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-   -   Please help me solve this issue on my 68 (http://forums.pelicanparts.com/porsche-911-technical-forum/668492-please-help-me-solve-issue-my-68-a.html)

fitchn 04-02-2012 11:47 PM

When you say "the bearing hub outer ring has been delicately tapped in", do you mean the race for the outer wheel bearing? Assuming its the same as my SC, the bearing races (inner and outer) must be pressed (or pulled etc.) fully into the hub. If the races are not fully seated you would get nasty vibration and early bearing wear, perhaps just as you describe.

rolls 912 04-03-2012 05:59 PM

Yes Noah, that's exactly what I'm concerned about, my races have been tapped In delicately with a wooden block.

Should I remove and get them pressed?

fitchn 04-03-2012 07:28 PM

Someone else will certainly chime in, but I would say yes. I recently replaced my front wheel bearings and built a puller (similar to the homemade pullers that people on this board have put together for installing the rear wheel bearing) out of some custom machined aluminum pieces and 1/2'' threaded rod. The aluminum pieces are small enough to just clear the hub but not the bearing races. I took this approach since I have access to a machine shop, but not a press.

A preliminary test that you could do is to take a pair of calipers and using the "depth" measuring mode take some measurements from the front surface of the hub to the bearing race surface. If the race is fully seated then you should get fairly consistent measurements around the entire circumference, I think I recall a few thousandths of "runout" on mine once they were fully seated in the hub. You could also try to feel to determine if there is any space between the bearing race and the part of the hub where it meets a hard stop. It would be important to do the above measurements for both the inner and outer races (inner = inboard side towards the car, outer = towards the road wheel). Posting some pictures might help as well.

Good luck.

rolls 912 04-03-2012 10:54 PM

Wheels off
 
Great info guys.

Wheels off. Can't get my caliper into the hub to obtain an accurate measurement. I'm going to take it to a shop for pressing regardless just to be safe.

Jim, tried your wiggle technique. Doesn't appear to have any play. Although when i press up from underneath the strut with all my strength (which isn't much) there's a very faint click coming from the ball joint at the bottom of the strut (only can lift half an inch). Everything is brand new.

Checked the spacer for trueness although it would not offer the aforementioned symptoms if it was warped IMO.

Any other suggestions please advise.

For those that are new to the thread, two sets of new bearings and still the same symptoms.
Cheers

jrolstin 04-03-2012 11:04 PM

Has anyone mentioned to check the alignment yet? Or do we know it is good?

rolls 912 04-04-2012 01:10 AM

Hi
Alignment is good. The fact that the wheel wiggles when off the ground is probably more the issue IMO.

Also, the disk hub is from zimms. There s no chance that this could be the culprit?

docrodg 04-04-2012 08:21 AM

Quote:

Originally Posted by rolls 912 (Post 6665966)
Great info guys.

Wheels off. Can't get my caliper into the hub to obtain an accurate measurement. I'm going to take it to a shop for pressing regardless just to be safe.

Jim, tried your wiggle technique. Doesn't appear to have any play. Although when i press up from underneath the strut with all my strength (which isn't much) there's a very faint click coming from the ball joint at the bottom of the strut (only can lift half an inch). Everything is brand new.

Checked the spacer for trueness although it would not offer the aforementioned symptoms if it was warped IMO.

Any other suggestions please advise.

For those that are new to the thread, two sets of new bearings and still the same symptoms.
Cheers


The ball joint is moving? Worn out? A worn lower ball joint is dangerous and should be replaced. Not sure if this is the case form your description but if it is...

rolls 912 04-04-2012 06:16 PM

Spindle pic
 
Yes, ball joint is new....

Looks like the culprit is the actual spindle. Although I am surprised given its so light at the front.

Where to from here - im stumped? Do I get it rechromed?

Does anyone happen to have the correct spindle measurements for a 68?

TIA
http://forums.pelicanparts.com/uploa...1333592108.jpg
http://forums.pelicanparts.com/uploa...1333592134.jpg
http://forums.pelicanparts.com/uploa...1333592161.jpg

rolls 912 04-06-2012 04:20 AM

Can anyone help?
 
Can anyone comment on the spindle situation?

How do I obtain the correct measurements? Any thoughts about the appearance of the spindle?

TIA

fitchn 04-06-2012 10:25 PM

bump, any advice from the brain trust?

Fishcop 04-07-2012 01:45 AM

Roland , you photo of the spindle looks to me like a bearing failure of some sort - at least you've probably found the culprit. It does look like the race has spun on the spindle and possibly ruined the hard chrome. Can you get a photo with it cleaned up and free of grease? Can you measure the spindle and see if there is a significant loss of metal?

You could got to all the trouble and expense of replacing the strut and spindle and probably still have issues with unknown components. I don't think the race is a particularly tight fit - my first thought is to "cheat" and get the inner face of the race hard chromed which will reduce the diameter and give you back your interference fit. I've also had success with some of the Loctite bearing retaining adhesives designed specifically for this application. Another brand is Titan #7620 which works just as well.

The hub races should be pressed (or pulled with the right tools). I always use the heat/shrink technique with the hub in the oven for 15 min at 130ºC and the race in the freezer for 30 min. They almost drop in doing this.

The sleeve pressed up to the back of the spindle is where the dust seal seats - this is replaceable.

