The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: RogerSB on 27.05. 2019 16:17
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Hi everyone,
Yesterday evening I started my forks overhaul. Things went fairly easily until I tried to remove the first oil seal holder, no way, tried & tried, applied a little heat from hot air gun, strap wrench, but eventually I had to carefully (without damaging the thread) take a hack saw to it (see photo). The problem was that someone in the past had completely destroyed the internal slots so the removal tool just rode up two nice ramps and slid around. Also they were stuck with some type of thread locking compound. Happily the other holder was ok and I managed to unscrew that one fairly easily with the tool. So new oil seal holders *sad2*.
As I suspected the springs definitely need replacing, they’re either poor repro or very tired. They look ok, clean and without any sign of rust but one measures 10 1/2” the other 10 5/8”. However, although I thought I may have to replace the stanchions and bushes they seem ok (well, to me they do). There isn’t any scoring and both top bushes slide up and down the stanchions smoothly with no detectable play. There’s is a polished shiny patch, just above the oil holes, on both stanchions and on one there is a mark running part way around the circumference, which I can just detect when I run a finger tip over it but it’s not cracked or pitted. I imagine it was the start of some corrosion at sometime in the past when the bike was laid up or standing idle for a length of time, but luckily caught and arrested in time. It can be seen near the bottom bush in photo no 2.
I’m fairly competent and happy to take things apart and put back together again, having spent a lifetime doing it, but I’ve not got any engineering facilities (but I have got a M&W vernier gauge *smile*) nor am I a trained mechanic or engineer. I know it’s difficult to judge from photos, but any comments, confirmation (or not) of my observations would, as always, be welcome.
Roger.
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Some of the best I've seen, usually they are well pitted and gouged. Light scoring is of no real consequence, and if the seals did not leak before, I would use the legs with no worries.
Check for bowed legs by rolling on a flat surface, wash the sliders out, and test fit the new oil seal holders on the sliders first..no fun struggling to get the threads to mate after you have got the top bush circlip in place and they don't fit. Take care with the threads, they cross easily, and a smear of silicone or hylomar will seal them and retain any weeping oil within the holder.
Use the bottom yoke pinch bolt as a clamp to hold the leg still when you tighten the bottom bush nut.
Swarfy.
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Some of the best I've seen, usually they are well pitted and gouged. Light scoring is of no real consequence, and if the seals did not leak before, I would use the legs with no worries.
Check for bowed legs by rolling on a flat surface, wash the sliders out, and test fit the new oil seal holders on the sliders first..no fun struggling to get the threads to mate after you have got the top bush circlip in place and they don't fit. Take care with the threads, they cross easily.
Use the bottom yoke to hold the leg still when you tighten the bottom bush nut.
Swarfy.
Thanks Swarfy, that's encouraging and, as always, you come up with some good advice, like temporarily clamping the stanchions in the yoke to tighten the nut (I never thought of that to undo) and I used my vice with an old towel around them. Luckily both nuts unscrewed easily. Yep! I'm going to be careful buying the oil seal holders as I've heard some don't have the slots inside to be able to use the tool.
I've stripped and rebuilt a few Brit bikes in the past - but that was many years ago and details get forgotten. Here's photos of a D1 Bantam I restored in the 80s and used as my everyday commuter transport to and fro the city of Plymouth. I was light and great for that, especially in the ice and snow. The young lad in the photo is my son (now nearly 50 *eek* ). Parked in the background is my dark green 1950 Austin Devon and pale blue 1963 Morris 1000. Both cars were restored by me. The Austin Devon was used in one of the Miss Marples series.
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I bought some seal holders from dragonfly and they had different diameter slots for the tool to the oem ones, so the standard tool would not work anyway, I’ve since read this is not unusual.
A patch of chrome fell off within a year so I’d buy stainless next time.
I use ptfe plumbing tape twisted to form a piece of string (I think bsa might have used string or hemp) to act as a seal at the very bottom of the seal holder thread. I don’t wrap it around the actual thread in true plumbing style, i don’t use any sealant glue, this is so the next owner will not struggle to get the holders off *eek* in my limited experience oil leaks at the thread are not common and probably mean something else is not right.
