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How much power can a 8.75 rearend handle? #1094420
10/14/11 07:11 PM
10/14/11 07:11 PM
Joined: May 2010
Posts: 171
Georgia, United States,
Crock Offline OP
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Crock  Offline OP
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Well I have a promotion to Ssgt(USMC) and reenlistment bonus coming the beginning 2012 so I'm about to either purchase the 426 short block or supercharge my current setup. I'm trying to come up with the best bang for my buck.

Quick Overview: Restomod 66 Plymouth Belvedere
My entire build 6.1 Hemi, 727 torque flight/B &M shift kit/ported and polished intake/ported and polished heads/ TTI long tube headers/ 180 thermostat/SLP under drive pulley/741 housing /3:55. Gears/Detroit True-trac sure grip/power steering delete pulley/ B & M 2400-2800 stall converter non lock up, 90 mm TB with nitrous injector, cold air intake, catch can, Cam specs Intake Duration 267 Lift .583 Exhaust Duration 270 Lift .566.

This is what I posted on the SRT forums and a response I got back was. "You also should think about the capacity of your 727 and rear."
Well I asked about the 727 a while back and found out they are really they can hp and tq in the ranges of 700 to 800 with stock parts and upgraded value body but my question is what will the stock 8.75 rear end with stock axles handle? Also what other weak leaks do you see if any?
People have boosted that the 6.1 block bored to 426ci supercharged will make 600 or better.

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094421
10/14/11 07:34 PM
10/14/11 07:34 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Romeo MI
What will the car weigh... my opinion its weight that
kills a 8 3/4.... this same question is asked ever
other week.... you could try the search

Re: How much power can a 8.75 rearend handle? [Re: MR_P_BODY] #1094422
10/14/11 08:27 PM
10/14/11 08:27 PM
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dennismopar73 Offline
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it can handle all of it right before it breaks !!
, weight n hp as mr p says
i would think, livable under 600 hp at the wheel, on a 3000@ car just guess

ok i rethink that, if stock axels, and stock rear, under 450 hp i twisted axels on my volare with a basic stock 440 running 11.90
wiegth was 3560

Last edited by dennismopar73; 10/14/11 08:35 PM.
Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094423
10/14/11 10:10 PM
10/14/11 10:10 PM
Joined: Jan 2003
Posts: 8,016
Polson, MT
DoctorDiff Offline
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Anything with 375 hp and a 4-speed came with a Dana 60 from the factory.

Re: How much power can a 8.75 rearend handle? [Re: DoctorDiff] #1094424
10/14/11 10:17 PM
10/14/11 10:17 PM
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dennismopar73 Offline
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not everything,
dana was an option on alot of the cars ,
and not all 440- 4 speed cars for sure,
we ran deep into the 10 with stock rear ends, after market axles
i even know couple guys running in the mid 11 with resplined ,
i do not recomend that for sure,
had more issues with u joints than rears,

Last edited by dennismopar73; 10/14/11 10:21 PM.
Re: How much power can a 8.75 rearend handle? [Re: dennismopar73] #1094425
10/14/11 10:22 PM
10/14/11 10:22 PM
Joined: Jul 2008
Posts: 30,252
Florida STAYcation
dIc dOc Deity ! Online penguin-006
The village idiot's idiot
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Florida STAYcation
And then back-in-the-day ... MOST T/F cars had an 8 3/4 ... with 2500 hoes-power ....

BUT ... they never really hooked-up ...

Re: How much power can a 8.75 rearend handle? [Re: dIc dOc Deity !] #1094426
10/14/11 10:34 PM
10/14/11 10:34 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Quote:

And then back-in-the-day ... MOST T/F cars had an 8 3/4 ... with 2500 hoes-power ....

BUT ... they never really hooked-up ...




I've been very happy with my 8 3/4... its a alum
center now but I use to run a stock center with a
stock cone posi....... and thats a 1.19 60'... but
my car is light

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094427
10/14/11 10:45 PM
10/14/11 10:45 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
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It will be fine that 6.1 doesn't make enough power to break that 8.75. I ran my junk to 11.39 w/ stock axles, stock ring/pinion no worries.


[IMG]http://i66.tinypic.com/pui5j.jpg[/IMG]
Coming soon!!!!
Re: How much power can a 8.75 rearend handle? [Re: Mr.Yuck] #1094428
10/14/11 11:17 PM
10/14/11 11:17 PM
Joined: Jan 2007
Posts: 437
south central pa
bdaz smblk Offline
mopar
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south central pa
The 8 3/4 will take it but the 741 case is the weakest one you can get.


