I'm going to attempt a 4.11 rear swap into my 3/4ton based on the tech tip. I have this rear from a donor and I think it may have had the 'tag' indicating a 'locker' rear end. Based on the pic, is this the case? [img]https://photos.app.goo.gl/XUWXxcK4wfM1PrxK7[/img] [img]https://photos.app.goo.gl/EMdzA57MHzmZ65Jr6[/img] If it is, is this still a good donor?
The casting numbers you show won't tell you if it's a locker or not. Probably the only way you can know for sure is to pull the cover off and inspect.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
A locker would work fine, just a preference. Most lockers are not that, but are "limited slip" with clutch packs behind the side gears that restrict the differential action. Once you pull the cover off, look thru the openings in the differential case for the clutch packs and possibly preload springs. If it's an open differential, there will just be spider gears (two or three, depending on the design), and the side gears connected to the axle shafts. First pic is an example of limited slip differential. Second is an open differential. Pics are generic that I got from the web.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I doubt that's a locker or limited slip differential. You can check by sticking an axle into one of the side gears and turning it. If it's an open differential, the pinion probably won't turn, but the opposite side gear will turn the opposite direction. If it's a limited slip, the pinion will turn if one axle is turned.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Yes, I believe that is a limited slip carrier. If the ring gear was turned 90 degrees where the clutch pack tabs were visible, it would be pretty obvious. That type has 4 spider gears, arranged in such a way that different axle speeds with power applied to the driveshaft makes the clutches try to engage and match the axle speeds to each other. You'll need to learn to "cost" around sharp turns, as applying throttle makes the vehicle try to "straighten out the turn". Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Ok, I will try that out, but regardless all I care about are the 4.11s. My other question is; is it worth replacing a pinion seal in this now? It doesn't appear to have been leaking.
Look at the rectangular part just inboard of the axle gear teeth- - - - -I believe it's part of a multi-disc clutch pack like one I ran in a dirt track race car back in the 1970's. That one also had a fully enclosed carrier where the spider gears were not visible. Try inserting an axle shaft into one of the side gears and see if it can be turned without also rotating the ring gear- - - - -if it's a "locker" it will take a considerable amount of effort to make the axle turn with the ring and pinion blocked in some way, like holding the pinion flange in a vise. On an "open" rear end, the axle gear will turn easily. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Unless it's showing visible signs of leakage, stains on the pinion housing, etc., I'd recommend leaving it alone. It's very easy to upset the pinion bearing preload and induce a hum or rapid bearing wear, chasing gremlins that probably don't exist. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Ok, another question about the tech article. Does gasket sealer go on both sides of all gaskets in the process? I'm assuming the answer is 'yes' since it doesn't specify.
Gasket sealer is a crutch- - - -clean, straight flanges don't really need sealers to keep gaskets from leaking. If I use any at all, a brush-on liquid like Permatex Super 300 applied sparingly is usually my choice. Most people use way too much sealer, or the wrong type for the job at hand. Seeing gobs of RTV oozing out of a joint in all directions sort of screams "amateur" to anyone who makes a living fixing vehicles. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
The gasket should seal without sealer. Heck, Chevy makes exhaust manifolds that are designed to bolt to the block without gaskets. That's a hostile environment that typically doesn't leak. The rear axle is a little less hostile.
A smear wouldn't hurt. But you have to look at what you're working with. Is the same exact gasket material that was being used when that axle was built? Or is it the modern replacement. Sometimes the old techniques in the manual don't apply anymore.
BTW, somewhere I still have a roll of that old, super hard cardboard-y stuff they used to make gaskets out of.
Got the diff removed and cleaned up. Went to put the new gears in, which is a pita and ripped the gasket. New one's coming on Monday and I need a new u-joint as well. Going ok, but I had plans to drive it this weekend and I'm missing out!
One of the nuts got a bit rounded when removing the u-bolts from the u-joint. Threads look pretty fine, does anyone know what size these are?
Take one down to your FLAPS and get new u-bolt setups. They're pretty common and still available in the size you'll need.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
You definitely scored on that rear. That’s definitely a real locker assembly. Those are even more rare than the 4.11’s itself. I wish mine had one for climbing my steep dirt driveway.
Grade 8 nuts are available by the thousands on Ebay, and also at any good hardware store. What's with the obsession about replacing good-condition U bolts with no thread damage? Those are fine threads, either 5/16-24 or maybe 3/8-24. What size wrench fits the nut? If it's a 1/2" wrench, the thread is 5/16. If the wrench size is 9/16", you need a 3/8" nut. Just replace the nuts, not the U bolts! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Agree with Jerry. Odds are anything you might find will not be up to OEM quality on u-bolts. And "if" I needed to use the nut show with the rounded shoulder, and "if" I could turn it with a 6 pt. socket I wouldn't let that keep me from driving. That said, first choice would be to replace any less than perfect nuts.
Got me some grade 8 nuts and lockwashers and finished her off tonight. Got to take her up and down the road and it was awesome. I actually used first gear to pull out of the garage and it was noticibly better. Looking forward to taking it out tomorrow for a run down the highway 😀
Definitely faster, 3rd is so much more comfortable to downshift into. Have to get a good app for speedo but is there anyway to change the speedo gears and get it somewhat accurate again?
I use a Garmin GPS for a speedometer since I changed the tire size on my road trip truck- - - -resulting in a better cruise RPM with less toggling in and out of torque converter lockup constantly. That gave me about a 5% speedometer error, indicating faster than actual road speed MPH on the speedo. There are correction gearboxes made to alter speedometer cable rotation speed to account for different tire sizes, 2-speed rear axles, etc. Also, some transmissions can be fitted with different-size speedo drive gears, using an offset-center gear carrier that can be rotated to accommodate speedo cable drive gears with different numbers of teeth. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
So, I picked up a spare SM420 from a later truck, 1/2 ton I believe. What are the chances that the speedo gear in this trans is at least closer to the accuracy I need for my 3/4 ton, now that I have the 4.11 gears?
4.11 ratio axles in 3/4 tons were almost always used behind automatic transmissions. The odds of finding a 4 speed with the right speedometer drive are pretty slim. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Goach2, You can get a Speedometer Cable Ratio Adaptor from Summit or Jegs. Figure out how far off you are and insert the in-line adaptor to your transmission and the problem is solved, no need to search for hard to find gears.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
it is in rhe tech article, so I'm assuming it's the consensus.