8 inch conical wheel gap at fork leg

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Bigden28
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8 inch conical wheel gap at fork leg

Post by Bigden28 »

Hi all
I have a problem with my front wheel. Everything is standard but I've ended up with a gap between thw edge of the distance piece and the inside of the fork leg (see pics). Has any one else had this????????? :cry:

Thanks
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Re: 8 inch conical wheel gap at fork leg

Post by minetymenace »

mmmmm <201

37-3932 Description: Distance piece - front wheel spindle, inner side right bearing

see this drawing here item 9 I think.

Should go on the other side (RHS as you are sitting on the bike), inboard of the bearing and should not be visable on the outside on the left (or at all as it should be within the hub)!

Hope I'm right!
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Re: 8 inch conical wheel gap at fork leg

Post by Bigden28 »

Hmmm indeed. Here is the Triumph parts book. Item 17
T25SS parts book 1.jpg
T25SS parts book 2.jpg
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Re: 8 inch conical wheel gap at fork leg

Post by minetymenace »

Just checked my Trumpet book, and it’s the same as the BSA, so I'm guessing your book is wrong. I have a couple of bikes with comical front hubs (Meriden and Small Heath), both are as this site.

The wheel assembly is centred on the axle by the various shoulders, spacers, circlip and bearing retainer then the brake plate is held in place by a nut. The whole lot (wheel, axle, brake plate et al) then would float between the forks but for the brake anchor on the right hand side. The clamp on the left has no precise lateral positive location (I don't count the annular groove which is there to assists assembly). There is therefore no reason for a spacer between the left hand side of the wheel and the left hand fork leg as in your drawing. The draughtsman probably has his mind on the strike rather than his work, trust the BSA every time!

However the fact that no one else has seconded my thoughts might indicate that I am wrong :???:
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Re: 8 inch conical wheel gap at fork leg

Post by skippy »

I'll second that apart from a little grease and dirt.
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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

as far as i'm concerned, regarding the front wheel, the Haynes manual and the BSA factory workshop manual are both correct.
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

I think some of the confusion was caused by Triumph including the distance piece (W3932) which is missing from the BSA conical wheel. As far as I can tell, nobody can work out what it did on the Triumphs as it didn't serve the purpose of either a spacer or a dust cover. I think most Triumph owners simply leave it off.
1971 B25T x 2
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Re: 8 inch conical wheel gap at fork leg

Post by minetymenace »

but you must put a spacer behind the RH bearing otherwise the wheel will flop about.
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

I notice that the spacer 37-3932 was only present in the 1972 8" conical hub but not in the 1971 version, according to the database. All my B25/b50's have 6" hubs but I wonder why this spacer was necessary - why didn't they just machine the shoulder on the axle to suit? If the database is correct, why was the spacer only necessary in 1972?

Interestingly, I've just looked at the Triumph version in a bit more detail and I think they simply drew the diagram of the 8" conical hub wrongly. Triumph part number W3932 equates to 37-3932 and I think they simply drew it on the wrong end of the axle.

It seems many Triumph owners were very confused by this parts diagram and so tried to add a spacer on the LHS of the axle when it was never in the design.
1971 B25T x 2
1971 B50T
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

Just taken a 1971 8" hub apart and, as per the database, there was no spacer behind the RH bearing, just the circlip. I wonder why the spacer was added in 1972? The parts drawings appear to be exactly the same except for the spacer and the bearings are the same.
1971 B25T x 2
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Re: 8 inch conical wheel gap at fork leg

Post by Bigden28 »

Thanks for all the help everyone.
Just to add to the confusion my 1971 parts book for the B25SS lists the distance piece but doesn't show it on the diagram :?:
B25SS parts book 1.jpg
B25SS parts book 2.jpg
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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

a problem can arise when we build a wheel from a box of parts of unknown origin, ie; disc brake spindle into a drum hub.
i had comical problems some time ago. so i had (what i thought was) a good look at it and wrote up a description. this is copied from my notes:

"to the best of my knowledge,

THE COMPONENTS:

(this is not an assembly guide), left to right, that is, opposite side to the brake, towards the brake, are;


circlip - that fits in the hub, in a groove. the groove is quite often damaged by bearing removal and insertion.

outer dustcap/ grease retainer - this has a rolled lip on the inner hole and the outer edge,
the lips go to the inside of the hub, the flat side up against the circlip.
(note: make sure the inner lip does not touch the inner ring of the bearing)

the bearing (hoffman 120 - 20mm-47mm-14mm. all bearings in conical hubs are the same)

inner grease retainer/dustcap, this one only has a rolled lip on the outer edge, the edge that meets with the hub.


the rest of the components are on the right side of the wheel.
starting from the left (inner) side. here the axle has a step machined in it, the diameter is still the same.