3120lb, small block, 10.5" tire, NA, through exhaust, full int, WITH 83/4 REAR, 9.0 at 150mph
Re: How much power can a 8.75 rearend handle? [Re: dennismopar73] #1094429
10/14/11 11:41 PM
10/14/11 11:41 PM
Joined: Jan 2003
Posts: 8,016
Polson, MT
DoctorDiff Offline
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All 440/4-speed B and E bodies and all '66-'71 426/4-speed cars came with a factory installed Dana 60 rear.

A Dana 60 was optional behind some 440/426 automatic cars.

Even the super rare 440/4-speed C-body came with a Dana 53 rear.

Re: How much power can a 8.75 rearend handle? [Re: DoctorDiff] #1094430
10/15/11 02:53 AM
10/15/11 02:53 AM
Joined: Nov 2009
Posts: 3,082
St. Paul , Mn.
tubtar Offline
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I have to side with Mike here..........weight and hook are what kills them.
The factory was worried about longevity and heavy footed kids costing them a ton on warranty work or they would not have spent any extra by installing 60's in cars.
They have a good point.
But an 8 3/4 will take a lot if it is set up right.
Back brace , aftermarket cap and axles make them a heck of a lot tougher than how they left the factory.
Not Dana tough , but pretty sturdy.

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094431
10/15/11 06:03 AM
10/15/11 06:03 AM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
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The stock 8-3/4" will take alot of power with an automatic trans. Once into the 11's and quicker you may be pushing it. Cost wise, I think the Strange S60 is less expensive than upgrading the 8-3/4" with all the performance parts?

Re: How much power can a 8.75 rearend handle? [Re: 451Mopar] #1094432
10/15/11 08:01 AM
10/15/11 08:01 AM
Joined: Mar 2003
Posts: 1,629
pa
572charger Offline
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our 3400lb cuda ran 11ohs and 10.90s we changed the ring and pinion about every 60 passes [3times] till we got a dana in it that was back in the 80s we were on a budget, ported 906s trws 30 over and the best cam of all time 590 purple shaft


606 hemi pump gas best 9.60 at 142mph on motor
05 hemi daytona 1500 go-mango 4wd quadcab
2007 hotrod mag pump gas drags runner up, roadkill nights dodge big tire winner 2018 2019 back to back
Re: How much power can a 8.75 rearend handle? [Re: Mr.Yuck] #1094433
10/15/11 10:19 AM
10/15/11 10:19 AM
Joined: Jan 2003
Posts: 27,421
Balt. Md
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383man Offline
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Balt. Md
Quote:

It will be fine that 6.1 doesn't make enough power to break that 8.75. I ran my junk to 11.39 w/ stock axles, stock ring/pinion no worries.




Same here all stock 8-3/4 but with my 493 I am starting to worry. When my funds let me I plan to go to a Dana. Ron

Re: How much power can a 8.75 rearend handle? [Re: bdaz smblk] #1094434
10/15/11 10:46 AM
10/15/11 10:46 AM
Joined: Dec 2003
Posts: 22,695
Bitopia
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jcc Offline
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Bitopia
Quote:

The 8 3/4 will take it but the 741 case is the weakest one you can get.




However that might be splitting hairs, as I suspect anything a 741 will not handle, a 742 is not not far behind in also being overpowered. Biggest drawback IMO to a 741 is likely avaliable gears and having a big aversion to bypassing a 742 and going with a Dana.

Last edited by jcc; 10/15/11 10:50 AM.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
Re: How much power can a 8.75 rearend handle? [Re: 383man] #1094435
10/15/11 10:46 AM
10/15/11 10:46 AM
Joined: Feb 2004
Posts: 6,257
acworth / N. georgia - south e...
cheapstreetdustr Offline
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acworth / N. georgia - south e...
Say no to stock axles...yank em..and get aftermarket..
or youll be building a new car ...
a broken axle will put you on your lid...
Dont listen to anyone who says stock axles will be fine..if you can't afford $175.00 axles..
you cant afford to run the car..IMHO..

ive seen them break twist and sheer on 6cyl cars with slicks..

my

fwiw..Im going 10.60's 3280lbs on a mark williams built 8.75 rear..


365" Iron J heads,,3480lbs best 1.39 60ft on SS springs.10.54,124 mph ...6.67 1/8th et.average 60fts 1.46 w/ small cam &.063 no2 pill tagged & insured
[image][/image]
Re: How much power can a 8.75 rearend handle? [Re: cheapstreetdustr] #1094436
10/15/11 01:53 PM
10/15/11 01:53 PM
Joined: May 2010
Posts: 171
Georgia, United States,
Crock Offline OP
member
Crock  Offline OP
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Posts: 171
Georgia, United States,
Let me clear up a couple things. My car originally was a slant 6 car with the 8.25. I remove it and replaced it with the 370ci 6.1 Hemi. First I had fun with the 8.25. and 293 ring and pinion the car was so fast on the top end that the car would float from side to side it was very scare but after that I upgraded to heavy duty springs and aftermarket pinion bump stop. I replaced the 8.25 with a friends 8.75 in a car he was taking to have crashed. I've already had trouble finding a stronger yoke for the 741 case. What is the strongest case out of the 741, 742, and 489? Is the 741 exterior its weak point and if so anything to help it or upgrade to a different case.

