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Newbie reamer questions (longish)

Hello everyone,

You've all been very helpful answering my few questions in the past, so I hope you don't mind me taxing your collective intellect now.

Briefly, I'm trying to replace the unlubricated plain steel bearings in my motorcycle swinging arm with lubricatable needle roller bearings. The bearing I'm using is an HK1816, a standard bearing with ID 18mm, OD 24mm. The current steel bearing ('bearing' is glorifying it a bit, it's more like a sleeve) is a press fit in the swinging arm.

Having removed this with a vice and a few appropriate sockets, I'm left with a hole in the swing arm into which I need to install the bearing. The questions:

Do I need to ream this hole for the bearing? Is running a 24mm drill through it an alternative? Will a few minutes fettling with fine (800?) wet and dry wrapped round a dowel be OK?

I found

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which is very interesting and quite helpful, but as an exercise in logic, why do they differentiate between imperial and metric adjustable remers? If it's adjustable, then it surely doesn't matter what units you use.

Finally, is there an equivalent to a reamer for a shaft? Or, rather, what is the way to produce an 'accurate' 18mm diameter shaft to fit inside the bearing? At the moment the shaft is too tight, so is wet and dry the answer?

Thanks for your time.

John

Reply to
John Montrose
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There are a number of questions here which I am sure the others will answer better than I can, but why use needle bearings when a plain phosphor-bronze bearing would be better, have more surface area and would retain libricant better than a needle ?

My BMW's all had taper-roller bearings for the swinging arm but suffered from localised wear as the thing never rotated enough to spread the load across a larger area. Needles are possibly a worse case as they only have minute areas of contact onto what sounds like an unhardened shaft. Localised corrosion was another problem, as the lubricant was not always retained amongst the rollers.

To get a decent fit you would need to make the shaft first and then get the P/B bearings reamed in situ, as they will reduce in size if pressed in with anything but a very light press fit. Lubrication should be with a decent grease or heavy oil, something like 140EP.

I'd be wary of needles which can't rotate, but the others may take a different view?

Peter

-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

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Reply to
Peter A Forbes

I agree with Peter - having just replaced bearings in the rear trailing arms of my Fiat Tempra estate (prior to a holiday on Irish roads!) I can vouch for the fact that small diameter bearings don't seem to last. These were taper roller bearings with of course their own inner races, but the small angular movement & relatively high loads seem to break the rollers nevertheless. I also remember that Mini's had similar trouble - they had a needle roller on the outside & a bronze bush on the inside & on mine at least the needles went first. I'd use a bronze bush &, if there are no current greasing arrangements, I'd drill & tap either the arm to take a nipple or two, or even the shaft itself like the old Mini arrangement.

----------------------------------------------------------------------------------------------------- snipped-for-privacy@boltblue.com John Lloyd - Cymru/Wales

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Reply to
John.LloydUNSPAM

John,

My son's Husky motorcycle had four small needle races on the swinging arm, two on each side. The needles ran in special hardened inner and outer steel cages. The outer cage was pressed into the swinging arm and the inner cage was pressed onto the main shaft. The races were sealed with rubber seals and lubricated with a grease nipple on each side. I maintained the bike and made sure they had fresh grease each time the bike was used. After 18 months (from new) the bearings failed. When I took them apart some of the needles had broken and others had turned by 90 degrees in their cages, what a mess! I replaced the bearings and we sold the bike. Three points from all of this: Needle races must run in hardened inner and outer cages. They must be heavy duty bearings and it would be worth speaking to a bearing specialist for their advice. There must be a way to control the end float on the swinging arm.

Bronze bushes would be an easier solution.

Regards, Martin Perry

Reply to
Martin Perry

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