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The only thing I can think of is to simply slide the bellows seal down toward the transfer case, snugging the face of the seal against the case (or actually the lip on the output shaft cluster). Then maybe a zip tie around the front end of the bellows to encourage it to stay in place?
it's not possible to slide bellow closer to tc. There's a lip on output shaf and groove on propeller shaft for keeping plastic boot in designed position. In may imagination this 3mm gap designed for moisture evaporation on high speed. I was thinking to put some rubber foam shim. But this is not guaranty 100% sealing. Some moisture can be longer inside. I see just next solution to make sleeve and small rubber boot. Ujoin is working thith very small angle. I'm looking for somebody who has access to lathe. The sleeve should be with two grooves, one for rubber oring for sealing and second for metal spring to keep it in place. Or we can use 2 ball joint boots. One for sealing u joint, second for propeller shaft coupling.
Since I'm lazy and cheap, my solution would be a large felt washer, that can be forced over the output shaft, and would fill the gap between the bellows and the nose of the gear cluster. That way, it would prevent moisture getting in, but would also allow it to evaporate if it did. The other plus would be that it would take about 5 seconds to install. :-) Itwould look a lot like one of those washers they sell for battery terminals, only a little larger.
Full disclaimer that I'm not an engineer, but when I went down the rabbit hole of shims and pre-loads I came across various designs and testing approaches. Given the nature of tools and precision required for this, it's not feasible to measure each assembly (these are highly mass produced units) and likely this was done once by engineers during R&D testing using very expensive rigs to simulate the transmission but without the transmission to determine what proper shims are require to achieve the required preload.
I don't think the preload can be measured here. You would have to assemble the entire transfer case, which means you are not measuring preaload on each bearing.
What I did is ensure that new bearings and races where identical thickness. There were slight variation and I ended up not using one of the bearings.
If the replacement bearings last me another 100k miles it will be a win.
It's going to be an interesting process, no doubt. I'm still trying to decide whether I'm going to try to measure each gear cluster individually, or just go for both of them, and divide by two. I figure if I get it somewhere in the reasonable range, I'll call it a day.
I was given some comfort by the relatively wide range of preload that should, according to Timken's life calculation, outlast the car. My gut feeling is that as long as I can twist both clusters by hand, the preload can't be so dramatic as to drastically shorten the life of the bearings. That's my theory, and I'm sticking to it! :-)
Also, to avoid munching yet another output shaft seal, I think I'm going to drop the right exhaust, so I can swing the prop shaft in and out after assembling the transfer case. That will save a whole lot of fighting and wrestling, which is no doubt where I managed to mess up the seal.
On trying to add a seal between the bellows and the transfer case housing, I'm not going to worry too much about that. There are some real advantages to living in the desert, so I doubt it's ever going to see anything too dramatic. It would be nice to seal it off, to protect that impossible u-joint inside the gear cluster, but I suspect it will also outlast the car.
At the risk of stating the obvious, a regular seal won't work because the angle of the shaft is constantly changing. The "disk" on the end of the bellows acts as a slinger and throws anything that gets on it outward. Probably the best you can do without a total redesign.
I am an engineer, but not the right kind, so I showed this thread to my brother who is a rotating equipment specialist. His only comment was, “Yes, it’s a car and they designed it so it would last about 8 years with the lack of maintenance that most drivers give it. If it was a commercial off-roader it would be designed so it could be maintained.” These little trucks are at least 10 years old and I guess those that still have theirs are doing pretty well at keeping them going.
My "felt disc fix" was envisioned in the "slinger" category, and to just take up the majority of a bigger gap. I don't think I'll do it to mine, since the bellows lip is pretty tight and there's no room for much of anything in the (small) gap. Maybe my aftermarket bellows is a little different than the OEM design.
I am an engineer, but not the right kind, so I showed this thread to my brother who is a rotating equipment specialist. His only comment was, “Yes, it’s a car and they designed it so it would last about 8 years with the lack of maintenance that most drivers give it. If it was a commercial off-roader it would be designed so it could be maintained.” These little trucks are at least 10 years old and I guess those that still have theirs are doing pretty well at keeping them going.
unfortunately he is right. My truck-based LX570 has 5 serviceable U-joints that you grease every 15-30k miles.
Tough part is that with labor costs, nobody wants to spend on extra maintenance and cars are designed as such.
I finished my TC project. 50km test drive only tires and wind noise noticeable.