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I have not used them yet but got a stainless set of oil seal holders from Barleycorn, they look really good, the price was right, Simon is helpful and was local. The old ones still look OK and I could not get them off and did not want to cut still good holders, so the new ones are in a box awaiting the demise of the old ones.
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I've had BSA's (A7, B31, GS, M21 etc for over 50 yrs and rebuilt many of their forks without problems. Until my GF. New S/S holders (because I was getting tired of replacing rusting chrome ones on my other bikes) and one leaks at the thread, even with PTFE. Problem sorted now - it no longer leaks because it's run out of oil. Frankly, after all the hassle I've had with that bike I can't be bothered to fix it. After the oil problem I put it at the back of the shed and there it stays. But to the issue of fork seal holders - as I said, I can't be bothered to look into the leak on the GF, but if I did I was wondering whether the recess for the seal could be too deep, meaning the thread bottoms out before the seal is compressed against the fork slider. Anyone experienced this?
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Funny that you mentioned that RD. I realised that checking the relative depths of the slider and holder threads on my forks, only the friction of the seal in the holder kept it in place, and with the leg moving like a fiddler's elbow (a less crude expression of the old in out), there was a good chance the seal would dislodge and move up and down. I made thick section thin wall aluminium washer which supported the seal on the deflection stroke.
Took a bit of experimentation to get the thickness right to support the seal gently, while allowing the holder to screw fully home so that the washer was clamped between the bottom face of the seal and the top of the slider. I thought it an improvement, and for all I know the seal moving could be the reason they weep on many bikes. Touch wood, no leaks.
Swarfy.
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Done a trial fit of the top bushes this morning to know what shim sizes I need to get. I used a pair long nose locking pliers with a cable tie to protect the threads and clamped the end of the circlip in place, then worked around pushing it down into the grove. Took about 30 seconds for each fork leg. But that was after spending an hour late last night trying to do it with just a screwdriver. Lost the clip several times when it shot off like a bullet and I must have spent half the time looking for it amongst the other stuff in my garage. Hope it's as easy with the stanchions etc in place.
Regarding oil seal holders: I was planing to buy stainless steel ones but the supplier I want to use is out of stock at the moment. That's Monty's Classic Motorcycle Workshop in Cornwall. Monty is also a former marine so I like to support him when possible. Also at the same time I want to buy fork springs, a rear sprocket, sprocket bearings and a few other bits and I can drive there and see what I'm buying. He has chrome ones in stock, which are made by LF Harris, in Torquay (who started building Triumph Motorcycles again in the early 80s after Meriden closed), so they should be high quality.
I have a pair of NOS Halls NA181 oil seals with metal bodies that I'm going to use. Could it be the new all plastic ones that are now generally available that are not deep enough and causing problems?
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Swarfy – glad to see someone else thinks along the same lines. From an engineering point of view, shouldn’t the holder clamp the seal before bottoming out on the thread? That’s what I intend doing in future.
And as for shimming the top bush – that’s another ‘director’s girlfriend’ design. The way it’s made you can’t get it tight because if you took up all the slack the circlip wouldn’t go in. For the design to work the circlip would either need to be a flat one, or located at far less than half its wire thickness. In the latter case the bush could easily push the circlip out. Wonderful.
*pull hair out*
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RD. Yes, but the seal would be clamped slightly in compression as the holder bottoms against the slider shoulder. Otherwise you will get a gap between shoulder and holder. Closing this gap will squash the seal, so your washer needs to be just thick enough to prevent the seal moving, but still allow the holder to screw down to the slider shoulder.
I greased everything and put a dab of body filler in the gap between the bottom of the seal and the top of the slider, then tightened down the holder. The cured filler came out easily because of the grease, and gave me the basic height of the required spacer washer.
Blame the cost accountants for the wire circlip. A conventional flat internal circlip would do a better job, and be less hassle to service.
Swarfy
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The circlips are a pain but you can replace them with the A65 damper rod fork spacer which goes between the top bush and the lower edge of the oil seal. part 68 5134
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Julian Once more you brought the Cavalry. Just had a look at Drags parts list for 1966, there it is, described as a Widgett, around £10 each. No wonder they have excellent stock. Fork or seal spacer would be a better description.
I made my support washers long before the luxury of internet parts searches, but even so never considered an official part like this would ever exist.
Thanks once more for your attention to detail.
Swarfy.