I plan on stroking the 6.1 to a 426ci hemi and adding the supercharger to create 600 hp to the rear wheels.

The car is a street car full interior so i estimate it weights 3600. Engine was 800 pounds out the crate. Currently has a 8.75 with 3.55 ring and pinion.

Axles, back braces anything else I need to strength this rearend. I already have rear disc brakes to stop this breast.

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094437
10/15/11 05:05 PM
10/15/11 05:05 PM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Quote:

Let me clear up a couple things. My car originally was a slant 6 car with the 8.25. I remove it and replaced it with the 370ci 6.1 Hemi. First I had fun with the 8.25. and 293 ring and pinion the car was so fast on the top end that the car would float from side to side it was very scare but after that I upgraded to heavy duty springs and aftermarket pinion bump stop. I replaced the 8.25 with a friends 8.75 in a car he was taking to have crashed. I've already had trouble finding a stronger yoke for the 741 case. What is the strongest case out of the 741, 742, and 489? Is the 741 exterior its weak point and if so anything to help it or upgrade to a different case.

I plan on stroking the 6.1 to a 426ci hemi and adding the supercharger to create 600 hp to the rear wheels.

The car is a street car full interior so i estimate it weights 3600. Engine was 800 pounds out the crate. Currently has a 8.75 with 3.55 ring and pinion.

Axles, back braces anything else I need to strength this rearend. I already have rear disc brakes to stop this breast.


The 742 case is the best for hot rodding, a Dana 60 is way better If you must or insist on using the 8 3/4 rear buy a steel cap and a steel billet yoke for the pinion gear. Mu street car made 564 hp to the rear wheels on a Mustang chassis dyno with the 8 3/4 in it with 3.91 gears, i ended up breaking them, I broke a set of 4.10 and some other gear sets. I finally bent the housing so bad(no back brace)that it pulled the welds loose on the ladder bar mounts, I had a real hard time getting the right side axle out after it broke also, the right side is bent so bad from the center out to the backing plates you can see it I bought a used Dana 60 from a 3/4 ford pick up (3.1/4 thick diameter axle tubes ) and had it narrowed, put the ladder bars mounts back on it and put the Mopar axle bearing ends on it so I cuuld reuse the same brakes and axles I used a used set of dana Corp 4.10 and a new Strange Engr. 35 spline spool. My car(1971 Duster, original six cylinder witha pump gas 518 low deck stroker) car weighs 3450 with me inn it with teh 8 3/4, I haven't reweighed it since adding the Dana so it may weigh another 10 to 40 lbs now, probally around 20 lbs more The car pushes(by hand by me) way easeir than it ever did with the 8 3/4


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: How much power can a 8.75 rearend handle? [Re: Cab_Burge] #1094438
10/16/11 12:47 PM
10/16/11 12:47 PM
Joined: Jan 2004
Posts: 550
Ma
Voluster Offline
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Ma
I just went 9.59 at 139 with a 1.36 60 ft last weekend with a 8 3/4 on a drag raidal

We figured 720 hp the car weighed 3460


Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094439
10/16/11 01:09 PM
10/16/11 01:09 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Romeo MI
Quote:

Let me clear up a couple things. My car originally was a slant 6 car with the 8.25. I remove it and replaced it with the 370ci 6.1 Hemi. First I had fun with the 8.25. and 293 ring and pinion the car was so fast on the top end that the car would float from side to side it was very scare but after that I upgraded to heavy duty springs and aftermarket pinion bump stop. I replaced the 8.25 with a friends 8.75 in a car he was taking to have crashed. I've already had trouble finding a stronger yoke for the 741 case. What is the strongest case out of the 741, 742, and 489? Is the 741 exterior its weak point and if so anything to help it or upgrade to a different case.

I plan on stroking the 6.1 to a 426ci hemi and adding the supercharger to create 600 hp to the rear wheels.

The car is a street car full interior so i estimate it weights 3600. Engine was 800 pounds out the crate. Currently has a 8.75 with 3.55 ring and pinion.

Axles, back braces anything else I need to strength this rearend. I already have rear disc brakes to stop this breast.




