Rear end suggestions

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Joel Chapman

Joel Chapman

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Hey everyone. I think the rear end on my 71 dart is giving out so I’m looking into possible replacements. Any one have any suggestions on a good company to go with for gears? It’s going in a 71 swings with a 360/904 combo that will be used more for a cruiser, but I do like how it goes when I put the pedal down lol. What’s the best bang for the buck in your opinion? eBay options worth looking into at all for a strictly cruising application?
 
Most name gear manufacturers would be ok - Motive, U.S. Gear, Richmond, etc. The trick is finding a reasonably priced differential oriented local business. A 4 wheel drive shop might be a good start, but shop around. For cruising, you could get an 8 1/4 rear to rebuild while still driving, which were OEM in A-bodies from 1973+. 8 3/4 are cool, but getting expensive. Dana 60 simply isn't needed. Mail order places like Moser, Dr. Diff, Summit, even Rock Auto, etc. would be good sources for parts, if in stock. Might be cheaper than through a local shop, but again, shop around.
 
Joel Chapman said:
Hey everyone. I think the rear end on my 71 dart is giving out so I’m looking into possible replacements. Any one have any suggestions on a good company to go with for gears? It’s going in a 71 swings with a 360/904 combo that will be used more for a cruiser, but I do like how it goes when I put the pedal down lol. What’s the best bang for the buck in your opinion? eBay options worth looking into at all for a strictly cruising application?
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Talk to Cass.
Strange S-60 for Mopar, Ford, Chevy/GM
 
Joel Chapman said:
Hey everyone. I think the rear end on my 71 dart is giving out so I’m looking into possible replacements. Any one have any suggestions on a good company to go with for gears? It’s going in a 71 swings with a 360/904 combo that will be used more for a cruiser, but I do like how it goes when I put the pedal down lol. What’s the best bang for the buck in your opinion? eBay options worth looking into at all for a strictly cruising application?
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Proper torque converter 3500 or higher no less at all. Everyone makes the same mistake when it comes to improving performance. They think gears!
 
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If a 8.25 rear you can steal a track lock with 3:55 gears out of a jeep dana 30 rear cheap. I have one in my 440 dart no issues at all.
 
Joel Chapman said:
8 3/4
2.76 ratio
Open
Click to expand...

Relatively easy swap would take about an hour..you can score a new/rebuilt chunk (center section or third member) and a new set of new axels from dr diff. Sometimes dr diff is low on the chunks, I have used a fellow in northern Nevada on two of my cars to rebuild the chunks.. he did a fantastic job.. pm me if you want his info.
 
Oldmanmopar said:
Proper torque converter 3500 or higher no less at all. Everyone makes the same mistake when it comes to improving performance. They think gears!
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It’s not that I’m going for performance, just been trying to fix a vibration and noise and the more I dig/get things looked at the more it seems to possibly be a driveshaft/rear end problem.
 
easy check is the rear motor mount.. aka the transmission mount... then the universal joints, then the pinion angle, then the spring bushings..

Could also be a resonance from the exhaust system as well.
 
Heywodja said:
easy check is the rear motor mount.. aka the transmission mount... then the universal joints, then the pinion angle, then the spring bushings..

Could also be a resonance from the exhaust system as well.
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So out of all of things you just listed, the only thing that hasn’t been swapped for new/check is the pinion angle. It has a single exhaust at the moment but I’m trying to go dual here shorty. Other than swapping the 318 to a 360, I’ve done my best to keep the car as close to stock as possible. I did put new 340 rear leaf springs in the car when I replaced the old clapped out ones.
 
Joel Chapman said:
8 3/4
2.76 ratio
Open
Click to expand...
Call Cass at/or visit Dr.Diff .com where there are plenty of 8-3/4 parts and packages. When my wife’s 8-3/4, 3rd member gave up, I ordered and had Dr. Diff send me a 100% new center section. Click the boxes to order the parts you want inside and they will assemble and ship it to you. You can also, if you like or need, also order stringer racing axles. If you need or want.
 
Check the drive shaft for propper yoke alignment.

If you have the shaft with the rubber insulator between the rear yoke and the main shaft there is a possibility it is not properly aligned

My dart was one that from the factory was not aligned properly and was replaced in 67 by the dealer.
 
Dana67Dart said:
Check the drive shaft for propper yoke alignment.

If you have the shaft with the rubber insulator between the rear yoke and the main shaft there is a possibility it is not properly aligned

My dart was one that from the factory was not aligned properly and was replaced in 67 by the dealer.
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Plan on getting the drive shaft out the car today and checked out.
 
Jackstands under the axle; get it to vibrate; look at the driveshaft. Maybe unbolt the u-joint and turn the shaft 180. Check the u-joints for freedom of movement; might have been installed too tight or off center. Put two large hose clamps on the driveshaft and try them turned different ways to see if the vibration changes. Coast down a hill, try neutral, try engine off. Which gear does it vibrate in? What speed? Accelerating or decelerating? Brakes or not?
 
Bang for the buck? Large bolt pattern?

Ford 8.8 I'd say in this day and age. Damn 8 3/4 and 8 1/4 are getting quite expensive.
 
CudaFactHackJob said:
Jackstands under the axle; get it to vibrate; look at the driveshaft. Maybe unbolt the u-joint and turn the shaft 180. Check the u-joints for freedom of movement; might have been installed too tight or off center. Put two large hose clamps on the driveshaft and try them turned different ways to see if the vibration changes. Coast down a hill, try neutral, try engine off. Which gear does it vibrate in? What speed? Accelerating or decelerating? Brakes or not?
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Acceleration around 30+ but seems to calm down around 50
 
CudaFactHackJob said:
Jackstands under the axle; get it to vibrate; look at the driveshaft. Maybe unbolt the u-joint and turn the shaft 180. Check the u-joints for freedom of movement; might have been installed too tight or off center. Put two large hose clamps on the driveshaft and try them turned different ways to see if the vibration changes. Coast down a hill, try neutral, try engine off. Which gear does it vibrate in? What speed? Accelerating or decelerating? Brakes or not?[/QUOT
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by freedom of movement do you mean while the u joints are installed into the center section?
 
Joel Chapman said:
Hey everyone. I think the rear end on my 71 dart is giving out so I’m looking into possible replacements. Any one have any suggestions on a good company to go with for gears? It’s going in a 71 swings with a 360/904 combo that will be used more for a cruiser, but I do like how it goes when I put the pedal down lol. What’s the best bang for the buck in your opinion? eBay options worth looking into at all for a strictly cruising application?
Click to expand...
The first thing I'd suspect is a u-joint(s) problem. If not that, then maybe the nut backed off on the rear companion flange/pinion. A somewhat longer shot would be a tire/wheel issue. I'd look at the simpler solutions and diagnosis before spending a lot of money.
 
Yes. The joints are sometimes installed too tight. You can remove the driveshaft and flop the joints to make sure they move freely. But I think the problem is in the motor. Like a vacuum leak causing a lean condition to one cylinder or a bad plug wire or plug, or carbon buildup in one cylinder causing pre-ignition. An imbalance problem ALWAYS becomes more pronounced with the rpm of the part.
 
rustycowll69 said:
The first thing I'd suspect is a u-joint(s) problem. If not that, then maybe the nut backed off on the rear companion flange/pinion. A somewhat longer shot would be a tire/wheel issue. I'd look at the simpler solutions and diagnosis before spending a lot of money.
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U joint that goes into the rear end is new. Didn’t even think bout swapping out the front one so will look into that. Also as far as wheel and tires I’ve had the alignment done and had the tires rebalanced
 
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