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how much hp can a 8.75 differential take? #1170475 02/02/12 09:25 AM 02/02/12 09:25 AM
Joined: Jul 2005 Posts: 640 Graz, Austria DGS OP mopar
DGS OP mopar Joined: Jul 2005 Posts: 640 Graz, Austria	Trying to decide on which differnetial I should get for my street driven Charger. I wante to get a Detroit TrueTrac but read somewhere that they only take about 300-350 hp. Is that true? I'm currently making about 400 hp at the flywheel but have plans for a 500" stroker (automatic car btw.). Tires are 295/50 so there is plenty of rubber for traction. Don't wanna get a Dana and rather stay with my 8.75" - are there better options than the TrueTrac?

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170476 02/02/12 10:32 AM 02/02/12 10:32 AM
Joined: Jan 2003 Posts: 75,092 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,092 A Banana Republic near you.	HP is not the killer , its torque . What is the car ? Weight ? What is the tire brand you are using ? How will you be driving it ?

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170477 02/02/12 10:49 AM 02/02/12 10:49 AM
Joined: Sep 2006 Posts: 616 TP Exit 7, NJ, USA DANA60 mopar
DANA60 mopar Joined: Sep 2006 Posts: 616 TP Exit 7, NJ, USA	It would be better with a 742 casing, or 489 of course. You should be OK with your app. Keep in mind that the Max Wedges, and early HEMI SS cars could use Danas , but preferred the 8 3/4 because of the ease of gear changes. Yeah, a big ole Dana underneath has a cool look, but if you have the 8 3/4 then you should be fine. 7049737-IMG_3511.jpg (248 downloads)

Re: how much hp can a 8.75 differential take? [Re: DANA60] #1170478 02/02/12 10:53 AM 02/02/12 10:53 AM
Joined: Jul 2005 Posts: 640 Graz, Austria DGS OP mopar
DGS OP mopar Joined: Jul 2005 Posts: 640 Graz, Austria	Car is a 1970 Charger R/T 440 auto. weight is around 3800lbs, tires are BFG Radial T/A 295/50 R15 diff case is a 489 driving style? mostly regular street driving with an occasional stop light to stop light sprint

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170479 02/02/12 10:54 AM 02/02/12 10:54 AM
Joined: Nov 2009 Posts: 2,177 ill D dennismopar73 top fuel
dennismopar73 top fuel D Joined: Nov 2009 Posts: 2,177 ill	8 3/4 alot stronger than you think, and will hold up quit awhile. Age is a killer anything will break over time, always use new gears bearings, and a good yoke! set up will be the main deal ,if not right will cost you in the long run! try to find a good case 742 is one of the best cases to look for, 489 is most common, some will say the 741 is weaker, but , I have run it , raced it never issue , but as I said age and passes, yes, hp /tq /weight, also plays somewhat into the mix, good luck!

Re: how much hp can a 8.75 differential take? [Re: dennismopar73] #1170480 02/02/12 10:57 AM 02/02/12 10:57 AM
Joined: Jul 2005 Posts: 640 Graz, Austria DGS OP mopar
DGS OP mopar Joined: Jul 2005 Posts: 640 Graz, Austria	I know that the 8.75 is a reliable axle - I'm concerned about the sure grip differential. Especially the Detroit TrueTrac.

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170481 02/02/12 11:09 AM 02/02/12 11:09 AM
Joined: Jan 2003 Posts: 24,562 Brookeville, Md Mr.Yuck Not enough dumb comments...yet
Mr.Yuck Not enough dumb comments...yet Joined: Jan 2003 Posts: 24,562 Brookeville, Md	300-350?? they put them behind 440-6 cars and Hemi's. It depends on what stall/gear..sticky tires? I have a stock 8/75 w/ 3.91's and 500+hp no issues. I think you can do a few things to make them stronger...backbrace, Cal-traks..anything that helps them from Twisting. I went with a Nodular unit from Randy's a few years ago for my S/C'd 440 no issues. [IMG]http://i66.tinypic.com/pui5j.jpg[/IMG] Coming soon!!!!