Mark Williams caps, back brace and after market axles...
thats a heavy car to have a 8 3/4 live in

Re: How much power can a 8.75 rearend handle? [Re: Voluster] #1094440
10/16/11 01:14 PM
10/16/11 01:14 PM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
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Aurora, Colorado
I think the 489 center section with the crush sleeve elminator kit should be stronger than the 742?
My gripe is I priced out the cost of doing all the upgrades (yoke, gears, caps, spool, bearings, axles, and backbrace) and it was near the same cost as a new S60 rearend (and I could use my stock 8-3/4 in a different car anyhow.)

Re: How much power can a 8.75 rearend handle? [Re: 451Mopar] #1094441
10/16/11 01:28 PM
10/16/11 01:28 PM
Joined: Jun 2003
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Romeo MI
MR_P_BODY Offline
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Romeo MI
Quote:

I think the 489 center section with the crush sleeve elminator kit should be stronger than the 742?
My gripe is I priced out the cost of doing all the upgrades (yoke, gears, caps, spool, bearings, axles, and backbrace) and it was near the same cost as a new S60 rearend (and I could use my stock 8-3/4 in a different car anyhow.)




The alum center is based off of the 742

Re: How much power can a 8.75 rearend handle? [Re: Voluster] #1094442
10/16/11 08:16 PM
10/16/11 08:16 PM
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Posts: 22,695
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jcc Offline
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Quote:

I just went 9.59 at 139 with a 1.36 60 ft last weekend with a 8 3/4 on a drag raidal

We figured 720 hp the car weighed 3460






tic, tic, tic........

Last edited by jcc; 10/16/11 08:17 PM.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
Re: How much power can a 8.75 rearend handle? [Re: jcc] #1094443
10/16/11 08:31 PM
10/16/11 08:31 PM
Joined: Nov 2004
Posts: 2,825
Sk. Canada
RemCharger Offline
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Sk. Canada
Block?... convert? balancer? rod? crank? sprag? u joint? rocker? timing chain? lifter?

whats the ticking all about?

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094444
10/16/11 09:17 PM
10/16/11 09:17 PM
Joined: Jan 2003
Posts: 1,855
Staten Island N.Y.
Dap Offline
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Staten Island N.Y.
So far mine has been fine. Alum center with a spool,footbrake at 3300lbs.


PRH446
10.084 @ 135.21 mph N/A through chambered mufflers,3300lbs. Stock stroke wedge
Re: How much power can a 8.75 rearend handle? [Re: Dap] #1094445
10/16/11 11:27 PM
10/16/11 11:27 PM
Joined: Dec 2009
Posts: 20,600
in a cattle trailer down by th...
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Guitar Jones Offline
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in a cattle trailer down by th...
The 742 is the strongest as it has the largest rear pinion bearing of any passenger car rear end, including the 489. Yes the pinion shaft diameter is slighly larger at 1 7/8 than the 742 at 1 3/4 but that's already larger than the Dana 60 pinion shaft so it's a non issue. It's the size of the rear bearing that keeps pinion head deflection to a minimum.


"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094446
10/16/11 11:46 PM
10/16/11 11:46 PM
Joined: Nov 2010
Posts: 914
tn
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robnbird Offline
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robnbird  Offline
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tn
If I have to ask about a 8 3/4 Im not going to be very confident. better off with a 60 or a 9" ford in my oppenion.

6875082-mocar.jpg (249 downloads)
Re: How much power can a 8.75 rearend handle? [Re: Guitar Jones] #1094447
10/22/11 03:17 AM
10/22/11 03:17 AM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
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The new Mopar Action magazine claims the 489 case has a larger pinion and bearing (and yoke splines)?
The aluminum cases are pretty expensive. I though the bare case was around $800?

Re: How much power can a 8.75 rearend handle? [Re: 451Mopar] #1094448
10/22/11 10:09 AM
10/22/11 10:09 AM
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ill
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dennismopar73 Offline
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that is correct , the 489 case is stronger, but you have top replace the crush sleeve with the bushing kit,

Re: How much power can a 8.75 rearend handle? [Re: dennismopar73] #1094449
10/22/11 10:18 AM
10/22/11 10:18 AM
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Posts: 1,058
bigfork mn
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dragram440 Offline
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bigfork mn
Going on 2 years with my 8 3/4 running cosistant 10.60's with a 3800lb car! with 35 spline axles spool and back brace.


