Chris

Towards the end of our last track day I could feel something was not right, car up in the air there was play on the drivers side wheel and it felt like wheel bearing slack.

I found I could not get rid of the play no matter how tight I made the adjustment, figured OK order new bearings.

New bearings fitted and it is better but I still can't get rid of all the play.

Looking at the spindle there is a ridge where the arrow is pointing, not much but definately feel it with a finger nail no problem.





So is this my issue?

Chris

cdbtx

I'm pulling mine tonight.. we can compare photos..

dr bob

That will do it. The section where the bearing cone rides on the spindle needs to be a continuous diameter all the way down to where the taper starts towards the inner bearing surface. Take yoour old bearing cone, cleaned, and slid it down the spindel. It should slide smoothly, with no rocking and no change in friction as you slide it on.

This symptom is often seen when the bearings are overtightened. The heat from the brake rotor transfers to the hub, which then expands. That expansion adds pre-load to the bearing that's supposed to have a slight amount of clearance for lubricant film on the rollers. The bearing starts to drag under the load, and the inner race spins on the nose of the spindle. It galls a little and wears the clearance in the spindle that you see. There's usually a tellltale bluing of the bearing rollers, and sometimes on the cup (outer) bearing section in the hub. In severe cases the bore in the hub is also damaged by the localized bearing heat and the vibration, so be sure to check that bore when you pop the races out.

Unfortunately there's no good cure for the damage short of spindle replacement. I've seen where "mechanics" have tried to raise a little of the metal in the worn area by using a center punch, but this is a limp-home-from-the-track method at best.


Setting bearing clearances and preload is not rocket science, but every scientific method I've seen makes the rash assumption that there's no prior wear on the bearings. Adjusting used bearings is an art form I think, learned by touch and feel. I often claim to have that experience even though it's usually followed shortly by installing new bearings and seals.

With used bearings that have not just been repacked, I use the inch-pound torque-limiting screwdriver to adjust preload to 10 inch-pounds on the adjusting nut. This is less than three-fingers tight, for those playing at home. If there's still play in the bearings, it's likely time for replacement. The preload torque varies slightly with thread pitch on the adjusting nut, and with the consistency of the wheel bearing greas in use, but generally 10-15 inch-pounds is correct on cars I've owned. It's better to be a little loose than a little tight. On the 928, the front bearings and seals are common sizes used in many other Porsche and and other cars. I like the better european bearings rather than the asian imports, but that's just a personal preference. Point is, they are too easy to replace if they are at all worn.

HTH!

BC

What brands are the European? Timkin? SKF? Instead of what asian brands? NTK?

Chris

Yes it helps, not what I wanted to hear but I figured as much.

Thanks

Chris

marton

manual says;
Adjust front wheel bearing, noting the following points:
Tighten clamping nut slightly, turning the hub. Slacken clamping nut until the thrust washer can
just be moved with a screwdriver under finger pressure. Do not use hub as a lever for screwdriver.
As Dr Bob says, that is quite loose

Marton

atb

These are the kinds of things that happen when Sharky has to share the pool.

dr bob

It's really hard to say by brand any more, since even SKF (France) and Timken (USA) often shop out common bearings to the lowest bidder. Look on the box itself to find out I guess. I have sorted through boxes of the same bearings from the same manufacturer, and seen three or four different countries of origin on the different boxes. If the quality meets the "manufacturer's" specs almost any of them should be OK.

-----


I bought a new pair of Rollerblade-type skates early this year. Supposedly the wheels have ABEC-9 bearings in them. Generally, the higher the ABEC rating, the smoother the bearings should be. So ABEC-9 should be a really smooth fast ride. But ratings can be deceiving and are often fudged by offshore manufacturers. To get the smooth roll, the ***** and races are often made of softer steel so they can be ground and polished to a finer finish. That should mean a smoother roll but it also means that the ***** and races are more likely to be damaged since they are so soft. The skates felt like the brakes were on. Replacement name-brand ABEC-5 bearings, 16 of them, cost more that the new skates did.

In the post-war (that's dubya-dubya-eye-eye) days when Japan was striving to gain a foothold in American markets, they would copy the American goods right down to the "Made in USA" lettering cast into the products. The same situation is showing up in products coming from emerging countries, where a copy of a part can easily include all the ratings that applied to the original part. Karen bought an electrical something-or-other a few weeks ago, with a label on the cord with a genuine-looking UL symbol on it. Fine print on the label says "meets the standards of" rather than the normal "UL approved" rating though. No hint that it was ever submitted for testing and approval, just a "we thinks it's good enough" rating from the manufacturer. Don't want to hold up global commerce waiting for a real seal of approval, do we?

Chris

I needed the laugh thanks

Chris

Mrmerlin

I have found that most of the 928 front spindles i have worked on all have wear marks where the inner bearing rides, check the bottom of the spindle in your picture, the outer bearing at the tip of the spindle looks like it has started to seize........ either due to loss of lubrication or too tight or extreme loading leads to the question were these parts..... 1, made to the correct tolerance 2, what was the hardness supposed to be 3, was the metal hardening process done correctly , as Bob says itswheel bearings are better loose than tight and a worn spindle will let the brake rotor wheel assembly move out of plane with the caliper so it will also cause more brake squeal due to this

Chris

All I can say is I replaced the bearing 4 years ago and after installation I have never had to look at it again. I screw up all the time so maybe it was a combination of events.

Either way I need to get a new spindle, I am going to dismantle tonight to make sure I don't need anything esle and then I will order one.

Chris

Chris

Not sure about the seized bit but the wear is worse on the underside and there is even a ridge on the inner bearing.



Good news is it came off pretty easily.

Chris

Mrmerlin

Yes most visible wear will be found at the bottom of the inner seat area for the INNER wheel bearing, this is what causes the wheel to have top to bottom play and the wheel bearing should not be tightened to try to remove the play it wont do any good but it will cause the bearings to run hotter and eventually seize You will probably need to replace the spindle as the outer bearing seat area is now worn and will make lots of play

GregBBRD

Most of the european brands available here are made in China or Mexico, now. I've not been able to make any of these live on the track. If you can find German SKF or ***, they will work great!

Since I can't find German bearings, I always use Timken and never order them as a set. I always order the race and the bearing as individual pieces. The quality seems much better.

a4sfed928

Very clever Greg !