Discussion in '1974 - 1978 Mustang II Talk & Tech' started by CobraIIboy, Aug 11, 2013.

  1. Hello, folks. I'm new to this site, but I'm hoping to learn a lot from you all. I am hoping to get my hands on a Mustang Cobra II soon. I don't know much about it, just that it's got a 302 and automatic tranny. It's blue with white stripes. What I want to do with this car is make it a real runner. I would like to rebuild the engine with high compression pistons, and a 4-barrel carb, etc. But, I don't know much about the drive train, such as what size is the differential, etc. Can the stock rearend take the added horsepower? Will the automatic need rebuilt, also? Can it take the abuse of a higher horsepower engine? What mods can I do to make it handle very well? Sorry for all the questions, but I'm very excited about this. I really don't even know what year it is yet.

    Thanks in advance!!!
  2. Wow! Nobody here can help?
  3. Hey CobraIIboy,
    I'm new to the site like you, but definitely not new to II's. I'm working on a '78 right now myself. To answer a few of your questions... the stock rear is the 8" and can handle a reasonable amount of power from a mild build. If you have the limited slip, even better. If you're looking to build huge power (throw on a blower, etc.) then you'd probably want to swap in a 9" (which requires custom fabrication, etc.) With our cars over 35 years old now, it's possible things have already been upgraded. You can tell if you have the 8" if it has a plain back-side without a bolt-on cover and a bunch of bolts on the front around the carrier assembly. Stock 8" would also have come with 4-lug axles while the 9" would usually have 5, but 5-lug conversions can be done to the 8" as well so it's best to check the differential itself.
    If it's an automatic behind the 8-cylinder, it's most likely the C4 with small bellhousing. The stock C4 can also hold up to mild upgrades without issues. They can be rebuilt to handle huge power as well and a good shift-kit can have you banging shifts with the best of 'em.
    On the suspension side, probably the best thing you could do would be to get some nice subframe connectors (search for Stumpy's, available at a very reasonable cost and relatively simple to install). Some wider rims & tires will also greatly help, check the sticky for guidance on what might fit. I've put some late-model Mustang 17" wheels on mine using P245-45ZR17's and some 2" 2-piece 4-to-5 lug adapters. Otherwise just making sure all the stock components are in good shape is a good start (all the bushings, tie-rods, ball-joints, springs, shocks). Tubular a-arms are available and make for a nice upgrade as well. Don't forget to address the brakes -- the tiny front rotors and old-school calipers could definitely stand to be upgraded especially if you get some larger wheels.
  4. Thanks for the reply. I was hoping that the differential and tranny could hold up. I don't plan on a blower or anything that exotic, just a cam upgrade, better compression, and a 4 barrel carb. Not sure if headers would be preferred, but a good dual exhaust system is a must. I don't yet know if the car has a Traction Lok or not, so if not, are those still available? Are the sway bars competent for a good handling vehicle, or should I upgrade those, as well?
  5. Headers are a great idea, but only a couple of options will work, and I believe only one manufacturer still making them. You can still pick up a trac-loc new ($$$) or used but many v8's came with it. Easy to check, just jack up the rear (both wheels off the ground) and rotate one of the rear wheels. If the other side goes in the opposite direction you have an open diff. If it goes in the same direction (or doesn't go) then you have the traction loc (doesn't go might mean you'd need to rebuild it which isn't too difficult). If you can find upgraded sway bars that's always a good thing. I believe two sizes were available, the one with the thicker bar on v8's or various 'handling' packages.
  6. Headers will bring out more HP, and I have had cars with headers in the past. I understand that they can make an engine breathe better, but the noise inside can be very annoying. I hope it does have the trac-lok. I don't have the $$$ to spend on a new one, and I would be very cautious about a used one.

    Are the sway bars made aftermarket? I can see I will need to invest in larger wheels. Not too many choices in 13 inch tires nowadays.
  7. The 8" in my '75 has a locker and 4.56 gears in it, and the otherwise stock C4 in it has a TCI stall converter in it, and my car has run high 12s at the track and dynoed at 286rwhp (meaning well over 300hp at the flywheel). The 8" and C4 are pretty durable.
  8. That's great news. I can only hope that it has a trac-lok.
  9. So fellas, is it an 8" or an 8.8"?
  10. Definitely 8", a carryover part from the 1st gen classics. No differential cover, front-bolted third-member. And a nice chunk of plastic under the gas-tank strap to keep it from exploding like a Pinto when it's pushed into the differential after the 3mph bumpers give way. :shrug:
  11. It's an 8", it's like a baby 9"... Kind a like the 7.5" is a baby 8.8", but the 8" is actually a lot tougher than the 7.5".