67' charger 499 RB 10.57 at 127
Re: How much power can a 8.75 rearend handle? [Re: dennismopar73] #1094450
10/22/11 01:27 PM
10/22/11 01:27 PM
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in a cattle trailer down by th...
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Quote:

that is correct , the 489 case is stronger, but you have top replace the crush sleeve with the bushing kit,




That may be debatable but I don't think so. MP could have used any case they wanted to pattern their aluminum case after and they chose to use the 742. There is no debate that the 742 has the biggest rear pinion bearing and that makes it a better choice despite the pinion shaft size. Which as I pointed out earlier is a non issue.

Just how much better is a 742 though? I don't know. I'm not an engineer but I don't think it's a significant difference.


"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: How much power can a 8.75 rearend handle? [Re: Guitar Jones] #1094451
10/22/11 02:19 PM
10/22/11 02:19 PM
Joined: Mar 2009
Posts: 1,058
bigfork mn
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dragram440 Offline
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bigfork mn
Quote:

Quote:

that is correct , the 489 case is stronger, but you have top replace the crush sleeve with the bushing kit,




That may be debatable but I don't think so. MP could have used any case they wanted to pattern their aluminum case after and they chose to use the 742. There is no debate that the 742 has the biggest rear pinion bearing and that makes it a better choice despite the pinion shaft size. Which as I pointed out earlier is a non issue.
I have the 742 that must be why it hasnt broke yet!
Just how much better is a 742 though? I don't know. I'm not an engineer but I don't think it's a significant difference.




67' charger 499 RB 10.57 at 127
Re: How much power can a 8.75 rearend handle? [Re: dragram440] #1094452
10/22/11 03:54 PM
10/22/11 03:54 PM
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MN
hemidup Offline
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Just spit one out at the track today. It made it a whole whopping 3'. Hopefully the trans is still good, but doubt it.


Jerry Williams.
Re: How much power can a 8.75 rearend handle? [Re: hemidup] #1094453
10/22/11 04:45 PM
10/22/11 04:45 PM
Joined: Mar 2009
Posts: 1,058
bigfork mn
D
dragram440 Offline
super stock
dragram440  Offline
super stock
D

Joined: Mar 2009
Posts: 1,058
bigfork mn
Quote:

Just spit one out at the track today. It made it a whole whopping 3'. Hopefully the trans is still good, but doubt it.



What was it in? How much power? How many passes did it last?


67' charger 499 RB 10.57 at 127
Re: How much power can a 8.75 rearend handle? [Re: dragram440] #1094454
10/22/11 05:54 PM
10/22/11 05:54 PM
Joined: Jan 2003
Posts: 8,935
Holly/MI
D
Dean_Kuzluzski Offline
master
Dean_Kuzluzski  Offline
master
D

Joined: Jan 2003
Posts: 8,935
Holly/MI
Quote:

Quote:

Just spit one out at the track today. It made it a whole whopping 3'. Hopefully the trans is still good, but doubt it.



What was it in? How much power? How many passes did it last?




Launch rpm? Stall? Aftermarket or factory R&P?? Stock caps? How heavy?


R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
Re: How much power can a 8.75 rearend handle? [Re: Dean_Kuzluzski] #1094455
10/22/11 07:20 PM
10/22/11 07:20 PM
Joined: Sep 2009
Posts: 500
MD
JACK1440 Offline
mopar
JACK1440  Offline
mopar

Joined: Sep 2009
Posts: 500
MD
we started twisting the stock axles splines in the 10.90's. car weighs 3400. I agree. at least buy the hardened axles. It's definitely worth it for the safety. we went to a dana.

Re: How much power can a 8.75 rearend handle? [Re: dragram440] #1094456
10/22/11 08:54 PM
10/22/11 08:54 PM
Joined: Nov 2008
Posts: 833
MN
hemidup Offline
super stock
hemidup  Offline
super stock

Joined: Nov 2008
Posts: 833
MN
Quote:

Quote:

Just spit one out at the track today. It made it a whole whopping 3'. Hopefully the trans is still good, but doubt it.



What was it in? How much power? How many passes did it last?




489/3.91 gears. 73 Dart Sport with a 550 crank hp motor.


Jerry Williams.
Re: How much power can a 8.75 rearend handle? [Re: JACK1440] #1094457
10/22/11 09:15 PM
10/22/11 09:15 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

we started twisting the stock axles splines in the 10.90's. car weighs 3400. I agree. at least buy the hardened axles. It's definitely worth it for the safety. we went to a dana.




