rear wheel bearing

[Alan L]

OK the time has possibly come. I have read previous threads on how people have done these and it does not look simple. Been very content not to have done one yet.
Now it looks like I have some play in one bearing after checking the car over from a track run. Finally seem to have enough fuel and tuning - just.
Now I am looking at a bearing job.
So my first Q is - if you have some play, can you try and adjust that out by tweeking the crush washer further? Or once out of spec is it a replace job?
Thanks
Alan

[miquel]

No

[miquel]

hay que cambiar rodamiento

[s5uewf]

I had to do this several years back and used this thread or one very similar for reference ... used PVC for some of the pieces. It all worked out pretty simply:

Rear Wheel Bearing Removal

[Alan L]

Another great thread - thanks. I am mainly using one by DAP930.
Trying to pull the hub right now. Gonna have to fabricate something better than what I have right now. Just using stuff in the shed right now.
Hopefully that thread gives a clear idea where to measure the axial play from. My manual seems to show the gauge off the hub (not the rotor). But the picture ain't great. Seems to make more sense off the rotor edge - but that would give a bigger number. My hub and rotor seem to be one piece.
Regards
Alan

[dap930]

Alan,

When i did this job, I measured axial play by setting up a magnetic dial indicator base on the spring plate with necessary adapter bar to get the dial indicator located to brake disk. It is easier to grasp the brake disk to check end play.

Is your rear wheel making noise from bearing failure or are you just seeing excessive end play? My inner seals were shot letting in dirt which resulted in bearing failure.

Be aware there are rear wheel bearing replacement threads on the forum that are for the regular 911 wheel bearing which is a single double row cartridge bearing that does not apply to the 930.

[Alan L]

Hi Dennis - thanks for the reply. You did a superb write up on your job.
The rotor makes most sense to measure axial play. Just that the pic in my manual is a bit unclear and suggestive of using the hub. I have a 2nd version of the manual which may be clearer.
Symptoms - nil. I was just checking the car over on the hoist after a track day - after rebuilding the fuel system. I did feel a slight 'thonk' in the car while pitching it into corners. Really felt more like a sway bar bush etc. But was hunting for anything and found a slight play in one bearing. I doubt it is the cause of the 'thonk' but it will need some attention. Just trying to part the hub from the trailing arm right now.
Regards
Alan

[Alan L]

Right - my 2nd pic is a little clearer - the dial gauge seems to be close to one of the wheel studs. Measured without the rotor hub on. Makes some sense as you eliminate any rotor hub movement.
But if using the rotor then aprox double the book tolerance would be acceptable.
Now to pull the axle hub....
Alan

[Alan L]

OK - while I am waiting to ping the hub off I tried tightening the crush washer a bit more - to see if it made a difference. Nothing to loose. That means being able to measure the axial play - which I need to do after the install anyway. So trial run basically.
I am having a problem getting this measurement right. I can feel play in the hub - small but obvious. If I push/pull the hub I can feel it move and hear it clunk. I get 0.1mm in/out on my dial gauge (4 thou).
If I try the L-R movement, which is what I think I should be doing for axial play, I get near zero difference.
Where am I going wrong here?
Thanks
Alan

[Alan L]

So the bearings were on the way out - but no obvious symptoms - just a small bit of play. The inner one shows signs of the wear when the car sits too long - as someone has posted previously (dap930 thread I think).
Just to add something to the pool - I always keep one outer shell of any bearing I pull. And do a 1mm grinder cut thru it, and use it to seat the new bearing. They ping out easy.
Not sure if I can do this this time - not using a press. But I have a box full of cut, old bearing shells.
This job has been done before on my car - these are Timken, and there are punch marks in the housing where the old ones have been punched out.
I just have to separate the outer bearing from the shaft now. Proving stubborn and I don't have the tool Dennis used. Have to make a new plan.
Alan

[1979-930]

You're braver than I am Alan.
I just did my rear wheel bearings due to a little play in the left rear.
However I chickened out and took the car to Salerno Motorsports a couple miles from my house and paid the 6hr shop charge.
Ben has done thousands in his lifetime and I was way more confident in his ability than mine.
And based on the fact the loose bearing had been replaced by someone in the past and the good side was factory tells me this job is easy to do wrong. Good luck with yours.

