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  Possible to economically set up an 8" Street/Strip RearEnd?

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Author Topic:   Possible to economically set up an 8" Street/Strip RearEnd?
MDF99
Gearhead

Posts: 234
From: Hamilton, Ohio, USA
Registered: May 2001

posted 12-01-2001 02:03 PM     Click Here to See the Profile for MDF99   Click Here to Email MDF99     Edit/Delete Message   Reply w/Quote
My 66 Mustang has the stock 8" rearend. I'm building up the 289 currently. I'd rather not deal with the hassle and expense of tracking down and modifying an 8.8" or 9" rearend to work in my car. I've heard that you can set up a stock 8" to handle 350-400HP or so. What's the good setup fella's? I'd like to convert it to posi and use a 4:11 gear. Thanks.

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badazzcougar
Gearhead

Posts: 132
From: Seattle
Registered: Oct 2001

posted 12-01-2001 02:19 PM     Click Here to See the Profile for badazzcougar   Click Here to Email badazzcougar     Edit/Delete Message   Reply w/Quote
depends how far your building up a 289 If its at or below 300 HP ( which it probably will be. BTW there a LOT of "400 HP" cars out there that would actually dyno at 300HP so thats not a bad number at all ) then the 8 inch will work fine especially if your using a close to stock converter with an automatic . You only break rear ends if you hook up at high rpm or with lots of torque. I dont think you'll do either of those.

By the way if this is for a more than occasional driver you may not be happy with the 4.11 gears. Gears like that devastate your gas mileage. 3.20-3.50's are much better suited to daily drivers or cars that see use for more than stoplight to stoplight. Go with the posi but since your 289 mustang wont be a drag race monster then don't go overboard on the gears especially if you arent using tall tires. 26 inch tires and 3.50's are plenty stout for a streeet car that sees double or triple duty.Ive got 4.10's in my 70 cougar and before the motor was removed for a little frankensteining I was getting 6-8 mpg on a good day and thats with fairly tall 28" tires. Thats what 400 horsepower will get you in the real world. I'm a glutton for punishment though.

[This message has been edited by badazzcougar (edited 12-01-2001).]

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MDF99
Gearhead

Posts: 234
From: Hamilton, Ohio, USA
Registered: May 2001

posted 12-01-2001 04:52 PM     Click Here to See the Profile for MDF99   Click Here to Email MDF99     Edit/Delete Message   Reply w/Quote
This rearend will be behind a T-5.

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badazzcougar
Gearhead

Posts: 132
From: Seattle
Registered: Oct 2001

posted 12-01-2001 04:59 PM     Click Here to See the Profile for badazzcougar   Click Here to Email badazzcougar     Edit/Delete Message   Reply w/Quote
Then by all means go with the 4.10's. That overdrive willl help out a lot. I'm not sure on the T5 rating but I seem to recall that they'll hande up to around 275 ft lbs of torque which you'd be doing well to get out of that 289 . The 8 inch shouls hold up well as long as your not brutal with it and use slicks with traction aids in the suspension. remember you'll only break it if your tires hook up which rarely happens in street cars with street tires. Its a leightweight car, I wouldnt worry too much. Even so. You can usually find good deals in the paper on 9 inch rear ends and you can find a early bronco 9 inch with tracloc in the $400-$500 range . I read the for sale classified ads every single day and the local nickle ads and theres always something like that . You'll spend that much setting up a 8 inch. figure out what it will cost to do the 8 inch and I think you'll find a used 9 inch bronco or narrowed job will cost the same or less.

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65_289
Gearhead

Posts: 761
From:
Registered: Jul 2001

posted 12-01-2001 05:12 PM     Click Here to See the Profile for 65_289   Click Here to Email 65_289     Edit/Delete Message   Reply w/Quote
I am putting down 282 ft-lbs with my 302. I have decided to go with a 9", since I am using slicks and drag shocks and will be adding a locker and traction bars. Plus, since I plan on a stroker, I am going with 31 spline axles as well. If you plan on upgading hp, and trust me, you will, then look at a 9" or 8.8"

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Mpcoluv
Gearhead

Posts: 1333
From: Charlotte NC usa
Registered: Apr 2001

posted 12-01-2001 05:20 PM     Click Here to See the Profile for Mpcoluv   Click Here to Email Mpcoluv     Edit/Delete Message   Reply w/Quote
The best thing you can do for an 8" is to install an 8" detroit locker. The stock 8" diff only has two spider gear. Spider gear breakage is the main failure of an 8".
Someone also makes a "locker" setup that you can put in the stock differential.
Fordmuscle.com did an article on this several months ago.

