The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: sprint on 02.07. 2013 09:58
-
I am looking to replace the blind layshaft needle bearing and would appreciate some advice.
Firstly I will need to get some sort of drift made to drift it out. I can get some internal dimensions from the existing bearing but can somebody advise what the outside diameter of the blind needle bearing is as the drift will need to pass through the mounting hole and clear it with out damaging or scoring the surface.
Once I have a suitable drift, unless there are/is an alternative, should it be driven from the inside out or from the outside in? There looks to be a blanking disc on the outside which needs to be removed so I guess it will need to be drifted from the inside?
Is it fairly easy to drift out the old one and fit the new one and are there any problem areas to be aware of?
Thanks
Andy
-
HI Andy
I have a new needle bearing, I have not had time to go and measure up for a drift
Heat the case with a hot air gun or smallish propane torch
I think the bearings are the same as Triumph T120/40 if you have those??
HTH
John
-
Thanks John
It does look similar to the one used in the T120 box, but I don't have to check with.
-
HI Andy,
Bearing o/d is 0.875in.
HTH
John
-
Thanks John
There is what appears to be a blanking disc on the outside of the G/B where the L/S blind needle bearing is? Does not show up on any diagrams so is this right/normal?
I take it that this means that you have to drive the bearing out from the inside or do you have to remove the blanking disc first and drive it in?
-
Have you tried 1/2 filling the bearing with grease and put the shaft in and give it a sharp whack with a hide mallet? Often works with bush's. Warm the case first.
Cheers
-
Have you tried 1/2 filling the bearing with grease and put the shaft in and give it a sharp whack with a hide mallet? Often works with bush's. Warm the case first.
Cheers
Thanks for the suggestion, which I have not heard of before. Might give it a try as it would save the hassle of having to get a drift made up. Though the bearing journal depth of the shaft will not allow it to knock it right through?
I take it that there is a blanking disc, as on photo, or is that part of the bearing?
-
The grease method if it works pushes the bearing out to the inside. Once it's moved a bit a pilot bearing puller can do the rest. Worth a try.
Cheers
-
Hi Andy, Musky,
The needle bearing has a blind end made in one piece with the outer shell, so the grease trick wont work!!
I figure that the whole lot will push outwards from the inside of the box
The end cap is similar to a frost plug in construction, a tap in the centre tightens it after fitting, that is of course if you can find a new one *????*
I have used epoxy resin as an aid to sealing them on Burman boxes where they are the only thing holding in the oil *ex*
Heating the casing will help with removal and is essential for bearing replacement, where it should push in when the case is hot and bearing and inserting tool (layshaft) are chilled in the freezer
HTH
John
-
The needle bearing has a blind end made in one piece with the outer shell, so the grease trick wont work!!
Bugga!!
-
Thanks for the replies.
It looks like a drift is the only solution.
Andy