Center shaft tc side bearing shim -0.1mm. Output shaft -0.1mm. Rotation torque 2 gears , cover bolts 20nm, bearings ang gears lightly atf lubricated is 3.4-3.6 nm. Ready to go
Got my GLK transfer case re-rebuilt yesterday. What fun! ;-)
I ended up taking about 0.15mm off the rear output shaft cluster spacer, and 0.6mm off the front output shaft cluster spacer. I wasn't able to get a good rotational drag measurement, but worked out a reasonable proxy (calibrating my wrist using a similar size shaft).
I should add that the bearings I used on the first rebuild (which clearly had too much preload - they were difficult to rotate together by grasping the rear output shaft) still looked pretty good, even though they had a couple thousand miles on them. I'm confident they'll now outlast the rest of the car.
I did a video on the updates / lessons learned, including how to NOT munge that super-fragile (!) front output shaft seal (spoiler - I dropped the front driveshaft, which is itself a super-fiddly process). There's a "tutorial" in the middle part of the video using the (excellent) resources from Timken. Hope it all helps someone...
Thanks for the comprehensive write up as it provides a good insight of what needs to be done, however I definitely won't be able to DIY this.
I heard the whining noise today at 1500 rpm and the sound lessens as it passes 1500 rpm. Is my symptom similar and would expect a similar fix to the transfer case? I'm bringing the GLK to my indie and just want to be sure that fix is done properly by the transmission shop.
Also I didn't notice a list of parts, could you please list them with quantity?
Timken NP312842
Timken NP577617
Timken NP925485
It’s been 4 years but I’ll try my luck. I have the same issue with my 2012 GLK. I’m just curious to know what was the issue with yours and how did you fix it?
Not sure what you're asking, but I think it's fairly clear what the problem(s) (plural) with the posters' cars were. Either the conical gears failed, or the U-joint inside the front output shaft gear cluster failed. Either one results in a lot of similar work - and most (including me) just did both fixes to prevent having to tear the transfer case apart again (and maybe again... see my story). ;-) I did a couple videos on the process which will tell you pretty much all the parts, tools and techniques you need to rebuild / fix your transfer case. Yeah, they're long - but it's a complex and involved fix, though well within the reach of a competent DIYer.
The post immediately above yours will link you to the SECOND of the two videos - kind of a "lessons learned since the first video", but you really should watch both to see what you're in for. There is a link to the first video in the second video's description, and a lot of info you need in both the video's descriptions.
Not sure what you're asking, but I think it's fairly clear what the problem(s) (plural) with the posters' cars were. Either the conical gears failed, or the U-joint inside the front output shaft gear cluster failed. Either one results in a lot of similar work - and most (including me) just did both fixes to prevent having to tear the transfer case apart again (and maybe again... see my story). ;-) I did a couple videos on the process which will tell you pretty much all the parts, tools and techniques you need to rebuild / fix your transfer case. Yeah, they're long - but it's a complex and involved fix, though well within the reach of a competent DIYer.
The post immediately above yours will link you to the SECOND of the two videos - kind of a "lessons learned since the first video", but you really should watch both to see what you're in for. There is a link to the first video in the second video's description, and a lot of info you need in both the video's descriptions.
I already went through all the material here but there is a tiny difference between the issue here and mine: the noise just kick in around 1500rpm when it’s on lower gears and when I’m driving uphill. When it’s flat or it’s on N there is no noise. I think either the engine mount or transmission mount goes bad and that why I asked this question from @louiet3.
Any way thanks for your reply.
I hope the problem is just the motor mounts. FWIW, with my car, the bad motor mounts were obvious starting the engine, and idling (yes, I did a video on that). There was definitely more vibration / noise transferred to the cockpit as a result, though (on my car at least) it didn't seem to be speed or RPM-dependent.
One thing I'd add is that there is at least a little advantage to doing mounts and transfer case rebuild at the same time - having the front half of the exhaust system out just gives you that much better access to the transfer case, though it's gonna be a long job knocking out both at the same time (should it come to that - hope it doesn't).
To be honest, since replacing the transmission mount on my GLK250, I haven't heard any light clicking or other unusual noises in the driveline in the 35-40mph range. I would sometimes hear a faint clicking noise at those lower speeds and wondered about the transfer case, U-joint, front prop shaft and other related items. The new mount has eliminated that, along with a slightly smoother drive and a bit less road noise too. All good in my book.
Now, motor mounts are probably going to be a PITA but I'm hoping it's not as involved as on the gasser V6's. If anybody has a link to a How-To vid for motor mounts on a GLK Bluetec, I'd appreciate it.
andreigbs, I think the difficulty will be similar for all the 4Matics, though it could be a bit easier on the diesel variant I suppose. I'm really not familiar with the layout of the Bluetec models, but I assume that the axles and the exhaust will be in the way on a 4Matic variant. RWD - probably a piece of cake (relatively speaking).
04-25-2023, 05:41 PM
