Front Wheel Bearing Upgrade Options?

[PickleRick93]

Got under the rig today. The lift is the top hat style welded spacers. Likely RC if ordered along with the side steps.


Not a smoking gun for bearing failure as it provides 2 inches of lift and the upper control arms installed allow for proper alignment geometry.

Went ahead and replaced both front wheel bearings as both have tight spots and feel like worn inline skate bearings. The drivers side with less than 3 miles from the dealership was roaring the worst.

I dont like my wheel fitment, the hubs on the wheels do not align with the hubs on the bronco. This shouldn't kill wheel beings but I could be missing out on a slightly better ride and better tire wear. Some measurements of the wheel hub and purchase of centric ring spacers are in my immediate future.

I'll update the life span I get on these mvotech supreme/btx wheel bearings.

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[NC_Oak]

the hubs on the wheels do not align with the hubs on the bronco.

explain this - are you talking centerline or something funky

 

[PickleRick93]

The bronco is a hub centric wheel mating surface. The fuel wheels that came on the bronco have too large of a hub opening for the (93 mm iirc) bronco hub so they rely on the lugs/wheel studs to hold the wheel centered. It's not ideal. It works but could be a safety concern/premature tire wear concern.

Ford installed new tires on it during the inspection process, I'm wondering if the rims came with these rings and the dealership forgot to put them back on. Seem like some pricey wheels not to be offered with adapter rings

 

[illverado]

I copy and pasted some engineer’s math on this topic, keep in mind the wheels in your pic are wider than 8” too so it’s substantially higher load on the hubs than even these calculations and this is static load, parked, not hitting potholes at speed bouncing the outer edge of the tire that’s 50lbs heavier hammering the suspension.

Stock (+55mm offset): The wheel centerline is 55mm outward from the hub mounting face.

With 1.5-inch spacers (+16.9mm effective offset): The centerline shifts outward by 38.1mm more, totaling 55 + 38.1 = 93.1mm from the hub.

With zero-offset rims (0mm): The centerline is 110mm from the hub (assuming an 8-inch rim, where half the width is 4 inches or 101.6mm, adjusted by offset).
Force: Assume a static load of 1,125 lbs per wheel (4,500 lbs / 4). The moment (torque) on the bearing is force × distance.
Stock: 1,125 lbs × 0.055m = 61.875 lb-m (83.9 Nm).

Spacers: 1,125 lbs × 0.0931m = 104.74 lb-m (142 Nm).

Zero-offset: 1,125 lbs × 0.110m = 123.75 lb-m (167.8 Nm).
Stress Increase:
Spacers vs. Stock: 142 / 83.9 = 1.69x (69% increase).

Zero-offset vs. Stock: 167.8 / 83.9 = 2.0x (100% increase).

Zero-offset vs. Spacers: 167.8 / 142 = 1.18x (18% more stress).

 

[PickleRick93]

Are the guys running 37-40 inch tires replacing the wheel bearings with every scheduled oil change?

 

[Brian_B]

I copy and pasted some engineer’s math on this topic, keep in mind the wheels in your pic are wider than 8” too so it’s substantially higher load on the hubs than even these calculations and this is static load, parked, not hitting potholes at speed bouncing the outer edge of the tire that’s 50lbs heavier hammering the suspension.

Stock (+55mm offset): The wheel centerline is 55mm outward from the hub mounting face.

With 1.5-inch spacers (+16.9mm effective offset): The centerline shifts outward by 38.1mm more, totaling 55 + 38.1 = 93.1mm from the hub.

With zero-offset rims (0mm): The centerline is 110mm from the hub (assuming an 8-inch rim, where half the width is 4 inches or 101.6mm, adjusted by offset).
Force: Assume a static load of 1,125 lbs per wheel (4,500 lbs / 4). The moment (torque) on the bearing is force × distance.
Stock: 1,125 lbs × 0.055m = 61.875 lb-m (83.9 Nm).

Spacers: 1,125 lbs × 0.0931m = 104.74 lb-m (142 Nm).

Zero-offset: 1,125 lbs × 0.110m = 123.75 lb-m (167.8 Nm).
Stress Increase:
Spacers vs. Stock: 142 / 83.9 = 1.69x (69% increase).

Zero-offset vs. Stock: 167.8 / 83.9 = 2.0x (100% increase).

Zero-offset vs. Spacers: 167.8 / 142 = 1.18x (18% more stress).