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MDF99
Gearhead

Posts: 234
From: Hamilton, Ohio, USA
Registered: May 2001

posted 12-01-2001 05:53 PM     Click Here to See the Profile for MDF99   Click Here to Email MDF99     Edit/Delete Message   Reply w/Quote
I saw the Fordmuscle article where they installed the Powertrax Lock Right locking differential. I've found these for as little as $225 for an 8" application. I don't plan on dropping in a stroked 351 torque monster anytime soon, nor do I ever plan on putting slicks on this car. What else would help it out? Are the axles good to go?

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MDF99
Gearhead

Posts: 234
From: Hamilton, Ohio, USA
Registered: May 2001

posted 12-01-2001 06:13 PM     Click Here to See the Profile for MDF99   Click Here to Email MDF99     Edit/Delete Message   Reply w/Quote
Here's an interesting thread from the archives talking about 8" rearends...

https://mustangsandmore.com/ubb/Archives/Archive-000009/HTML/20000507-12-000107.html

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chips67
Gearhead

Posts: 662
From: louisville, ky, usa
Registered: Jul 2001

posted 12-01-2001 08:10 PM     Click Here to See the Profile for chips67   Click Here to Email chips67     Edit/Delete Message   Reply w/Quote
65-289, your 31 spline axles will be great, but dont underestimate an 8 inch or a 9 with 28 splines. for the other guys, a t-5 has a very low first gear ratio, lower than the old stangs that ran toploaders. keep that torque multiplication factor in mind. my car is making enough power now that if it hooked would run 11's in the 1/4 all day and still not come close to breaking the 28 spline axles.

------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.

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steve'66
Gearhead

Posts: 9489
From: Sonoma,CA,USA
Registered: Mar 2000

posted 12-01-2001 08:42 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by MDF99:
I saw the Fordmuscle article where they installed the Powertrax Lock Right locking differential. I've found these for as little as $225 for an 8" application. I don't plan on dropping in a stroked 351 torque monster anytime soon, nor do I ever plan on putting slicks on this car. What else would help it out? Are the axles good to go?


Matt,

That'll work, but a Detroit is better because it includes a new stronger differential case. A Detroit soft locker would be a lot quieter on the street! The 8"s 28 spline axles are the same as a 9"s 28 spline axles. Upgrade the bolts in the 8" and you should be good to go as long as you stay away from slicks.

SteveW

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n2oMike
Gearhead

Posts: 2694
From: Spencer, WV
Registered: Jan 2001

posted 12-02-2001 09:58 AM     Click Here to See the Profile for n2oMike   Click Here to Email n2oMike     Edit/Delete Message   Reply w/Quote
If you don't plan on putting slicks on the car, don't fool with a 4.10 gear. Use a 3.55 or 3.73.

First gear on standard T5's is 3.35. World class T5's have a 2.98. Wide ratio toploaders have a 2.78 1st, close ratio units have a 2.32

4.10's on street tires and a T5 will do nothing but spin. You won't have any speed at all in first gear. On the STREET, you'll be MUCH happier with the 3.55 or 3.73.

Personally, I would run the 3.55's with a standard T5, or 3.73's with a World Class (2.98 1st gear unit). This would make the car feel like it had 4.11's with a toploader.

-------------------------------------------

tranny ratio x rear gear ratio = overall gear ratio

Close ratio TL: 2.32 x 4.11 = 9.54

Wide ratio TL: 2.78 x 4.11 = 11.43

Standard T5: 3.35 x 3.55 = 11.89

World Class T5: 2.98 x 3.73 = 11.12

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

[This message has been edited by n2oMike (edited 12-02-2001).]

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