a bearing abutment ring/spacer slips on the axle from the right (threaded end), and rests against the "step".

at this point let me say, that if your wheel was approximately 3/16" or 4.5 to 4.6mm to far to the left,
then perhaps this ring/spacer was/is missing.

next is a grease retainer/dustcap which has no rolled lips but is dished.
this bears against the circlip but not the abutment ring. ie, to the hub not the axle.

next is the bearing,
the centre ring bears against the abutment ring and the outer ring against the grease retainer.

next is the bearing retaining ring (sometimes called the outer dustcap/grease retainer).
which screws into the hub with a lefthanded thread, ie. counter clockwise.

then we have the brake plate.

and finally, the backing plate locknut, which screws onto the axle with a righthanded thread (normal - clockwise).

once again i stress. this is not how to assemble. the best explaination of that procedure is
in the factory and the haynes manuals, in my opinion.


ALIGNMENT:
my thoughts on the alignment of the front wheel are;

the alignment of the front wheel in the forks is all dependant on the right bearing being in the correct position.
this can be affected in 2 ways.

firstly,on it's outer ring by the distance between the circlip and the bearing (ie, the thickness of the grease retainer).
and secondly, on the inner ring of the bearing, by the thickness of the bearing abutment ring.

so, when we think about it.
on the righthand side we have, the axle, the bearings inner ring and the brake plate all locked together and stationary.
so, theoretically, as long as the abutment ring is on the axle and the grease retainer is present between the circlip and
the righthand bearings outer ring, then the alignment should be ok, and brake function should be ok also.

i do not believe that anything on the lefthand side matters. i think as long as you loc-tite the bearing to the hub and
the bearing to the axle, all will be ok.
in fact if the circlip groove on the lefthand side of the hub is damaged, which it often is during bearing replacement and
is irrepairable. then a sealed bearing could be used, dispensing with the need for a dustcap/grease retainer on the outside
of the bearing.
a spacer (similar to the bearing abutment ring, but of a calculated length) could be slipped over the end of the axle,
between the fork stanchion and the bearing, to be safe."

i hope this makes sense and helps someone.

steve
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

Bigden.
You are absolutely right. My 1971 parts catalogue shows 4 parts at the bottom of the parts list which it indicates are not illustrated. In addition to the spacer, it also lists the return spring 37-4014 for the brake lever which is shown on the 1972 diagram.

Steve m.
This is all academic for me because all my B25/B50 are in T or MX configuration. I have the 1971 SS wheel because that was fitted to one of my B25's when I got it.

Nevertheless, the implication of all this is that the spacer should probably be present on both the 1971 and 1972 8" hubs. At face value, it looks like the spacer must have been a late mod (after the 1971 drawing has been produced) to, perhaps, adjust the lateral position of the axle after it had been designed for some reason. I could well imagine that it was far cheaper to add a spacer rather than re-machine or change the machining of the axles.

However, this doesn't not completely stack up because if they had done this then the thread on the right-hand end of the axle would have been 3/16" too short.

I think I'll have another look at my SS wheel, which doesn't have the spacer, and see whether there is a problem with its lateral positioning between the forks.
1971 B25T x 2
1971 B50T
1973 B50MX
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

I stand corrected - my 1971 8" hub does have the spacer 37-3932 - just didn't notice it when I pulled the hub apart yesterday.

Clearly a late mod to the axle design adjusting the position of the shoulder against which the right-hand bearing is positioned - almost certainly cheaper to add the spacer than to scrap axles that had already been manufactured.
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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

AWJD wrote:Clearly a late mod to the axle design
quite possible and possibly late but still pre-production. the wheel i used for that write up was untouched, from a July '71 B50SS (4 years old when i bought it).

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Re: 8 inch conical wheel gap at fork leg

Post by minetymenace »

mod or fup?
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Re: 8 inch conical wheel gap at fork leg

Post by AWJD »

I was trying to be polite!
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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

could have been either...as we know. :roll:
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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

that Trumpy drawing looks bloody awful. has anyone ever seen that spacer on the lefthand side actually on a wheel on a bike :?:
even though Bigden28 has solved his problem(i hope). i'll post a couple of pictures here today so we can all see things proper like.

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Re: 8 inch conical wheel gap at fork leg

Post by steve m »

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Re: 8 inch conical wheel gap at fork leg

Post by Barry Creary »

Very nice detail Steve <127
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Re: 8 inch conical wheel gap at fork leg

Post by Bigden28 »

Well done Steve. Looks like you've solved it. :ban
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Re: 8 inch conical wheel gap at fork leg

Post by skippy »

Well documented Steve, that sort of thing will be helpful in the future.
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Re: 8 inch conical wheel gap at fork leg

Post by bbenxe »

To resurrect an old topic...I have come across this issue myself, but I do have the abutment ring inside...

