the rear end on my 70 d100 locked up today then threw the drive shaft. the rear is completly locked. im hoping to just get a near center chunk and replace it. i need to know how to identify the rear i have and any info on how to change the center would be great. this is my daily driver so ill have to drive my valiant till its fixed and the gas is gonna empty pockets real quick thanks.:wack:
rear end question?
- Thread starter rigrunner
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69B-Cuda
Well-Known Member
assuming from your post, the "center chunk" drops out the front of the axle housing and the back of the housing does not have a cover plate, It is more than likely a Mopar 8 3/4. Take the wheels and brake drums off, remove the nuts holding the brake backing plates to the end of the axle tubes, ans slide the axle shafts out about 6 ". Then you can remove the bolts holding the chunk in and it comes out the front. (driveshaft has to be disconnected of course)
thanks. it does come outta the front and the bacl of the center housing is sealed. i count 10 bolts around the center section. is there a particular rear i need to get the parts from. the local junk yard has a 77 73 and 68.
69B-Cuda
Well-Known Member
on the side of your chunk, it will have some numbers, 741, 742, and 489 are the 3 numbers. If you are getting the whole chunk, those numbers don't matter. They have to do with physical size of the pinion. 489 is the strongest, but unless you are turning some serious horsepower, you should be fine with any of them. You need to know the gear ratio though (probably want that to match yours pretty closely), and the size of the yoke for the u-joint (there were 2 sizes I believe)
great thanks. when you say on the side of the chunk is it on the outside? gonna go the the junk yard in the morn and see what they have. will take the yoke with me for comparison. if i was to luck up and find a sure grip will that also fit my housing? just running a stock 318 with 3speed manual.
69B-Cuda
Well-Known Member
yes, numbers are on the outside of the chunk, driver side, up towards the front. If it has a suregrip, it will fit in your housing, they are the same overall dimensions as the open carrier. The clutch type suregrip is the desirable one. It is rebuildable. (same as a Dana powerlock)
cudamark
Well-Known Member
I agree except for the part about sliding the axle shafts out 6". If you don't plan on changing the seals (I would unless they're new) you don't want to let the axle shaft rub on them or sit with their weight on them or they might get damaged and you'll have the pull it apart again and do some cleanup this time. If you luck into a sure grip or not, you'll also need to set the axle shaft end play. It's VERY important so, if you've never done it before, I'd get a service manual or run a search to check the procedure. It's not difficult.....you basically need a slight amount of end play so the bearings don't overheat but not so loose as to cause leaks and brake problems. Oh, and those 3rd members are kinda heavy and awkward so be carefull handling them. They like to bite fingers too if you get them in the wrong place!
ok thanks for all the info. if i dont find one with the same yoke size is there a way around that? and also will be putting in new axle seals and bearings while apart. cant find any pics on what this adjuster looks like so if anyone can post one it would be great. thanks again
cudamark
Well-Known Member
Some pinion flanges can be swapped and some can't. It will depend on the case number and spline count of the pinion shaft. The axle shaft end play adjuster is part of the RH (passenger side) axle bearing retainer. There is also a small lock tab under one of the nuts to keep the adjuster from moving after you've adjusted it so don't lose it!
69B-Cuda
Well-Known Member
ahh thanks cudamark, I forgot about the end play... I have green bearings in mine at the moment and it has been a while since I set the end play. Good call on damaging the seals also.
...............68 would be best.........next 73 as they both have 8.75s........the 77 will have a cover on the rear and isnt interchangeable with urs.........kim......
cudamark
Well-Known Member
Just about any '57-74 car, truck, or van with an 8 3/4 could be a candidate but I'd stay away from the '57-64 models as they have a different thrust block and may require extra machine work to get the end play in specs. As mentioned, try to match case numbers if you plan to swap parts but in any case, try to get one with the same u-joint size and with the ratio you need. You actually had one lock up eh? I've seen them fail in a dozen different ways but never a lockup. When you get it apart, take a few photos and post them here. I'd be curious to know what came apart and why.
will do/ i spun up some gravel and it started whining. roared on decell and locked tires. left side still turns right side locked. someone told me the axle splines can have diff counts is this correct> guess ill pull one before i go and count my splines. thanks again all will update as i get it done. gonna be a little slow first time and i only have a day a week to work on it.
the only gear ratio close to my 3.55 was 3.23. it came out of a 68 fury. still a 721 case and thats what i had. for 84 bucks i think i did alright. how much will the 3.23 gears change my running from the 3.55. thanks again for all the help. still confused on the end play adj but will figure it out when i put it together.
cudamark
Well-Known Member
Looks like the pinion nut came loose or off. Either that or the pinion bearings got destroyed in a hurry! The 3.23's will give you a bit more mileage and lower engine RPM at a given speed and a little less acceleration off the line. A good gear for general driving. The axle shaft end play is just the amount of movement that the shaft will have pushing in and pulling out on the flange. Use a dial indicator to measure how much it has. The book say .008-.018 but I don't like anything over .012. I've seen them leak at looser specs. Make sure you do the measuring with both sides off the ground and brake drums off as well.
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