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This thread is full of useful information and tips! Thanks guys.
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The circlips are a pain but you can replace them with the A65 damper rod fork spacer which goes between the top bush and the lower edge of the oil seal. part 68 5134
As soon as I saw your post Julian I remembered reading about that somewhere *eek* but where? Eventually I remembered - it was on here! *conf*
https://www.a7a10.net/forum/index.php?topic=10447.msg77762#msg77762
Reply no 7 by jjbsa in 2016.
(Edit) I see feked.com sells them:-
Fork Retaining Ring/Cup - B25, B40, B44, A7, A10, A50, A65 + Triumph TR25W
OEM: 68-5134, 97-2643
£4.25 (add vat + pp).
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I'm going to give the retaining cups a try. Just ordered 2 from feked and with vat and 2nd class post cost £12.54.
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I'm going to give the retaining cups a try. Just ordered 2 from feked and with vat and 2nd class post cost £12.54.
I'd like a report about using them please.
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Anywhere else stock them at a reasonable price? Stopped buying from feked unless I really have to as I'm tired of being ripped off with their postal charges.
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Will certainly do, GB.
RDfella, I've wanted to buy from them before but quit out because of the high postage shown, but they automatically default your order to priority postage. At the checkout stage to the left (somewhere) there's a selection of postal choices, including 1st Class and 2nd Class. As I'm no hurry for them (driving to Monty's tomorrow for fork bits and still lots to do) I opted for 2nd at £1.95 (see the order picture).
Also British Bike Bits (Burtons) have them for £5.94 each plus postage.
https://www.britishbikebits.com/fork-retaining-ring-cup-bsa-triumph
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A50 / A65 Fork bush retainer cup placed on A10 fork leg to see how it fits. Plenty of inner diameter clearance for stanchions, in my case a 0.010" shim under it to take up all up and down movement of bush. Top is slightly bigger in diameter than threads on fork leg (so a little filing needed) and thickness is 1mm - so should be a good tight fit up against the oil seal. Takes seconds to fit.
Collected the bits I need from Monty's Classic Motorcycles on Thursday evening and had the foresight to take one of my fork legs with me and a good job too as the last pair of oil seals he had one of them wouldn't screw on the fork leg as there was a some unwanted chrome on the thread. Now waiting for a pair of stainless steel ones to arrive from Barleycorn. That is another story, which I'll tell later when more time.
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So, to check my understanding: you can use these instead of the orrible circlip?
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So, to check my understanding: you can use these instead of the orrible circlip?
Hi GB,
For what I can tell at the moment the answer would be yes. All they do is squeeze-fit between the the top of the bush (no circlip needed) and the oil seal to hold everything securely in place. Shims just go on top of the bush (so under under the retainer), as necessary, to take up any movement. Literally they just drop in place in a second or two. What I can't do at the moment is screw an oil seal holder, with seal fitted, all the way down on the fork leg threads to squeeze the retainer between seal and bush to see if it goes all the way down and close the gap between fork leg and oil seal holder, but I don't envisage a problem. It has a convoluted shape so it may be designed to compress as required. As mentioned the retainer's material thickness is 1 mm and the lip sits on the top of the fork leg - so that increases the measurement from the bottom of fork leg thread to top by 1mm, which may be a good thing to hold the seal tightly in place.
I'll be able to let you know when I get the oil seal holders and try it.
If Julian says they can be used - they can be used.
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Spent some time filing the bush retaining cups to fit my A10s fork legs today. Had to file about .5 mm all round the circumference of the larger end for them to pass comfortably past the threads in an oil seal holder and I also eased out the smaller end to give a similar clearance between it and the stanchion, as I don't want to risk it touching and scraping the stanchions when they move up and down. Whether it's the same old story with reproduction parts *dunno* but whether spending time filing them to make them fit is any quicker or easier than struggling with the circlips I'm not so sure :!, especially as I found a fairly easy way to fit the circlips after struggling initially to fit one for an hour without success. Anyway, maybe a worthwhile exercise. Now waiting for my new oil seal holders before I can make any further progress. In the meantime I've started to dismantle the gearbox to check it.
As I'm just a self taught amateur mechanic through a lifetime of working on my own British motorcycles and classic cars and with no engineering experience I've posted a photo showing the clearance I've made and would welcome opinions by those more qualified.
