Early 944 front wheel bearings adjustment.

Dark Skies · 09-23-2006, 05:49 AM

In the Porsche and Haynes manuals the correct approach is to adjust the retaining nut until the washer beneath it can still slide with moderate pressure from the tip of a screwdriver.

However, I find that this doesn't quite take up the slack and that with the wheel bolted back on (car still jacked up) that grasping the wheel and push-pulling firmly still produces slight wobble. Consequently I still suffer from vibration at the steering wheel at 70 mph. Everything else in the steering chain has been elimnated. Good shocks, new suspension arms and bushes, new wheel bearings, new ball joints and so on. Wheels have been balanced

I'm minded to adjust the bearings with the wheel bolted to the hub (cover removed) and, using a screwdriver, turn the nut until all freeplay can be just felt to be taken up (push-pulling and tightening until float ceases). However, in doing this I find that the washer beneath the nut has zero chance of moving - short of levering the screwdriver against the hub interior.

It seems to me that if you follow the accepted method you suffer from excessive vibration and the possibilty of damage to the bearings through 'chatter'.

On the other hand tightening the nut until all slack is removed (as well as vibration), appears to risk overloading the bearing and an earleir onset of wear.

I always find this simple job always takes longer than it ought - because I constantly flip from one worry to another.

What's considered the best practice?

SoCal Driver · SoCal Driver's Garage

The tappered roller bearings will load up with the weight of the car. Any tighter on the adjustment and you will burn out the bearings. Most wheel vibration is from bad tires and/or alignment not properly adjusted bearings.

Dark Skies · 09-23-2006, 08:41 AM

Cheers SoCal. I erred on a slight tweak so that the washer can be moved without levering but required reasonably firm pressure with the finger pressing on the shaft of the screw driver. Sound about right?

SoCal Driver · SoCal Driver's Garage

I usually tighten using the rocking wheel test. I want to feel just the slightest play in the bearings when rocking the wheel at the top. One should check the bearings too. Actually better to check the races for scoring and/or pitting.

Spin the wheel as you snug down the split nut then with the wheel stopped do the rocking thing while adjusting the nut. Check it after you tighten the cross screw in the split nut.

Zero10 · 09-23-2006, 08:18 PM

If the inner bearing is worn out no amount of tightening will take all of the play out of the wheel.

I tighten until I have to lever the screwdriver against the edge of the hub to move the washer. That is the only way I can get the play down to what I would consider acceptable.

A loose wheel bearing can give you an intermittent wobble in the front end, but if you have a consistent wobble I would have your wheels/tires balanced.

Dark Skies · 03:59 AM

Ah - so reading both the latter posts it seems as I was pretty much on the right tack - spinning the wheel whilst I tightened the nut and push-pulling for play. And Zero's experience re leverage of the washer is what I was finding to be the case when play was just on the cusp of being eliminated.

I took the car onto a smooth stretch of highway up to 70 mph today. Considerably improved with just a hint of vibration - I think a slight tweath further and it'll be sorted. Cheers lads.

Zero10 · 09-24-2006, 12:42 PM

Some argue that I over-tighten the bearings, but I pack mine with Mobil 1 CV/bearing grease. It is a bright red grease that turns brown and gets runny if it is ever overheated.
I replaced my wheel bearings, tightened them down then went on a 450 mile highway trip without stopping for more than 5 minutes on the whole trip.
Upon arrival I inspected the wheel bearings (I thought they were loose, turned out to be ball joints. Long story) and all of the grease was still a nice happy bright red color, and there was no play at all in the wheel bearings.