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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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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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Joined: Nov 2009
Posts: 2,177 ill
dennismopar73
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,177
ill
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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.
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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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Joined: Nov 2009
Posts: 2,177 ill
dennismopar73
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,177
ill
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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.
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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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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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
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Joined: Jan 2007
Posts: 437 south central pa
bdaz smblk
mopar
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mopar
Joined: Jan 2007
Posts: 437
south central pa
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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
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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
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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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
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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
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Joined: Feb 2004
Posts: 6,257 acworth / N. georgia - south e...
cheapstreetdustr
master
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master
Joined: Feb 2004
Posts: 6,257
acworth / N. georgia - south e...
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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]
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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
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Joined: Aug 2003
Posts: 43,007 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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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)
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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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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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
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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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.)
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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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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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
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Joined: Jan 2003
Posts: 1,855 Staten Island N.Y.
Dap
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,855
Staten Island N.Y.
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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
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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
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Joined: Dec 2009
Posts: 20,600 in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,600
in a cattle trailer down by th...
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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.
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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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Joined: Mar 2009
Posts: 1,058 bigfork mn
dragram440
super stock
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super stock
Joined: Mar 2009
Posts: 1,058
bigfork mn
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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
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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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Joined: Dec 2009
Posts: 20,600 in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,600
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.
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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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Joined: Nov 2008
Posts: 833 MN
hemidup
super stock
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super stock
Joined: Nov 2008
Posts: 833
MN
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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.
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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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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'
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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
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Joined: Dec 2003
Posts: 22,695 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,695
Bitopia
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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.
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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
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Joined: Mar 2006
Posts: 9,791 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,791
MI, usa
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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
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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
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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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!!
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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
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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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
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Joined: Nov 2007
Posts: 1,600 Alberta Canada
StrokerAspen
top fuel
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top fuel
Joined: Nov 2007
Posts: 1,600
Alberta Canada
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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
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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
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Joined: Oct 2004
Posts: 16,452 Canada
CrAzYMoPaRGuY
I Live Here
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I Live Here
Joined: Oct 2004
Posts: 16,452
Canada
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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!!!!
CrAzYMoPaRGuY
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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
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Joined: Dec 2009
Posts: 20,600 in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,600
in a cattle trailer down by th...
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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.
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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
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Joined: Jan 2003
Posts: 3,104 Wheels up, MO
nhramark
master
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master
Joined: Jan 2003
Posts: 3,104
Wheels up, MO
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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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