Low-Speed Shudder: Rear Diff Issue? | Ford Explorer Forums - Serious Explorations

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Low-Speed Shudder: Rear Diff Issue?

sfbayjay

Well-Known Member
Joined
January 22, 2008
Messages
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City, State
Cleveland-ish, OH
Year, Model & Trim Level
2002 XLT SOHC 4L V6
My 2002 Explorer XLT has a "shudder" when turning left or right at low speed. Feels like it's in 4WD, but it's not -- it's in "Auto". Gas mileage (highway) is holding steady at about 20.5 mpg, so I'm fairly certain I'm not "stuck" in 4WD.

This shudder only happens at low speeds, like when pulling out of a parking place. I only feel it when I'm accelerating -- once I lift my foot of the gas, the shudder stops. I feel it mainly in my hands, coming through the steering wheel, and I can hear it, too. It SEEMS to be coming from the front, but then I read here in the forums that even though it may feel like it's coming from the front, it's probably the LS rear differential. (http://www.explorerforum.com/forums/showthread.php?t=156709&highlight=low+speed+shudder+turning)

I am going test the integrity of the clutch packs as recommended in post number 5 of this thread: http://www.explorerforum.com/forums/showthread.php?t=215754&highlight=clutch+packs

So here's the meat of my question:

I recently (6,000 miles ago) changed my rear diff fluid and added a friction modifier. I used Mobile-1 75w-140 synthetic gear oil and a friction modifier called Trans-X Posi-Trac Limited Slip Gear Oil Additive (http://www.crcindustries.com/auto/content/prod_detail.aspx?PN=402508&S=N). Got the modifier from AutoZone. It came in a 7-oz tube. Before changing, I read that you should use only 4 oz. of friction modifier, so I didn't use the whole 7 ounces. Now I realize that Ford's XL-3 modifier comes in 4-oz. containers. So... ...maybe I should have put all 7 oz. of the Trans-X stuff in? I NEVER had this shudder problem before I changed the diff fluid. It started happening about 1000 miles ago.

So should I:

(1) Add more of the Trans-X friction modifier to the rear diff?
(2) Add Ford's friction modifier to the rear diff? (would it hurt to mix Ford's goop with the Trans-X goop?)
(3) Change rear diff fluid again and use Ford's XL-3 modifier?

Any advice much appreciated! Keeping my fingers crossed that the clutch packs aren't toast...

Thanks a million! Gotta love this forum!
 



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OK, here's an update.

Checked torque required to overcome rear diff clutch packs as described in post number 5 here: http://www.explorerforum.com/forums/showthread.php?t=215754&highlight=clutch+packs.

Seems OK, as I needed about 30 ft-lb of torque to overcome the clutches and spin the wheels. About the same on each side.

For grins, I decided to check fluid levels in both front and rear diff's and in the transfer case.

All levels are good. Front diff and trans case fluids look brand new.

BUT -- the rear diff fluid looks wierd. If I didn't know better, I'd say there was water in it?? Kind of gray/silver and sort of opaque/milky looking. Didn't smell burned, but gear oil never smells too good, you know? Compared the rear diff fluid to a spot of brand new fluid and BIG difference. New stuff is bright yellow and clear. How would this have happened? Maybe all of the old fluid wasn't drained with the last changeout and whatever was left in there contaminated the new? Or, maybe the friction modifier changes the appearance of the diff fluid -- but that much?? Hmmm...

So -- my first inclination is to get the stuff out of the rear diff ASAP. Do I need to? The stuff's only been in there for 6000 miles...

Since a rear diff fluid change is a pain in the A** (I don't have the right wrench to remove the drain plug) and the fluid alone will be about $50 (including the Ford friction modifier) -- any thoughts or suggestions?

Maybe I should just add some more friction modifier and see what happens?
 






Stupid question but, your truck is Auto 4x4 right? Are your front and rear tires the same dimensions??
 






i'd still change it imo, any chance that diff was under water?
Typically if you pull a boat and drop it in serveral times a year it would be a good idea to change it yearly, although the recommendation is to change it every time its under water. . .
 






It just sounds like your 4X4 auto is getting tripped when you are turning sharply. Most likely your tires are worn out or something is off, like tire pressure.

The rear fluid always looks like crap on mine and unless you have had it under water, it's probably fine.
 






I am recently noticing the same problem as described in the beginning of this thread. My tires are practically brand new and the pressures are at 30F/35R or as the door plate recommends. Almost feels like a binding. I have not checked the fluids yet as this just starting occuring after a 2000 mile out of town trip. I will update with anything that I come up with as well.
 