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170482 02/02/12 11:14 AM 02/02/12 11:14 AM
Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O 70Cuda383 Too Many Posts
70Cuda383 Too Many Posts Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O	Quote: I know that the 8.75 is a reliable axle - I'm concerned about the sure grip differential. Especially the Detroit TrueTrac. I don't know who told you the Detroit TrueTrac is only good for 350 ft lbs of torque. I seem to remember a story a few years ago in one of the mopar mags where Detroit said "you can't break this diff. you'll break other parts before you blow up this true-trac." and they tried to break it with slicks big block power and 11 second time slips (all from memory, it's been a few years since I saw that article) I had a detroit true trac behind my 383 stroker making 535 ft lbs of torque, in a 4200 lb pick-up truck, with a manual transmission it did just fine. Photobucket sucks

Re: how much hp can a 8.75 differential take? [Re: Mr.Yuck] #1170483 02/02/12 11:17 AM 02/02/12 11:17 AM
Joined: Jul 2005 Posts: 640 Graz, Austria DGS OP mopar
DGS OP mopar Joined: Jul 2005 Posts: 640 Graz, Austria	Got the hp info from there: http://www.carcraft.com/techarticles/ccrp_1002_limited_slip_differentials/viewall.html

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170484 02/02/12 11:17 AM 02/02/12 11:17 AM
Joined: Jan 2003 Posts: 75,092 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,092 A Banana Republic near you.	Quote: Car is a 1970 Charger R/T 440 auto. weight is around 3800lbs, tires are BFG Radial T/A 295/50 R15 diff case is a 489 driving style? mostly regular street driving with an occasional stop light to stop light sprint 8.75 will be fine , you'll have little traction with those tires , just don't buy a cone type suregrip of any make.

Re: how much hp can a 8.75 differential take? [Re: 70Cuda383] #1170485 02/02/12 11:21 AM 02/02/12 11:21 AM
Joined: Jul 2005 Posts: 640 Graz, Austria DGS OP mopar
DGS OP mopar Joined: Jul 2005 Posts: 640 Graz, Austria	Quote: Quote: I know that the 8.75 is a reliable axle - I'm concerned about the sure grip differential. Especially the Detroit TrueTrac. I don't know who told you the Detroit TrueTrac is only good for 350 ft lbs of torque. I seem to remember a story a few years ago in one of the mopar mags where Detroit said "you can't break this diff. you'll break other parts before you blow up this true-trac." and they tried to break it with slicks big block power and 11 second time slips (all from memory, it's been a few years since I saw that article) I had a detroit true trac behind my 383 stroker making 535 ft lbs of torque, in a 4200 lb pick-up truck, with a manual transmission it did just fine. sounds good to me! I'll get a TrueTrac then and sell my cone style SG (looks almost new but is a Borg Warner type).

Re: how much hp can a 8.75 differential take? [Re: JohnRR] #1170486 02/02/12 11:22 AM 02/02/12 11:22 AM
Joined: Jan 2003 Posts: 24,562 Brookeville, Md Mr.Yuck Not enough dumb comments...yet
Mr.Yuck Not enough dumb comments...yet Joined: Jan 2003 Posts: 24,562 Brookeville, Md	Quote: Quote: Car is a 1970 Charger R/T 440 auto. weight is around 3800lbs, tires are BFG Radial T/A 295/50 R15 diff case is a 489 driving style? mostly regular street driving with an occasional stop light to stop light sprint 8.75 will be fine , you'll have little traction with those tires , just don't buy a cone type suregrip of any make. no kidding I put the slicks on the shelf and put my 265/60/16 T/A's on the car and it's like I'm driving on ice. One small blip of the throttle and the tires start turning...doesn't matter if I'm in 1st 2nd or 3rd at almost any speed.

Re: how much hp can a 8.75 differential take? [Re: Mr.Yuck] #1170487 02/02/12 11:44 AM 02/02/12 11:44 AM
Joined: Apr 2005 Posts: 15,134 Kelowna, B.C. Canada D DPelletier I Live Here
DPelletier I Live Here D Joined: Apr 2005 Posts: 15,134 Kelowna, B.C. Canada	Yep, 295 BFG's have very little traction and that's what it's all about: TRACTION, not HP, not torque....TRACTION is what can hurt diffs. There is no problem with an 8 3/4 being used for the OP's stated useage. Even occasional track use with slicks and it would be just fine. Dave 1970 Super Bee 440 Six Pack 1974 'Cuda 2008 Ram 3500 Diesel 2006 Ram 3500 Diesel 2004.5 Ram 2500 Diesel 2003 Ram 3500 Diesel 2006 Durango Limited [url] http://1970superbee.piczo.com [/url]