The other advice you've received so far has been excellent - certainly try rotating your wheels around to see if the issue is common to the one corner or if it's following the one wheel. I'd also consider letting someone else balance and align your car... They probably should have picked this issue up (thought maybe I'm being a bit harsh?). The best alignment and set up I ever got was a little grotto like shop that did not do race cars, just wheel alignments...

rolls 912 04-07-2012 02:12 AM

Chrome
 
Thanks John - always appreciate your help! This issue has been the most frustrating as there are so many variables. Since the new rubber installation, the vibration is unbelievable. I've rotated the wheels twice. Balanced three times.

Spindle.
Although it looks worn, when you run your finger along it it feels baby bum smooth.
I've measured with my caliper and theres no run out. Do you happen to know what the measurement should be?

What makes me suspicious of this hub is that when the wheel is on, I can feel a very slight wiggle through the tyre. To be sure ( don't laugh) I was thinking of attaching a long shaft onto the end of the spindle when everything is assembled and then try wiggling again to visually ensure the wheel is moving independently of the hub. Opposed to the wheel and hub moving as one ( isolates a defective ball joint).

Fishcop 04-07-2012 04:09 AM

If there's no runout or damage to the spindle, then you could just have got a dodgy bearing... it happens.

But more likely, if you weren't 100% that your bearings were seated properly I think there's a chance that you were never able to tighten up the axle nut and keep the correct torque. Each time you torque it up it feels "right" but once back on the ground and rolling the bearing races move and you've lost the correct tension all over again.

rolls 912 04-07-2012 04:29 AM

I've put another new set, same problem.

I don't torque the axle nut, I just use a screwdriver and wiggle the washer ever so slightly. I hope I haven't stuffed it buy using this method.

Anyway more checking tomorrow. Thanks for the advice.

Grady Clay 04-07-2012 04:52 AM

Roland,

I’m concerned about the spindle also.
As John suggests, disassemble and clean everything for measurements.
Yes, you should pull off the seal race (green arrow). This is an easily replaceable part.

I’m particularly concerned about what appears to be a ‘lip’ or ‘step’ (red arrow).
This appears to be the edge of where (another) bearing ‘spun’ (violet bracket) at some point.

http://forums.pelicanparts.com/uploa...1333802798.jpg




While the outer bearing race is press-fit in the hub, the inner race was a ‘tight slip-fit’ on the spindle.
If there was ever a bearing failure, the inner race could spin on the spindle causing the damage I think I see.

Find a micrometer that is calibrated to 0.001 mm (~0.0001”).
It will take some care to measure the spindle OD as differential temperature and other influence this precise measurement.
We can find the exact (new) measurement.
The bearing manufacture specifications should give the bearing ID to more decimals than we can measure.

I recommend you remove the strut assembly from the chassis.
Disassemble the strut, including the steering arm/ball joint assembly.
Since all these are relatively new, it should be easy.
I recommend you disassemble the other side also.

You may have a few choices of repair.
A new spindle/shock tube would be nice, but….
You can have the spindle ground so the smaller OD surfaces are flat, round and without any ‘steps’.
Not having any ‘steps’ is critical for strength.

You will notice that the spindle has a polished radius back under the seal race.
This is also critical for strength.

A new bearing inner race ID can be plated to fit the smaller diameter of the modified spindle.
Plating has the advantage of being exactly (atom-by-atom) the same thickness everywhere and very controllable.

It should be possible to remove the spindle from the shock tube by cutting (turning in a lathe) the weld at the bottom of the tube.
This will allow the spindle to be turned on a lathe or centerless ground.
(If you centerless grind the spindle, you must make a piece that balances the assembly around the axis of the spindle.)
The spindle can be re-welded to the shock tube as before.
You can (should?) add two reinforcements behind the spindle and to the shock tube (like later RSRs).


Now … if all this seems to get out-of-hand expensive or difficult, the entire front suspension, steering, shocks (bigger) brakes, etc. from 1969-1989 will retrofit to your car.
You even might consider this ‘bolt-on’ mod while you are restoring your SWB suspension.

Who has the spindle dimensions? SmileWavy SmileWavy SmileWavy

Best,
Grady

Grady Clay 04-07-2012 04:59 AM

Quote:

Originally Posted by Fishcop (Post 6672395)
...

But more likely, if you weren't 100% that your bearings were seated properly I think there's a chance that you were never able to tighten up the axle nut and keep the correct torque. Each time you torque it up it feels "right" but once back on the ground and rolling the bearing races move and you've lost the correct tension all over again.

John,

Yes, this happens if the outer races are not seated against the step in the hub.
It can also happen if the seal race is not seated against the spindle.

If these happen, then the bearing 'adjustment' appears looser than previously set.
Roland, have you had to re-adjust the bearing to get the same 'clearance'?

More likely the (new-ish) inner bearing ID is too large compared to the (worn) spindle OD.
This allows the inner bearing inner race to move radially on the spindle.

Best,
Grady

docrodg 04-07-2012 05:55 AM

Did you preload the bearing when you first installed it? You are supposed to torque down the clamping nut to 10.8 ft lbs while turning wheel,then back it off until thereis just play in the washer but not the wheel.

I went through the factory manual and there is no specification on the spindle noted anywhere.

rolls 912 04-08-2012 03:21 AM

Hub
 
Great info here guys, really appreciate the help.

I stripped everything down again (drone) and used loctite per johns recommendation. Upon reassembly I noticed an imperfection on the face of the hub. The lump was making the surface uneven. The aluminum spacer was therefore sitting slightly proud which created a very small wiggle. I have filed the lump down, about the size of ones thumbnail. It has made a big difference. Still not perfect but much better. Rather strange to have such a large lump just near the base of the thread of one of the wheel 'bolts'. I'm also going to try driving without the hubcaps to see if that influences anything.

So, not solved but a heap better. Thanks!

R


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