Hi Folks,

I own a 93 Aerostar Ext. with the 3.0L engine. According to the decal and my shop manual, its axle has a 4.10 ratio with limited slip differential.
There was also a ratio of 3.73 available. What exactly is the difference, what are the advantages and disadvantages of both ratios? And what's that thing about the limited slip differential? When accelerating on snow the van seems to slip like any other car. And last, do you people service your axles(fluid changes etc)?
Lots of questions but I am really curious about this issue.

Tom Ucen

 

First, the 4.10 means the driveshaft turns 4.1 times for every revolution of the rear axles and tires. And 3.73 means 3.73 times. 4.10 gives more leverage, if you will, for the engine to move the weight of the van. The trade off for better performance is somewhat higher revolutions of the engine at highway speeds and therefore greater fule consumption and more noise. The limited slip differential uses a component called a "clutch pack" instead of differential gears. This clutch pack allows a small percent of the power to be transmitted to a splinning wheel on a loose surface to help move the van where without it, the vehicle may remain stuck. This clutch pack can wear out after many miles.
Yes, it's a good idea to have the differential oil change from time to time. And also to have the limited slip clutch pack tested.
At about 30K miles particularly if trailer towing is about right. With the limited slip, a small tube of Ford's limited slip modifier oil must be added along with the differential lube. To test the clutch pack, jack up only one rear tire off the ground and with a clicker type torque wench using one of the lug nuts on the wheel rasied, you should see about 20lbs of resistance before the clutchs begine to slip. I don't have my factory service manual with me at work but if you chose to do this test, let me know and I'll look up the exact spec's. This is a simple explanation of the questions you asked and not intended to be very complete. Hope this helps.

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"I own a 93 Aerostar Ext. with the 3.0L engine. "According to the decal and my shop manual, its axle has a 4.10 ratio with limited slip differential.
There was also a ratio of 3.73 available. What exactly is the difference, what are the advantages and disadvantages of both ratios? And what's that thing about the limited slip differential? When accelerating on snow the van seems to slip like any other car. And last, do you people service your axles(fluid changes etc)?
Lots of questions but I am really curious about this issue."