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#1050292 - 04/25/17 02:41 AM rear end  
Joined: Jan 2015
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lonk Offline
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lonk  Offline
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Joined: Jan 2015
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Broken Arrow, ok
What is teh max HP that the stock rear end can handle? My rear end is all stock and in great shape. i was thinking about replacing the engine with the chevy crate engine 19210009.

https://www.summitracing.com/parts/nal-19210009/overview/make/chevrolet


Thanks
Lonk

#1050300 - 04/25/17 10:33 AM Re: rear end [Re: lonk]  
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Razinhail Offline
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Kansas City Area, MO
I believe I've read other people around here saying it can handle up to 300-350-ish HP. As long as you're not launching hard you should be fine, but with that motor I wouldn't take the car to the track.

Disclaimer: I have no real experience with this, that's what I've read others around here saying in other posts before. Just passing the information along.



1984 Monte Carlo SS with a stock 305 H.O. and stock TH350C
#1050304 - 04/25/17 02:02 PM Re: rear end [Re: lonk]  
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upflying Offline
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Reno, NV
I still have the stock 10 bolt 7.5 open diff behind my LS3. I know its on borrowed time but I don't race, do burnouts or spin donuts. It also helps my tires are slippery Firestones. Sticky race tires would turn my rear end into spaghetti. When I go WOT, I wait until I'm past 25mph. Open diffs might be safer for street driving anyway. A Posi might send me into a wall.

Last edited by upflying; 04/25/17 02:06 PM.

86 MCSS Notchback coupe, LS3, 4L65E, QP 9", Eaton Truetrac, 4 wheel disc, column shift, Dakota Digital, silver with maroon bench interior

#1050305 - 04/25/17 02:08 PM Re: rear end [Re: upflying]  
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PB86SS/87LS Offline
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New Berlin, WI
Originally Posted by upflying
I still have the stock 10 bolt 7.5 open diff behind my LS3. I know its on borrowed time but I don't race, do burnouts or spin donuts. It also helps my tires are slippery Firestones. Sticky race tires would turn my rear end into spaghetti. When I go WOT, I wait until I'm past 25mph. Open diffs might be safer for street driving anyway. A Posi might send me into a wall.


Cheaper on tires too, just need replace one after awhile instead of two laugh


-86'SS 383 CCC QJet- BRF 2004r-8.5" 3.42
-87'LS 350 MAF/SD TPI- CRF 2004r-7.5" 3.42
-81'Grand LeMans Safari Wagon 350 CCC Q-Jet/CZF 2004-r/8.5" 3.73
-07'TBSS Stockish daily driver
[Linked Image]
#1050307 - 04/25/17 02:59 PM Re: rear end [Re: lonk]  
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DiamondSnake Offline
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Québec, QC
I'm still on the stock Rear-end and my current combo is on the 360-370 ish HP and 410-420lbs torque.
So far it's holding up ok. Careful on launches, but no burnouts,no racing, no Sticky Drag tires.
The best thing you can do is avoid spinning and locking tires imo, what i mean is, The worse thing you can probably do is punch the car at WOT from nill and the tires start spinning at X high rpms and then Stick hard to the pavement. (example : one wheels spins on the side of the road because of dirt and then locks up on clear pavement). That could break axles and whatever else in there.

This is the image i was given by guys at the shop. Imagine you're holding a pencil and you're pushing on the center with your 2 thumbs, the pencil bends but does not break unless you put a lot more pressure on it. if you're tires free spin and then lock hard on the pavement, it's like putting max pressure on the pencil. It will break.
I hope that makes sense?


Last edited by DiamondSnake; 04/25/17 05:09 PM.
#1050313 - 04/25/17 03:36 PM Re: rear end [Re: PB86SS/87LS]  
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upflying Offline
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upflying  Offline
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Reno, NV
Originally Posted by PB86SS/87LS
Originally Posted by upflying
I still have the stock 10 bolt 7.5 open diff behind my LS3. I know its on borrowed time but I don't race, do burnouts or spin donuts. It also helps my tires are slippery Firestones. Sticky race tires would turn my rear end into spaghetti. When I go WOT, I wait until I'm past 25mph. Open diffs might be safer for street driving anyway. A Posi might send me into a wall.


Cheaper on tires too, just need replace one after awhile instead of two laugh

Good point, especially since these tires are hard to find and/or not made anymore.


86 MCSS Notchback coupe, LS3, 4L65E, QP 9", Eaton Truetrac, 4 wheel disc, column shift, Dakota Digital, silver with maroon bench interior

#1050314 - 04/25/17 03:44 PM Re: rear end [Re: lonk]  
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Hunter79764 Offline
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Grand Prairie, Tx
By the same token, you can probably hang 5 lbs on the middle of a pencil with both ends supported, but if you pick those 5 lbs up an inch and drop them, that pencil will soon be two pencils... In other words, shock loads break parts. Roll into the throttle and you should be ok. You might be one of the lucky ones that can absolutely beat on it without breaking anything, but don't count on it too strongly.