I think you have your offsets lined up backwards.

+55 is inward offset
The spacer shifts it back outward.

 

[87-Z28]

Lots of strange and conflicting information in this thread. 9” wide wheels have a center line at 4.5” from edge. So 5” backspacing has a positive 12.7 mm offset (1/2”). That is not super aggressive. Not even negative. The pic does seem to show a negative offset but hard to tell. No idea where the quoted 1” offset comes from.

Scrub radius dictates moment arm and thus applied moments to wheel bearings in front. Negative offset wheels have increased scrub radius for a 35” tire.

 

[illverado]

I think you have your offsets lined up backwards.

+55 is inward offset
The spacer shifts it back outward.

Copy/pasted, yeah the first “outward” should have been “inward”

 

[illverado]

Lots of strange and conflicting information in this thread. 9” wide wheels have a center line at 4.5” from edge. So 5” backspacing has a positive 12.7 mm offset (1/2”). That is not super aggressive. Not even negative. The pic does seem to show a negative offset but hard to tell. No idea where the quoted 1” offset comes from.

Scrub radius dictates moment arm and thus applied moments to wheel bearings in front. Negative offset wheels have increased scrub radius for a 35” tire.

The wheel mounting face isn’t the center of the bearing though so positive offset is required to get the centerline of the wheel closer to the center of the bearing so it’s not hanging out on a huge lever. Stock wheels are 7.5” wide +55mm (ideal) or 8.5”+35mm. A 10”+ wide heavy wheel with what looks like zero offset or worse is super aggressive for the geometry of these things (hub) longevity wise imo when you apply the math from my comment carried over from a totally different discussion for perspective purposes.

 

[PickleRick93]

I feel like this thread has been completely side tracked. Many bronco owners have experienced extremely premature front wheel bearing failure, even on stock wheels.

While these wheels do set past the fender flairs I wouldn't classify them as aggressively offset compared to many of the set ups commonly ran on 4x4s today.

I was hoping to gather information of what brands could be a possible upgrade over that of OEM Ford bearings which seem to be hit or miss with quality.

 

[PickleRick93]

Unfortunately I don't see a way to disassemble these wheel hubs without cutting. If anyone knows a secret please fill me in.

If I could pull it apart to get bearing dimensions I could then see if I could rebuild an OEM hub/housing with some heavier duty bearings

The lip on the backside of the hub appears to the an issue for pressing it apart

 

[87-Z28]

Many bronco owners have experienced extremely premature front wheel bearing failure, even on stock wheels.

I doubt this. Wheel offset and scrub radius dictate the bending moments applied to the wheel bearings so that is really the main point.

Curious if @Ducati1098 has seen many wheel bearing failures on stock wheels.

 

[Ducati1098]

I doubt this. Wheel offset and scrub radius dictate the bending moments applied to the wheel bearings so that is really the main point.

Curious if @Ducati1098 has seen many wheel bearing failures on stock wheels.

Every once in a while on some vehicles, usually just due to age.
But I have never seen a Bronco with a bad wheel bearing yet though. Certainly not a common issue that I'm aware of.

 

[87-Z28]

The wheel mounting face isn’t the center of the bearing though so positive offset is required to get the centerline of the wheel closer to the center of the bearing so it’s not hanging out on a huge lever. Stock wheels are 7.5” wide +55mm (ideal) or 8.5”+35mm. A 10”+ wide heavy wheel with what looks like zero offset or worse is super aggressive for the geometry of these things (hub) longevity wise imo when you apply the math from my comment carried over from a totally different discussion for perspective purposes.

Of course. My comments were not about your post but more general.

Your analysis of the bearing moments is accurate just not complete. The applied moments are the force (normal force acting on tire contact patch centroid) times a moment arm. The full moment arm distance needs to include the vector addition (direction matters) of 1) the distance from wheel centerline to the bearing centerline (as you stated and have calculated). But also 2) the scrub radius.

Moments generated by the scrub radius are superimposed onto the wheel bearing. These moments are reacted by the upper and lower ball joints (which are pinned) thus the knuckle must react this bending moment via the wheel bearings.

 

[Brian_B]

I feel like this thread has been completely side tracked. Many bronco owners have experienced extremely premature front wheel bearing failure, even on stock wheels.

I think you are the only one I can recall having a bearing failure really. I'm sure there are some more around here, but it just doesn't seem to be that wide spread.

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