First, installed bearing in Both cylinder heads. Horz & speedo drive worm spacer seems OK nice free movement gripping worm drive. Vert with plain spacer just seems a little tighter, not notchy but not as free moving - Would anyone like to comment, basically from experience does this sound OK? Secondly, when I took shims out I kept them all together and tie wrapped them. Horz went back OK no axial movement and nice free rocker movement. Vert head inlet side, one side only had a thick shim on one side and has 0.18 movement mearsued with feelers and exhaust had a thick shim plus 2 thin shims. I could not get the second one in which was 0.3 and it left 0.28 axial movement. I think I will measure all shims to see what thickness they all are. But, does any comments about shimming the rockers. Is a bit of axial movement OK. Cheers Gaz
I've rebuilt a few heads and never noticed any tightness after replacing the bearings. Are you sure you didn't mix any of the shims up? It's easier done than you'd think. What came out must go back in again. Whatever, try to minimise the axial movement and arrange the shims to centralise the rockers on valves. Particularly important on the closers where you definitely don't want them contacting the valve stem.
Derek, Thanks for your input. I pressed the outer bearing in with socket I had lapped the end of. It was very flat and contacted both inner and outer shells of bearing. I First pressed it in then rotated the bearing it was very free but I put my finger inside and was able the move the spacer, so I just nipped it up a bit more. I will see if I can back it off a bit. Regarding the shims. I am certain I tie wrapped them up as soon as I took them out but that was 3 years ago. It is the closing rockers and was going to install the valves and measure to gap between rocker and valve to get it central. I will measure all the shims, I may have to order some new ones to take out the axial movement and centralise the rocker. Thanks again for your input. Cheers Gaz
The spacer is sandwiched between the bearings with the inner bearing against a shim between it and the shoulder on the camshaft. The cam nut should be torqued to 70 Nm.
Yes, I am OK with that bit and realise there is a shim on the shoulder of the cam shaft. What I am trying to avoid is - If you don't get the outer bearing race (which is the one you would usually push it in with) in the right position, when everything is sandwiched between cam shoulder and nut, the inner race will transfer a load through the balls to the outer race and try to move it. I thought by pushing the bearing in with something that was flat and contacted both inner & outer race faces I would get the outer race in the correct position when the inner race hit the spacer. Cheers Gaz
The inner bearing rests against a shoulder in the head. When the nut is torqued up everything should line up unless the outer bearing isn't correctly seated for some reason.
Sorry Derek, when I was talking about the outer bearing it was the one on the pulley side not the one in the end cap. Cheers Gaz
Yes, I know. The inner bearing rests against the shoulder in the head. The one in the end cap just supports the end of the camshaft and doesn't locate anything.
Sorry Derek I hope you are not getting frustrated with me, I do value your input. So yes, the bearing in the end cap + shim just support the shaft end, the Inner bearing butts up to the cam shaft shoulder with a shim fitted. The bearing I originally said felt a bit tight was the outer one one the pulley side. I am only commenting again as the picture you sent did not show this one, and it this one I was a little concerned with and just wanted to make sure my method of assembly was correct. How did you press yours in. Cheers Gaz
No worries. I pressed the outer bearing in using a socket that fitted to the outer ring of the bearing. The diagram is from the workshop manual for the i.e models. It's the only one I had that showed a cross section of the head but, as you say, it doesn't show the outer bearing. But when the cam nut is tightened the sleeve, and the worm gear on the horizontal head will be nipped between the 2 bearing inners and both bearings will be pulled together. I can't for the life of me remember whether there is a shoulder behind the outer bearing or not but I'd have thought not. So that the outer bearing finds it's own position relative to the inner with the sleeve nipped up. If there is a shoulder, that would determine the position of the outer bearing but unless the spacer is exactly the right length an axial load will be placed on the bearings. When the head is fully together, the camshaft will be located between the inner bearing and the bearing in the support block. There should be a .020mm shim (A) against each bearing. See the diagram above.
When I had to replace the tacho worm gear on my 750, I did it with the engine in the frame...... I pulled the bearings in place with the worm gear in between them......(I admit to adding a small drip of Bearing Fit onto the inside of the worm gear because I wasn't going to have to change the damn thing again)......... ......I then wound the silly pulley nut up as tight as possible..........(My torque wrench had been borrowed at the time)......... I noticed that the cam was a bit tight in the bearings, but like gaz says, not grating or lumpy..........just not quite as free as I had expected....... I thought WTF, it will ease off and re-assembled the rest, fired it up and off I went for a trundle. That was 6 years ago and about 10,000 miles done.
My main line of thought here is that if you press a bearing into a hole you press it in on the outer part of the bearing and if you put a bearing on a shaft you use the inner part of the bearing to press it on with. If you don't you are transfering the load from either the inner or outer through the ball bearings and run thr risk of damaging the balls or housing. Well, I heated the head up a bit in the oven only to 80/90ish for 10-15mins then very lightly tapped the spacer back from the inside (the spacer has a smaller i/d than the inner bearing). It only took a few light taps and the bearings freed up. Problem - I can feel some very slight notches. This is how I installed the bearings and while drawing it out I realised my mistake. First I pressed in the inner bearing. Then I pulled the outer bearing into position supporting on inner & outer parts but only supported the inner bearing on its outer part. I should have supported both bearings on both inner and outer parts and believe this would not have loaded the bearings up (at least not as much). Thanks again for all input - just got to sort those shims out now. Cheers Gaz
