860GT Rear Wheel Drum Brake Spacer Quest for Clarification

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rjk40
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860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Wed Jan 23, 2019 12:45 pm

Hi All,

I know that Steve's sketch of spacer in sprocket carrier is for disc brakes, and since I have a drum, I ask for clarification on a certain spacer.

See the three pics at:

https://www.flickr.com/photos/124760992 ... 2723190952

The first pic shows the ringed spacer in the orientation of which it was removed after bearing removal from the brake drum . I believe that this is correct, but a lot on this bike has not been per factory.

The second pic shows the "headed" spacer in between bearings in the sprocket carrier (old bearings shown for reference), with the headed end pointing away from the sprocket, and with the small spacer in between the bearings, slid over the headed spacer. Leftmost is the spacer in question, has a "stepped" hole, the larger end of which fits nicely on the non-headed end of the headed spacer. It would seem to be where it should rest, but I cannot visualize it after the bearings are in. Any help is greatly appreciated. Craig, I'll buy you another dinner if you can help.

The third pic shows the stepped hole on the mystery spacer in closer detail.

Since Steve's sketch of the sprocket carrier assembly is for disc brakes, I seek clarification on the location of the mystery spacer before I press in the new bearings. The 860GT parts manual is not clear on the shape of these spacers, as many of you know.

Thanks kindly in advance.
Regards,
Richard in Florida

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Craig in France
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Craig in France » Thu Jan 24, 2019 1:29 am

rjk40 wrote:
Wed Jan 23, 2019 12:45 pm
I ask for clarification on a certain spacer. <snip> Leftmost is the spacer in question, it has a "stepped" hole, the larger end of which fits nicely on the non-headed end of the headed spacer. The third pic shows the stepped hole on the mystery spacer in closer detail.

It would seem to be where it should rest, but I cannot visualize it after the bearings are in.

I seek clarification on the location of the mystery spacer before I press in the new bearings.
Hi Richard,

Agree, the parts book is simply wrong on this occasion. Seems they lifted the drawing out of the 750 book, rather than draw it again properly.

I think you have it. Going back to basics, the spacer is there to keep the bearing(s) aligned/in the right place/not crushed when the axle nut is done up. To do this, the spacer must bear on the inner races of the two bearings that it separates. As long as it's doing this, it's doing its job.

So if one end fits happily over the headed spacer, then that's the orientation it which it should go.

Also:
Have a look at the photos in the Haynes manual. Now, I'm pretty sure that the relevant photos there, 9:2g and i, where taken during DISASSEMBLY - you can see the cush drive rubbers are still in place whereas in photo 9:2e which is clearly labelled as a reassembly shot, they're not.

So, when you go to put the thing back together again, the sequence of these two photos needs to be reversed. If I'm right that means: bottom bearing - stepped spacer - top bearing- headed sleeve. Attachment below, photos in (what I believe to be ) the correct order.

HTH

Craig
Attachments
860 rear wheel.jpg

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Thu Jan 24, 2019 12:02 pm

Hi Craig,

I am sad to say that the pieces do not fit as I had assumed:

When I position the headed and stepped spacers in their supposed "would be" position once the bearings are installed on their flats, the headed spacer's "head" protrudes over 1/2 inch from the sprocket carrier, whereas 9:2f in the Haynes clearly shows the headed spacer flush under the bearing's flat washer.

When properly positioned without the stepped spacer, the headed spacer fits perfectly into both bearings, flush. I'm beginning to think that I am either going loopy or that I have a spacer that maybe belongs elsewhere. (????)

Three spacers are involved, per my Flickr pics:

1. The headed spacer, which will reach perfectly flush through both bearings when installed
2. The unstepped spacer, which fits perfectly between the two bearing flats, and which slides over the headed spacer
3. The stepped spacer, which throws a monkey wrench into the mix.

Without the stepped spacer, the unstepped spacer properly sits between the bearings, as does the ringed spacer in 9:2d for the other part of the hub, so I am really unable to find a home for the stepped spacer.

Sadly, the parts manual, as you agreed, is harmful to reality; sometimes mislabeled as "mystique"; my 1969 Norton Commando certainly had some of that, like a leather clutch plug washer and Whitworth threads, neither being common here in the U.S. colony.


I am bewildered, still seeking an answer, but I do appreciate your research, and when the mystery is solved will heed your recommendation on the order of reassembly, once I recover from the embarrassment of not taking adequate pics on disassembly.


The quest for enlightenment continues....

Regards,
Richard

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Craig in France
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Craig in France » Fri Jan 25, 2019 4:54 am

rjk40 wrote:
Thu Jan 24, 2019 12:02 pm

Three spacers are involved, per my Flickr pics:

1. The headed spacer, which will reach perfectly flush through both bearings when installed
2. The unstepped spacer, which fits perfectly between the two bearing flats, and which slides over the headed spacer
3. The stepped spacer, which throws a monkey wrench into the mix.

