Rear end options

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by fastmonkeywheel, Jun 11, 2007.


  1. fastmonkeywheel

    fastmonkeywheel Member

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    So I got my II back on the road finally, put about 100 miles on it yesterday just driving it around. I'm keeping the boost at 10psi right now until I get a better tranny and rear end.

    I currently have a RAD-4 (I think that's what it's called) and the 6.xx rear end that came stock with my 2.8L. By the end of summer I'll be making an easy 300hp and close to 450hp by next summer. This is a street/strip car and I really want trac-loc. A friend found 2 Exploders at the junk yard both with 8.8's, 3.73's and t-loc. He's going to put one in his 68? Mustang. So I have the option here of grabbing the other 8.8 or getting his 8".

    From my friend's research he said that the Exploder's 8.8 should bolt right into his Mustang, but he's going to do some measuring when he gets home. I figure it's hard to beat $80 for a rear end like this. If the spring perches are close enough it might just bolt right in.

    Any thoughts here?
  2. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Hard to beat the price and parts availability for the 8.8, but don't expect it to "bolt right in".

    There will be perch issues, unless you intend to ditch the II shock plates, and even then, the width between perches may be an issue.
  3. MUSTANG J

    MUSTANG J Member

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    You may find this interesting!

    http://pintopage.fordpinto.com/Poisonous Pinto.htm

    The 8" Ford can handle quite a bit of abuse! If funds permit I would put the 8.8 in though, because parts are easier and cheaper to come by. I think (oh here we go) the 8.8 would be stronger in modified form. From my research the only bolt in rear end for a Mustang II, is the Mustang II rear-ends :rlaugh: The 1975-1980 Granada (5 bolt drum brake), 77-80 Lincoln Versailles (9" ford with 5 bolt with disc brakes!) and 65 Mustang (5 bolt drum brake) are close, but no cigar.
  4. fastmonkeywheel

    fastmonkeywheel Member

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    So, looks like I'm getting a 7.5" w/ Trac Loc and 3.45 gears for pretty cheap. It's out of an early 80's Mustang GT (before they started putting 8.8's back there). A lot of Merkur guys around here are running 7.5" rear end's and putting down about 450-500hp with IRS setups. I think it'll hold up just fine, a boosted 2.3 doesn't have that torque shock that a V8 would have. I think that's what really matters with the strength of the rear end.

    Putting the 7.5 in should be the same amount of work as the 8.8, but the 8.8 I was looking at was 5 lug and would require new rims, which aren't in my budget right now. This way I can find a set of 4 lug fox rims from the junk yard. It won't be pretty with unmatched wheels, but my goal is functionality first then cosmetics.
  5. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Fox pattern is the same as II
  6. Blue coyote

    Blue coyote Founding Member

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    The 7.5 IS a decent axle, but I'd trust an 8" more. I ran a 200 hp 2.8 with a 5-speed, 2.48:1 T-case, 4.10 Trak-Lok (emphasis on the "LoK" ), and 32" mudders in a BII with a 7.5 and had NO problems even with 5K+ power-shifts.

    Its still a C-clip axle, though, and smaller than the 8"
  7. fastmonkeywheel

    fastmonkeywheel Member

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    So what can I find a 8" t-loc unit in? I haven't picked up the 7.5 yet. I just realized that there are quite a few Bronco II's at the junk yard. I'm not against going with an 8". It turns out that my friend is going to be reusing his 8" in a Tempest he's building up so I don't have the option of getting his.

    What's the best way to identify the rear ends? I've always been horrible at doing so.
  8. parthos

    parthos Founding Member

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    Generally an 8 inch rear end is lighter than a 9 inch, I don't know much about the 8.8. But what I can tell you is the 8 inch is a pretty tough unit. My car sees ton of street use with stock 4 lug axles, and 6.9x passes down the 1/8th mile 1.55 60 fts pretty regularly. I know I need to upgrade axles, but so far tech hasn't said anything. A manual transmission will put more stress on the rear than an auto. If you feel like building a rear end, you can get some pretty trick housings, and use 9 inch stuff, or you can use an 8.8 and weld on spring perches.
  9. fastmonkeywheel

    fastmonkeywheel Member

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    You know, all this time I've been ASSuming that I had a 6.75 because the car was an original 6cyl. I was doing some research and read that I might have an 8" in there already. Here's a couple of pictures of what I have. I'm going to keep looking for pictures of 6.75" and 8" rear ends to see if I can visually determine. I'm sure you guys who already know would be able to tell by looking.

