WarrenBoostit
Member
Well long story short, recently I had to get my shredded RDU replaced by Ford. The car was originally brought in because the RDU was singing/whining at any speed during deceleration. After a much too lengthy process, Ford finally replaced the differential with a new one. While the persistent whine was fixed, I noticed pretty immediately that decelerating from 75-68 mph introduced an even louder whine, which was diagnosed as a bad preload. I brought it back to Ford, and they said the RDUs come prebuilt from the factory, so the only fix was to order another one, which at least I was confident I probably wasn't getting something rebuilt, because I had to wait for a new one to get shipped into the dealership for about a week. Start driving it after the 3rd RDU went into it and everything sounds ok (I should mention the whine seemed louder in the heat, and the days I picked it up the local temp had cooled off a bit).
I asked my guy at Ford if I should follow any sort of break in period, and he said while typically you can just slap it in and go, since I'm on an e30 tune pushing decent horses above stock, I should give it a decent break-in period of about 300 miles with no hard shifts, pulls or launches before I start to hit it harder. I've been following this well, I kept it below highway speeds for the first 70 miles or so, and as it is my daily, I've driven it to work a few days and gone from ~70 miles up to about 200 very lightly and gentle. Today, and potentially because the heat went from high 60s to mid 80s again (but maybe not), I noticed deceleration from 75 mph to 68 causes the exact same singing as the last new RDU, just much, much quieter and subtle. That brings me to a few questions I'd be really thankful for if anyone here had advice about:
1. Should I just ignore it for now and finish my break in period?
This whole RDU replacement event has taken roughly 2 months to finish, largely because the first three weeks were wasted by Ford dealership techs unable to push a troubleshooting attempt of my keys not starting my car further than replacing the batteries in my key in the wrong direction (a long, unrelated, and extremely frustrating story). I only kept visiting that dealership because they put such an effort forward of feeling ashamed and lopping off nearly all of the cost on initial inspection and troubleshooting. I want to drive my car to it's potential at least a few times before MN winter comes along to ruin everything. Additionally, this new RDU has a year long warranty, so I can address the issue later if it becomes more concerning, but I don't want to ignore it if it's definitely a problem.
2. Are two new RDUs having this issue a sign of something wrong elsewhere?
I just find it interesting that two different RDUs, likely assembled at separate times as the first one was the only one Ford had in stock, both had the same issue (albeit at different volumes) at the exact same speed range.
3. Should I do a fluid change immediately after the break-in period is over?
I know for regular differentials, this is typically recommended, but Ford seems to think their RDUs are "special". Additionally, sooner rather than later I'd like to get some Redline Lightweight Shockproof fluid in it that a lot of people around here recommend (and would definitely appreciate links or more info about type or quantity if you have any). I've also heard this can be used in the PTU? Ideally I'd like to not replace the RDU for the rest of the ownership of the car, as once it's out of warranty ponying up another $3k+ for a new one would not be fun.
Thanks for any advice you guys can offer, this thing is really turning into quite a headache.
I asked my guy at Ford if I should follow any sort of break in period, and he said while typically you can just slap it in and go, since I'm on an e30 tune pushing decent horses above stock, I should give it a decent break-in period of about 300 miles with no hard shifts, pulls or launches before I start to hit it harder. I've been following this well, I kept it below highway speeds for the first 70 miles or so, and as it is my daily, I've driven it to work a few days and gone from ~70 miles up to about 200 very lightly and gentle. Today, and potentially because the heat went from high 60s to mid 80s again (but maybe not), I noticed deceleration from 75 mph to 68 causes the exact same singing as the last new RDU, just much, much quieter and subtle. That brings me to a few questions I'd be really thankful for if anyone here had advice about:
1. Should I just ignore it for now and finish my break in period?
This whole RDU replacement event has taken roughly 2 months to finish, largely because the first three weeks were wasted by Ford dealership techs unable to push a troubleshooting attempt of my keys not starting my car further than replacing the batteries in my key in the wrong direction (a long, unrelated, and extremely frustrating story). I only kept visiting that dealership because they put such an effort forward of feeling ashamed and lopping off nearly all of the cost on initial inspection and troubleshooting. I want to drive my car to it's potential at least a few times before MN winter comes along to ruin everything. Additionally, this new RDU has a year long warranty, so I can address the issue later if it becomes more concerning, but I don't want to ignore it if it's definitely a problem.
2. Are two new RDUs having this issue a sign of something wrong elsewhere?
I just find it interesting that two different RDUs, likely assembled at separate times as the first one was the only one Ford had in stock, both had the same issue (albeit at different volumes) at the exact same speed range.
3. Should I do a fluid change immediately after the break-in period is over?
I know for regular differentials, this is typically recommended, but Ford seems to think their RDUs are "special". Additionally, sooner rather than later I'd like to get some Redline Lightweight Shockproof fluid in it that a lot of people around here recommend (and would definitely appreciate links or more info about type or quantity if you have any). I've also heard this can be used in the PTU? Ideally I'd like to not replace the RDU for the rest of the ownership of the car, as once it's out of warranty ponying up another $3k+ for a new one would not be fun.
Thanks for any advice you guys can offer, this thing is really turning into quite a headache.
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