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Discussion Starter · #1 ·
Ok, I did '88 rear end (eg: for '88 + front brake) swap a couple months ago, new bushings (almost) throughout. I was advised to use all parts from yr I was swapping in. I re-sealed the '88 (from junk yard) calipers as well.

However, the rear stays (eg: stays from axle to underbody next to gas tank) from the '88 had slighly different size bushings & bolts on both ends. The '86 bolts were larger diameter on both ends. The '88 stay bolt size on underbody flange was considerably smaller than flage hole... I was afraid it would enlargen flange over time.

So I decided to use the '86 stays. Stay bushings I ordered were for '88, so I put those in '88 stays and installed 'em until I got '86 stay bushings.

The entire '88 rear end: bushings, wheel bearings, brakes... everything, was smooth as silk, much improved ride (etc. etc.), and stability in turns w/the stabilizer bar was noticable. Real happy.

Just got around to putting '86 stays w/new bushings in this weekend. I had to pull hubs in order to remove bolt for the stays on the axle, also drilled same hole to accomadate larger '86 bushing bolts. (NOTE for anyone doing same thing: 7/16 in. bit works out to .004 over bolt size. Machinists tell me .002 is what they shoot for on such things, but .004 is no worry. That's what I used, and fit is acceptable I think).

So anyway, I did passenger side 1st: pulled hub, drilled, installed stay, put it all back together. Took it around the block for test drive, and there was a damn loud grinding. The sound came on each revolution of the wheel: more frequent when faster, less so when decellerating.

Hmmm... hard to figure. I repacked rear bearings when I installed '88 rear end, they were smooth... how could it be bearings? But what else could it be? Looking at that assemble, there's only a few moving parts:
disk <> caliper/pad alignment
bearing(s)
The rear stay bolt on axle doesn't come close to hitting anything moving in that assembly.

Befuddled, I took that bearing apart: cleaned it up, inspected thoroughly, it was fine. Put it back together: grind grind grind. :roll:

Hmmm. Could it be the brake, somehow???/// everything there looked fine. Nevertheless, not having a clue I removed entire caliper (left E. brake hooked up on other side). Took it around the block: grind grind grind. :roll:

I bounced this off a couple friends, all pretty good mechanics (one's factory Porsche guy). No certainty at all there, but grasping for straws speculation was the bearing. Ok, but I looked that thing over really well... not any sign of any damage/wear/ridge/pock marks or burn.

I decided to swap hubs side to side. Pulled the drive side, took bearing apart as w/passenger, throroughly inpsected (it was fine), and installed 'em both on opposity sides. Went for spin around the block (passenger caliper still removed), and no grinding!!! YEAH!

Then I gently pulled e-brake, and bam: exact same grinding on driver's side. :roll:... WTF?

Both bearings fit very tight on axle stub: no looseness, play whatsoever. I can't imagine worn stub has anything to do w/it. Further, now w/brakes bled and all calipers back on, no such sound when braking w/pedal.

I went back and adjusted e-brake cables very carefully according to bentley spec. Same thing, on driver's side now. So I repeatedly (maybe 6 times) got going around 25 mph, eased on e-brake to near stop, and repeated.

The grinding now seems to have disappeared: went out for 30 min drive this morning, all speeds and hard cornering both ways... still, no grinding.

I'm real troubled by that sound, and have no idea what was causing it. This is first time I haven't been able to positively identify mechanical problems, and the indefinate nature of this one leaves me uneasy.

My "wrench buddies" all just say: "that's weird".

Anyone ever experience something like this??... or any insight.

Thanks.
 

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Pure speculation, but could some metal filings have wandered in between the pads and the rotor while drilling - manifested themselves as a grinding sound and then worked their way out of wherever they were trapped?
 

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Discussion Starter · #3 ·
SteveTheFolkie said:
Pure speculation, but could some metal filings have wandered in between the pads and the rotor while drilling - manifested themselves as a grinding sound and then worked their way out of wherever they were trapped?
Thanks Steve.

