Mk3 Inner Chaincase Support

Hello,
The inner chaincase support bolt fitting, the book says to fit the washer before fitting the chaincase.
The parts manual shows a washer either side of the cradle, a lock nut right side, a plain nut between the cradle and chaincase.
The thick washer was on the support when I dismantled it, but where does it go?
Inside the chaincase or outside the chaincase?
Help.
Does this look right ?





Thank you.

Hi

I am pretty certain that it is a bush that goes on the outside of the inner primary case so it is between the hexagonal portion of the stud and the inner face of the primary case gives a better surface for the case to locate on.

Thanks, so is the thick washer the bush you mentioned?

GRM 450 said:

Thanks, so is the thick washer the bush you mentioned?

Click to expand...

Yes sorry the thick washer

Thanks plj850,

Makes sense, I looked at the mark from the old washer on the outside of the chaincase, where the thick washer would go, and the mark is from a smaller diameter washer than the thick one. But I don't trust any thing the way it was on this bike.
Some of the work was realy questionable.

Thanks for your help

Regards Graeme.

Mine is fitted up differently and your way, although seeming to follow the parts book (which is a bit odd in some areas) will make it quite difficult to adjust the support behind the chaincase.

I don't recognise the thick washer in that location.

I have the long hexagon bolted tight to the engine cradle with no adjusting nut. I then run the support nut right in, followed by a washer and fit the chaincase. Once the case is secure at the front, it's then a simple matter to bring the nut out by hand until it just prevents the inner case from being distorted as the nut inside the case is tightened.

It would seem a lot more of a fiddle to do this on the cradle side and would mean clamping the stud through the inner chaincase first and then adjusting which is not what the manual describes.

The Mk111 had a complete lack of development during its short production period and the literature all seems to have been prepared before the model launch and was not revised or corrected at the time.

The assembly as shown in the parts book is probably how it was originally intended to be?

But it works better the way 79x100 has suggested, and that is how it is fitted on my own MkIII.

However, extra packing washers (three?) will probably need to be added between the long hexagon and the cradle, otherwise the nut on the inside of the cradle will run out of thread before the support is pulled tight against the cradle, and there may also be an insuficient amount of thread left protruding into the primary case for the securing nut, if those packing washers are not fitted?

I've got quite a thick stainless washer next to the cradle and that seems to be enough. I do see that the thread protrudes a little further through the plate than I would expect if it was designed like that. I don't recall a problem with the thread length inside the chaincase and heaven knows, it's been on and off often enough over the years :?

The thick washer that appears in Graeme's photo would do the job admirably and it does look like a factory type of washer. Could this be a production refinement that doesn't appear in the literature ?

79x100 said:

The thick washer that appears in Graeme's photo would do the job admirably and it does look like a factory type of washer. Could this be a production refinement that doesn't appear in the literature ?

Click to expand...

Could be?

And it would certainly make more sense if the support was turned around, and the thick washer then placed between its hexagon and the cradle, as that would space it out by a similar amount to the four thin washers I have on mine?

79x100 said:

Mine is fitted up differently and your way, although seeming to follow the parts book (which is a bit odd in some areas) will make it quite difficult to adjust the support behind the chaincase.

I don't recognise the thick washer in that location.

I have the long hexagon bolted tight to the engine cradle with no adjusting nut. I then run the support nut right in, followed by a washer and fit the chaincase. Once the case is secure at the front, it's then a simple matter to bring the nut out by hand until it just prevents the inner case from being distorted as the nut inside the case is tightened.

It would seem a lot more of a fiddle to do this on the cradle side and would mean clamping the stud through the inner chaincase first and then adjusting which is not what the manual describes.

The Mk111 had a complete lack of development during its short production period and the literature all seems to have been prepared before the model launch and was not revised or corrected at the time.

Click to expand...

Sounds good but how is the nut secured on the outside of the primary chaincase? Fitted the other way around the adjustment carried out next to the cradle is locked up with the nyloc nut.

plj850 said:

Sounds good but how is the nut secured on the outside of the primary chaincase? Fitted the other way around the adjustment carried out next to the cradle is locked up with the nyloc nut.

Click to expand...

When the nut on the inside of the chaincase is tightened, it will pull the chaincase against the nut on the outside, which secures it. Although it is best to tighten them both against the chaincase by equal amounts, so that the chaincase isn't pulled inwards.

L.A.B. said:

plj850 said:

Sounds good but how is the nut secured on the outside of the primary chaincase? Fitted the other way around the adjustment carried out next to the cradle is locked up with the nyloc nut.

Click to expand...

When the nut on the inside of the chaincase is tightened, it will pull the chaincase against the nut on the outside, which secures it. Although it is best to tighten them both against the chaincase by equal amounts, so that the chaincase isn't pulled inwards.

Click to expand...

I stand corrected

There is no "correct" method to illustrate proper shimming for ALL Commandos in this respect, with one simple illustration and "one size fits all" washers/shims.

If you hope to retain your inner chaincase in good form, without cracking the bosses on the crankcase mounting end, and without distorting the oil sealing face, you MUST first fit up and snug down the pillar bolt, then dry fit (snugly) the bare inner primary case to the crankcase with the appropriate gasket. At this stage, you carefully measure the gap between the outer face of the hexagonal section of the pillar bolt, and the inner face of the primary case, then add as close to that exact dimension as possible in washers/shims.

The last trick to all this is that somewhere in the initial assembly stage, your power unit and transmission, bolted in place in the isolastic engine mounting cradle system, must be properly aligned to each other. Fitting up the primary case should result in a very-nearly square alignment for the primary chain when properly shimmed. So, the entire assemblage is all lined up nice and neat, and later adjusting on the primary and final drive chains retains that alignment as square as possible, eliminating rapid wear and/or failure.

