replaced differential
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New User
Joined: Nov 2004
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replaced differential
I have a 1994 Mazda B4000 4x4 truck with manual 5 speed that recently had the back differential replaced with a used differential from a Ford Ranger. The truck runs fine in 2 wheel drive but when placed in 4 wheel drive, the back tires speed up for a second causing a shudder. This shudder continues until I disengage the 4 wheel drive ,place it back into 2 wheel drive and the truck runs fine again. Is the problem with the way the mechanic installed the differential or some other problem ?
Post Fiend
Joined: Feb 2003
Posts: 6,940
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From: Eastern WA
I don't understand the thing about the "back tires speed up for a second." However it does sound like you've got two different axle ratios. The shudder is caused by the tires skidding as the two axles are fighting one another. The transfer case is going to take a beating when driving like this.
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differential replaced
the mechanic who installed the differential just counted the teeth and its the same number as the old differential, he says there's nothing wrong with the gear ratio and it must be something else. he just took it to a transmission place , he suspects its the transfer box .
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New User
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replaced differential
here's more on the replaced differential.....the mechanics placed the truck on a hoist and put it in 4 wheel drive. The 4 wheel drive works perfectly on the hoist but when they put a load on it (put it back on the ground) the same problem occurs . they're stumped. Any ideas where they could look next ?
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
Check and compare the front and rear axle ratios for yourself. They MUST be the same. You could, but don't need to count teeth; instead jack up each end, turn the driveshaft, and count the number of driveshaft turns to make one full rev of both wheels (applies to limited slip, both wheels turning at the same time). If only one wheel turns when rotating the driveshaft (ie, non limited slip), count the number of driveshaft turns to make two wheel revs. This will be your ratio for the axle. They both must must match, exactly.
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Senior User
Joined: Mar 2004
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From: Indianapolis, IN
Or, just look on the tag on your door ( i think thats where). It should tell what gears the truck came with originally. then check the tag on the rear diff to see if it is the same. For 3.73 gears it will say either 3L73 for limited slip or 3 73 for open diff. I think the same applies for 4.10's either 4L10 or 4 10.
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