Dear Bob,
very informative your comments about taper or ball bearings.
You are right, that the risk to put to much strain on the stub axle, when
you use a spacer and shims, is much lower, than when you fit preloaded
taper-roller bearings without spacer.
But I still have the "feeling", that because with taper bearings the load on
the bearings are pushing the inner ring of the outer bearing hard against
the nut, and so the thread on the stub axle gets more load than with ball
bearings. A wedge always wants to slip sideways when loaded.
I know we hardly ever hear that the stub axles crack at the thread, and I
agree, that the stress to the area where they usually crack is the same with
ball or taper bearings.
It's interesting to see, that you are producing repair stub axle-inserts.
Maybe to repair a cracked axle using your inserts, is safer than to fit for
replacement a old tested axle.
Must put this info to my files !!
Gerhard
-----Urspr|ngliche Nachricht-----
Von: Robert Grunau [mailto:cgrunau@pathcom.com]
Gesendet: Sonntag, 20. Januar 2002 18:39
An: Gerhard Maier; Bob Rich; DSBonar@aol.com; mg-mmm@autox.team.net
Betreff: RE: taper-bearings
Gerhard, Bob, etc.
There is nothing wrong with using tapered roller bearings in front hubs of
MMM or T type MGs as long as you use the bearing spacer and shim the spacer
to allow full tightening of the stub axle nut. Therefore the stub axle can't
tell if you have tapered roller or ball bearings. Modern method of no spacer
and finger tight stub axle nut will weaken the assembly as the effective
diameter of the assembly is decreased to the stub axle diameter. USE and
SHIM the SPACER!!
Tapered rollers have some advantages, the outer race can be Loctited into
place to take up some wear in the hub. The bearings are adjusted with shims
to remove all slack in the bearings. No preload is required or desireable,
just get the hub to rotate freely with no play.
Ball bearings can't be adjusted to compensate for worn hubs or worn bearing
spacers. How can you tell if the bearing spacer is too long? Ball bearings
do have an advantage that you can buy them sealed and "greased for life". No
messy greasing required.
.
I have used tapered roller front wheel bearings for many thousands of miles
on several TCs, including my race TC, with no problems. I magnaflux
inspected the stub axles and no cracks.
Speaking of stub axles, I make a stub axle insert for the MG TA, TB, TC and
I believe these will also fit MMM cars. The axle material is ASTM 4140 HT
and SR and has 130,000 psi tensile strength with good ductility. The stub
axle inserts are very nicely machined on a CNC lathe with good radius. If
your stub axle is cracked in the steering knuckle, bore out the axle portion
and press in a replacement stub axle with an interference fit. I have done
dozens of repairs on steering knuckles and all fully successful. Race proven
over four years in my MG TC race car.
Regards from Canada,
Bob Grunau
Bob,
here within our MMM-group always are discussions about risks using tapered
bearings for front axles, instead of the original straight roller bearings,
because with tapered bearings there seems to be much more load on the nut,
and so on the stub-axles, and they might not be designed for that, and could
crack ??
There are also other reasons for not changing the system:
straight-roller bearings don't waste so much energy than a preloaded tapered
one.
you get the straight-roller bearings easy in the sealed version.
straight-roller bearings are much cheaper.
they never need to be adjusted again.
you don't confuse the next rebuilder of your car in 20 years time!
What's your opinion?
Gerhard
-----Urspr|ngliche Nachricht-----
Von: owner-mg-mmm@autox.team.net [mailto:owner-mg-mmm@autox.team.net]Im
Auftrag von Bob Rich
Gesendet: Sonntag, 20. Januar 2002 17:17
An: DSBonar@aol.com; mg-mmm@autox.team.net
Betreff: Re: Front suspension -PA
Don,
I'm sure the "taper" reference in your catalogue refers to the bearing, and
not the stub axle. The original bearings were not tapered - straight roller
bearings with a tubular spacer but they can be replaced with Timken pattern
tapered rollers, which are easier to adjust.
Cheers, "Bob".
> From: DSBonar@aol.com
> Reply-To: DSBonar@aol.com
> Date: Sun, 20 Jan 2002 10:45:09 EST
> To: mg-mmm@autox.team.net
> Subject: Front suspension -PA
>
> I'm rebuilding the front suspension for PA 1823. Unfortunately, the
original
> bearings are missing. Therefore, I took the stub axles to local bearing
shop
> and we took dimensions for replacement sealed bearings directly from the
> axle.
>
> When I look in catalogue for replacements I see two different sets offered
> ... one states tapered. According to measurements we took, there is no
taper.
> What am I missing? Bad job of measuring or ... did stub axles change (like
> steering boxes, etc.) part way through production?
>
> Thanks
>
> Don B.
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