Need help diagnosing a transfer case/front driveshaft noise (video inside)

[audiquattrot]

turn volume all the way up.

On my way into work today, I was pulling away from a stoplight.....and heard a loud clack clack sound (not axle). There was a split second hesitation when i initally hit the throttle, and it pulled away.

I put the car on the lift after work, and started diagnosing. The only noise that I was able to notice was this below. I was spinning the front wheel/driveshaft to replicate the sound. It sounds like it could be coming from inside the transfer case but i can't say for sure....or maybe the splines of the shaft? I forgot to check under the plastic housing (although im not sure if I would've seen anything)

On the highway there is no noise whatsoever. In its' low gears under torque do you hear the loud metal knocking noise. The sound is loud enough to turn heads.

http://youtu.be/nPJS4daQbhA

[Chruby99]

Did you just replace that case?

[nando]

sounds like stripped driveshaft splines to me. what were you using for lubrication? had it ever been stripped before? used t-case?

[audiquattrot]

yeah the transfer case was used, but it was rebuilt by my friend who knows these cars VERY well. All new seals, etc. If the splines on the shaft are in fact stripped, is it safe to say that the splines on the transfer case are stripped as well? or is there no way of telling w/o taking the shaft off. I have another spare shaft laying around, but the teeth look a bit worn. I'm not sure what kind of lubricant my friend used when we replaced the case.....something was used, just not sure what.

[nando]

usually if the splines on the shaft are damaged, it damages the transfercase splines too.

taking off the shaft is pretty easy. it's the only way to tell.

you have to be very specific with the lube on the front shaft. it has to be able to do 3 things extremely well:
resist water
resist oxygen
resist extreme pressure

the original factory grease does these things. Stuff like brake grease and CV grease do not - they will wash away, oxidize, and squish out, leaving your splines unprotected. that is why they strip. My car had been through 3 transfercases when I bought it because the dealer mechanic didn't know and they left the splines totally dry each time. it only lasted about a year like that, and stripped on me too.

you can get the factory grease from BMW motorcycle dealers apparently. I have no such dealers anywhere near me, but there are alternatives - I've been using Molykote BR2-plus for years, it's similar (spec'd a little higher actually) and you can get it from MCmaster for under $20. Somebody else posted another one a while back they found locally, that was pretty much the same thing, but I can't recall what it was. I bought mine online, one tube would last a lifetime even if you had 10 ix's to maintain.

with the proper grease, it will last forever. My parts car had the original grease in there, the splines looked like new - and it was a total beater with 225,000 miles of hard use on it. I haven't had to replace a shaft in 6 years since finding the right grease, whereas before I was lucky to get a year out of it.

[audiquattrot]

got the car fixed (for now).....the splines on the front driveshaft were stripped a bit, so were the the splines on the tc side. Friend had a spare shaft w/ good teeth that we put in, and we added 1/4" washer to the bolts on the guibo side to push the shaft in a bit more. There is still a lil play there but not nearly as much as before, so I'd expect it to hold up temporarily.

If I do have the shaft lengthened....how much further do you guys recommend lengthening it by....and will a machine shop be able to regroove the worn splines on the spare shafts i have?

[vert_this]

why don't you just mod a OE one? by adding the spacer and hardware. The mod has to be on here somewhere,.. I found it..

http://savarturbo.se/~mattias/motor/pictures/ix/shim/

[audiquattrot]

why don't you just mod a OE one? by adding the spacers and longer hardware. The mod has to be on here somewhere,.. I found it..

http://savarturbo.se/~mattias/motor/pictures/ix/shim/

awesome link. Any idea where i can have a shim like that made?

[vert_this]

awesome link. Any idea where i can have a shim like that made?

call a local machine shop..a lot less than a custom shaft for sure..

[audiquattrot]

call a local machine shop..a lot less than a custom shaft for sure..

i wonder if i can go thicker than 1/4" I know there is a lot more room to go in there, than that.

[vert_this]

i wonder if i can go thicker than 1/4" I know there is a lot more room to go in there, than that.

maybe use washers to work as the spacer to see what is too much before you have it fabbed up...he gets and added 33% of contact. I would say that is more than enough unless your boosted in which case nothing may be safe...

[audiquattrot]

maybe use washers to work as the spacer to see what is too much before you have it fabbed up...he gets and added 33% of contact. I would say that is more than enough unless your boosted in which case nothing may be safe...

great! thanks for the advice!