8 3/4 rear end help

Transmissions and Rear Ends

  1. slant6billy

    slant6billy Well-Known Member

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    Need some insight.
    8 3/4 742 sure grip center mid 60s & B body rear (68 charger donation)
    Green axle bearings - so no adjusters on the ends anymore

    Can we pull the thrust spacer out?

    It is not a cone style diff.

    Problem we are seeing with the thrust spacer in: The second axle to be installed will not fully go into the carrier.

    2nd question: How does one remove the thrust spacer? Don't say sledge hammer!
     
  2. jamf

    jamf Active Member

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    If it's a power lock, (two halves that bolt together) the thrust block is two little t shaped buttons that go in from each side and are held together with a roll pin. Often the roll pin is broken and they stick to the end of the axle and fall into the rear end when pulling the axles. At least, that's what always happens to me.

    Pull the center back out and stick a long punch in one side of the carrier and drive the roll pin out and pull em apart.
    Save em, I've bought a few rears and center sections with em gone or one mashed between the ring gear and carrier, etc.
     
  3. MiradaMegacab

    MiradaMegacab Well-Known Member

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    Remove the thrust block as suggested.

    A cheesy alternative is to remove material from the axle.... not recommended.
     
  4. slant6billy

    slant6billy Well-Known Member

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    thanks. I think we will use one of the axles as a "punch" to push through the spacer
     
  5. Justwondering

    Justwondering Well-Known Member

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    Billy -
    I love reading the questions you ask and the answers folks provide.
    You are far, far braver than I about taking your car apart.
    And I generally have no clue what you are doing, why you are doing it, or how...
    but it makes my brain cells keep working trying to keep up with your projects....
    thanks man
     
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  6. BudW

    BudW Moderator Staff Member

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    Are you sure you are using the correct axles?
    Note: I’m not saying anyone is, just trying to rule out the possibility.

    The reason I mention it is the ’66-67 B-body 8¾” differential housing is 54.250” (55-¼”) wide.
    ’68-69 B-body 8¾” differential housing is 54.936” (55-15/16”).
    ’70 B-body 8¾” differential housing is 54.906” (55-29/32”).

    Going from widest (’68-69) to narrowest (‘66-67) of the sizes is 11/16”, or 11/32” per side, longer. If someone is trying to stick the wider axles into the narrower housing, it will cause a length error.


    I’m not a fan of using the green bearings for street usage. I really don’t see any advantage to using them to begin with, over the stock bearings – but that is my opinion.
    BudW
     
  7. Joe12459

    Joe12459 Well-Known Member

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    The only real advantage to the green bearings is if you want to convert to disc brakes. Most, if not all of the disc brake conversion kits available require green bearings. I wasn't thrilled about running them in my RR or my Mirada, but I've put around 8000 hard street miles on each of them, with no issues yet. I'm sure they won't last nearly as long as the stock tapered bearing, but they're easy enough to change.
     
  8. BudW

    BudW Moderator Staff Member

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    Which is understandable. Adjustable rear axles and aftermarket rear disk brakes are not very compatible.

    For some reason, I not in the mind-set of putting rear disk brakes in place of drums (for street use).
    I guess the reason is, I don’t want the rear to “brake more” than the fronts do, or direction of car may want to swap directions under heavy braking (if that makes any sense).
    It could be I’m concerned about nothing – IDK.
    BudW
     
  9. Joe12459

    Joe12459 Well-Known Member

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    I always use an adjustable proportioning valve and adjust it as close to even as possible, with the fronts doing just a little more than the rears. I just like the discs because there's virtually no fade, even under extreme driving conditions, which is how I like to drive.
     
  10. BudW

    BudW Moderator Staff Member

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    Thumbs up!
     
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  11. 80mirada

    80mirada Well-Known Member

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    Baer Racing rear kit for Mopar required the factory bearings, and Dr Diff kits also work with stock bearings if I remember correctly
     
  12. Joe12459

    Joe12459 Well-Known Member

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    That's good to know. I love my disc setup, but it would be nice to run factory bearings.
     
