Found my 915 noise source, lots of questions

[yelcab1]

Finally got the input shaft nut off with 2 home made tools: 1) cluth plate screwed into the wall to hold the shaft in place, and 2) a welded up 42mm socket to turn the nut. It still takes a long breaker bar and 2 foot cheater bar.

[Fishcop]

My solution...

[yelcab1]

Fishcop

It is too clean to be on the way out. It must be a picture of it on the way back in with a Wevo plate ...

[yelcab1]

The case came back from the machinist, ... with a new CV flange bearing / race. In removing the old bearing from the differential, I notice there is a shim under the bearing. $1000 question ... does that mean I now have to check the differential and adjust the way it fits in the housing with respect to the side load shims? how?

[Peter Zimmermann]

Originally Posted by yelcab1

The case came back from the machinist, ... with a new CV flange bearing / race. In removing the old bearing from the differential, I notice there is a shim under the bearing. $1000 question ... does that mean I now have to check the differential and adjust the way it fits in the housing with respect to the side load shims? how?

Need more info! What do you mean by "CV flange bearing"? Are you talking about the diff carrier bearings? There are two, and each has spacers that determine both bearing pre-load and backlash.

[yelcab1]

Originally Posted by Peter Zimmermann

Need more info! What do you mean by "CV flange bearing"? Are you talking about the diff carrier bearings? There are two, and each has spacers that determine both bearing pre-load and backlash.

Differential carrier bearing, one on the left, one on the right, cone shape.

[Peter Zimmermann]

Originally Posted by yelcab1

Differential carrier bearing, one on the left, one on the right, cone shape.

The pre-load and backlash should both be checked when the carrier bearings are replaced. Note that the pre-load spec for FAG & SKF bearings is different...

[yelcab1]

can you point me to a source if information? the Bentley manual does not have any.

[Peter Zimmermann]

Originally Posted by yelcab1

can you point me to a source if information? the Bentley manual does not have any.

pm me...

[Matt Monson]

To answer a question from a few pages back, yes, we do plate the races to oversize them. However it's not chrome. We use a far more malleable metal that's more workable and not going to cause distortion to the race when it's reinstalled in the case.

[Fishcop]

Hi Matt

Good to know... allbeit a little late for me

[yelcab1]

I got the input shaft and gears back together, tightened the big nut to 165lbs, and found that the gears 3 and 4 move back and forth a bit, about 0.2mm. pictures show the feeler guage where the gap is. My guess is it is normal because these gears have to free-wheel on the input shaft. If there is no gap, they don't spin. Is that right?

[yelcab1]

I like to clean up the input shaft threads a bit. Does anybody know what size tap and die that is? Not the 42mm (clutch side), but the smaller side where the 1st gear is.

[Peter Zimmermann]

Originally Posted by yelcab1

I got the input shaft and gears back together, tightened the big nut to 165lbs, and found that the gears 3 and 4 move back and forth a bit, about 0.2mm. pictures show the feeler guage where the gap is. My guess is it is normal because these gears have to free-wheel on the input shaft. If there is no gap, they don't spin. Is that right?

Correct, you need play for each "loose" gear so that they can turn on their needle bearing.

Cleaning threads. I've always used a nifty tool called a thread file/restorer that I've had in my toolbox for about 30 years. It has a length of "file" for each thread pitch, takes a little time to use, but does a fantastic job.

[yelcab1]

So, the 2 shafts were assembled dry. I used a heat gun on the pieces to go on the output shaft and they all slid home without any problem without a press. I installed the gear stacks in the case at this point. I am at the point of mounting the intermediate housing. Is it acceptable to pour some oil on the gear stacks just so they don't start out spinning dry on start up?

[yelcab1]

I replaced both of the differential carrier bearings (SKF). lacking any instruction on how to adjust the preload, I installed the diff, marked each of the outter race with 4 lines of markers, put the cover on, torqued to 25Nm to close it up, and turned the output shaft with a drill, and removed the cover and the diff, looked at the marking left over and this is what I found.

speedo plate side of the diff, marked with red pen, the marking is all gone


Cover plate side of the diff, the marking is in black pen. The marking is almost all gone.


That is telling me, the preload is too much. Please help out and comment.

[yelcab1]

I am finished. It is in the car, running, and not making any more funny noises. A great big thanks to all the advisors on the board.