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1050317 - 04/25/17 04:20 PM Re: rear end [Re: lonk]  
Joined: May 2016
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Witness86SS Offline
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Witness86SS  Offline
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Hatfield, PA
Can you usually manage a short drive home on a blown rear or is it a tow truck job?


Justin
1986 Black SS
Upgrades: 350 L05 - Hooker Longtubes - FlowMaster True Dual 2.5" - Electric Cutouts - Electric Fans - Transcooler - Proforged Steering Kit - Astro Shaft - AR62 OUTLAW II Wheels - Energy Suspension Bushings - Bitflipper Chip - 87 ECM - Moog Springs and Ball Joints - Bilstein Shocks - Bucket Seats
#1050325 - 04/25/17 08:02 PM Re: rear end [Re: Witness86SS]  
Joined: Apr 2006
Posts: 3,552
GuysMonteSS Offline
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GuysMonteSS  Offline
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Kentville,Nova Scotia
Originally Posted by Witness86SS
Can you usually manage a short drive home on a blown rear or is it a tow truck job?



Tow truck.
Guy


GuysMonteSS '86 SS,513 BBC,AFR Heads,UDHarold/Bullet Custom Solid Roller Cam,706 lift,255/263 @ .050,Jesel Shaft Rockers,Balanced & Blueprinted,Doug Nash 4+1 5 Speed,Hurst In-Line Shifter,Ford 9 Inch Rear,SC&C Street Comp Stage 2+ Front End Kit...
#1050326 - 04/25/17 08:04 PM Re: rear end [Re: Witness86SS]  
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GuysMonteSS Offline
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GuysMonteSS  Offline
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Kentville,Nova Scotia
Originally Posted by Witness86SS
Can you usually manage a short drive home on a blown rear or is it a tow truck job?



Tow truck.
Its not the axles that will go its the spider gears that give up first.
When I blew up the 7.5 that was in my Monte when I bought,they looked like ground beef.
Guy


GuysMonteSS '86 SS,513 BBC,AFR Heads,UDHarold/Bullet Custom Solid Roller Cam,706 lift,255/263 @ .050,Jesel Shaft Rockers,Balanced & Blueprinted,Doug Nash 4+1 5 Speed,Hurst In-Line Shifter,Ford 9 Inch Rear,SC&C Street Comp Stage 2+ Front End Kit...
#1050328 - 04/25/17 09:02 PM Re: rear end [Re: lonk]  
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mmc427ss Offline
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mmc427ss  Offline
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Pottstown, Pa
I would buy that engine if that is what will make you happy for the coming years, put a few bucks in making sure the 200R will handle the new power, then drive sanely and you should get good life out of the 7 1/2. It's when you dump a lot of torque on a 7 1/2 and abuse it they could give up on you. Save your money now, get that engine/trans installed, enjoy the difference another 100 hp makes.

When you change rear, costs adds up quickly, you always need a different driveshaft, complete drop in rears are expensive, then we need to throw some parts at the brakes and do some suspension improvements. Easily can amount to thousand of bucks.
Bob

#1050355 - 04/26/17 10:13 PM Re: rear end [Re: lonk]  
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406monte Offline
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406monte  Offline
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Hubert, NC
I am also running the stock 7.5. I have only added a Auburn Posi unit and ARP wheel studs. I raced 1/4 mile every weekend running a pair of Mickey Thompson Street E. T's. My 406 with a 3200 stall making 427hp and 429trq ran 11's and 1.6 sixties coming out of the whole full throttle. I even pulled the front tires occasionally on a good track day.
I beat the snot out of it for over 10 years like that. There are a few of us that have been lucky and dodging the so called bullet with these rears. But. I guess I am a lucky one or just an anomaly lol.


84 Monte Carlo SC 406 SBC
78 Monte Carlo 305 sbc SOLD
78 Monte Carlo Landua 350 sbc SOLD
81 Malibu Classic 350 sbc SOLD
84 Monte Carlo LS 350 sbc SOLD
84 Buick Regal 229 v6 SOLD

#1050357 - 04/26/17 10:20 PM Re: rear end [Re: lonk]  
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88ss408 Offline
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88ss408  Offline
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miramichi, NB
I also am running a stick 7.625 rear. Do not run slicks though. No problems yet 539 tq.


1988 monte carlo ss 408 sbc
-----------------------------------------------------
1984 monte carlo cs 400 sbc
#1050360 - 04/27/17 01:08 AM Re: rear end [Re: lonk]  
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Onebadbowtie86 Offline
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Traverse City Michigan
My stock 3:73 limited slip never gave me an issue and worked great, even with 180k miles. 5k rpm clutch dumps at the track. If your cars an auto, the 7.5" will most likely live a long life. A lot of ls f bodys are running in the 11's on the stock rear.


'86 Monte carlo ss-Frame off resto-mod.
Ls2/t56/8.5"

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