in my initial post, i said that eventually my 302 should be pushing 225-250 horsepower. realisticly now, its probably about 190-200 horsepower. the engine is fresh, but it is stock, and i assume low compression. the only additions are a 500 cfm 4 barrell and dual exhausts. i dont know how accurate my estimation of HP really is. i know the car runs like a scalded dog, but i hardly consider it a hot rod. IF that day ever comes that i build my own 302, i intend to put a 262-270 cam, "289" connecting rods, and the custom flat top pistons that are required if you use 289 rods. this combo may actually produce more than 250 HP if i put a bigger carb on it. but other than the custom rod treatment, everything else will be modest. (that trick makes a 302 rev up fast!) what im getting at is... if this motor should near 300 horsepower (doubtful) will the 8 incher still hold up? it will not be used as a drag car, but as a very potent passenger car. the hope is i can find one of those 3:42 posi units (8 inch) from a mustang II. money is a major obstacle for me, so that is why im willing to find cheap/easy bolt on performance pieces. and if i found that 3:42 posi tomorrow, and slapped it into my existing setup, what could i expect, other than a very OFF speedometer? should the car still be ok for minor highway use? will that part hold up to 300 HP? thanks rr
I have an 8" in my 70 mustang it's been chassis dynoed at 308 Hp and 359 Tq I also have a t-5 trans . I've broken four 8" rears the only reason I have not changed is I bought an alburn possi and don't want to give it away. The failures have always been the caps so this last time I put in ARP stud kit and so far it's helped. Here's the formula for MPH to RPM MPH X trans gear X axle gear divided by tire dia X 336 = RPM you can remove the trans number if it's 1/1 65 MPH X 3.42 divided by 26" X 336 = 2872 RPM
Another factor to consider is the weight of the car. The lighter the car, the less stress is placed on th rearend and, therefore, is less prone to breakage.
For some reason everyone thinks mustangs are heavy well my 70 weighs 3120 Lbs and our 72 maverick weighs 3040 Lbs not that big of a differance I beleave it was the higher toque that the 351 is producing that's the differance not the weight
please read my post go to tail lights and my two cents, last post. Main Forum. Ford 8 inch rears are very strong!! Terry Gates AKA Bossmav
Want to get my nickels worth in here on rear brakage. Starting from the road or track surface; Traction offers a 'resistance' to the turning moment of the axle. It produces no torque of its own. Tire contact with theroad surface is a conversion from circular motion to straight line motion and just happens to need friction to do this. From the engine end; the combustion of the fuel/ air mix does convert to mechanical torque through the lever action of the connecting rod at angle with the crankshaft and its this supply of energy that can overcome the strength of any part that is subjected to the transmission of that torque, from the rods, crank, clutch, torque convertor, transmission, driveshaft, rear all the way out to the wheel centers and tires. The lower the driving gear the greater the torque multiplication. I hope no one is really serious about thinking traction causes the breakage. Traction produces no torque. If it does, you don't need an engine. Engine torque is all there is besides RPM and RPM is only a way for the engine to injest an increasing amount of air to burn and generate more torque. Horepower is only a mathamatical product of torque and RPM. Horsepower is torque X RPM divided by 5252..
