Rear axle bearings

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Mr B
Posts: 289
Joined: Fri Dec 09, 2016 9:07 am
Car(s): Four 3 litre Capri's and 2 Mark 1 GXL's

Re: Rear axle bearings

Post by Mr B » Sat May 11, 2019 7:55 pm

Hi guy's,

Check out the link below if you haven't already

Mr B

Posts: 2136
Joined: Tue Jul 29, 2008 6:40 pm
Car(s): 1984 B Reg 2.8i rebored to 2922cc near concours condition. Restored from near scrap condition.
1983 A Reg 2.8i Caspian Blue over Silver. Ongoing now roadworthy project from scrap condition
Location: England

Re: Rear axle bearings

Post by ollyw » Sun May 12, 2019 8:17 pm

Mr B wrote:
Sat May 11, 2019 7:55 pm
Hi guy's,

Check out the link below if you haven't already

Mr B

This is a good link, I did check this out a while back when I ordered my first set of bearings from them. (I’ve now gone through 2 sets)
One of theirs is in and sealing fine on the other side.

The points they make are valid and as a result I have gone into stellar engineering mode and checked the following (having luckily got access to a machine shop) and understanding a little bit of engineering terms.

1) half shaft spun up on a lathe, checking runout with a dial gauge proves the half shaft is not bent or oval.

2) checking the hole the bearing sits in with Vernier callipers confirms the axle end is circular and not oval but then I’d expect the bearing to be an interference fit if it was and then leak on the sides that aren’t tight.

3) measuring the depth of the bearing in relation to the housing it sits in reveals a small gap of about 0.30mm, not much but possibly enough to let oil through. I’m also assuming the bearing should not be so small in width that it could rock side to side. That would break the seal if it did.

4) I was able to pull the half shaft out by hand without a slide hammer. The only resistance I felt was the hylomar coming apart. So either the axle hole is oversized or the bearing is undersize.

I find it hard to believe the axle has been turned oversize, it would be extremely difficult to turn an axle up on a lathe accurately. Also my bearings didn’t leak before they were just a little noisy.

Whist they raise some perfectly valid points in this article as to the reasons why the bearings could leak, the truth is they are pattern parts which in my experience aren’t necessarily made to the exacting tolerances of the originals. I’ve also heard from an engineer that bearings are graded into categories based on their exacting measurements on production. The article is however very informative and I’m pleased it exists as I wouldn’t have know where to start.

Here’s a link to the bearing I’ve ordered. I’m intending to offer it up to the hole first and see how interference fit it is. I’ll report back. ... glebutton=

If it does work I would respectfully request all suppliers to stock these instead and hopefully put this leaking axle nightmare in the bin for a while.

I’m enjoying the challenge!

Olly W

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