I have verified the RH bearing is against the inner circlip, and that the abutment ring is between the spindle shoulder and bearing inner race. The abutment ring is 4.6mm deep.

I am using sealed bearings but included the grease retainer between circlip and RH bearing as this is part of the hub alignment.

I have removed the spindle and compared to another: some cosmetic variations but vital dimensions the same (although one a little worn). Both came out of wheels I disassembled and had the abutment ring inside originally.

I think that's all of the 'gotchas' but my brake plate still sits away from the leg!!

I can see that I could solve the issue by using two of the abutment rings, but something doesn't feel right about that...

What have I missed? I'm pulling my hair out!
20200425_150245 (1).jpg
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Re: 8 inch conical wheel gap at fork leg

Post by madsundaysurvivor »

Hello bbenxe,
I have never assembled a conical brake drum, but yes others similar and sometimes I have found similar problems.

thinks about the forks shaft and check that they are straight, may be they had an small crash, a slight bend from the triple clamp part can easily be a centimeter at the height of the wheel axis
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Re: 8 inch conical wheel gap at fork leg

Post by bbenxe »

Good point madsunday survivor - the stanchions are new and straight though. The yokes could be bent, but as the gap between the outer studs on the forks aligns with the indents on the spindle I believe this is not the case.

Dissembled the hub again this morning for triple checking. Here's a photo taken from the left, showing the grease cover against the RH inner circlip, and the RH bearing against that as it should be so I'm still perplexed.
20200426_124047.jpg
I am now going to re-assemble using two abutment ring spacers on the spindle as although this feels wrong, I believe it will solve my problem. The rim is offset relative to the forks by the same distance as the hub is offset to the anchor attachment so I believe this is a more or less satisfactory solution to move the whole lot slightly to the right.

I would be grateful if someone could verify some measurements I've taken of my spindle to see if that is where the problem lies. Please excuse my childlike garage scrawls.

EDIT: I NO LONGER NEED THESE MEASUREMENTS

My spindle measures:

-30.3 mm from shoulder to the end of the section on which the bearing sits.
-73.2 from shoulder to the centre of the indent in the spindle for the outer fork studs. (This is the key measurement I believe)
-83mm from shoulder to end of spindle
20200426_125934.jpg
The only other measurement I think that could be wrong is the positioning of the circlip within the hub. Measuring from the left as in the below pictures the circlip is 82mm from the lip of hub. This is probably better measured from the right but I am reluctant to disturb the RH bearing again now it is nicely seated.
20200426_130710.jpg
20200426_130656.jpg
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Re: 8 inch conical wheel gap at fork leg

Post by bbenxe »

Well the cause (but not the solution yet) was staring me in the face.

I'm confident everything hub and spindle related is correct. Moving the spindle between the fork legs gets me closer but the brake plate nut is contacting the slider before the anchor.

These two points of the slider are in a plane:
20200426_154756 (1).jpg
However these two points on the brake plate (base of anchor stud and top of brake plate nut) are not. The nut must be at the same height or lower than the base of the anchor stud if the stud is to butt up against the stanchion at the upper point:
20200426_154938.jpg
So, the solution? I'm not sure...

-A slimmer nut? I have two, one is 6.5mm tall, and one is 6.2mm. I was already using the slimmer of the two.
-Machine the brake plate so the nut screws in further? Not very appealing.
-Machine the stanchion and fork cap so the doesn't hit these parts first. Again, not very appealing.
-Put a 2.2mm washer on the stud between stanchion and brake plate. Seems the simplest!

Still not entirely what has gone wrong that this problem has surfaced. But I will be using the washer in the meantime.

Interested to hear any possibilities!
'71 BSA B50 street scrambler, '75 Bultaco 250 flat tracker racing as #404 in the UK DTRA National and European series
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Re: 8 inch conical wheel gap at fork leg

Post by bbenxe »

It seems the problem lies with the casting/machining of my brake plate. That or someone has been let loose on it.

The recess for the brake plate nut is only 4.5mm deep on mine, meaning the nut which is 6.2mm stands proud of the recess. A friend has measured theirs at 6.5mm deep.

The raised area of the plate that holds the anchor stud and shout touch the slider is 2.5mm proud of the rest of the plate on mine. On the same friend's, theirs is proud by 5mm.

All adds up to why my brake plate nut hits the slider before the brake plate, and so looks like a washer to fill the gap will have to be the solution!

I hope this proves useful to someone else in the future - a missing abutment ring is not the only possible cause of a 3mm gap between brake plate and slider, your plate itself could be amiss too...
'71 BSA B50 street scrambler, '75 Bultaco 250 flat tracker racing as #404 in the UK DTRA National and European series
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