rear end question
- Thread starter 86cutty
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The biggest problem with the 7.5 is the spider gears. They are what usually break in them.
Going with an aftermarket 7.5 carrier might help, but it is still a bandaid.
Best solution is to save the money that you would throw into the 7.5 and find an 8.5. They are around, just keep your eyes peeled.
You will be happier with it. Especially if you make any kind of power.
Just my 2 cents.
Going with an aftermarket 7.5 carrier might help, but it is still a bandaid.
Best solution is to save the money that you would throw into the 7.5 and find an 8.5. They are around, just keep your eyes peeled.
You will be happier with it. Especially if you make any kind of power.
Just my 2 cents.
i wouldnt even think of putting a dime into a 7.5 rear axle, when i put in my first big block in my 78 i wouldnt even drive it until i bout a 8.5 rear end. i've seen what happens to a 7.5 rear when it breaks and i would want to ruin the rear of the car. even on Spike tv's show "Muscle Car" they broke a 7.5 rear axle with a burn out with street tires and a basic 300 hp fuel injected 350 motor. Why take any chances on a 7.5 rear and wonder when it will blow. I have never heard of anyone ever making a 10 second pass on a 7.5 rear, that just a stupid tthing to do
I dont really want to build the 7.5 that i have it was just wanted to keep it together for a couple of passes.It has an eaton posi unit in it but if it blows it blows. I have another stock rear just so the car can still move around.I guess im going to have to save for the 8.5 rear.
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Well, the durability of these axles depends on application. Sticky tires and a 13 second car can kill one pretty easily, especially if it is in a full option G body that can tip the scales at 3600lbs. In a Monza (it's original application), it probably would last a lot longer, but it's probably 1,000 lbs lighter. It is a question of shock loads, which vary with the weight of the car, traction and torque. The drivetrain is like a rubber band being pulled tighter and tighter. Eventually, it will snap at it's weakest point.
Then again, if it is just a street car that runs only on street tires, it could last a very long time. The 8.5 axle however, is MUCH stronger and able to withstand lots more abuse. It is almost as good as the old 12 bolt Chevy rear end in critical dimensions ( pinion shaft diameter, ring gear, etc.). It has it's weak links too when pushed hard, but they are not normally seen in a street/strip car running slower than the 11's.
Then again, if it is just a street car that runs only on street tires, it could last a very long time. The 8.5 axle however, is MUCH stronger and able to withstand lots more abuse. It is almost as good as the old 12 bolt Chevy rear end in critical dimensions ( pinion shaft diameter, ring gear, etc.). It has it's weak links too when pushed hard, but they are not normally seen in a street/strip car running slower than the 11's.
If its for a high 13 second car that you plan to keep regular radials on I know you can get buy with a support cover. It will help hold it together spider gears especially. Eaton makes a good posi and it will take some money and may take some time to find an 8.5. www.taperformance.com makes support covers for the 7.5 you might talk to them as they should have more accurate fact driven answers to your question. I have seen where guys got a posi out of an S-10 for the 7.5 that use 28 spline instead of a factory 26 spline axels but you could not do that with your existing Eaton. I would not want to spend much on a 7.5 either but if a support cover makes it strong enough for your needs it might be an economical solution.
the engine was making about 500hp dyno proven looking for high 10 low 11 second pass with about 300lbs taken out of the vehicle.Im certain the rears gonna blow and i shouldnt even think about driving with it in but i was looking to get it together fast for a race but its gonna have to wait.
The 8.5's biggest negative if you plan to race would be the housing to axle tube joints can break loose and allow the center section to rotate instead of moving the car. This can be fixed by full welding the axle tubes to the center section. The posi would also not be the best for a race application, and you should look into a better unit from the aftermarket. Then, there are the axles which should be upgraded as well. All this assumes you can pull the tires regularly and want a bulletproof 8.5.
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