Front wheel - end float

[106500]

I've just completed some work on the front suspension on my Elan S4. This has included replacing the front brake discs. Having reinstalled the hubs and replaced the wheel, there seems to be excess movement (rocking from side to side). I assume this is the permitted end float. I tighten the castellated nut one more flat, no movement is perceptible. Just how much movement should there be - I'm worried about tightening the castellated nut on the stub axle such that theres no such movement. However I understand there should be some. Advice would be appreciated.

[type26owner]

The type of lubricant determines how much clearance or preload to use on a tapered roller bearing. With a grease it varies between some clearance and a small amount of preload. I prefer to preload it slightly. I use a socket on the nut and an extension. I grip the extension and tightened it just by hand as hard as I can. It's only a couple of ft/lbs at most. To get this correct the face of the nut must be sanded or faced on the lathe to get the cotterpin to line up so it will go in. Use disc brake wheel bearing grease only.

You should coat the felt seal with the grease to make it water-proof.

[Hamish Coutts]

The front bearings are tapered and should not be overtightened. Disaster lurks if you do so. (a bit over dramatic but you will more than likely overheat the bearing and damage the hub if you do)
I am not sure of the torque setting but I do know that it is not much (only a few lbs/ft). The manual I have says to tighten the hub retaining nut until there is no play in the hub (I use pointed nose plyers for this job as there is very little force needed. It is also best to have the disc pads removed at this point). The hub should revolve freely but there should be no play. Make sure the bearings are properly seated before you start.
Now loosen the nut by 1 flat - no more, again with the pointed nose plyers. Insert the split pin and Bobs your aunty so to say.
There should be slight play in the hub.
Please don't test the play with the wheel on because it will in all probability, feel excessive.
Make sure the hub is packed with grease and that the felt seal on the inner side is in good nick and also greased (helps keep the water out to protect the bearings)

Think that's about it.

Regards,

Hamish.

[twincamman]

I hope you repacked the bearing in the proper manner-----put a dollop of grease the size of a loony in the palm of your hand and scrape the bearing across it filling the bearing with the lubricant --repeat until full ----ed

[reb53]

A small amount of movement is required. When I loaded mine sufficiently to satisfy the local MOT testing station they overheated and blued up surprisingly quickly.
The large washer under the nut can get a worn groove in it's innermost outer edge which can make getting the correct amount of movement difficult. You can't get the nut just where seems best. In this situation flipping the washer around often works.
The other thing that can fool you is when the nut seems overtight and yet the bearing still has movement. This is caused, as I eventually worked out, by the stub axle having wear where the inner bearing sits so that it didn't matter how tight you had the bearing you could still move the wheel too much.
There are various proper ways of fixing this but the way I used is too barbaric to mention in this forum!

Ralph.
N.Z.

[steveww]

I use a method very similar to Keith. After repacking the bearings I tighten the nut up with a wrench deliberately too tight and turn the hub by hand a couple of times to ensure that all is bedded in. I then loosen the nut right off and do it up again finger tight. Use the largest split pin you can so that the nut turns as little as possible in place.

[rgh0]

The correct bearing end float is specified in the manual at 0.002 to 0.004 inch. You are only guessing if you set the end float by feel and should measure it with a dial gauge. I mouont the guage on a magnetic stand on the disk and measure end float off the end of the stub axle. The minimum spacing between the 2 holes in the stub axleand castellated nut slots is equivalent to about 0.004 inch end so you may not be able to get the end float into the spec range generally new bearing free up a bit as they run in so I set a new bearing a little tight if I have to. Swapping the large washer or swapping to a new castellated nut or maching a thou off can also be done to solve the problem.

You need the end float because as the hub is heated under brake loads the hub expands more than the stub axle. This pushes the inner races out and increases the preload on the bearing. Insufficient iniatl end float and you overload and overheat the bearings.

To much end float and the steering gets vague and you get brake disk knock off in corners.


Rohan

[steveww]

Rohan,

The earlier version of the workshop manual specified the end float as you say. Later version of the manual specify tightening the castle nut up to a specified torque (can't remember exactly what and I don't have the manual to hand) then backing off one flat.

I have doubled checked my finger tight method with a dial gauge and it is as close as any other method I have used plus a lot simpler.

I know about what happens to the bearings if too much preload is applied. The DPO had done just that and the bearings were all breaking up.

[type26owner]

Rohan,
Those values are conservative. If you have aluminum hubs and use the brakes until they are completely heat soaked and fade to nothing and use the cheapest dry grease then those values are valid.

The special tacky MoS2 filled disc brake grease available today makes running a slight preload possible with very little risk of a bearing failure. But I don't live in a really cold climate either.

[rgh0]

Keith

I suspect you are right and can run with tighter clearances compared to the orginal spec or a very slight preload and not have any problems with the heat loads into the hubs loading up the bearings in a normal road car use. The periods of heavy brake use are short in a road car and even if you overloaded the bearings it would only be for a short time.

With my race car when I come off the track with hot brakes all the end float has gone and the front hubs are in a very slight preload situation.

Rohan