My Strange axles are twisted about 3/4 of a spline right
where they come out of the spool... they've been the
same for 4 years now... not getting any worse... thats
on my alum center 8 3/4 with a back brace... 2400#
leaving at 5600 rpm on a 5600 stall with a 1.19 60'

Re: How much power can a 8.75 rearend handle? [Re: Guitar Jones] #1094458
10/22/11 09:25 PM
10/22/11 09:25 PM
Joined: Dec 2003
Posts: 22,695
Bitopia
J
jcc Offline
If you can't dazzle em with diamonds..
jcc  Offline
If you can't dazzle em with diamonds..
J

Joined: Dec 2003
Posts: 22,695
Bitopia


Quote:

Quote:

that is correct , the 489 case is stronger, but you have top replace the crush sleeve with the bushing kit,




That may be debatable but I don't think so. MP could have used any case they wanted to pattern their aluminum case after and they chose to use the 742. There is no debate that the 742 has the biggest rear pinion bearing and that makes it a better choice despite the pinion shaft size. Which as I pointed out earlier is a non issue.

Just how much better is a 742 though? I don't know. I'm not an engineer but I don't think it's a significant difference.




The 742 design may have been MP choice because of no crush sleeve and just maybe better current gear choice. Additionally, the weakest link is always the first item to be solved in design upgrades, and I would venture to guess mopar engineers at the time of the orignal 742 thought a larger pinion shaft dia was needed, maybe for less shaft deflection under high power between the pinion and the ring, which could lead to sheared teeth. With the new alum case reportedably designed 10%? stiffer, going back to the larger bearing non crush sleeve common 742 made the most sense

To add: I don't believe bearing size of the pinion is hardly any part of deflection issues. Roller bearings hardly deflect at all until complete failure. However a pinion load is cantilevered past the rear pinion bearing, allowing for possible deflection of the pinion shaft, a design shortfall the 9" does not have.

Last edited by jcc; 10/23/11 04:04 PM.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
Re: How much power can a 8.75 rearend handle? [Re: jcc] #1094459
10/22/11 10:04 PM
10/22/11 10:04 PM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Offline
master
dvw  Offline
master

Joined: Mar 2006
Posts: 9,791
MI, usa
I've run 8 3/4 in my Volare forever. 11.0@122, 1.53 60, 3875lbs. The 742,4.56 went from it to Dizusters 11.90 duster,to my buddys 10.80 GTX. It's still going. 100s of passes.
Doug

Re: How much power can a 8.75 rearend handle? [Re: Crock] #1094460
10/23/11 01:53 AM
10/23/11 01:53 AM
Joined: Jul 2004
Posts: 19,317
State of confusion
T
Thumperdart Offline
I Live Here
Thumperdart  Offline
I Live Here
T

Joined: Jul 2004
Posts: 19,317
State of confusion
Going on 8+ years all in the 10`s at 3200lbs. and I run the 742 case w/Richmond 4.11 gears, Dutchman 30 spline axles, stock caps and a backbrace.


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: How much power can a 8.75 rearend handle? [Re: Thumperdart] #1094461
10/23/11 09:15 AM
10/23/11 09:15 AM
Joined: Jul 2009
Posts: 694
Michigan
S
Super Scamp Offline
mopar
Super Scamp  Offline
mopar
S

Joined: Jul 2009
Posts: 694
Michigan
Quote:

Going on 8+ years all in the 10`s at 3200lbs. and I run the 742 case w/Richmond 4.11 gears, Dutchman 30 spline axles, stock caps and a backbrace.




LUCKY...Is correct word in this post.

The time is going to come when all of you 10 second cars hook up 1 good time and the weak link is going to cause you to spend lots of to fix you Trans/rear/and maybe the motor.

You all need one of these...

6884409-P1200101.JPG (258 downloads)

Just One Man's Opinion Mopar Mafia Racing
Re: How much power can a 8.75 rearend handle? [Re: robnbird] #1094462
10/23/11 10:33 AM
10/23/11 10:33 AM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
Too Many Posts
Challenger 1  Offline
Too Many Posts

Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Quote:

If I have to ask about a 8 3/4 Im not going to be very confident. better off with a 60 or a 9" ford in my oppenion.




OMG you said 9" ford on a Mopar site!!

Re: How much power can a 8.75 rearend handle? [Re: Super Scamp] #1094463
10/23/11 11:32 AM
10/23/11 11:32 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Quote:

Going on 8+ years all in the 10`s at 3200lbs. and I run the 742 case w/Richmond 4.11 gears, Dutchman 30 spline axles, stock caps and a backbrace.




LUCKY...Is correct word in this post.

The time is going to come when all of you 10 second cars hook up 1 good time and the weak link is going to cause you to spend lots of to fix you Trans/rear/and maybe the motor.

You all need one of these...




