bummer...@@!!#!... i need some serious reassurance now :-(

[beepbeep]

As some of you probably know...i went to my local dealer to change back wheel-bearing on my 930. ( Check out my earlier thread: http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=61810 )

They called me today to tell me that one bearing-race was broken and that there is a crack in the trailing arm hub...

So i probably need to change whole goddam trailing arm that costs arm + leg... :-(

Last time i went in to change my front bearings but found out that one axle was damaged by worn bearing so i ended up replacing whole strut-assy...for 1300$

Now it's back bearing and trailing-arm...i cannot say i feel too lucky right now :-(
(Should end up in 1600$ territory this one as well)

Well...just need to vent...

[Mike Feinstein]

Yikes! Did you visit them to see the cracks for yourself? Seems there's a trend devloping with your dealership.

[beepbeep]

Well i'll go to the dealer tommorow and take some pics of the hub with digital camera (and post them here...) , just to make sure.

[Superman]

Yes, please do take some pics and post them here. If you really need all those parts, then fine. But let's see the old ones, and the reason why they are suggesting replacement.

[Tyson Schmidt]

Did they even offer the option of a used part? Could have saved you a bundle on that front strut. Same with the rear trailing arm.

The spindle in front often wears out where the inner race of the bearing rides, due to sloppy bearings hammering away at it. I'm not surprized at that needing replacement. I had to do it to my '72, and many customer's cars as well.

[Early_S_Man]

Well, I have NEVER heard of a bearing race breaking in normal service on a car! There just isn't that much stress on the bearing or hub in normal use, not even if cornering at 1g under power!!! Are you sure you haven't smacked a curb during some spirited driving incident?

And, considering some of the suspicious quotes you have gotten from that dealer ... I would have to be suspicious that the damage was caused by an incompetent technician, and they are trying to stick YOU will the bill for parts they should be giving you, gratis, for the 'accidental damage' caused by incompetent help! You may need to question the shop supervisor very thoroughly about just who discovered the damage ... and whether the hub was even on the car at the time?

[beepbeep]

Well, i never tought a big sturdy hub like 930-ones would crack...and i never tought bad bearing would do so much damage, as there are two bearings in that hub but i guess you can never know...

Anyway, I'll take my digital camera to the shop and take few shots tomorow.

Bout hitting the axle...I did slide back from a car-lift ramp once and accidentaly hit my foil-thin 3-piece split wheel on a metal obstruction bending it's lip slightly but i never tought that that would do much harm...i was just creeping backwards and runout was so small (approx. 1mm) that they easily straightened the wheel...

Hmmm... :-(


BTW...how do you get those bearings out? I don't think they removed the arm but did the bearings with trailing arm on the car...i'll ask for exact details tommorow.

[john walker's workshop]

be careful to be as nice and unaccusing as possible to them. you don't want them to tell you to take a hike and hand you everything in a box. or do you?

[beepbeep]

JWS:

Good point! And no, i'm not accusing anyone...rather cursing my bad luck :-)

Actually i understand their way of thinking...they are dealer shop...they don't fiddle with old parts and they want to make sure everything is to their standards, so they tend to replace bad parts with new ones...and that's perfectly OK with me , at least as long as i can afford it :-)

[matt_d]

I hope you're talking about the wheel hub and not the trailing arm. I don't think either would/should crack easily (esp. the trailing arm) - that would be a major impact.

Hmmm ... I'm wondering how they took the hub out. I haven't taken mine out of the arm's outer bearing yet (light pressfit I think), but the hub's wheel flange did look kinda thin to me (thinner than the 911 hub I have, if I recall).

In a recent thread, JW mentioned carefully prying out the hub from a 911 by using dual crowbars on the brake caliper bolt heads. In looking at my 930 arm/hub setup, I'm not so sure this is possible - the caliper bolts aren't really close enough to get any leverage. I was leaning towards pressing them out since my arms are off a car.

I'll take/post more comparison pics tonight (911 vs 930 parts).

Smells to me like hammer-boy may have been called in on this one if the wheel hub is cracked on the wheel flange - or the trailing arm for that matter. I hope not ...

If needed, used 930 trailing arms are tricky to find too (not what you want to hear, I know). Do a search in the Pelican Used Parts section - I did find a guy who had a pair of 930 rear trailing arms minus hubs/stubs/bearings for $800 and he still had them a month ago. I never found anyone just selling hubs. Again, try www.msroadrace.com - I still see some separate arms, hubs, and stubs on their "specials" page.

