|
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
master
|
master
Joined: May 2008
Posts: 5,399
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
Posts: 52,972
Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
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: 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
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,855
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: 20,630
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
|
Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,630
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: dennismopar73]
#1094449
10/22/11 10:18 AM
10/22/11 10:18 AM
|
Joined: Mar 2009
Posts: 1,058
bigfork mn
dragram440
super stock
|
super stock
Joined: Mar 2009
Posts: 1,058
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
|
Joined: Dec 2009
Posts: 20,630
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
|
Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,630
in a cattle trailer down by th...
|
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: dragram440]
#1094452
10/22/11 03:54 PM
10/22/11 03:54 PM
|
Joined: Nov 2008
Posts: 833
MN
hemidup
super stock
|
super stock
Joined: Nov 2008
Posts: 833
MN
|
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: 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
Master
|
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: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
|
If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
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: 9,824
MI, usa
dvw
master
|
master
Joined: Mar 2006
Posts: 9,824
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
|
|
|
|
|
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.
