What year did they fix the 8 3/4 problem

General Mopar Tech Discussions

  1. fratzog lover

    fratzog lover FBBO Gold Member FBBO Gold Member

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    Don Garlits early Swamp Rat dragsters...had 8.75 rears. Blower, sticky slicks and all.
     
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    • 6t4polara

      6t4polara Well-Known Member

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      What rear end was in the Max Wedge cars.
       
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      • 440 PHIXX

        440 PHIXX The Island of Misfit Mopars FBBO Gold Member

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        The Dana may have been overkill for the street on 60’s tire technology. But as soon as you put on slicks something had to give. The 9 3/4” ring gear in the Dana distributed the shock load over a greater distance on the contact pattern. I’ve seen quite a few 8 3/4 ring gears with teeth missing, or chipped that were in race cars or healthy street engines on modern tires. The Dana is added insurance, if you want to bang the gears. I’m surprised they put the 8 3/4 behind the ‘68 BO and LO SS cars with automatic. They were probably all changed out in time. I do agree that in a street application, with tires that give the 8 3/4 would be fine. I beat the crap out of my Charger with the Dana, and it’s never been apart.
         
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        • flyingfarley

          flyingfarley Well-Known Member

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          8 3/4 was the only rear available in a max wedge powered 62-64 Mopar
           
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          • matthon

            matthon Well-Known Member

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            I also hear about how bad the ball & trunnion driveshaft is, but they were used and abused as well by max wedge cars and hemis.

            I've never heard of one failing, but I never had the pleasure to ask any old school drivers like Jenkins, by any chance did you?

            My 64 has both the b&t and tapered axles, it's no ground pounding big hp racecar, but I have complete confidence in both, and they are untouched original.
             
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            • RemCharger

              RemCharger Well-Known Member

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              Anything and everything will eventually be broken.
              2 buddy's at the track last year shit out Dana 60 gears.
               
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              • 440 PHIXX

                440 PHIXX The Island of Misfit Mopars FBBO Gold Member

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                Yeah but... were they under warranty?:D
                 
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                • RemCharger

                  RemCharger Well-Known Member

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                  No it turned into a wallet measuring contest :eek:
                   
                • 440 PHIXX

                  440 PHIXX The Island of Misfit Mopars FBBO Gold Member

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                  Just think how much quicker the 8 3/4’s would have given up the ghost.
                   
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                  • RemCharger

                    RemCharger Well-Known Member

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                    Still remember the day, on the polara. It was violent enough that it literally blew the distributor cap off. Figure that one out.
                    He was running about a 10.10.
                     
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                    • 1 Wild R/T

                      1 Wild R/T FBBO Gold Member FBBO Gold Member

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                      As I said earlier yes the Dana is beefier, no one is challenging that.. But the 8.75 is tougher that many folk give it credit for....

                      Are you familiar with the guy who goes by the screen name "Thumper" ? He builds custom carbs for allot of fast cars... His Dart has been well into the 9's for at least ten years now & was running low 10's for years before that... Still running his 8.75...

                      There are plenty of 10-11 second cars running 8.75's... It's not just slicks, you can run slicks, Thumper does... Slicks & a manual trans, you might get away with it if the car is light, heavy car forget about it....

                      If your running a stick & dump the clutch at 4K+ thats a huge shock load, If the tires don't spin the load is obviously greater... If the axle doesn't break than the driveshaft might, or the transmission, or the engine mounts, or the axle mounts, or the wheel studs... Your gonna find the weakest link... Thats racing ...

                      Remember that earlier comment of mine about Ford 9" not being all that tough? Well here is one of the common failures...

                      Screen Shot 2022-01-18 at 6.50.04 PM.png


                      Another...

                      Screen Shot 2022-01-19 at 9.50.38 AM.png

                      The one I was hoping to find but didn't is the failure of the pinion support... There's a reason Ford made the "Daytona" pinion support.... And Nodular cases, and bigger axles, and improved housings...

                      The Dana 60 rarely breaks but it was designed to live in a 1 ton truck so it's huge and it's heavy... Depends on a lot of variables but same width, same brakes, no tricks the Dana is about 45 lbs heavier than the 8.75...