I was pretty careful about drilling refuse... wiped everything real clean afterwards. Beyond that, grinding was still there when I tested w/caliper removed. But still seems like it's something I either inadvertantly did or something that happened from time I began 'till finished, since there was no hint of anything other than smooth prior to undertaking this one.

When I think about it, always I come back to the bearing... simply as logical candidate: the sound only hits briefly on each wheel revolution. But inspecting it thoroughly, it seems flawless.

Then there's the e-brake activated complication. But since noise was therew/out caliper, noise couldn't be coming from pads/caliper/brake assembly. So maybe it was exerting force on the bearing in such a way so as to activate the "grind".

But how can I wreck a wheel bearing by drilling hole in another surface? And I'm near certain as I can be, based on inspection, the bearing is good.

I'm wondering if there's something that can go wrong w/bearing outer sleeve in contact w/the hub... maybe a hairline crack or (???).

But now sound is gone. And under the circumstances, that's not too comforting. :roll:
 

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The only thing that comes to mind is some kind of shim that was inadvertently left off. I would expect it to be behind the bearing on the axle stub or something like that. Or maybe a retaining clip between hub and bearing out of place.
 

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Discussion Starter · #6 ·
cdaly said:
The only thing that comes to mind is some kind of shim that was inadvertently left off. I would expect it to be behind the bearing on the axle stub or something like that. Or maybe a retaining clip between hub and bearing out of place.
When I put that rear end in a couple months ago, my reading of the EPC for an '88 hub assembly looked like a large washer was supposed to go in there. eEuroParts tech person said no, as did local SAAB indy shop. I checked several '88/9(s) at the yard and none of them had one. Again though, thing is this rear end, bearing & all, ran smooth as silk from installation until this incident.

Jim Mesthan said:
Is the E-brake cable hitting the tire?
Don't think so, but I'll double check. I am sure the cable's properly routed through rubber grommet on the spring link arm.

I don't think the cable could have made that sound. To describe it more precisely, reminds me a bit of a cracked/broken shoe in a drum brake. The grinding sounds metal on metal: not like a direct head on impact, but a hard swipe. I'd say the sound lasted approx. 10-20% of each wheel's revolution.

I drove it only this morning, and sound disappeared as I described (from 1/2 dozen tugs on e-brake). Not knowing what it was, though, makes me damn nervous... been on my mind all day.

I'm thinking I'm going to get back under there and see if something may have happened w/the bearing stup sticking out of end of axle. I'm not sure, actually, how that thing is even mounted in there (welded?).

Anyway, thanks all for taking a shot @ this... :eek:
 

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Rust on discs? My cars will sound scrapey when they go back on the road after being laid up for the winter...
 

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Discussion Starter · #8 ·
Jim: e-brake cable is not rubbing.

cdaly said:
Rust on discs? My cars will sound scrapey when they go back on the road after being laid up for the winter...
The offending noise was still there after I pulled the caliper on "griding side".

This is like a Sherlock Holmes mystery... wish I could jump to the last chapter. :lol:

Other than a quik drive (eg. there was no noise taking it out yesterday morning), I won't have time to get into it again 'till next weekend.
 

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Jack it up, pull the caliper, put a stethoscope close to the bearing and turn the hub - you might just hear something under controlled conditions that you're missing while driving -
 

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Discussion Starter · #10 ·
SteveTheFolkie said:
Jack it up, pull the caliper, put a stethoscope close to the bearing and turn the hub - you might just hear something under controlled conditions that you're missing while driving -
That is something I'd like to do, but there was no sound w/out full weight on the wheels. It got me wondering if there was some kind of roller-tool the that a wheel could be lowered on which would roll w/full weight of car.
 

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Reminds me of the time I bent a dust-sheild, It drove me nuts untill I figured it out. Sometimes a worn bearing looks good and turns quite quietly until you put a half a ton on it.
 
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