Transfer Case chain and additional components
 

Hi all,


My 2005 3.0i has had an issue with the ATC500 transfer case for a while where it would kick when switching from P/D/R. From a cold start or too hard of acceleration with a bunch of weight in the trunk it will kick hard or as of recently grind from the TC. I did the actuator gear 1,000 miles ago and got rid of my 4x4 DSC light that would occasionally come on. But now with 173,xxx miles on the odometer, it probably needs to have the chain replaced. Also the front drive shaft has significant rotational play before it engages when spinning the wheels on jacks - not sure if that's normal, but it feels like it's related to a stretched chain. There's approx 35 degrees of play before it feels like the chain is engaged.



I wanted to know what should be done in addition to just the chain in the TC, like what else should I should replace since I'll be in the drive train area. I plan on doing the seals for the TC if they look bad. I think there are U joints or flex discs that are recommended to be replaced too.

Is there anything I need to do with the differentials while I'm down there too? Does my model X have the driveshaft spline issue?

Thanks

Replace both flex discs. Remember the rear shaft has a center shaft bolt at the carrier bearing. Replace the carrier bearing too. The rear diff is easy to reach for an oil change. The front diff requires stuff to be moved out of the way. I ordered oil squeeze bottles for easier refilling. 2004+ don't have spline issues like earlier models.

Excessive rotation on the front driveshaft to get the front wheels to turn is nothing to do with transfer case, more the front diff and axles (or guibo, which should be totally obvious).

Excellent, I didn't know that! Part of my issue seems to be related to the TC with the punchyness of the throttle and the grind from it on cold starts.

Is there a way to test the diffs/axles for issues to determine health before starting this project? I'll search the form tonight for this also.

Compare amount of play with another unit. Listen with stethoscope or piece of hose. Check for filings in the oil. Check axle and driveshaft splines for wear, being stripped or not engaged properly.

Ditto on the diffs. It's a quick job as long as you are down there. You probably know this, but pull the filler pugs first, just to make sure they will come out (before draining the oil out), and I'd recommend getting four new plugs, rather than fiddle with new crush washers, etc. At some point BMW switched over to washerless plugs, which is what you received from FCP when I did my diffs, or maybe its just whatever is in stock?...who knows what you may have on your car.

The front can be a pain to fill unless you get a pump or use this stuff: https://blog.amsoil.com/changing-gear-oil-made-easy/ I've had zero problems with the amsoil severe gear stuff in my diffs and the squeeze bag is genius.

If you end up doing giubos then you should replace the nuts (assuming the bolts look good). The nuts are the locking type that deform when tightened, so new ones are probably important.

I'll be interested to hear your Xfer case rebuild lessons learned, if you end up doing it. I've been planning on buying a cheap core on ebay and doing a full rebuild at some point, at my normal snails pace. 160k on mine now, so it would be nice to swap a rebuilt one in at some point before failure.

That might be a better option to make sure I'm not stranded, getting a used one and rebuilding it. They're not too expensive on ebay.


I compiled a parts list for the replacement that looks like:
ATC500 Refurbishment
Shaft seal 27107539266 $16.37
Gasket ring 07119963308 $0.25
Screw plug 27111226467
Dustcover plate 27107537663 $7.84
Shaft seal 27107539265 $16.37
Shaft seal 27107539262 $16.37
O-ring 27107609202
Dustcover plate 27107539212 $7.84

Front driveshaft
Universal joint 26117503159 $101.79
3x Hex bolt 26117551225 $1.77 - driveshaft to U-joint
3x Hex nut 07129904473 $0.47 - nut for driveshaft to U-joint bolt
3x Hex bolt 26207564559 $1.07 - mount on diff to U-joint

Rear driveshaft, how do I specify which ones are needed for the centering sleeve and joint.
Centering sleeve 26117526611 $11.32 - both necessary??
Centering sleeve hard 26117526806 $28.35 - both necessary??
Universal joint 26117511454 $120.93 - which one??
Universal joint 26111229360 $110.44 - which one??
3x Hex bolt 26117635643
3x Self-locking hex nut 26127536563 $1.00
3x Hex bolt 26117635643
3x Self-locking hex nut 26127536563 $1.00
Center Mount 26121229726 $94.94
2x Hex nut 07129904874 - for center mount
Dustcover plate 26111225088 $3.08 - for center mount

Do I need to do this also? Does 26117526822, the constant-velocity joint need replacing also?
6x Knurled bolt 26111229775 $1.77
3x Reinforcement 26117502653 $2.28
Flat gasket, metal 26111229078 $8.03
Muffler clamp 26117542264 $2.28
Constant-velocity joint with knurled bush 26117526822 $188.25
Washer-gasket 26117504635 $2.40
End cover with gasket 26117540778 $5.67
Snap ring 26111225017 $0.75
6x Hex nut with ribs 26111227843 $0.75


I'd also like to do the bolts for the exhaust and various other components that are removed during the process, so that I can get rid of rusted ones. I'll have to revise this as I do more research.

Remembering of course that you both have different transfer cases (NV125 vs ATC500).

Very true…best get the correct one to rebuild! No little plastic gear in the 2002…just a driveshaft that likes to corrode and strip!