How fast are you guys going when this happens and how sharp are you turning? If it's like coming out of a tight parking spot, it might just be the normal Auto 4X4 functioning. Mine comes on once in a while in a tight spot. Also if the tires are oversize as mine are, you can expect it more. And are the tires all the same brand and same tread wear?

Try putting it in 4wheel and driving around if you never use it, preferably on dirt. I have found that you need to use the 4 wheel once in a while to keep things in check, and in fact the manual recommends it. JUST DON'T PUT IT IN 4X4 AND MAKE TIGHT TURNS OR YOU WILL BIND IT UP!
 






Update from OP

OK -- checking back here with an update on this.

Rear diff hasn't been dunked since I've owned the truck.

Changed the rear diff fluid and modifier. Now running Mobil1 75W140 with Ford's OEM Friction modifer ($4.50 at local stealership).

Problem is still evident -- shudder at low speed when turning. Only when under power (i.e., accellerating). Foot off accellerator during shudder and shudder stops. Doesn't only happen on really sharp turns, but on pretty much any turn at low speed...

Tires are all the same size and age. Rotated regularly and wearing evenly. Getting old (~50K miles), but still have some treadlife left. Planning to change in the fall.

When I went into dealer for friction modifier, dealer tech says it's likely to be the clutch packs in the rear diff ("common"). He ALSO said that if it IS the clutch packs, then it's "not hurting anything" and don't worry about it.

Do we agree??

Also unhappy to report that I am now experiencing the dreaded "rear end whine" that has been written about so much here. It may be that I am paranoid now and listening more closely as I'm driving. But even my GF mentioned it while we were on the freeway last weekend. :(

Sounds like some kind of rear diff rebuild (per Ford TSB) is in order at some point.

How urgent is it to get this stuff dealt with? If I can live with the whine and shudder (sounds like a new dance move), is it urgent?

Thanks!
 






XCAMP, it happens sfbayjay describes it. Only when I am turning at a slow speed while accelerating. Tires are basically new and are OEM replacements. Sounds like it is normal. Although, as I am paying attention to it more, I do notice that sometimes it does not occur (under the same circumstances). I will try and find a place where I can engage the 4X4 but there are not many places around the Milwaukee area.
 






Op and Ext

I've looked through this thread and can't see where you have ruled out the 4WD system as the culpret. Why don't you make sure that that is not what is going on? Pull power fuses 17 and 18 or disconnect the connectors on the 4X4 control module and drive it for a day or two and see if the shudder quits. It is possible you are worried about the wrong thing.
 






I will give that a try (pulling the fuses) and see what happens. I am new to 4WD since I have either owned RWD, FWD or AWD and have never felt this type of shudder before.

So what does that mean then if pulling the fuses does work? Is the 4WD control system faulty or is it something else?
 






If you have any shudder rubbing when turning then it almost 100% the clutch packs. Refer to this post and TSB....


http://www.explorerforum.com/forums/...hudder+turning

I had this exact problem as well as rear end whine and had them replace clutch packs under my extended warranty :) Fixed all that and now drives like new again.

I had 97,000 kms when this was done.
 






If you have any shudder rubbing when turning then it almost 100% the clutch packs. Refer to this post and TSB....


http://www.explorerforum.com/forums/...hudder+turning

I had this exact problem as well as rear end whine and had them replace clutch packs under my extended warranty :) Fixed all that and now drives like new again.

I had 97,000 kms when this was done.

100% huh? :rolleyes:

These guys have pretty much got to figure out for themselves now whether it's the rear end clutch pack binding or the 4WD system activating. Then they can start figuring out what to do next.
 






Thanks for the suggestion re. the 4WD system. I'd like to try pulling the power fuses just to eliminate the 4WD module as the culprit here. Are fuses 17 and 18 in the fusebox under the hood? Anything special I should know or do before pulling them or replacing them afterwards? I generally shy away from all things electrical, whether automotive or in the house! :p:

Also, assuming it's NOT the 4WD system and is indeed the rear differential clutches, what is the group's opinion on the urgency of repair? Is this shudder hurting anything? And on a related note, is there any issue with waiting on the rear diff repair for the infamous "whine" that has recently surfaced? I've got a long road trip planned next week and want to know if I should hit the panic button here...

Thanks for the assist!
 






100% huh? :rolleyes:

These guys have pretty much got to figure out for themselves now whether it's the rear end clutch pack binding or the 4WD system activating. Then they can start figuring out what to do next.