                      But the thing I see as a bigger advantage of the 8.75 is the ability to swap 3rd members in about an hour...

                      A gear change on a Dana is a undertaking.. On an 8.75 when I was younger I could swap it out in 35-40 minutes & I would just for a weekend of fun, whether it was throwing in 3.91's for racing or throwing it a 2.76 one legger for a freeway cruise....
                       
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                      • chtampa

                        chtampa FBBO Gold Member FBBO Gold Member

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                        In 69 the center section was changed from the clutch style to the cone/spring friction style. Then there were issues with the air flow blowing oil out through the vent. The location of the vent was moved in 70. The change in the ingredients for current oils have increased the blowout issues.
                         
                      • 440 PHIXX

                        440 PHIXX The Island of Misfit Mopars FBBO Gold Member

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                        The Chrysler engineer’s are the ones that made the decision to go with the Dana 60. It was used in all the US 3/4 ton trucks, usually with full floating axles. Chrysler had Spicer/Dana build the passenger car rear for their needs. And if you look at the A12 package cars, that were clearly designed with competition in mind... they all came equipped with the Dana 60. 727 and 883.
                         
                      • 440 PHIXX

                        440 PHIXX The Island of Misfit Mopars FBBO Gold Member

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                        @1 Wild R/T I apologize. I don’t mean to come off as arguing if guys on here have the 8 3/4 and it is fine for them. Hell... I’ve been daily driving them since 2001. So 20 years of them behind me doing their job well! I have however been fortunate enough to have bought my 2 V code 4 speed cars back in the 80’s, and they both have the Dana 60. The ‘Cuda is a 4.10 and the Charger a 3.54. The GTX that I’m currently building has an 8 3/4. After going back and forth with new axles, a new center section and all the other parts to rebuild it... I think in my case I’d be better off getting a Strange 60 and being done with it. The 440 I’m building will be about 500HP, so it might be overkill. But who knows what the future looks like! :D
                         
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                        • Dipstick

                          Dipstick Well-Known Member

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                          As did most Top Fuel cars after they abandoned the Olds rear end. Most were right out of the wrecking yard and many had the small stem pinion. Those "sticky tires" were a joke compared to modern stuff, smoked them the entire length of the strip.
                           
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                          • Tang1964

                            Tang1964 Well-Known Member

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                            And that’s what you call educated.
                             
                          • khryslerkid

                            khryslerkid FBBO Gold Member FBBO Gold Member

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                            I never questioned the ball in trunion because in my eyes it looks beefier than a regular universal joint. I had mine completely apart replacing the boot and being north of 100k miles it still looked new with no wear that I could see.
                             
                          • F4R/T

                            F4R/T Well-Known Member

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                            Ever seen a 9” blow the pinion out the front? I have a good friend that runs NSS class and his buddy had a Buick that ate the 9”. The 9” also consumes more HP than a 8&3/4. I know the 8&3/4 seems to get kicked to the curb for a 9” and I never understood why. Some magazine did a big article on all the major brands and the best were the Dana 60 and the 8&3/4 .. Why toss in a 9” versus the Dana or 8&3/4?
                             
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                            • cdr

                              cdr FBBO Gold Member FBBO Gold Member

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                              A BUILT 9" is WAY stronger that a BUILT 8 3/4, I wont waste my time & money on another 8 3/4
                               
                            • 1 Wild R/T

                              1 Wild R/T FBBO Gold Member FBBO Gold Member

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                              A "Built" 9" gets an aftermarket yoke, either a Daytona front bearing support or an aftermarket front bearing support, either a nodular center section or an aftermarket center section, some level of aftermarket carrier be it a Detroit Locker, a four pinion style trac-lok, a spool or a tru-trac type unit... At the very least the 31 spline axles but usually 35 spline axles... And the option of 40 spline axles...

                              So what does Ford provide???

                              Can you even buy a Nodular center section for an 8.75? How many have you seen fail? Typically if one fails it's because something else failed in which case a nodular will likely fail.... You can buy aftermarket bearing caps, they need to be machined to fit & if you get that wrong you've gone backwards... I have seen girdles
                               
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