS=8 and https://arp-bolts.com/kits/bulk.php?PL=100&M=*&W=*&D=3&P=*&WS=*&B=1 Quote Link to comment Share on other sites More sharing options...
Bryan Posted October 24, 2021 Report Share Posted October 24, 2021 3 hours ago, James_Douglas said: On three different cars... The rear-end pumkins were in fact made by Dana. I do not know if Dana made the entire rear-end and just delivered them or if they delivered parts like full pumpkins and Desoto assembled the rear-ends. In any case, I suggest that people may want to check the ring gear bolts at their next opportunity. If the ring gear shifts even a very little bit...it will toss off the ring and pinion mess. The MOPAR service books state that "as little as .002" will cause the rear-end to make noise and wear prematurely. James Uh, I could believe that. My son works in a factory where they manufacture clothes washers..you don't see a mistake on one machine..usually the new guy has done + 100 of them before it's caught.. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 25, 2021 Author Report Share Posted October 25, 2021 The bolts I got from Winters Performance are made for them by ARP. I have to decide if I want to use the bend over metal locks or use locktite on the threads or both. ARP told me to use their assembly lube on the upper shaft and special washer and snug them down. Then one at a time in a cross pattern remove a bolt and put a couple of drops of locktite on the threads put it in and torque it. The pull another one and do the same...until done. The bolts are 12 point and I will need to get a 3/8 inch 12 point for my 1/2 inch drive torque wrench. Also, a 9.7mm drill bit (3.818) is on its way to open up the holes in the carrier from .375 to .381 which these bolts require. The stock 3/8 bolts are a little sloppy in their holes, not much but not a precision fit. Let hope I can do better. James Quote Link to comment Share on other sites More sharing options...
Booger Posted October 25, 2021 Report Share Posted October 25, 2021 I have a 10 bolt 3.54 pumpkin laying around. 15 spline axle Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted October 31, 2021 Author Report Share Posted October 31, 2021 So....I am in town for the weekend and I started to trial fit the 4.3 ring gear. I drilled the cracked carrier (for testing) to .003 over the ARP bolt shaft size. Just enough so it will slip through the hole. I then tried to mount the ring gear. No Joy. I then took one of the carriers that I had not drilled and measured some of the holes. They are all about .010 over the shaft size of the factory bolt. Ok, they used 10 thou clearance. So I drill the holes out on my test carrier so I have 10 thou of clearance over the ARP bolt shaft size. They go in but VERY tight to turn. So tight it will affect the bolt torque. Now I am wondering what the hell is going on. Is the new ring gear threaded holes not EXACTLY perpendicular? So I mount it on the carrier I have not drilled yet (the one I will ultimately use) and it fits and the factory bolts go in without it being a chore. So, what IS going on? After studying it for a while I figured it out. It also may explain why, if you have followed my thread, why the factory bolts were not tight on all three of the units. The factory bolts have a very small shoulder that is not threaded. In fact that shoulder is so small it may not even index much into the carrier when the steel locking plate is on the thing. So, the threaded section is what is "indexing" in the carrier hole. Threads are notorious in such situations as pounding down with the loads and a close look at the old bolts shows this is what is going on. It is on the order, the best I can tell, of .005 to.009 or so. I used a new bolt by comparison. So, what this means is the ARP bolts with a deeper shoulder that index fully with the carrier hole do not want to "move" to deal with any ring gear threaded hole alignment issues like the factory bolts did. So, I will have to drill or ream in .001 increments until the bolts will go down without creating any side loading that would toss off the torquing of the bolts. Now that brings up the first issue...the factory bolt failure and the loose bolts on the other units. I suspect that the ring gears are moving due to the threads pounding down over time and if it goes on long enough...loosening of the ring gear and then failure of the bolt. I can tell you that Winters Performance has two bolts with two different shoulder lengths that exactly match the hole in their carriers and I know that Currie has special bolts for their 9 inch Fords. I suspect that a fully indexed ring gear bolt is a good thing and one in which the threads are in the mating hole is a bad thing. A long wonky post for sure. I will be back at it next weekend and see what I get. James Quote Link to comment Share on other sites More sharing options...