Well unless you have had this problem then you can roll your eyes elsewhere. I was helping the OP and you come with rollie eyes...Gimme a break.

trust me...worked for Ford for 10 years and I can tell you this is the problem and has nothing to do with the 4WD. So please keep your rollie eyes on someone elses post FFS. :rolleyes:
 






OK, OK -- take it easy, guys! :rolleyes:

Appreciate the help and all suggestions. In the interest of eliminating variables, I am just back from an extended ride around city streets with power fuses 17 and 18 removed (i.e., 4WD completely defeated) per suggestions here. Alas, the shudder was still there.

So... ...although I'm happy to eliminate a possible bum 4WD module from the list of causes, I am still not happy to know that the rear diff clutches may indeed be to blame.

Can anyone chime in with some advice on how much I should be worried about fixing this right away?! As the shudder isn't really apparent at highway speeds or when going in a (relatively) straight line -- like on the freeway -- am I safe in assuming the worn diff clutches won't be an issue on a long freeway roadtrip??

Thanks again for the help. I'm a firm believer in trying anything and everything to troubleshoot in advance of spending $$ on parts or repairs, so all advice is much appreciated.

:thumbsup:
 






I had a very similar experience last year. I had changed my fluid using M1 and the same TransX additive. About a year and 15,000 miles later on my log I changed it again with Royal Purple (good stuff if you can find it) and the XL-3 additive. I remember that the shudder started a few months before I ended up changing it again, so probably about 10,000 miles. It cleared up the shuddering, but I think it took a little while to work in (not instantly). Now, 16 months and 20,000 miles later, its still fine.
I also, had some rear end gear whine like noise before and after. That turned out to be the 2 rear wheel bearings that I have replaced since then. Nice and quiet now. If you haven't done the wheel bearings yet, you will probably have to (all of them) eventually. That is easy to check. Just jack up the wheel and try to move it.
So, before your trip, Change it out. It is a pain in the ass, but not that hard. Or take it to the Ford dealer. They can't charge that much for it and would use the good Motorcraft additive. They would also probably do a full inspection for free. Whenever I bring mine in for something, they give me a full report of all the additional thousands of dollars worth of repairs I need. That way you would know what is lurking next for you to deal with.
 






Coled43:

Thanks for posting. As I mentioned before, I went ahead and changed the rear diff fluid (Mobile1 Syn 75/140) and used the FoMoCo XL-3 additive about a month (~1000 miles) ago. So far, I'm still getting the shudder.

Trying to figure out now whether it will hurt to drive this thing about 2,500 freeway miles next week with what are likely worn out rear diff clutches. Don't want to do yet another fluid change as the stuff in there now is brand new...

Also, regarding the rear-end whine -- I'm more than willing to check the rear hub/wheel bearing assemblies by checking wheels for play. BUT even if the bearings are starting to go, my "whining" noise from the rear is only apparent when I'm on the gas (steady speeds or accelerating) -- so I suspect the diff needs attention. If it were wheel bearings, I would expect to hear the offending noise even when coasting (foot off the gas), and so far I don't...

Can anyone advise whether worn-out rear diff clutch packs are a safety issue for a long freeway trip? Am I doing further damage by not addressing immediately?
 






Sorry, I didn't see that you had already changed the fluid. I do remember that mine didn't stop the shuddering after the fluid change right away, but I don't recall how long it took. I think you should be OK for your trip. Maybe it will improve. It may get worse, but probably not such that you get stranded or cause damage to anything else that wasn't already. It seems like the clutches would just wear more and damage to the gears would only come from contamination of the fluid. Since you changed fluid recently, that would help.
I agree about gear whine. I have noticed that wheel bearing noise can seem like it is coming from all over, but the on and off the gas part does point to the rear end. I think the Royal Purple diff fluid may have improved my whine. Maybe drain the fluid after your trip to see what it looks like and refill with RP or something other than M1 (I'm not a big fan of M1 myself).
I don't think I saw how many miles are on your Ex. Wheel bearings, at least the original ones, don't seem to last on these trucks. So, if they haven't been replaced yet, keep an eye on them. I found that they get loud enough to tip you off and then realized that I had been feeling/hearing them long before that. Mine has needed all 4 wheel bearings between 80 and 110K miles.
 



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i have a 04 explorer xlt and at 33k miles i was experiencing the same thing. they replaced the clutch pack stuff in the rear end.
good till = 55k miles when i got the rear end howl at 55mph, let off the gas it goes away.

TSB - 5-23-3 new ring and pinion, thicker fluid 75w140, and the friction modifier.


now= all better.


Thing is , if other people have the same symtoms as you/ common issues, chances are you vehicle has the same issue. :)


good luck!
 






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