I've been in the 8s with my 8 3/4... like I've said
a thousand times "I think its a weight issue"... JMO

Re: How much power can a 8.75 rearend handle? [Re: MR_P_BODY] #1094464
10/23/11 12:01 PM
10/23/11 12:01 PM
Joined: Oct 2003
Posts: 11,678
W. Kentucky
justinp61 Offline
I Live Here
justinp61  Offline
I Live Here

Joined: Oct 2003
Posts: 11,678
W. Kentucky
I'd say the OP is fine with what he has, if it breaks it will be the teeth on the ring gear. If he was hittin' it hard with a loose converter on a big tire then he'd need a Dana.

Just out of curosity to all the guys that claim the 741 is the weakest. How many pinion gears have you seen broken, not teeth but the actual shaft? All 8 3/4s are the same size (in their respective spline count) on the pinion where it is machined for the splines. I've never seen one break there, 741, 742 or a 489. Not saying it has never or won't happen, but all I've seen have broke the teeth on the ring gear for one reason or another.

Re: How much power can a 8.75 rearend handle? [Re: Super Scamp] #1094465
10/23/11 12:08 PM
10/23/11 12:08 PM
Joined: Jul 2004
Posts: 19,317
State of confusion
T
Thumperdart Offline
I Live Here
Thumperdart  Offline
I Live Here
T

Joined: Jul 2004
Posts: 19,317
State of confusion
Quote:

Quote:

Going on 8+ years all in the 10`s at 3200lbs. and I run the 742 case w/Richmond 4.11 gears, Dutchman 30 spline axles, stock caps and a backbrace.




LUCKY...Is correct word in this post.

The time is going to come when all of you 10 second cars hook up 1 good time and the weak link is going to cause you to spend lots of to fix you Trans/rear/and maybe the motor.

You all need one of these...


Guess I`m lucky I dont hook up good then even though I see 6"`s of air under the ft. tires.


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: How much power can a 8.75 rearend handle? [Re: Thumperdart] #1094466
10/23/11 12:59 PM
10/23/11 12:59 PM
Joined: Nov 2007
Posts: 1,600
Alberta Canada
StrokerAspen Offline
top fuel
StrokerAspen  Offline
top fuel

Joined: Nov 2007
Posts: 1,600
Alberta Canada
I ran a string of 10.70's on my 8 3/4 this year. Stock axles, stock caps stock gears and a stock cone sure grip. The car is 3400 race weight with exhaust on. HOWEVER I have a big squishy converter, and I think the 3.23 gears are saving the axles. Best 60' was a 1.55 buy most were 1.59-1.61. I plan on changing to a Dana 60 this winter. Here is a video of a 1.61 leave. It doesn't look like this set up will break anytime soon, but it's a boring launch.

http://www.youtube.com/watch?v=8-PO1bCE3E0&feature=youtube_gdata_player

-Kenny

Re: How much power can a 8.75 rearend handle? [Re: Thumperdart] #1094467
10/23/11 06:47 PM
10/23/11 06:47 PM
Joined: Oct 2004
Posts: 16,452
Canada
CrAzYMoPaRGuY Offline
I Live Here
CrAzYMoPaRGuY  Offline
I Live Here

Joined: Oct 2004
Posts: 16,452
Canada
Quote:

Quote:

Quote:

Going on 8+ years all in the 10`s at 3200lbs. and I run the 742 case w/Richmond 4.11 gears, Dutchman 30 spline axles, stock caps and a backbrace.




LUCKY...Is correct word in this post.

The time is going to come when all of you 10 second cars hook up 1 good time and the weak link is going to cause you to spend lots of to fix you Trans/rear/and maybe the motor.

You all need one of these...


Guess I`m lucky I dont hook up good then even though I see 6"`s of air under the ft. tires.






I was thinking the EXACT same thing when I read his post!


CrAzYMoPaRGuY
Re: How much power can a 8.75 rearend handle? [Re: Challenger 1] #1094468
10/23/11 06:52 PM
10/23/11 06:52 PM
Joined: Oct 2004
Posts: 16,452
Canada
CrAzYMoPaRGuY Offline
I Live Here
CrAzYMoPaRGuY  Offline
I Live Here

Joined: Oct 2004
Posts: 16,452
Canada
Quote:

Quote:

If I have to ask about a 8 3/4 Im not going to be very confident. better off with a 60 or a 9" ford in my oppenion.




OMG you said 9" ford on a Mopar site!!




Binder Dundat.

Pooched 6 different pumpkins with different brands of brand new gears, spool, 31 spline 4 spider posis, WAR cases, nodular cases, you name it. Jamie Roth, Ian Wood, the crazy AMC guy in Mission, everybody tried to build me a third member, none lasted!


No more 9" rears for THIS guy!!!!