Sniper Posted October 31, 2021 Report Share Posted October 31, 2021 Thanks for the update James, for myself at this point I'd be talking to my machinist to get his input on how to mate the ARP stuff properly. Maybe even consult the Freewheeling Tony Smith. My machine shop consists of a drill press, some good files and measuring tools. Not equipped to sort this out, that's for sure. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted November 10, 2021 Author Report Share Posted November 10, 2021 It looks like I bought myself some time. I picked up a pumpkin from a 1946 Desoto Limo that appears to be in OK shape. I cleaned it good and stuck it in yesterday. I ran Sondra to work this morning and at boulevard speeds like 35 to 40 it seemed fine. On flat level ground at 35 and with a light throttle I could just barely hear it. With the engine going good, I could not hear anything. This unit is a 4.3 to 1 unit. The contact patch looked good and the teeth had no pits or hard shinning spots. The bearing sounded ok when I had it on the bench but without a load...I did nothing but clean it inside and out and painted the thing. I did not even change the seal. It does move out from a traffic light much better in Second Gear with the 4.3 set from the old 3.91 set I have been using. We shall see after a freeway run or two. ********** I talked with some folks about the issue of all these units have torque issues with the ring gear bolts. Including ARP. The consensus is that it is possible that the steel bend over locking tabs that MOPAR used could "cold flow" after a load of 50 plus years and/or 75,000 miles. That would allow the bolt to loose its bolt stretch. That is why, in addition to galling, ARP uses those hardened steel washers on the hardware and locktite. This is a very plausible explanation and I may well just use ARP lube on the top of the bolts and Locktite Red on the threads when I rebuild the new unit. Now if this rear end is good for the time being, I can take a few months and rebuild the pumpkin slow with attention to detail. I may also send the NOS 4.3-1 ring and pinion out for super finishing. Has anyone every found some of these bronze cupped spider gear (pinions) thrust washers that go between the gears and carrier case? The ones that one side look like a moon crater. Best, James Quote Link to comment Share on other sites More sharing options...
Sniper Posted November 10, 2021 Report Share Posted November 10, 2021 You know, Chrysler was never one to change something if it didn't need changing. You might find a later model set of those thrust washers from something like the 8 3/4 will work. Unfortunately, I only have one 8 3/4 and it has a Sure Grip So I can't check mine for you. I think I sorted out the part number you need. 663479, it has an NSN as well, 3120-00-219-8946. If I read the parts book right it's the same part for all Dodge's, Plymouth's and Desoto's. I cant find anyone stocking it, but several NSN suppliers will do a request for quote, afraid to ask myself, lol. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted November 14, 2021 Author Report Share Posted November 14, 2021 (edited) Well, I took the car out for a long drive up from San Francisco up to Marin County. I needed to return a bench grinder to Harbor Freight. What junk. The thing ran for 15 minutes with no load and the case reached between 160F and 190F. Too bad as I was going to buy 3 or 4 of them to use as grinders, wire wheel mounts and for polishing as they have a speed control. At $150 delivered not bad...but they are just junk... Well, the rear end was quiet. At freeway speed the wind noise killed what little ring an pinion noise I got at 6 AM on a flat boulevard here in SF when all was quiet out. Runs a lot better off of the lights with the 4.2 versus the 3.91. Pulls better up Waldo Grade up to the Golden Gate Bridge as well. The extra 314 RPM in third gear is not too much of a change. Nor the 360 RPM in 3rd overdrive. What this will do for road trip mileage is yet to be determined. James Edited November 17, 2021 by James_Douglas 1 Quote Link to comment Share on other sites More sharing options...
Bryan Posted November 17, 2021 Report Share Posted November 17, 2021 This is going to sound crazy, but I wonder if there is any way a machine shop could adapt a modern ring to an old carrier. Wouldn't it be a matter of re-drilling holes in the carrier plate and threading to match a modern ring? Then adapting the matching pinion to the housing (length, bearing width, etc). I see where literature mentions the 8.75 starting in 1957, but never see anything about our vehicles (pre 1957). Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted November 17, 2021 Author Report Share Posted November 17, 2021 There are a whole host of issues why this would not work out well. One can have a custom ring and pinion gear made. I checked. about $4K to 5K. James Quote Link to comment Share on other sites More sharing options...
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