Without the stepped spacer, the unstepped spacer properly sits between the bearings, as does the ringed spacer in 9:2d for the other part of the hub, so I am really unable to find a home for the stepped spacer.
Richard, I think you're suffering from spacer over-inventory! :shock:

I must admit that I thought that what you first described as the 'Stepped Spacer' was in fact the spacer that goes in the hub. But now I see you say you've got one of those as well - your 'Ringed Spacer', unless I'm mistaken? See attachment.

I can't think of a home for a Stepped Spacer. As you say, you've got the right set-up for the cush drive bearings. And you've also got the ring spacer for the hub.

And that should be it.

P.s. Just a small clarification: the job of the 'headed spacer' is to keep the plain spacer where it needs to be. If it wasn't there, the plain spacer would drop out of place, making it very difficult/nigh impossible to put the axle thru. The Haynes calls it a 'sleeve' - and that's about right ;)
Attachments
Rick's spacer.jpg

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Fri Jan 25, 2019 6:51 am

Hi Craig,

Yeah, I have to agree. I have the two spacers that fit correctly between the two sets of bearings, and the sleeve as it's called in the Haynes, is called a bush in the 860 parts manual (yes, it would be a real nightmare to thread the axle without that sleeve holding the spacer in location). I don't see any cause for alarm before putting the four wheel bearings in with their appropriate spacers in between (... and yes, one of them being the ringed spacer, per your query by the pic; the stepped spacer is in the Flicker pics, and is the lonely orphan), and generously greased. I'm just really bamboozled at the presence of that durned stepped piece; it's really got me looking forward to Happy Hour. The darned thing has to go somewhere. Maybe when I start reassembly after the bearings are in, it will become evident.

Thanks kindly for your research.
Looking forward to a France visit again!

Regards,
Richard

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Craig in France
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Craig in France » Sat Jan 26, 2019 12:53 am

rjk40 wrote:
Fri Jan 25, 2019 6:51 am
<snip> the stepped spacer is in the Flicker pics, and is the lonely orphan ... <snip> )I'm just really bamboozled at the presence of that durned stepped piece <snip>
Ok, got you, Richard. (FWIW, the technical name for that feature is a 'counterbore').

Still mystified as to where it came from/where it goes ... :?. Stupid question: it's not a wheel spacer by any chance?
(Altho' even that question engenders another: why would it be counterbored?)
Attachments
860 counterbore.jpg

Vince
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Vince » Sat Jan 26, 2019 2:54 am

Sometimes people make spacers that become captured, stay in place to speed a wheel swop. Who knowns

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Sat Jan 26, 2019 7:00 am

Thanks for the comments, Gentlemen.

Craig, I had forgotten the term "counterbore" as I had not used the process or such a piece of hardware for a long time.

Vince, I am the original owner of the bike, bought it new, and there were never any wheel swaps. There have been some anomalies elsewhere, such as a quite different number of clutch pushrods: 11 instead of the usual 9 or 10 (Craig, you likely remember my thread on this...).

Since I have the proper spacers that fit in between the bearings on both parts of the wheel hub, as well as the same for the front wheel , I can safely proceed install the new bearings and spacers. The orphan certainly does not go in between bearings.

Looking at the questionable drawing in the 860GT parts manual, the rear wheel has three distance pieces:
- # 190 goes outside the wheel assembly between it and the swingarm
- # 185 appears to sit outside the wheel assembly at the sprocket, and it is not clear to me which piece of mine relates to it. Maybe this is the mystery piece.
- #480 is called a distance piece, but in the questionable drawing, looks more like a sleeve.

Again, I hope that one of two things will happen:

1. When I re-assemble it after installing the bearings, all will be well without the "orphan", or:
2. It will become evident as to where the durned thing lives.

Until then, I will continue kicking myself for not doing better 30 years ago at disassembly time, in the documenting of said parts, and still seek an answer to an unsolved mystery.

Regards,
Richard

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Craig in France
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Craig in France » Sat Jan 26, 2019 9:13 am

rjk40 wrote:
Sat Jan 26, 2019 7:00 am
<snip> Looking at the questionable drawing in the 860GT parts manual, the rear wheel has three distance pieces:
- # 190 goes outside the wheel assembly between it and the swingarm
- # 185 appears to sit outside the wheel assembly at the sprocket, and it is not clear to me which piece of mine relates to it. Maybe this is the mystery piece.
- #480 is called a distance piece, but in the questionable drawing, looks more like a sleeve.
Hi Richard,

I think you may very well be right. I kinda assumed that you had the wheel spacers 'put aside' somewhere - i.e your 'stepped spacer' wasn't one of them. But that was an assumption I had no right to make.

Also: I checked up on your 'stepped spacer' with a 750 expert. He said, "I have never seen that part before". And guess what? The 750 doesn't have that kind of wheel spacer ...

Maybe this may help Image

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Sat Jan 26, 2019 10:33 am

Thanks again, Craig,

# 185 may well be the mystery spacer. Too bad the picture of it in the parts manual is so mediocre; it certainly doesn't show a counterbore, even though it could well be that way.