  13. slant6billy

    slant6billy Well-Known Member

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    Yeah, I've got that personality defect that allows me to ask questions without fear. It gets me into trouble and I come off like a dumbass all the time. In the end, I am much smarter than I was and I supply a good laugh.

    So, What the Hell am I doing.........

    This is the upgrade to a bigger rear differential. So the F M J mopars only came with 7 1/4 and 8 1/4 size rears. That is the ring measurement in the diff. Now, the older sibling B body rear from 1962 to 70 will fit into an FMJ mopar and it is the even larger 8 3/4. A whole 1/2 bigger. But the design is a superior for the 8 3/4. It has the sealed back and the carrier loads from the front. This is called a banjo style rear. The 8 1/4 has the 10 bolts on the back. Since I destroyed a 8 1/4 rear in August this year, the upgrade is in the works. Gator has already converted to a 8 3/4 upgrade, but the rear was an open Diff( meaning one wheel spins) The desired "Sure Grip" is a limited slip (both wheels spin). So Gator got a sure grip diff from a builder and that is where we ended up this week. More to follow.
     
  14. AJ/FormS

    AJ/FormS Well-Known Member

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    Bud, I agree with you on rear disc brakes and here's why;
    Since we all know that rear drum brakes have to be strangled by a proportioning valve,it follows then,that drum brakes are more than adequate for the rear of a streeter. In fact if you run the rears straight to the M/C, and with 4 same sized tires mounted, you can get yourself into trouble really,really fast.
    Soooooo, why exactly would a streeter want db's on the rear? Oh, wait, I think it's coming to me; cool-factor.To each his own, I guess. But I wouldn't spend a nickle on rear db's for my streeter .

    Here's one for you; I assembled my car in 99. I took the P-valve out a couple of years later when the 295s went on. That was about 125,000 miles ago.In that time, I wore out the original circa used 1969 shoes, and replaced them with other used circa 1969 shoes. This tells me a few things. I am easy on brakes, or, circa 1969 shoes have magical qualities,or, the rear shoes are doing almost nothing,perhaps because the mechanic who installed them (me) did something wrong or is an; pick your own adjective.
    The car is, or has been,the best stopping street-car I have ever owned, and the second best I have ever had a ride in.And various other operators and passengers have concurred, on many occasions.
    I,of course, cannot say the same for a non-street car,obviously.

    BTW
    In a trac-loc/powerloc rear,One cannot drive the buttons out from the axle tube side. And if you could, it would immediately fall into the guts to be crushed by some other moving part, perhaps wrecking said guts. The chunk has to come out, the case disassembled and the buttons manually removed. Occasionally, as said earlier, the buttons are not very secure, and will sorta stick to the end of the axle as it is withdrawn.Sometimes it will fall off before the axle end emerges. If a button ever falls out/off when you pull an axle (not common, but for sure possible), you may never know it,until it jams between a couple of ring-gear teeth.
    Lots of guys have just fabbed up spacers or chopped off the axle ends. I'm just saying.
     
    Last edited: Jan 4, 2017
  15. BudW

    BudW Moderator Staff Member

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    I will not encourage anyone to add rear disk brakes on our car but, also, won't discourage it either.

    Could be wrong on the percentage but you want the front brakes to do 60% of the work on our cars, Any more than that, then the rear end of car will want to move to front of the road in a hard brake application (ie: car will want to spin out). Our disk brakes (11” rotor/10” drum) setups allow for that, and 11¾” rotor/11” drum) setups will do it better.

    Otherwise you will have to add a proportioning valve that will effectively reduce the effectiveness of rear brakes, a lot.

    I just don't see spending money or time on something that I will then have to modify to reduce capability or effectiveness

    Many front wheel drive cars today, the front brakes do about 80% of braking. A lot of cars built today, have tiny rear drum brake setups on them.