[Alan L]

Totally agree Derrick.
And if I had access to a Ben I would do the same. But such a Ben would not be found in the country.
You could count on one or two hands how many of these cars exist in the country. So Ben doesnt exist here. I am on the same playing field as whoever I took the car too.
I will plod on.
Slowly.
Regards
Alan

[Alan L]

OK, disassembly complete. Reassembly now. It will take a couple of weeks - waiting on bits from Pelican. I think I will be able to get the bearings locally. Find out this afternoon. So I can install the shells. Then I wait.
Meantime I would appreciate some explanation from those that have gone before, as to how they measured the 'axial' play. As per pic earlier I had my dial gauge on the edge of the bearing hub (as per porsche manual). Trying to twist the hub from L-R (side to side) gave me no obvious reading. But there was movement in the hub - I could basically see the hub sliding across the tip of the gauge. However I had in/out (push/pull) movement which registered on the gauge - about 4 thou.
Thanks
Alan

[356911930]

Alan,

For you reference:

RADIAL PLAY is the maximum displacement that one bearing ring can be displaced relative to the other ring in a direction perpendicular to the axis of rotation of the bearing. Radial play = ∆ r AXIAL PLAY, or end play, is the maximum relative displacement of the bearing rings, in a direction parallel to the axis of rotation. Axial play = ∆ a

I may be doing this job in the future, so I will be watching, and rooting for you!

I hope this helps,

Rahl

[Alan L]

So axial play is end play? In this case it would be in the direction of along the axle?
Push /pull, in/out?
Picked up the bearings this afternoon from local bearing shop. I live near a small rural town and they had the bearings in stock. Lot of agricultural industry close by. probably used on some harvester as well as 930s. Will have a go at installing the cones next week while I wait for the Pelican bits.
Alan

[MikeD930]

Alan...I think you are overthinking about what axle play is. The way you measured was correct. You measured .10 mm axle play which is along the axis of the bearing. You want zero to .05 mm axle play. I assume you ordered new spacers (these are crush able spacers between the bearings) to install with new bearings.

[dap930]

Alan,

Axial play is pushing inward and pulling outward on the hub. You are adjusting the endplay in the bearings just as you adjust the front hub bearings with the hub nut, however, dealing with the rear crush sleeve to set the rear endplay is a much more difficult task. If you marked the position of the rear hub nut in relation to the stub shaft prior to disassembly, that will get you in the ballpark when tightening (crushing the sleeve) the nut. Mine came back to the original marks with .001 inch endplay.

[356911930]

Yes Alan, push pull direction along the axle. The radial direction follows an arrow drawn from the center of the axle to the circumference of the brake disk.

Rahl

[Alan L]

Thanks guys. Just want to be clear on it. This is the make/break part of the job.
Dennis - yep - read you thread - several times. I have the marks.
Regards
Alan

[Alan L]

OK - the cones are in. Hopefully the right way round
A bit stressful as always - but reasonably straight foward. I had the cones in the freezer o/night and heated the hub each time with a propane torch. Not sure this helped a lot - it only got warm, but every bit helps. You can see I machined a lip on each locating plug to help center the cone. I used a M16x150 bolt to pull them in. If they started slightly off center I just knocked the plug until it looked centered, then pulled some more, check, tap, pull, check etc. Eventually it was well centered and just pulled straight in.
Can't go any further until my bits from Pelican arrive, but won't be far away. The outer hub is now in the freezer, getting ready to fit the bearing - after the seals and crush spacer arrive. I am going to heat the bearing in the oven at 50 DegC before pressing to the frozen hub. I am hoping I can do the same for the inner bearing when I assemble the two hubs..
Alan