Good morning all,
I am putting the timing side stuff back on my A65 and I have noticed an amount of end float in the cam and idler gear'
There is about 10 thou end float on the cam when pushed in but some of this will go when the engine gets warm and the new breather spring is doing its job so probably OK.
Does anyone ever bother shimming the idler gear? I have about 15 thou movement without a gasket so is this too much as the gasket will probably be easily another 15 thou making possibly 30 thou.
How thick is a compressed gasket and should I fit a shim?
Dave.
Hi Dave, with the expansion of aluminium it would probably grow by a thou rather than tighten up.
The question I have is what year motor is it? Which idler bushes have you get fitted? The top hat type or the plain type and do you have the correct idler Gear to match the idler gear bushes?
The crank case years probably don't make a difference, but from 69 on they went from using the top hat style bush to a plain cylindrical bush, the edge of the bush meets the face of the aluminium casing. Same for the inner timing cover as well.
For the idler gear they changed the back side of it, made it meatier. So that takes up the gap
Pre 69 on the left, post 69 on the right. Not sure what the end float should be but .010" seems a little excessive but apart from a bit of noise it won't do any harm.
Hi Allan,
The cases are possibly '71 so have the flush bushes and the idler I am using came out of '69/'70 cases again with the flush bushes so that should be OK. I have never noticed idler gear end float in my other A65 but then I have not had much reason to. Now that I have noticed I feel that I need to do something about it hence my question.
So without a gasket fitted there is about 15 thou of end movement so with a gasket this will increase by the thickness of a fitted, compressed gasket so perhaps up to 30 thou - too much I think.
I will sacrifice a gasket to see exactly how it increases the end play and make a shim to leave a perceptible bit of movement.
I would imagine that the change to the bushes was to save money but also probably indicates that there is very little thrust exerted by the idler hence no need for the thrust face of the earlier bush.
Dave.
I have never actually measured the end float to be honest. A 0.010" endfloat could be about right. My 68 is fitted with the later bushes (bronze shim behind the idler and a 71 inner timing case), been a while since I checked the end float, built an all correct 69 model and just working on a 71 at the moment. It'll want new bushes, but the current ones should stop me seeing what the end float is like.
Hi,
Are you using the earlier idler pinion and if so do you know how thick the shim is? I may have an earlier pinion which means it will be easier to fit a shim as at present I am trying to get one down to about 15 thou.
Dave.
Hi Dave, the current shim is actually the old bush just with the top hat removed and made to fit. I am going to demo for the later parts shortly. My 68 is using the early style gear on a 71 style spindle (has to be the late spindle because of the oil seal/late inner timing cover.
Hi Dave,
Just assembled a set of 71 cases, idler pinion etc. I'm getting 0.010" end float with the gasket in place and tightened up. Gasket had an Pre crushed value of 0.017"
Hope this helps.
How it feels is similar to my 68' from memory and the 69' I did.
Good afternoon Allan,
Just come in from the shed. I found an earlier pinion that is more dished and quite a bit lighter but the difference in thickness was barely visible using a straightedge across them. I swapped the spindles anyway and put my approx. 20 thou shim on and assembled the case with some sacrificial gasket under the screws. It turns but with no detectable end float so I may need to try and reduce the shim a bit more.
I did make a shim from and old bush but it was far too thick and would have taken me at least a week to reduce it.
If I can get a bit of end clearance I will stick with it and hope I have a slightly quieter timing side.
A bit of a sideways move here, but have you tried changing the 3rd gear pinions in a standard gearbox with pinions for close ratio 2nd? It opens up the gap between 3rd and 4th and so narrows the abyss between standard 2nd and 3rd.
Most of the time the gap is not a problem but climbing steep twisty hills the gap can be a pain when 2nd needs lots of revs to keep up a reasonable speed and 3rd means labouring the engine.
Dave.
Nice work Dave, what material have you used for your shim? I've got a selection of cam gears, some of them having a "bit more" tooth at the back than across the rest of the tooth, probably caused by this endfloat.
Another way of doing it might be to leave out the gasket, how ever you would then need to check if there's enough endfloat on the Kickstart quadrant and gear-selector shaft. If you run a tachometer this might also be a problem with the spindle off the oil pump. Just a thought anyway
Re: gearbox
I've never worried too much about the placement of the gears if I'm honest, I do prefer the close ratio box and it goes well with the tall primary and 19:42 sprockets. (Works out like 20:42), but it's not much fun on a club ride out as your never out of first gear, so I threw the standard box back in. It's an interesting thought though... if you can get the gears. I don't fancy striping the cr box down to do it. I have another plan for that unit.
I found a used lock washer with the right ID and removed the tabs. I think it was about 28 thou and I have got it down to just under 20. As there is only minimal side load on the idler pinion it will probably be OK but I am going to see if I can get some proper shims now I know the size.
To keep as square and flat as possible I used the bed on a pillar drill with some emery and a magnet to hold the washer. This means that I have not worn my skin away and the pressure exerted by the magnet should means a more even removal of material.
With the gearbox I have found that climbing steep twisty roads that some times the reduction in speed necessary for the tight bends means a bit slow for standard 3rd so changing down to 2nd results in a lot of revs to keep any speed up. The CR box could overcome this but as you say it is not good in traffic or for moving off on a steep hill loaded up with camping gear or two up or both.
I found some tatty looking CR gears in a box of bits so I have have the opportunity to try it and if it is worth it, I will find some better gears to make up a decent box. I will try it on my usual 650 as then I will have better idea if it works.
Dave.
Good idea with the shim/skimming the shim, I'd have been down to the bone with that one. I might try similar with some shim stock. I already know the current endfloat so can go from that.
On the Cr2nd gears, if you have any (even the tatty looking ones) that you would want to exchange with beer tokens I'd be interested.
I may have another pair of cr2nd pinions. I will have look tomorrow and let you know through a PM.
Dave.