Rear end feels like it's grabbing or binding under load HELP!

[Albear]

*part number (sorry i didn't completely proof read that last one...lol)

[wpoll]

Originally Posted by Albear

Honestly,
Impossible to have happened. I had a friend at BMW search the part using my Vin. My problem was my truck had the 1347mm and not the 1325mm driveshaft which made the pumpkin rare to come by. Also 4:10 gears which was verified using the Vin of the donor. It is identical down to the numbers. (Already thought of that). Do the rear diffs in the x5 have clutches (I don't think so, all that is controlled via transfer case)

No clutch in the diff...

xDrive or not? Is there an electric motor on the side of the transfer case? If so, it's xDrive. Pre-xDrive case is usually an NV125 (or LWX500) - xDrive is an ATC500

Re. diff gear ratio - if you have pre-xDrive, then disconnecting the front driveshaft (as Andrew suggests) will allow you to run RWD only. That way you can isolate the issue somewhat.

Don't think you can do this with xDrive.

[andrewwynn]

It's the opposite. I believe you can't disconnect front with pre xdrive. Xdrive let's you disconnect front with the transfer case motor


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[wpoll]

Originally Posted by andrewwynn

It's the opposite. I believe you can't disconnect front with pre xdrive. Xdrive let's you disconnect front with the transfer case motor


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Oopps - my bad - I always get that mixed up.

I guess then if you remove the front driveshaft on the NV125/LWX500 that will address the "bucking and binding" - the vehicle will not move at all!

[Albear]

Funny, but won't address my mobility issues..lol.
The diffs areally the same ratio.. it's defiantly coming from the rearward end of the truck.. just can't test it without it loaded or I could run it on the lift easily enough.

[wpoll]

A little more research indicates that fuse #46 in the glove box would disable the transfer case on an xDrive.

Reading also infers that removing the front drive shaft on the NV125 would work fine to reduce the car to RWD only, while removing fuse #46 does the same thing for an ATC500-equiped car.

If you can run it on a lift you might be able to spot what's going on but it really sounds like the front and rear drivelines are trying to run at different speeds...

[Albear]

I know these x5''s are prone to beimg rough on cv shafts and wheel bearings. Is it possible that the rears although inspect well and show no signs of play etc could still be bad? I just don't want to throw parts at it till it goes away..lol. as for the diff. .it's the exact original BMW part number as the one that was removed (and verified through BMW service dept), They can't be different gears so they're both the same ratios. Also, it would stand to reason as the diff doesn't fail as a common part, what I'm seeing now that the good one is in there, that what I'm experiencing is what killed the old diff. Just tracing the problem through the driveline is becoming taxing. It's spent a month already tracking down a diff, getting it in along with everything else noticed to be faulty.. (bearings, ball joints etc.) Now chasing this gremlin to make it driveable.

[Albear]

Okey dokey, so please just confirm if I'm right on this.. if it doesn't have the servo on the transfer case, then it's pre-xdrive and I can pull fuse #46 and that will disable the front end from trying to pull load (and if I disconnect the front drive shafts the truck won't move). If I have the older version, then simply pulling the front drive shaft will isolate the front end and allow the truck to move under rear wheel power only. Am I right on this?
(And thank you all for all the informative help!)

[Albear]

Sorry I butchered that question..lol apparently typing with my thumbs too quickly. I'll try that again, yes.. it's x drive according to the Vin decoder, utilizing the atc500 transfer case. So can I disable the front end drive by simply pulling fuse 46 and run it rear wheel to see if the problem is still there? If not, is there any way I can 100% disconnect power to the front wheels to see if it is indeed an issue between differentials?
Thanks again everyone
Barry

[EODguy]

Just on the off chance...

Did you check the lash on your new pumpkin? If the lash is off it can put so much pressure on the ring that it'll be hard as hell to turn (at least until it grenades)

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