    <a href="http://photobucket.com" target="_blank"><img src="http://i101.photobucket.com/albums/m64/fastmonkeywheels/DSCN1549.jpg" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>

    <a href="http://photobucket.com" target="_blank"><img src="http://i101.photobucket.com/albums/m64/fastmonkeywheels/DSCN1548.jpg" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>
  10. fastmonkeywheel

    fastmonkeywheel Member

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    From MustangII.org

    I guess I have an 8" already. Damn, and all this time researching an upgrade was wasted. Now I should figure out what gears I have and get some discs on there :).
  11. Blue coyote

    Blue coyote Founding Member

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    I think it was mostly the 4-banger cars that were most likely to have the 6 3/4.

    You might luck out and find the axle tag on one of the 3rd member bolts.
  12. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Door tag should tell you what gear and if trac-lok.
  13. fastmonkeywheel

    fastmonkeywheel Member

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    Date: 9/77

    VIN?: BR027102842
    Color: 2R
    DSO: 72
    Body: 60F
    Trim: AN
    SCH date: 09H
    Axel: 7
    Trans: V

    So, 3.40's with no trac-loc. Can it be added?
  14. THE COBRAMAN

    THE COBRAMAN pig 'rassler Founding Member

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    Manufactured in : September, 19/77

    Model Year of the car is: 1978

    Assembled at : San Jose, California Plant

    Body Style (from VIN) is : 2 Door Hardtop

    Factory installed engine: 171 c.i., 2.8 l, 2V, 6 cyl

    Consecutive Unit Number : 102842

    Exterior Color is : Bright Red

    District Sales Office was : San Jose

    Body Style (from Doortag) is : 2 Door Hardtop

    Interior Color is : White/Red Vinyl

    Scheduled date : August 09th

    Transmission : Three Speed Automatic - C3

    Rear Axle Ratio: 3.40:1 (open)
  15. Blue coyote

    Blue coyote Founding Member

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    I think there is still a Trak/Lok available for the 8".

    I'd be more worried about that C3, though. I've always considered the C3 and its decendents (like the--shudder--A4LD) to be under-kill for a 4-banger much less a V6...I'm glad my own 78 V6 coupe with 3.40's came with the (more reliable) C4.
  16. fastmonkeywheel

    fastmonkeywheel Member

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    Well, the C3 and 2.8 are long gone. I have a Fuel Injected Boosted 2.3 in there now with a *cough, cough* RAD-4 (need a T5 badly).
  17. Blue coyote

    Blue coyote Founding Member

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    Well, it should be all good then, eh? :D

    I still want to figure out a Toyo/Kogyo swap instead of a T5. Everyone around here thinks a T5 is made of titanium or something (a stock used 2.3 T5 goes for $400+ and a V8 one for $750& up...)
  18. MUSTANG J

    MUSTANG J Member

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    I would consider a lock-right. They work very well, and they are very easy to install. The ring and pinnion mesh are un-altered so you can pull it off in your drive way with common hand tools (They make one for the 8" Ford).

    http://www.powertrax.com/lockright.html
  19. fastmonkeywheel

    fastmonkeywheel Member

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    I know how you feel about the T5, it looks like I might be going C4 instead. I think I might have my hands on a 2.0 C4 bell and tranny. It'll be so much cheaper to build up the C4 than it would be to build up a T5. I like to shift, but with the power output I'm planning for, the C4 is perfered. Just think, trans brake, 3000 stall with a shot of nitrous off the line to help me get into boost.
  20. parthos

    parthos Founding Member

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    8 inch for sure... currie makes aluminum center sections for them, richman makes gears, auborn makes limited slip diffs, powertrax no slip is a good unit (what I run), and i think you can still get a detroit locker. Oh and dutchman makes axles for them, and I think so does currie

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