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+--- Thread: Who knows their bearings.... (/showthread.php?tid=8863)
Who knows their bearings.... - Denis Sweeney - 04-09-2023
I am beginning to put "stuff" together to build a spare engine for Ruby and am sorting thro' my many boxes of bits.
I knew I had some bearings tucked away but had never really studied these.
I attach hear a word document with a picture of said bearings and detail out what the markings on each of the bearings and original packaging they were in.
These have never been used and have sat in my shed for nearly 40 years...... yes, yes I know, I should have checked all of this out a long time ago!
However can anyone shed any light on whether any of these are suitable for an A7 early Ruby two bearing engine.
Cheers Denis S
RE: Who knows their bearings.... - Tony Press - 05-09-2023
Hi Dennis,
The FAG Bearing MS12 is a deep groove ball bearing equivalent to an SKF RMS 10 - with a 1 1/4" bore- it is not an Austin 7 Rear Main Bearing.
The Hoffman RMS 12 is a roller bearing equivalent to an SKF CRM 10 with a 1 1/4" bore and is an Austin 7 Rear Main Bearing.
If still clean and not showing any corrosion it should be alright to use.
The SKF Bearing is an angular contact ball bearing but I cannot find the SKF number CFM 10. If the bore is 1 1/8" x 2 13/16" od x 13/16" wide it could be a half the two front crankshaft bearings.
Cheers Tony
RE: Who knows their bearings.... - Chris KC - 05-09-2023
(05-09-2023, 12:15 AM)Tony Press Wrote: If still clean and not showing any corrosion it should be alright to use.
Aye, there's the rub.
RE: Who knows their bearings.... - Denis Sweeney - 05-09-2023
Thanks guys they have not been cleaned up and there is fairly hard grease in some.
Does the OOO have any meaning? I saw in the Companion reference to O and OO fit on Hoffman bearings so is OOO another fit?
I have a crankcase I purchased at Moreton that has had the front bearing housing repaired and it is marked “narrow bearings” on both front and rear repair plates.
Does this mean I need specific bearings, sorry if this is a dumb question, but I need to ask
Cheers again
RE: Who knows their bearings.... - Denis Sweeney - 05-09-2023
Just for your info, I have soaked all three bearings in paraffin and cleaned them, not thoroughly as yet, but clean enough to note there is no corrosion on any of the races or rollers, they are all clean bright metal.
The inner and outer mating surfaces of each bearing are clean polished surfaces and have no marks to indicate they have ever been installed. I cannot detect any play in any of the bearings.
However having never held a clean dry bearing in my hand other than hub bearings etc, I am surprised how much noise they make when spun, is this normal for new bearings??
I have not oiled the bearings as yet as I will leave them overnight in the paraffin and will thoroughly wash them out tomorrow.
RE: Who knows their bearings.... - Chris KC - 05-09-2023
I think you are right about the 'OOO' mark Dennis, though I couldn't tell you what it means in detail, nor whether it's likely to be a problem on an A7.
I assume 'narrow bearings' is a reference to the later narrow width A/C pair - as opposed to the earlier ball & roller set-up. Naturally the new lip must be located to suit one or the other. If you have a copy of the Companion you can extract the relevant dimensions out of Jack French's article on p.112 & check what depth you have on the case itself.
No marks on the races is good news. Older bearings often have corrosion etching (dark marks which won't polish off) and these do affect bearing life - by how much is another question. You certainly don't want anything you could feel with a finger tip.
Paraffin is fine for cleaning but it does tend to promote corrosion over time - I'd be inclined to blast it out with WD40 over a basin.
RE: Who knows their bearings.... - Hugh Barnes - 05-09-2023
I was rather hoping that someone would have given the definitive '000' answer by now, but I will toss may hat in the ring. I think the '0', '00', '000' indicates the amount of play in the bearing. ie, the tolerance of the fit between the two parts, '000' being the 'best' fit. I remember Ray Walker having saved a '000' bearing for someone/thing specail, but it soon rumbled away like any other rear main. That's not to say that will happen to you, Dennis!
RE: Who knows their bearings.... - Chris KC - 05-09-2023
Here you go:
https://www.classicbritishspares.com/blogs/news/16180669-triumph-bsa-crankshaft-bearings-clearance
"OOO" is a "C3" internal clearance or 'loose' - notionally intended for use where both inner and outer races are an interference fit on the shaft / case or perhaps where thermal expansion works against running clearance. Some would say a good choice for racing or sports engines, where nothing wants to be 'tight'.
RE: Who knows their bearings.... - Hugh Barnes - 05-09-2023
Ah, perhaps I had it the wrong way round, then. See, I told you we needed someone more informed than I!!
RE: Who knows their bearings.... - Tony Press - 06-09-2023
(05-09-2023, 01:17 PM)Denis Sweeney Wrote: Thanks guys they have not been cleaned up and there is fairly hard grease in some.
Does the OOO have any meaning? I saw in the Companion reference to O and OO fit on Hoffman bearings so is OOO another fit?
I have a crankcase I purchased at Moreton that has had the front bearing housing repaired and it is marked “narrow bearings” on both front and rear repair plates.
Does this mean I need specific bearings, sorry if this is a dumb question, but I need to ask
Cheers again
000 is C3 internal clearance or internal clearance greater than normal.
If used on the rear main bearing with a very firm fit on the crankshaft it should be ok if not a bit more rumble from the rear.
(05-09-2023, 01:17 PM)Denis Sweeney Wrote: Thanks guys they have not been cleaned up and there is fairly hard grease in some.
Does the OOO have any meaning? I saw in the Companion reference to O and OO fit on Hoffman bearings so is OOO another fit?
I have a crankcase I purchased at Moreton that has had the front bearing housing repaired and it is marked “narrow bearings” on both front and rear repair plates.
Does this mean I need specific bearings, sorry if this is a dumb question, but I need to ask
Cheers again
As mentioned the Austin 7 Angular Contact pair have narrow outer rings- in earlier crankcases two 30 thou washers were fitted but later the housing depth was reduced. (refer Woodrow)
We have pairs of standard AC bearings machined to suit.
Unfortunately these are not matched pairs but usualy a pair of unmatched bearings can be used as a pair although I recently found one pair for the differential required an 8 thou spacer.
When mounted as a pair the outer rings must be in contact but not difficult to rotate
Unlubricated bearings should never be spun.