Re: how much hp can a 8.75 differential take? [Re: DGS] #1170488 02/02/12 11:55 AM 02/02/12 11:55 AM
Joined: Sep 2004 Posts: 22,873 Chicken coop dustergirl340 Chicken Little
dustergirl340 Chicken Little Joined: Sep 2004 Posts: 22,873 Chicken coop	Heavy weight + lots of torque + sticky tires = ouch

Re: how much hp can a 8.75 differential take? [Re: dustergirl340] #1170489 02/02/12 12:30 PM 02/02/12 12:30 PM
Joined: Jan 2003 Posts: 24,562 Brookeville, Md Mr.Yuck Not enough dumb comments...yet
Mr.Yuck Not enough dumb comments...yet Joined: Jan 2003 Posts: 24,562 Brookeville, Md	Quote: Heavy weight + lots of torque + sticky tires = ouch We will find out in the spring. I have a few upgrades and I'm going to run it 100% for the 1st time. Looking for about a 1.50 60 foot and 11.teens (or better)at 120+ 7049902-run.jpg (207 downloads)

Re: how much hp can a 8.75 differential take? [Re: Mr.Yuck] #1170490 02/02/12 12:35 PM 02/02/12 12:35 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	A billet cap and studs will keep things together better. As stated above, torque applied is what loads the gears. R.

Re: how much hp can a 8.75 differential take? [Re: dogdays] #1170491 02/02/12 12:42 PM 02/02/12 12:42 PM
Joined: Jan 2003 Posts: 9,436 Blair County,PA 62maxwgn master
62maxwgn master Joined: Jan 2003 Posts: 9,436 Blair County,PA	Were the 8 3/4 not strong enough for the 62/65 Super Stock cars ?

Re: how much hp can a 8.75 differential take? [Re: 62maxwgn] #1170492 02/02/12 12:49 PM 02/02/12 12:49 PM
Joined: Jan 2003 Posts: 75,092 A Banana Republic near you. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,092 A Banana Republic near you.	Quote: Were the 8 3/4 not strong enough for the 62/65 Super Stock cars ? Maybe they were for those ... ... you can do all the mods you want to the 8.75 , billt caps , axles , back brace the rear , spool , in the end the weak link still exists ... the gears ... running up my post count some more .

Re: how much hp can a 8.75 differential take? [Re: JohnRR] #1170493 02/02/12 01:16 PM 02/02/12 01:16 PM
Joined: Apr 2005 Posts: 15,134 Kelowna, B.C. Canada D DPelletier I Live Here
DPelletier I Live Here D Joined: Apr 2005 Posts: 15,134 Kelowna, B.C. Canada	Quote: Quote: Were the 8 3/4 not strong enough for the 62/65 Super Stock cars ? Maybe they were for those ... ... you can do all the mods you want to the 8.75 , billt caps , axles , back brace the rear , spool , in the end the weak link still exists ... the gears ... Sure but if Mopar never chose to start using the Dana 60, all we'd hear is how much better the 8 3/4" is over a GM 12 Bolt! Truth is the 8 3/4 is a relatively stout setup and was used behind many Hemi, Max Wedge and 440-6 cars with no huge issues. If you are going to build a drag car then sure, use the Dana, but for most people and most applications the 8 3/4" works just fine. Dave 1970 Super Bee 440 Six Pack 1974 'Cuda 2008 Ram 3500 Diesel 2006 Ram 3500 Diesel 2004.5 Ram 2500 Diesel 2003 Ram 3500 Diesel 2006 Durango Limited [url] http://1970superbee.piczo.com [/url]

Re: how much hp can a 8.75 differential take? [Re: DPelletier] #1170494 02/02/12 01:19 PM 02/02/12 01:19 PM
Joined: Jan 2003 Posts: 24,562 Brookeville, Md Mr.Yuck Not enough dumb comments...yet
Mr.Yuck Not enough dumb comments...yet Joined: Jan 2003 Posts: 24,562 Brookeville, Md	Go get a Furd 9"...all the racers use them

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