Moss taper bearings don't fit

[Euan Hoosearmy]

Ordered two sets of taper bearings from Moss last week. Annoyingly the inner ones (bigger ones) don't fit as they're too small.

The stub axle measures up as 25mm, the inner diameter of the bearing is 24.6mm.

Looking up on some bearing specialist sites, that type of bearing (30205) is supposed to have an inner diameter of 25mm.

Is 0.4mm (15 thou) a normal tolerance for this kind of thing or have I been sent some poor quality bearings?

Alternatively, do I have a "oversize" stub axle? The outer bearing drops on fine, that's supposedly got an inner diameter of 17mm but according to my verniers is ~16.8mm.

[Euan Hoosearmy]

Update : They're sending me a second set to see if they fit....

[Splat]

Frankly, I wouldn’t buy anything from Moss any more. The “quality” of their parts is beyond crap. I’ve had head studs made from cheese and bearing sets that have lasted less than 100 miles.

After numerous attempts to set up the front hubs using Moss’s shonky parts, I contemplated going down the taper roller route. But in the end, I installed the correct, face-centred SFK bearings about ten years ago (use the search facility to find the part numbers), have done between one and two thousand miles per year since, and haven’t had any problems with them, whatsoever! I drive the car pretty fast (with a few track days) but have never experienced any vibration or pad knock back (MGB callipers, Mintex 1144 pads and cross-drilled 9” rotors).

[Euan Hoosearmy]

Unsurprisingly the replacements didn't fit either - the variation in inner diameter across all four bearings was enlightening - smallest was 24.67mm largest was 24.86mm.

Do I just go to a specialist bearing supplier and get some SKF bearings of type 30205 and 30303 and hope that they fit...? The Moss inner bearings have a "2C" suffix which I believe means they have more clearance than standard - is this important in this usage?

[Morris]

That's interesting to hear.

I pretty much through my whole bank account contents at Moss during my build...

I fitted taper bearings bought from them, but I never thought to check the tolerances.

Following 850 miles, I've had no issue with the front end. Having said that I've never managed to remove all the initial movement from the brake pedal (it's not air in the system, and the rear end is all adjusted).

[Splat]

Apologies, but it’s now well over a decade since I did my own extensive research into the front wheel bearings issue! I seem to remember that I discovered that the original bearings were manufactured by a long-defunct Birmingham supplier and had been unavailable for decades.

However, whilst not “exactly” identical, SKF offered a pair of bearings that were very, very close. Following the endorsements of others, these were what I fitted. As I wrote above, they’ve now seen many thousands of miles of running, with absolutely no issues.

These are they (I keep a drawer-full of spares for the car, “just in case”):

[Splat]

PS if you DO go down the SKF route, then they’re NOT cheap! But do shop around, as prices vary massively.

[Euan Hoosearmy]

@splat - please can you measure the inner diameter of the bigger of the pair (3205) and let me know - I'll then (hopefully) know if the Moss Bearings are too small or it's my stubs that are oversize. The bearing should have an inner diameter of 25mm

[Splat]

Both sets of bearings are still in their sealed packaging, which I’m reluctant to open (the cellophane, rather than the outer box!).

However, I just so happen to have a pair of uprights on the shelf, too! The axles measure out at 25.04mm and 25.07mm diameter at their widest. Hope that helps.

[Euan Hoosearmy]

@Splat - Thank you - your stub axles are slightly larger than mine, so Whoever makes the bearings for Moss has iffy quality control... SKF it is then...