    Most trucks do have large 4 wheel disk brakes on them, but they also have a variable purporting valve attached to the rear suspension. As truck is weighed down the rear brakes get a larger amount of braking capability – or less when truck bed is empty.
    In most cases, when a truck bed is empty, the rear brakes are only along for the ride and are not working.


    With all of that said, rear disk brakes do look very cool. IF you have the proportioning valve set up right - then it can help braking when driven hard.

    For a majority of people visiting this forum, rear drum brakes will be more than fine, and spend your money in other areas of the car.
    BudW
     
  16. Joe12459

    Joe12459 Well-Known Member

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    The advantage I find with rear discs has less to do with braking power, as it has to do with fade. I can drive my car like an a**hole all day, and I do, without heating up the brakes or experiencing any fade. Just my opinion.
     
  17. slant6billy

    slant6billy Well-Known Member

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    Yeah, about your driving.... we need to discuss that sir........

    We can talk about it during the drive...hahaha
     
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  18. AJ/FormS

    AJ/FormS Well-Known Member

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    Yeah ,we don't all drive like that,lol

    Bud,
    I have no idea about the bias, although I seem to remember the P-valve reducing the rear line pressure to 76% of the front. But When I set my brakes up; I had the KH 4-piston calipers in front And I had exactly one set of spare pads. New rotors were not available at the time, and I had only one spare pair. I had no idea if in the future, I would ever be able to find replacements for those.
    So my thinking was to set up the rear brakes to do way more work. That eventually lead to 295s going on in the back, cuz 10 x 2.5s have a hard time locking them up, even with a gutted P-valve.Then I fine-tuned the rear power with wheel cylinder bores.
    The end result is that the rear shoes now wear out about two or three times as often as the front pads. But rear shoes are cheap and common. So in traffic and light stoppage, the rear on my car IS doing a lot of work. But those 295s are saving my front brakes.
    When braking really hard as in testing, it felt like someone threw out a parachute back there. The whole car just sorta squats, with very little brake dive. And you better be prepared, cuz with lap-belts only,the passengers upper body, suddenly gets very heavy, and it's a- wanting to migrate towards the windshield. No girls allowed!
    Oh and BTW, I have a manual trans and a10.9 SCr. So the engine brakes pretty good when I lift.
    I mention this not to be argumentative, but to show what worked for me.
    And no, I have never been able to make 10 x 2.5s fade, lol.
    I suppose in certain forms of racing it might be possible, but as a streeter?
     
    Last edited: Jan 5, 2017
  19. 7T8 Custom

    7T8 Custom Well-Known Member

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    I have never had a vehicle that I`ve driven on a regular basis (car, truck, work truck, front or rear wheel drive) that I havent gotten sideways at least a few times just to see how it reacts. Had my one month old, 22 foot long 10,000 Lb. 350 transit work van sideways in the snow just today to how it would behave in case somebody else does something stupid in traffic and I have to do some sudden extreme driving.
     
  20. AJ/FormS

    AJ/FormS Well-Known Member

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    I heard you guys got a bit of precip. out west there......lol. But it seems that in southern BC, the precip doesn't always know what it wants to be at this time of year.
    When I was a kid, Dad said Vancouver was a dry place to be in July. So in 72, Dad took us there. I was 19. Alberta was BLAZING hot. Vancouver was cool as a cucumber.
    I went again in 75,with a couple of hi-school friends.Cool and rainy.
    In 77, I took my new wife there on a motorbike,for our honeymoon. It was cool and rainy. We woke up in the tent on the Island one morning, rolled out of bed, and SPLASH! : I guess I coulda picked a better spot to pitch the tent,eh? I was 25, and none too bright I guess. We put on our wetsuits, took the ferry back, and scooted on home; to heck with BC, and haven't been back since.
    The following year, I took her to South Dakota in July. It was BLAZING hot and sunny! We were friends again.
     
    Last edited: Jan 6, 2017