8 replies to this topic

[Glenn]

Saw that Jim does NOT reinstall the rear dust seals in his rebuilt hubs. Mine are going to the shop this week to be pressed in and I'm wondering why/if I should leave the seals off.

I have the new ones but not sure of the "advantage" of not replacing them.

[Bench Racer]

Well, according to the rules & the FSM, opp's never mind that would be starting an argument.

[Glenn]

Well, according to the rules & the FSM, opp's never mind that would be starting an argument.

Next time I'm running tech I'll add it to the list

[FTodaro]

Maybe Jim can chime in, I just did my rear bearings and installed new dust seals on the knucle. It may be overkill but it would keep water out of the hub side of the bearing, I just greased my up when in installed. The only down side to using them that I can see is resistance, the up side is durabity.

[Glenn]

Maybe Jim can chime in, I just did my rear bearings and installed new dust seals on the knucle. It may be overkill but it would keep water out of the hub side of the bearing, I just greased my up when in installed. The only down side to using them that I can see is resistance, the up side is durabity.

My thoughts exactly.

[SaulSpeedwell]

Maybe Jim can chime in, I just did my rear bearings and installed new dust seals on the knucle. It may be overkill but it would keep water out of the hub side of the bearing, I just greased my up when in installed. The only down side to using them that I can see is resistance, the up side is durabity.

There is no Runoffs Championship for durability

Drag is drag, and you want as little of it as you can legally achieve. The Miata rear wheel bearing (i.e. 323 front wheel bearing) changed designs from sealed to shielded (one side). Shielded has less drag. The little piece of paper inside the box tells you to put it in wrong because the little piece of paper was written for the FWD car whereby the shileded side would be additionally sealed by the hubcap.

Buy shielded ones, and make the knuckle seal as ineffective as possible. If you want to be like Mike (Collins), then buy four wheel bearings and swap the parts around until both sides are shielded. Now you will beat all those other cheaters!

[FTodaro]

There is no Runoffs Championship for durability

Drag is drag, and you want as little of it as you can legally achieve. The Miata rear wheel bearing (i.e. 323 front wheel bearing) changed designs from sealed to shielded (one side). Shielded has less drag. The little piece of paper inside the box tells you to put it in wrong because the little piece of paper was written for the FWD car whereby the shileded side would be additionally sealed by the hubcap.

Buy shielded ones, and make the knuckle seal as ineffective as possible. If you want to be like Mike (Collins), then buy four wheel bearings and swap the parts around until both sides are shielded. Now you will beat all those other cheaters!

the Mazda bearings (where they have the backwords directions in the box) were just shielded on one side, and the bearings I bought from Auto zone were shielded on both sides. interestingling the orginal bearings were shielded on bothe sides, only the replacement bearings were shield on one side.

So should I remove my knucle seal and get a few less points on the coeficient of friction?

[Ron Alan]

There is no Runoffs Championship for durability

Drag is drag, and you want as little of it as you can legally achieve.

So how much does the amount of grease affect drag? Was messing around with an old front hub...man with no grease that baby spins like my old skateboard wheels! But question is will it last this way(rhetorical question Farley!)and if not, will to much grease affect drag...Saul??

[SaulSpeedwell]

So how much does the amount of grease affect drag? Was messing around with an old front hub...man with no grease that baby spins like my old skateboard wheels! But question is will it last this way(rhetorical question Farley!)and if not, will to much grease affect drag...Saul??

Great Q, Ron - although I'm not sure I have a perfect answer. From the bearing manufacturer's standpoint, there is definitely an "optimal" amount of grease, and it is way less than most shadetree mechanics put in. But, grease is diabolically expensive - and thus the manufacturer will tend to put in as little as he can get away with.

Pop a new one apart - that is the close to the "right" amount. It is some # of ccs calculated to be some % of the volume between balls/races/cages. On the fronts it isn't as important because the grease just flows into the hubcap area. There is also extra volume between the two rows of balls. I add 10-20% (one finger-swipe worth) and fail bearings less than most I know. I also re-torque them one time after one session of "break-in", before I stake the nut. I also don't tie my car down extra tight - in fact, I like it if it rolls back and forth a little (a LITTLE ...) in the trailer.


Look on a stock Miata and you will generally not see grease pouring out of the bearings seals and coating the hub boss. Look on the average SM and grease and grime is all over the seal area - because it got moved out there from heat and pressure pushing the "extra" grease that wa sput in there when being "repacked". But - more or less, the balls will move the grease out of the way.

Grease is also an environmental (and health/safety) concern for manufacturers - I think the "new" (almost "dry" and "crumbly") Mazda suppliers' grease sucks compared to the original (smeary, buttery, Vaseline-y) Mazda grease you find in original cars. I do believe some greases are better than others for drag, and I believe Redline CV-2 is somewhat overrated - most in SM swear by it, but I don't believe there is anything magical about it except that it is better than the "new" OEM grease and too much grease is still better than too little, at least for durability purposes.

Over the years I believe there is enough anecdotal evidence to support that TOWING is a primary contributor to bearing failures. The harder the car is tied down and the longer the tow, the more likely you are to lose a bearing in the 2-4 hours after that.

I'd run a knuckle seal just to keep the Boemlers happy .... but I'd run one that wasn't very "effective" ... and I'd run those double-shielded bearings ...