I had a chance to work on replacing my cardan shaft, as the one in the car gave me the famous symptoms of 'midget in console banging with a hammer'.
Important things to remember:
- replace flex disc at same time (worn out shaft bearing will cause wobble that in turn stresses the rubber disc out when you drive - I inspected mine and there were cracks when looking closely)
- take your time, no rush
- follow each step in sequence
- read each step completely before doing the work for that. There are things that will speed your work once you are aware of them.
If you do not normally work on cars, no problem. Expect about half a day worth of work.
If you work on cars already and are a DIY person, expect about 2 hrs worth of work.
Expected cost savings by DIY: about $1200 - $1400 total.
REPLACEMENT PARTS INFO:
1. Drive shaft - purchased from www.coloradodriveshaft.com - cost:
$475 including $100 charge for core (you get that money back after you return
your old/bad part). Nice thing is that they provide a pre-paid and
pre-addressed label for UPS, which you put on the shipping box you receive to
ship old part back, and they do hi speed balance the shafts as well. They state
that their shafts are much sturdier than originals, and will not fail, but I
have no way to verify that.
2. Flex disc - purchased from ebay - cost: $90 shipped.
3. Rear drive shaft bolts - I did not replace mine with new ones, just made
sure to tighten them up nice (tightened to 10 ft-lbs more than in spec)...seemed
all fine, even with their coating. Service manual calls for replacement of
these bolts though, so the call is yours.
I hope this will help the next one with this issue.
QUESTIONS/ANSWERS SECTION:
1.
Q: A question - was there any concern with centering the center bearing in the tunnel? Porsche has a special tool for this (basically looks like
a big foam block the fits the tunnel and the driveshaft to make sure it's running true and straight. My plan if I need to do this is to mark the location
of the mounting plate under the car, and reinstall it in the same spot (and bolt up the bearing assembly to the same spot on that plate.)
A: I address porsche tool (to align bearing) in picture 11 and 12.
If you have the tool, great. If not, you can still do it. Without tool, you have to ensure that you bolt the bearing to bracket as the
last thing in this DIY. You make sure you affix the bracket back into same location you took it out of (making marks around edges and bolts).
Tighten the 6 bolts to spec (in pics). Then you put in the two bolts for the bearing but make sure they are nice and
very loose. Then, reach up into the space and move the shaft and bearing in up/down then left/right motions (move it in all directions).
Observe where the bearing settles by noting where the bolts stop on bracket. Do this a few times and you will see that they will settle same spot. Remember,
the bracket is what aligns the bearing up/down. The porsche tool does not align that. Also, after you have tightened down the rear and front of shaft, and after
the bracket is in, the only way for the bearing bushing to go is sideways. Since it has 2 bolts, the sideways motion is not that much. By reaching and moving it
up, you allow the bushing to settle in its natural position (least strain).
After you note where the bolts rest, take a flat screwdriver and mark the bolt positions on the bracket (do this so that during torquing down you do not affix
to improper position - important as this is where most screw ups will occur).
After marking the bolt positions, take your socket and gently start tightening both bolts few turns each. When they are snug, make sure they align
with the marks you made and continue to torque down until they no longer move out of their positions. Then just torque down to spec (in pics) and you are
done. Bearing aligned and job finished.
Thanks again.
*** EDIT*** - I was gone for a while and all my pics had been removed from my tutorials. Regardless how it happened, here they are.