Rear End Carnage!!!!!

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lildemonkid

lildemonkid

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Needing a little help from that awesome mopar community. Went out last night to "Break-In" a new carb on a healthy 440-4 speed car with a 8 3/4 rear, and redefined the term break-in. Ended up chunking the rear end.

From a quick visual, I found that the carrier main caps broke. (if thats adequate for the damage that resulted)

So big question is..... are there billet caps? Or are they even replaceable without replacing the whole center section? (tried to do some searching on the WWW....) Or does someone recommend something else to beef up the 8 3/4. Would like to stay away from buying/building a dana.

And without further interruption..... let the carnage be seen!
 

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To beef up a 8 3/4...replace with Dana 60....
 
Why continue to dump money into an 8 3/4. There is a reason that Ma Mopar put 9 3/4 behind 440 with 4-speeds. Dump that money in that 8 3/4 and then throw on some slicks so you can really bust it up next time.
 
It's an original 8 3/4. Not my dart. But is there a way to keep what it has? It's not in the budget to swap to a dana.....
 
lildemonkid said:
It's an original 8 3/4. Not my dart. But is there a way to keep what it has? It's not in the budget to swap to a dana.....
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How much money do you have to continue to dump into 8 3/4s till you think you have broke even to the expense of a Dana? How much is your time worth to continue to fix something that should be replaced?

Nobody is saying to toss the 8 3/4 in a dumpster. Put it aside so you still have the original drivetrain.
 
Well lets lay it all on the table. Run to the sun at myrtle beach is in a month. The center section hadn't been touched in at least 10 years other than fluid changes. Before that, never gone through. Even if the case for the center section has to be replaced and all the internals also, looking at $1k from moser. It's over $2k for a dana 60 assembly, then have to get the brake adapters for the current disc setup.
 
[ame]http://www.markwilliams.com/Catalog/pg36.pdf[/ame]
 
lildemonkid said:
Well lets lay it all on the table. Run to the sun at myrtle beach is in a month. The center section hadn't been touched in at least 10 years other than fluid changes. Before that, never gone through. Even if the case for the center section has to be replaced and all the internals also, looking at $1k from moser. It's over $2k for a dana 60 assembly, then have to get the brake adapters for the current disc setup.
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I've never paid more than $1300 for a Dana; and that was only once as it was exactly the width I needed with a new power lock and new 5.38 in it. Nobody says you have to go brand new.

Why would adapters be necessary? Car 8 3/4 and 9 3/4 have the same axle flanges.

However, with limited time till that cruise, you're probably better off looking for steel caps to last you until the next time. I think I saw where one of the other members posted that info for you. Good luck on your cruise.
 
Those caps are threaded to match the pig section so i dont think you can just mix and match caps, The threads may not line up . Looks like your cap safety strap did its job....oh, thats a lock.:laughing:
 
So has anyone heard of replacing the crush washers in the nose with solid shims? Someone i know has a 700hp 440 running an 8 3/4. Per his word, if you replace the crush washer with solid shims, you can avoid the crush washer collapsing and causing the main caps failing.

Has anyone seen/ experienced this modification?
 
you can run the crush sleeve eliminater but it can still certainly break, ask me how I know
 
lildemonkid said:
So has anyone heard of replacing the crush washers in the nose with solid shims? Someone i know has a 700hp 440 running an 8 3/4. Per his word, if you replace the crush washer with solid shims, you can avoid the crush washer collapsing and causing the main caps failing.

Has anyone seen/ experienced this modification?
Click to expand...

That is hogwash, the caps break because the ring gear is being pushed away from the pinion. It happens on 742 cases also, and those DONT use a crush sleave. The crush sleave sets pinion bearing preload, has nothing to do with cap breakage.
 
when we redo a rear do we measure the carrier bearing bore diameter? I did, and found the bore on my 742 .002"-.003" larger than the bearing race. stuff breaks where there is slop and banging around so I sanded the cap faces down
 
The 8 3/4 vs Dana 60 debate is as old as the cars they came in. No one is going to question the facts that a Dana 60 is stronger than any 8 3/4. That said I have raced on 8 3/4 rear with SS springs for many years and many passes in 3300 lb cars running low 9's. You mentioned yours was a 4 speed. Maybe driver error? Was the driveline slack out before you launched the car? Did it wheel hop? What was the condition of the internals before it came apart? It's very easy to throw rocks at the 8 3/4 and condemn it without the whole story.
 
If it's just the cap buy a set of billet or find another case and take it easy until you can get something stronger.
 
Did the gear teeth break? Can you post a picture of the ring and pinion?

FWIW, I carry a new, super-duty 489 casting with thick, forged steel caps and billet adjusters already installed $300.
 
Yeah, the car was launched. It hooked and even with traction bars it wheel hopped. Broke teeth off the ring gear, and the cap that is pictured above.

DoctorDiff, its looking like the 8 3/4 is going to stay. Can't convince my old man its time to upgrade. What do you recommend to keep this from happening again? I know very little of the internals of a rear. But i know all the external factors to keep from wheel hopping and to make sure there is linear power application. Hopefully we can prevent this on multiple levels.
 
Wheel hop is a no no and will lead to nothing but heartache. When I ran a 8 3/4 I also ran 002/003 SS springs. Upon checking the car out after I ran it this way I discovered that the rear slicks were planting so hard that the rear housing had dented the shocks where they pass by the housing from axle rap up. I installed a adjustable pinion snubber with about 1/2" clearance to the floor and that took care of the problem. The car would 60 ft. in the 1.38 range.
 
The sequence may have been broken teeth from the ring gear jamming between the ring and pinion gears and breaking the caps, not the other way around. The HD 489 case Dr Diff has sounds like a good plan.
 
lildemonkid said:
So has anyone heard of replacing the crush washers in the nose with solid shims? Someone i know has a 700hp 440 running an 8 3/4. Per his word, if you replace the crush washer with solid shims, you can avoid the crush washer collapsing and causing the main caps failing.

Has anyone seen/ experienced this modification?
Click to expand...

Been beating on mine for 12+ years and the last 5+ have been in the hi 9`s at 3200+ lbs behind a 470 stroker w/a spacer and even stock caps and 30 spline axles. I just got the nodular 8 3/4 from DrDiff w/35 spline axles and it has ford 9" style forged caps and is heavier and stronger than any 8 3/4 diff out there apparently but a 4 speed kills stuff so the Dana may be a smarter move.............:coffee2:
 
lildemonkid said:
It hooked and even with traction bars it wheel hopped.
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So, 8 3/4 behind a healthy HP motor with a stick and then traction bars on top of that. No offense intended, but how long have your father and you been involved with MOPARs? I'm sure you get some laughs at your expense at the track with traction bars on a MOPAR.

Traction bars are not necessary on a MOPAR and even have the opposite effect. You want the leaf springs to expand to plant the rear axle. A classic MOPAR drag racer trick was to take the rear spring clamps off to allow the rear of the springs to expand even further. Please dump the traction bars unless you have found some reason why they work that everyone else is not aware of. I'm sure if you try to sell them and price them right, a bow tie driver will be quick to snag them up.

The MOPAR chassis book may be a useful guide for getting you out of your wheel hop predicament. Just a suggestion.

Once again, I hope you get it back together in time for your cruise. You shouldn't have an issue as street tires shouldn't hook enough to create any future carnage.
 
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