[Fot] Differential Pre-load

Thu Jan 30 06:02:14 MST 2020

Makes sense.  If the tech assumed it was a modern style bearing, he would
lock it down. Shame, shame. Since I never work on my street cars (who has
time) I only about the newer styles when a wheel bearing failed on my
daughters Escort ZX2 and daddy was called in to help!  I learned then that
the tapered bearings I was familiar with were completely different than the
modern cage assemblies we see on American vehicles.  Those do get swapped
and locked in place.

[image: image.png]

Bob Kramer

On Thu, Jan 30, 2020 at 6:50 AM <van.mulders.marcel at telenet.be> wrote:

> Hallo Bob, the stub axle and bearings were discoloured by the heat and the
> stub axle was literally broken off, I don't remember anymore where. I
> suppose the inside threaded part was broken off.
> The inspector at the MOT obviously didn't know that these wheel bearings
> should have some free play, contrary to modern cars. My friend felt unsure
> about it and  he didn't  argue with the MOT inspector. He also did not undo
> the tightening when he had left the MOT station
> Marcel.
>
> ------------------------------
> *Van: *"Bob Kramer" <rkramer56 at gmail.com>
> *Aan: *"van mulders marcel" <van.mulders.marcel at telenet.be>
> *Cc: *"TeriAnn J. Wakeman" <tjwakeman at gmail.com>, "fot" <
> fot at autox.team.net>
> *Verzonden: *Donderdag 30 januari 2020 12:59:14
> *Onderwerp: *Re: [Fot] Differential Pre-load
>
> Only a post mortem on the parts could tell for sure, but it is fun to
> speculate. If we take the inspector at his word and the wheel bearing was
> “loose”, the question of why that condition existed should have been
> answered before tightening down the hub. Either bearing could have already
> sustained damage from misalignment and bringing damaged and scarred rollers
> back to spec could quickly result in overheating and terminal failure.
> That would not be fun.
>
> Sent from my iPhone
>
> On Jan 30, 2020, at 4:08 AM, van.mulders.marcel--- via Fot <
> fot at autox.team.net> wrote:
>
>
> TeriAnn,
> Some years ago, a friend of mine took his freshly restored TR4 to the MOT.
> There he was told he had to adjust the front wheel bearings. He tightened
> these there and then to pass the MOT and on the way home a stub axle broke
> off because the bearing had seized, luckily without too much damage :
> besides the  stub axle and brake caliper bracket,  a wing had to be
> repaired.
> Marcel
> ------------------------------
> *Van: *"fot" <fot at autox.team.net>
> *Aan: *"fot" <fot at autox.team.net>
> *Verzonden: *Donderdag 30 januari 2020 10:16:08
> *Onderwerp: *Re: [Fot] Differential Pre-load
>
> On 1/30/20 2:11 AM, van.mulders.marcel--- via Fot wrote:
>
> Barry, if that is true about the rollers/races, how do you explain the
> prescripion about the front wheel bearings : you need to back off the stub
> axle nut to get some play for the bearings?
> Marcel
>
> Likewise with Series Land Rover wheel bearings. Leave them tight and they
> quickly die.
> TeriAnn
>
>
> ------------------------------
> *Van: *"fot" <fot at autox.team.net> <fot at autox.team.net>
> *Aan: *"fubog1" <fubog1 at aol.com> <fubog1 at aol.com>, "Bob Kramer"
> <rkramer56 at gmail.com> <rkramer56 at gmail.com>
> *Cc: *"fot" <fot at autox.team.net> <fot at autox.team.net>
> *Verzonden: *Woensdag 29 januari 2020 19:02:55
> *Onderwerp: *Re: [Fot] Differential Pre-load
>
> Preload is more for the life of the bearings than the gears. You preload a
> bearing to take up manufacturing tolerances and account for the anticipated
> (by the manufacturer of the bearings) wear during their life time. There
> does need to be some 'squeeze" between the bearing races and the rollers or
> the rollers will not roll in lubrication. If any of you have ever rebuilt
> the rear outer suspension on old XKEs, the tapers roller bearing in the
> outer wishbone pivots wear out because the wishbone only moves up and down
> a few degrees. The tapered roller bearings never fully rotate and cause the
> rollers and race to pit. Roller bearing must roll 360 degrees around to
> survive. Preload makes them do that.
>
> Barry
>
> On Wednesday, January 29, 2020, 09:41:34 AM EST, Bob Kramer via Fot
> <fot at autox.team.net> <fot at autox.team.net> wrote:
>
>
> I think the main reason a specified amount of  preload is required is that
> it sets it up so that the bearings roll under mild tension. To tight and
> the components slide over each other.  Too loose and they cock in place.
> Without rolling, bearings will soon fail the same way a lifter that doesn't
> spin fails.
>
> Bob Kramer
>
>
>
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