When I disassembled the bike thirty years ago, I kept the pieces loosely grouped by category (engine, tranny, wheels, frame, etc.), so the mystery continues. Then again, this bike has been anomalous in other ways (kinda like the 1975 factory just threw parts together.....).

Once I get the rear wheel assembly together and sitting in the swingarm, it will become evident, hopefully, that the part is truly an orphan and/or that I have also become loopy. If the pieces all line up properly, the sprocket tracks the chain in good alignment with the primary sprocket, and the other side brake cable and torque arm are also lined up properly, I shall the retire this orphan to my "hall of horrors", which has had such items as 1969 Norton Commando valve guides, a transmission mainshaft in two pieces, and a leather clutch plug washer all from same same beast. If there is space on the left side to be accounted for, then the mystery is solved if I can get the orphan to reside properly there.

Also, I really appreciate your checking with a 750 expert as well.

At least it has been deduced that I have the correct spacers that reside between both sets of rear wheel bearings, thus I can proceed to press in the new sealed bearings. Then, on to the next challenge.

Best Regards,
Richard

Vince
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Vince » Sat Jan 26, 2019 4:28 pm

By wheel swop I didnt mean a change to a completely different wheel, I was talking at a pit stop for fast work and having the spacer stay attached to the wheel and a factory part. Just a guess.

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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by ducadini » Sun Jan 27, 2019 12:45 am

From memory now : both the drumbrake and the sprocketcarrier have the inside triangular shaped.
The width of that shape is what keeps the bearings (2 in each) apart, therefore the spacer that is fitted is at least 0.1 mm longer and probably 0.5 mm.
The shape of the spacer on the outside of the carrier isn't important since its only work is to keep the sprocketcarrier from rubbing the swingarm.
Only critical dimensions are inside diameter 17.5 mm, outside diameter corresponding with inside of the seal that is fitted on the outside of outer bearing and the length so it fits between the swingarm.
However, when a PO fitted another axle-carrying spacer (180 on Craig's pic), like that of the 750 which was longer because it would go through the swingarm with Seeley thingies, then that spacer would've been cut shorter AND if not done correctly, the OUTER spacer would have to be modified to fit over it.
If You look closely at Craig's pic, Ducati probably took the 750's drawing and modified it (poorly) : part 180 with red Arrow seems to have a threaded end, just like the 750's had.
I fitted 2RS bearings, with inbuild seal, so the outer seal wouldn't be the only protection for those bearings.
I took the extra friction they created for granted :-D

Measure the space for fitting the bearings, measure the spacers that should go between them and when that's correct (or nearly correct Italian style) fit everything and ride the bike :vroom:

ciao
ducadini
Nego i ricordi peggiori
Richiamo i migliori pensieri

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Sun Jan 27, 2019 6:43 am

Hi Ducadini,

The spacers that go in between the two triangular spaces is established; they each meet perfectly with the flats that the bearings sit against, thus they will properly function.

The large spacer (# 190) sits between the brake drum and the swingarm.

No spacers of mine have any threaded ends.

I am installing new bearings from Steve at Bevel Heaven (6, two for front hubs, and 4 for the rear...); all are sealed bearings.

Hopefully all will become evident once I have installed the bearings and reassemble the rear wheel assembly.

Thanks for the info.

Regards,
Richard

rjk40
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by rjk40 » Sun Jan 27, 2019 11:09 am

Gentlemen,

I may have deduced the answer to my question and hoisted on my own petard as a result.

The "mystery" piece, now likely identified as #185 in the infamous 860GT parts manual, has an outside diameter that exactly matches the outside of the inner race of the sprocket bearing(s). This would make sense, as it will keep the bearing from contacting the inside of the swingarm on that side. I hope that this is true, as it makes sense, and I cannot find any other way to keep that bearing from colliding with the swingarm inner face on that side. Hopefully, the chain will then track properly on both sprockets, and the wheel will spin nicely on the axle when mounted into the swingarm.

I will likely be pressing in the new bearings on the morrow, and shortly thereafter will be assembling the unit to temporarily store it back on the swingarm until I get the new spokes and rims. If all works, you will likely hear (even from thousands of miles away...) the sound of me hitting my ever-flattening forehead for being so inept at documenting things in the past.

Thanks to Craig, Vince, and Ducadini for your efforts.

Regards,
Richard (semi-lucid in Florida)

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Craig in France
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Re: 860GT Rear Wheel Drum Brake Spacer Quest for Clarification

Post by Craig in France » Mon Jan 28, 2019 12:45 am

rjk40 wrote:
Sun Jan 27, 2019 11:09 am
The "mystery" piece, now likely identified as #185 in the infamous 860GT parts manual, has an outside diameter that exactly matches the outside of the inner race of the sprocket bearing(s). This would make sense, as it will keep the bearing from contacting the inside of the swingarm on that side.
It might also explain why it's counter-bored. Are the ends of your axle, the threaded part, a smaller diameter than the unthreaded length? If they are, you may very well find that they fit into the counterbore of the spacer.

Just a thought ...
Attachments
860 rear wheel 6.jpg

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