Wheel offsets and spacer plates

I have heard that using wheel spacers puts extra stress on wheel bearings. Yes, I agree that as a wheel is moved further away from the hub, this increases the leverage and therefore the stresses placed on the bearings. Are we all in agreement on that?

Last Saturday while helping with my suspension mods, Tristan was bugging me (in a friendly manner) about the Sunfire rims on my '84, saying that they had too much positive offset. This results in the wheels/tires being tucked into the fender more than the factory Fiero wheels. It's not bad in the front, but I agree it's more noticeable in the back. I said I wanted to use a spacer to move the rear wheels back out towards the edge of the rear fender, and Tristan mentioned about this being bad for the bearings etc. But is it?

Tristan and I debated the issue and got nowhere. I felt it was too difficult to visualize and discuss without a diagram. So here it is. The point I was trying to make with Tristan, and he couldn't see it, was that if you move a positive offset wheel out with a spacer, it's no different than using a wheel which has a more negative offset as long as the end result is the same. By "end result", I'm referring to where the wheel/tire is in relation to the fender, or in relation to the pivot point of the lower control arm.

Looking at the diagram below (which I know is not drawn "correctly"), if the wheel on the left is a stock Fiero rim, and the wheel on the right is a Sunfire rim (with more positive offset) being used with a spacer, can anybody tell me that this is going to make ANY difference in regards to what stresses the wheel bearings will experience? I say in this situation the stresses on the bearings are exactly the same as each wheel/tire ends up in the same location relative to the car/suspension. 

Comments?

 

As Colby mentioned, the mass is essentially being held "further out" from the hub. The weight is worth more force (Consider ten pounds of thrust held six inches away from the head of a ratchet versus ten pounds held a foot away; The second will transfer more force)

But the tire is not where the weight is being applied to the bearing - the inner face of the rim is. As for picturing it as a simple lever - that's fine. But how you're picturing it is going about it wrong. The part of the rim where the lug nuts actually press down on, that's where the torque is applied to the bearing. By moving it out, you are increasing the net torque by means of increased leverage.

Pat, I think the question you should be asking is not whether there actually is additional stress but rather, something like: "should I be concerned about additional stress leading to premature failure of the bearings?".

I think so long as the wheels aren't overly heavy you would probably be fine. Although I have no experience with them, I'd probably be seeing more results about failed bearings in the Google searches I've done tonight if it was a common problem.

Cheese wrote: I think so long as the wheels aren't overly heavy you would probably be fine.

Yeah, when you consider the huge wheels and tires that Johnny has on his car, and his SC3800... and he has something like two inch spacers installed!

 

Cheese wrote: ...rotational torque is redundant as all torque is rotational

Give me a break. It's late and I'm old.

 

For the RECORD, I had no problem with the 1-1/4" wheel adapters on the rear,
some asshole didn't check for LOOSE NUTS HERE

You make a valid distinction here.  I was assuming that the spacer was part of the hub, since it is bolted to the hub not the wheel.  So assuming this, my explanation would still work no?

I'm not so sure about the center of mass negating the leverage however.  This in a sense is what Patrick is suggesting.  He is wondering if having the center of mass right over the bearing would counteract the effects of the spacer.  I think not.  Ignoring cornering effects, the same amount of vehicle weight is present.

Would you agree?

The Dawg 

Cheese wrote: For the sake of argument, what happens if you were to weld the spacers on to the wheel? Does this now mean that the wheel is now mounted directly against the hub? If the spacer is now apart of the rim, then the rim is now mounted right up to the hub and by your explaination (assuming I am understanding correctly) the negative effects should now be mitigated. That seems doubtful to me, and taking into consideration the location of the centre of mass of the wheel gets around this nicely.

GET YOUR STORY STRAIGHT guys.. about poor Johnny and yes I agree about more stress on bearings !

For the RECORD, I had no problem with rear wheel bearings using 1-1/4" wheel adapters on the rear,
some asshole didn't check for LOOSE NUTS HERE


I had no problems with wheel bearings, just ALIGNMENT SHOPS (LOOSE NUTS) !

I only got Capt to change BEARINGS because they where 25years old,
but look what he found (from DALES ALIGNMENT) LOOSE NUT !!!!!



Found one bad (cheap) bearing right out of the box and replaced it with my old bearing and I'm still driving with it and one cheap bearing.
Since then I got two new costly bearings that I'll be installing next week when doing the bump steer suspension and keep the old ones for spares.

Hugh has spacers front and back with turbo V8 power, will see how that works out ?

There are three things to consider with regards to spacers: Spacer size (Mechanical advantage), tire and rim weight (Mechanical force) and driving style/road condition (Additional shock force).

Johnny Boy might be able to get away with large rims and spacers because he is a sane driver. During autocross conditions, where we have the rough road and hard braking and acceleration, those forces will now really compound the existing stress.

 

As for your thought-question about welding the spacers, I can't imagine why it would help. The weight is still being held away from the hub; That torque still maintains a mechanical advantage.