6885081-cars.jpg (159 downloads)

CrAzYMoPaRGuY
Re: How much power can a 8.75 rearend handle? [Re: CrAzYMoPaRGuY] #1094469
10/24/11 04:23 AM
10/24/11 04:23 AM
Joined: Aug 2006
Posts: 2,141
junction city oregon
V
viperblue72 Offline
top fuel
viperblue72  Offline
top fuel
V

Joined: Aug 2006
Posts: 2,141
junction city oregon
The 8 3/4 is a strong rearend. Set up correctly I think it will work fine for you. Id get some aftermarket axles however. With only a 2400-2800 stall you won't be pushing your luck imo.

Re: How much power can a 8.75 rearend handle? [Re: viperblue72] #1094470
10/24/11 12:07 PM
10/24/11 12:07 PM
Joined: Jan 2003
Posts: 5,762
Hot Rod Ridge
FastmOp Offline
master
FastmOp  Offline
master

Joined: Jan 2003
Posts: 5,762
Hot Rod Ridge
In may I was down to eight cars and the chick I was racing went red. I had a 5.99 dial in on it when the 8&3/4 let go. It broke the trans too.
So I stuck a Dana in it, now I can tranzbreaking it every pass and not worry

Re: How much power can a 8.75 rearend handle? [Re: FastmOp] #1094471
10/24/11 12:56 PM
10/24/11 12:56 PM
Joined: Dec 2009
Posts: 20,600
in a cattle trailer down by th...
G
Guitar Jones Offline
Paddle faster! I hear banjo music!
Guitar Jones  Offline
Paddle faster! I hear banjo music!
G

Joined: Dec 2009
Posts: 20,600
in a cattle trailer down by th...
Quote:

In may I was down to eight cars and the chick I was racing went red. I had a 5.99 dial in on it when the 8&3/4 let go. It broke the trans too.
So I stuck a Dana in it, now I can tranzbreaking it every pass and not worry




The last street gear I had broke the teeth on the ring gear on the final points night with 4 rounds to go. I needed one more round to win the track championship. That thing made it through 4 more passes and not only did I win the championship but I won the race too. When I pulled it apart the next day I was amazed it lasted the rest of the night. It looked like it shouldn't have made it onto the trailer.


"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: How much power can a 8.75 rearend handle? [Re: Guitar Jones] #1094472
10/24/11 02:13 PM
10/24/11 02:13 PM
Joined: Jan 2003
Posts: 5,762
Hot Rod Ridge
FastmOp Offline
master
FastmOp  Offline
master

Joined: Jan 2003
Posts: 5,762
Hot Rod Ridge
Mine made the tranny make bad noises in any gear and was trying to lock up as I was pull'd off the track. As I was pulling it up to the trailer it lock'd solid and I had to load it with the floor jack and winch. Good Times!

I do think the OP is fine and should be ok, but it has a small chance of breaking every time it launch's hard.

Re: How much power can a 8.75 rearend handle? [Re: hemidup] #1094473
10/25/11 03:23 AM
10/25/11 03:23 AM
Joined: Nov 2008
Posts: 833
MN
hemidup Offline
super stock
hemidup  Offline
super stock

Joined: Nov 2008
Posts: 833
MN
Quote:

Just spit one out at the track today. It made it a whole whopping 3'. Hopefully the trans is still good, but doubt it.




Quoting myself here....

Lost 18 teeth off the ring gear. Output shaft married itself to the aluminum planitary and of course the sprag was toast. Luckily it didn't split the case.


Jerry Williams.
Re: How much power can a 8.75 rearend handle? [Re: Challenger 1] #1094474
10/25/11 07:45 AM
10/25/11 07:45 AM
Joined: Jan 2003
Posts: 1,855
Staten Island N.Y.
Dap Offline
top fuel
Dap  Offline
top fuel

Joined: Jan 2003
Posts: 1,855
Staten Island N.Y.
Quote:

OMG you said 9" ford on a Mopar site!!




I think it is ok to say Ford here. They are one of the site sponsors..


PRH446
10.084 @ 135.21 mph N/A through chambered mufflers,3300lbs. Stock stroke wedge
Re: How much power can a 8.75 rearend handle? [Re: Dap] #1094475
10/25/11 11:07 AM
10/25/11 11:07 AM
Joined: Jan 2003
Posts: 3,104
Wheels up, MO
N
nhramark Offline
master
nhramark  Offline
master
N

Joined: Jan 2003
Posts: 3,104
Wheels up, MO
I think if you sit down with a piece of paper and cost out making the 8 3/4 stronger vs installing a Dana, you will have your answer. Either way get some good axles in that thing.

BTW congrats on your promotion!


[image]http://s1126.photobucket.com/user/nhramark1/library/Racing[/image] 9.100 @ 150 mph 5.780 @ 120 mph
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