21-02-2019, 12:27 AM
Thank you everyone for your help and comments. AS promised in my last post, I would let you all know what has transpired;
I rang Hoffmanns and spoke to one of their technical people. He told me that the big difference between a caged and uncaged roller bearing is that the uncaged version will withstand greater loads, including shock loads, but only at a slower speed that a caged bearing. During my net surfing last night trying to find an answer, I came across some bearing data sheets that suggested that the maximum rotational speed fora MRJ 1 1/4" bearing was 12000 rpm for an oiled bearing and 8000 for a greased bearing, the difference presumably because a flow of oil will keep the bearing cooler.
Hoffmans couldn't give me a max rotational speed for the uncaged roller, but given that a standard Seven Box Saloon engine revs to about 3,500 rpm, the uncaged roller should be fine and it appears to be the case that it will withstand greater shock loads that the caged bearing. I have in mind the loads imposed when cylinders are firing twice per engine revolution.
I then spoke to Jamie at Seven Workshop, He told me that RHP stopped making MRJ 1 1/4" bearings about six months ago and he has been struggling to find a suitable replacement. His bearing suppliers recommended the Hoffmann bearing as a suitable substitute. He could get Chinese pattern bearings, but said that he didn't want to go down that route.
So it was Hobson's choice, although I was a little reassured by the conversation that i had had with Hoffmanns. So, this morning, after walkmg the dog, I fitted the bearing. I used a cable tie to keep the rollers in position , and, yes, Chris KC, I have used bearing fit on the inner track. I think that reliability and making sure that the inner track has no possibility of spinning on the crank is more important that than worrying about how to get it to bits in the future, besides, Loctite 641 is destroyed at temperatures above 200C so I do not perceive a problem getting it off if I have to in the future. And I have a puller plate like that of Zetomagneto's ( it is part of a Mini/1100 flywheel puller set that I have had for years) so I can make a serious puller like the one in the photos.
The clutch and flywheel are back on and the only jobs I have to do are to replace two manifold studs and check the tappets. The plan is to get the engine back in and running at the weekend.
The crank certainly turns over more smoothly so I am hoping that the engine will now run more sweetly. Cross Fingers!
I rang Hoffmanns and spoke to one of their technical people. He told me that the big difference between a caged and uncaged roller bearing is that the uncaged version will withstand greater loads, including shock loads, but only at a slower speed that a caged bearing. During my net surfing last night trying to find an answer, I came across some bearing data sheets that suggested that the maximum rotational speed fora MRJ 1 1/4" bearing was 12000 rpm for an oiled bearing and 8000 for a greased bearing, the difference presumably because a flow of oil will keep the bearing cooler.
Hoffmans couldn't give me a max rotational speed for the uncaged roller, but given that a standard Seven Box Saloon engine revs to about 3,500 rpm, the uncaged roller should be fine and it appears to be the case that it will withstand greater shock loads that the caged bearing. I have in mind the loads imposed when cylinders are firing twice per engine revolution.
I then spoke to Jamie at Seven Workshop, He told me that RHP stopped making MRJ 1 1/4" bearings about six months ago and he has been struggling to find a suitable replacement. His bearing suppliers recommended the Hoffmann bearing as a suitable substitute. He could get Chinese pattern bearings, but said that he didn't want to go down that route.
So it was Hobson's choice, although I was a little reassured by the conversation that i had had with Hoffmanns. So, this morning, after walkmg the dog, I fitted the bearing. I used a cable tie to keep the rollers in position , and, yes, Chris KC, I have used bearing fit on the inner track. I think that reliability and making sure that the inner track has no possibility of spinning on the crank is more important that than worrying about how to get it to bits in the future, besides, Loctite 641 is destroyed at temperatures above 200C so I do not perceive a problem getting it off if I have to in the future. And I have a puller plate like that of Zetomagneto's ( it is part of a Mini/1100 flywheel puller set that I have had for years) so I can make a serious puller like the one in the photos.
The clutch and flywheel are back on and the only jobs I have to do are to replace two manifold studs and check the tappets. The plan is to get the engine back in and running at the weekend.
The crank certainly turns over more smoothly so I am hoping that the engine will now run more sweetly. Cross Fingers!