[Superman]

I'd agree with John that you should be respectful and it sounds like you will be. Your little wheel bending incident would not have been sufficient to damage hubs, bearings, etc. IMHO. I am suspicious of this conclusion that your hub is bad, so I'd want to see for myself. According to my understanding, 930 rear bearings top the list of things to NOT try to do at home.

[matt_d]

Here are some comparisons of a 911 and 930 trailiing arm/hub area;

Comparison (911 top & left, 930 bottom & right);



Pretty cool how somone broke this 911 arm - I didn't do it, I picked it up for just such a comparison. Broke the cast iron caliper right off at the mounting lugs and broke the arm at one of the widest sections. Must have been a vicious rear end hit.

Notice how much beefier the 930 arm is (to hold the dual bearings) - it's also further outboard about 25mm. This is a '78 930 arm, so a rear wheel spacer is used. In '81, I think the wheel hub mounting face was moved outboard and maybe had a generous radii like the 911 hub - eliminating the spacer.

Here's a close-up of the 911 hub - notice the generous radius behind the wheel mounting flange (I didn't press it in all the way, but close);


Here's the 930 hub close-up. Note not much of a radius behind the wheel hub flange;


Here's the inside view of the 911 hub - the splines make up half of the inside hub and the end of the hub is almost flush with the inboard surface of the bearing (again, I didn't press it all the way in);


Here's the inner view of the 930 hub - the splined portion is the hub. The smooth portion is the inner bearing inner race (pardon the grease, I haven't cleaned them up yet). Beepbeep -I'm guessing your inner bearing froze up and the stub axle was turning on the inner race (the grinding noise) - your stub axle might have some good scoring. The grease on these parts is very dry - I'd say shot;


I'm really interested to see where these parts could have cracked - none of these parts are what I would consider fragile. I was surprised how easily the stub axles were to insert/remove - they just slid in/out with little effort.

[beepbeep]

According to the mech, there is a crack on the both sides of bearing races...

If bearing race is like this "O" then crack would be in this direction "<------->" ...

I'll go there in 30 mins to check it out...stay tuned.

[beepbeep]

OK guys...i've just been there and looked at the state of things. and of course, these guys are pro's and perfectly right...my sway-arm is cracked where bearing races are mated...

I guess previous owner hit the curbs sometime before, which put a crack into the trailing arm, which progressed and widened until race wasn't supported enough so it broke (after i tightened it)...not a sort of things you usually check before you buy the car. Live and learn.

All in all, i opted to replace cracked trailing arm with used one if possible, or new one if used cannot be found. They will also replace all four CV-joints (they are worn) and of course bearing on new arm...(i'm thinking about replacing bearing on the other side as well...as a precaution.) This is probably going to tackle all driveline problems (i already replaced all front bearings).
Price? Around 2000$ :-(

Here are the pics:

[matt_d]

Bummer - that's definetly going to need replaced. You've got me thinking that I really need to check mine once I've gotten them apart.

Don't let them pitch the rear trailing arm - these things are hard enough to find. If you can find a REALLY good aluminum welder and machinist, it might be salvageable - at least as a backup.

No one ever said Porsche ownership was cheap or easy ...

[RJM3]

You might be able to repair this crack with New Technology Products second generation aluminum repair rod....works with any torch and the rod that they sell >>>I,ve had good luck with this product....their no. is 877-809-8715...Could save some bucks regards rjm

[911nut]

I wouldn't recommend repair welding any casting, especially one that is as highly stressed and a trailing arm. The fact that it's aluminum makes matters even worse.
Find the nearest trash can and drop it in.

[beepbeep]

No welding thanks...i'm going to get used one if possible or buy a new one.

[dtw]

Originally posted by 911nut
I wouldn't recommend repair welding any casting, especially one that is as highly stressed and a trailing arm. The fact that it's aluminum makes matters even worse.
Find the nearest trash can and drop it in.

I agree- I've been in 930s cornering at triple digit speeds. The experience had a sufficient pucker factor, without considering any patched up load-bearing suspension items.

Send the casting to Audi. They can probably melt it down and get an entire A8 unibody out of that beast.

[Early_S_Man]

beep,

I was halfway expecting to see fresh hammer and tool marks on that control arm!

But, what I saw was worse in one way ... there is only ONE way that I can imagine that the cracks happened in such close proximity ... massive radial forces applied trying to expand the bearing race! Want to venture a guess what could generate such forces? Try 800-1200 lb-ft of torque applied trying to 'tighten up' some rear wheel bearing play! Does that ring any bells about some of your posts in the recent past? Anyone remembe something about a 'crush' bushing or spacer?