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Drive side roller bearing 67 Tr6 #712719
10/25/17 11:47 pm
10/25/17 11:47 pm
Joined: Apr 2017
Posts: 335
NJ USA
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Mori55 Offline OP
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I noticed my crank drive side roller bearing just slides on the crankshaft. It doesn’t feel loose just slides right on. Is this normal ? Bearing looks good no wear marks at all.


Last edited by Mori55; 10/26/17 12:04 am.
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Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712752
10/26/17 7:45 am
10/26/17 7:45 am
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Scotland
kommando Offline
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It would have left the factory with a slight interference fit but sliding fit is ok as once the crank nut is torqued the inner is locked to the crank flywheel face, you do have to ensure that nut cannot come undone with blue loctite on the thread and use the correct torque as if it does loosen the bearing inner will spin and wear the main shaft.

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712765
10/26/17 10:07 am
10/26/17 10:07 am
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Mori55 Offline OP
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Would it help if I used Loctite bearing retaining compound ?

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712766
10/26/17 10:21 am
10/26/17 10:21 am
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angeles city, rp
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jaycee Offline
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on the shaft and inner race? yeah you could but as kommando said its not necessary. and if you ever wanted to remove that inner race its not going to be a pleasant experience

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712778
10/26/17 1:24 pm
10/26/17 1:24 pm
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kommando Offline
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I would leave the loctite off the shaft, it does weird things to the internal clearances of the bearing occasionally and unless the nut comes loose would be doing nothing.

Re: Drive side roller bearing 67 Tr6 [Re: kommando] #712826
10/26/17 8:12 pm
10/26/17 8:12 pm
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Mori55 Offline OP
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Originally Posted by kommando
It would have left the factory with a slight interference fit but sliding fit is ok as once the crank nut is torqued the inner is locked to the crank flywheel face, you do have to ensure that nut cannot come undone with blue loctite on the thread and use the correct torque as if it does loosen the bearing inner will spin and wear the main shaft.

Actually I think that's what happened. I can see a small spiral wear mark right by the crank on the main shaft. But under the whole bearing.

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712831
10/26/17 8:30 pm
10/26/17 8:30 pm
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kommando Offline
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It's been caught just in time then. Did you buy that lottery ticket wink .

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712861
10/27/17 1:58 am
10/27/17 1:58 am
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Mori55 Offline OP
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Here a pic of it. One side of the shaft looks like a small groove by I can barely feel it with my finger nail. But the other side is smooth. I know it sat for over thirty years if that had anything to do with it.
https://www.flickr.com/photos/94624046@N05/shares/yNGvrU

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #712881
10/27/17 7:57 am
10/27/17 7:57 am
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Scotland
kommando Offline
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Yep, you caught it just in time. Sitting for 30 years will have had no effect on the shafts.

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713000
10/28/17 3:58 pm
10/28/17 3:58 pm
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Posts: 1,071
Lancaster, California
C.B.S Offline

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Lancaster, California
I would have the crank welded and then cut back down to size. I had this problem with my '68 TR6R and Marine Crankshaft in Riverside, CA fixed it. Better than new!

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713073
10/29/17 12:52 pm
10/29/17 12:52 pm
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Mori55 Offline OP
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I took took the roller bearing out and it said v3 , it also had a scribe on it that said 7923k any idea what that meant ? The timing side bearing had three dots that assume meant c3 clearance ?

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713077
10/29/17 1:26 pm
10/29/17 1:26 pm
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Scotland
kommando Offline
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The V3 is a vibration rating and has little to do with the internal clearance but you see it a lot on Hoffman bearings fitted at the Factory so this bearing is original or fitted as a spare early in the bikes life, 3 dots is C3, 7923k is possibly a batch number the significance will be lost by now.

Re: Drive side roller bearing 67 Tr6 [Re: C.B.S] #713079
10/29/17 1:44 pm
10/29/17 1:44 pm
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Mori55 Offline OP
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Originally Posted by C.B.S
I would have the crank welded and then cut back down to size. I had this problem with my '68 TR6R and Marine Crankshaft in Riverside, CA fixed it. Better than new!

Originally Posted by C.B.S
I would have the crank welded and then cut back down to size. I had this problem with my '68 TR6R and Marine Crankshaft in Riverside, CA fixed it. Better than new!

My biggest problem is shipping. I’ve had ups damage my cylinders. I had the wrapped in bubble wrap and stuffed with papers and fragile written on it. I think when it says fragile they throw it around.

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713080
10/29/17 1:48 pm
10/29/17 1:48 pm
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Scotland
kommando Offline
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Quote
I think when it says fragile they throw it around.


Secret cameras have confirmed this is the case in the UK.

Re: Drive side roller bearing 67 Tr6 [Re: kommando] #713100
10/29/17 6:02 pm
10/29/17 6:02 pm
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Mori55 Offline OP
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Originally Posted by kommando
The V3 is a vibration rating and has little to do with the internal clearance but you see it a lot on Hoffman bearings fitted at the Factory so this bearing is original or fitted as a spare early in the bikes life, 3 dots is C3, 7923k is possibly a batch number the significance will be lost by now.

Thanks !

Re: Drive side roller bearing 67 Tr6 [Re: kommando] #713131
10/29/17 10:47 pm
10/29/17 10:47 pm
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Mori55 Offline OP
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Originally Posted by kommando
The V3 is a vibration rating and has little to do with the internal clearance but you see it a lot on Hoffman bearings fitted at the Factory so this bearing is original or fitted as a spare early in the bikes life, 3 dots is C3, 7923k is possibly a batch number the significance will be lost by now.

So the DS bearing with v3 and no dots is a CN bearing ?

Last edited by Mori55; 10/29/17 10:59 pm.
Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713199
10/30/17 1:25 pm
10/30/17 1:25 pm
Joined: Dec 2004
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Scotland
kommando Offline
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From John Healy's list

Triumph Unit 650CC 1966-1972 Roller D.S. CN (70-2879) - RHP MRJ1 1/8-CN

And no dots would normally mean CN.

Re: Drive side roller bearing 67 Tr6 [Re: Mori55] #713255
10/30/17 10:30 pm
10/30/17 10:30 pm
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Isle of Wight, UK
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koan58 Offline
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Even some experts seem confused on this, when I ordered bearings from TMS I received ones with specs differing from those I had been advised of on this site.
On enquiring directly, I was referred to John Birch at Harris. I both spoke and had this email interchange with him on the subject:

Hi John,
I am sorry to still be bothering you on this, but there is plenty of technical discrepancy, to make anyone of a technical mind uncomfortable.
Please see the following link, which equates 2-spot with CN condition bearings.
Where does the C3 spec for the drive side roller come from?
I thank you for your time in clearing up this most important matter, main bearings

http://pdf.directindustry.com/pdf/rkb-europe/rkb-bearings-catalogue/27918-138142-_62.html

Dave Holmes

From: j------@lfharris.co.uk
To: koan58@hotmail.com
Date: Wed, 5 Dec 2012 11:21:06 +0000
Subject: 70 2879

David

Pre 1970 the caged roller 70 2879 came in 2 spot which translates to C3 condition and is satisfactory for your application, as TMS stated. Latter 750cc after 1979 went to C2 which is graded to the crank journal and the closest tollerance, your crank would not apply.

Chis/John


At the end of the day, I returned the C3 to TMS (who were only following the best advise as they saw it) and got a CN from Grin I think it was. Just goes to show how difficult this is. Dave


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