Ok, I understand how the pillar bolt, (chaincase support bolt) supports the inner chaincase.
If I turn to bolt around and use the thick washer to space it off the cradle, it is nearly a perfect length to the outer side of the inner chaincase. it can then be adjusted to suit.

When I do a dummy fit the gearbox shaft isn't centered in the hole of the chaincase.
I can take up most of this misalignement with moving the chaincase up and forward before tightening the 4 bolts.
Then I assume the gearbox has to be loosened and moved to get better centering of the gearbox shaft ????

As the chaincase ends up being heavy when it's complete, and is only positioned by 4 bolts, a pillar bolt and a seal, what stops it from sagging and wearing away the seal on one side ?

Then how do you fellows make sure the gearbox shaft is parrallel with the crankshaft ????

Graeme.

grandpaul said:

If you hope to retain your inner chaincase in good form, without cracking the bosses on the crankcase mounting end, and without distorting the oil sealing face, you MUST first fit up and snug down the pillar bolt, then dry fit (snugly) the bare inner primary case to the crankcase with the appropriate gasket. At this stage, you carefully measure the gap between the outer face of the hexagonal section of the pillar bolt, and the inner face of the primary case, then add as close to that exact dimension as possible in washers/shims.

Click to expand...

Shimming is unnecessary on a MkIII (the actual model in question) as the positioning of the inner half of the MkIII primary case is done using the inner and outer securing nuts which can both be adjusted along the threaded support stud.
First the chaincase support stud is fitted to the cradle, and the MkIII inner case fitted to the crankcase, then the inner and outer chaincase securing nuts are tightened on either side to lock it in position, whilst making sure the case isn't pulled either way as the nuts are finally tightened.
The MkIII inner and outer primary cases are also much stronger and more rigid than the earlier type cases, so the range of "adustment" will be fairly limited.

L.A.B. said:

The assembly as shown in the parts book is probably how it was originally intended to be?

But it works better the way 79x100 has suggested, and that is how it is fitted on my own MkIII.

However, extra packing washers (three?) will probably need to be added between the long hexagon and the cradle, otherwise the nut on the inside of the cradle will run out of thread before the support is pulled tight against the cradle, and there may also be an insuficient amount of thread left protruding into the primary case for the securing nut, if those packing washers are not fitted?

Click to expand...

Make that 3 of us. Mine is set up the way you and 79x100 have it. Mine also had 3 shims or washers and not one thick one.

Also do as others sugges and do a dry fit and make sure everything is spaced out as you don't want the inner primary flexing inward. Like you, I always look for washer marks as that has enabled me to fit a few that I could not remember where they went.

I think the manual illustrates 3 or 4 shim washers. I only used 3.

Coco said:

L.A.B. said:

The assembly as shown in the parts book is probably how it was originally intended to be?

But it works better the way 79x100 has suggested, and that is how it is fitted on my own MkIII.

However, extra packing washers (three?) will probably need to be added between the long hexagon and the cradle, otherwise the nut on the inside of the cradle will run out of thread before the support is pulled tight against the cradle, and there may also be an insuficient amount of thread left protruding into the primary case for the securing nut, if those packing washers are not fitted?

Click to expand...

Make that 3 of us. Mine is set up the way you and 79x100 have it. Mine also had 3 shims or washers and not one thick one.

Also do as others sugges and do a dry fit and make sure everything is spaced out as you don't want the inner primary flexing inward. Like you, I always look for washer marks as that has enabled me to fit a few that I could not remember where they went.I think the manual illustrates 3 or 4 shim washers. I only used 3.

Click to expand...

Should shims (perfectly acceptable ) be used when a bush is avaiable and any slight adjustment may be made up by taking up the slack by adjusting the nuts on the support stud. I also agree that shims are not really required as the adjustment is available at eithet end of the support stud ?

Of four Mark IIIs that I've done 2 didn't need shimming, 2 did.

Wierd, but true.

Mentions being made of "adjustment" is the same thing I'm referring to, I believe. A shim is a shim is a shim... (unless it's a washer?)

grandpaul said:

Mentions being made of "adjustment" is the same thing I'm referring to, I believe. A shim is a shim is a shim... (unless it's a washer?)

Click to expand...

Sorry Paul, but you don't seem to understand what we are saying?

With this arrangement the "shims" or "washers" are there to space the support stud away from the cradle, as they are fitted between the support stud hexagon and the cradle, they are not used to space the inner case out from the cradle, that adjustment is done simply by screwing both the inside and outside chaincase nuts along the threaded support stud.


Here's an ant's eye view of the support stud assembly

(apologies for the poor picture quality, but it wasn't an easy photo to take!)

L.A.B. said:

grandpaul said:

Mentions being made of "adjustment" is the same thing I'm referring to, I believe. A shim is a shim is a shim... (unless it's a washer?)

Click to expand...

Sorry Paul, but you don't seem to understand what we are saying?

With this arrangement the "shims" or "washers" are there to space the support stud away from the cradle, as they are fitted between the support stud hexagon and the cradle, they are not used to space the inner case out from the cradle, that adjustment is done simply by screwing both the inside and outside chaincase nuts along the threaded support stud.

Click to expand...

Hi I guess confusion arises because spacing the the support stud away from the cradle would appear that (without having all the parts in front of me) is no different from supporting the stud away from the chaincase, in essence the overall distance between the two components i.e cradle and case is the important dimension not which end the shim/adjuster nut/bush arrangement is unless this is fixed by the threaded sections of the stud. Anyway this is a long thread for a simple prob One last thing washers srictly speaking are used to spread the load of a threaded fastener shims are not but that is way too pedantic.