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The widget should self centre when all assembled - the outer diameter of widget and seal should be just about the same so that widget is automatically centred by the seal holder and cannot touch the fork shaft.
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especially as I found a fairly easy way to fit the circlips after struggling initially to fit one for an hour without success..
Hi Roger, could you recap the easy way to fit the circlips please *smile* I have to do this soon....cheers
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Hi Roger, could you recap the easy way to fit the circlips please *smile* I have to do this soon....cheers
Hi Jules, described in my reply 7 of this topic. Once the end is clamped in place I pushed the circlip down with with a screwdriver starting from the clamped end first. Went in fairly easy - but that was without a stanchion getting in the way.
The widget should self centre when all assembled - the outer diameter of widget and seal should be just about the same so that widget is automatically centred by the seal holder and cannot touch the fork shaft.
Spot on Julian, when pointed out it becomes so obvious - but pity I never realised that before I started filing *sad2*. I was a little peeved at them being a bigger diameter than the fork leg threads and then I got carried away with the file (and lack of engineering skill). I did also open up the centre to give plenty of clearance to the stanchion and when it gets clamped up tight between bush and the oil seal I'm hoping it'll stay put. Oil seal holders were delivered yesterday so I'm going to fit forks today (hopefully).
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Progress so far: Forks assembled today and starting to connect the wiring in the nacelle.
The fork bush retaining cup (widget) was very easy to fit and everything went together well, slid the oil seal holders on stanchions, then retainer cups, shims, top bearings, bottom bearings, clamped stanchions in the yokes to tighten bottom nut, PTFE around fork leg threads and a couple of turns of string in the grove and screwed it together with an oil seal holder tool.
When I ordered the stainless steel oil seal holders from Barleycorn Engineering Simon said he'll be honest and warn me that some have had a problem with them not screwing on their BSA's fork legs. He told me he’s invested a lot of money in a business partnership with a multi million pound manufacturing company near him to manufacture them, only to have problems with the threads not being the right size for some fork legs. With some there's been no problem and happy BSA owners. Puzzled and concerned by this variation, he got together with the company he's been working with and they have carried out some tests and investigations and discovered there is a variation of seven thou in the thread diameter on bikes made by BSA in the mid 60's to the ones made in the early 50s. I can't remember if he said early 50's were the smaller or the other way around.
With my agreement he has used the oil seal holders I bought from him as a test (that’s why it’s taken so long for me to get them). His idea was to open up the thread slightly to try to eliminate the problem by making 'a one size fits all' as it's better for them to screw on easily than being too tight or not fit at all. As it seems to be successful in my case his plans are to do the same for the others he has.
(Edit): Referring to the above: Is this why this seller is making such a bold statement in the description?
https://www.ebay.co.uk/itm/BSA-CHROME-FORK-OIL-SEAL-HOLDERS-BSA-A-B-C-models-29-5310-Made-in-ENGLAND-S-S/282536850999?hash=item41c8823637:g:dXUAAOSwPYZU8X~C
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G'day Roger
Mine must have been in the Fing tight/not fit batch. I dread the day I have to get them back off.
Cheers
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I've had more trouble with the chrome ones. Not only do they eventually rust, but the fit is invariably all over the shop. One size fits nothing would be appropriate, in this case usually caused by varying thicknesses of chrome in the threads. PITA.
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Hi Julian/Roger, I'm interested in looking at these for my '56 A10, but for the life of me when I google them and look at the assy diagrams from Draganfly et al for A65 I cant see where/how they fit, maybe they were only used for a short time or something?.....what am I missing here, are they that obvious how they fit and why cant I see them on the assy diagrams from Draganfly etc?? Apologies if I'm being dense here *sad2*...
I think you are saying that they simply replace the circlip because they actually crush into place hence do away with shimming too, is that right??
can you share an assy diagram and process please...thanks
PS I did notice in the Draganfly schematics that they have an "oil scraper" that seems to fit over the seal too, is that usable on A10, (could be a useful dust seal)??
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The widget was used in 1966- 1968 A65 forks, plus the B25 B44 with damper rod forks.
See this diagram, it is item 24.
www.draganfly.co.uk/index.php/bsa/bsa/a50-a-a65/1966/category/254-front-forks
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I think you are saying that they simply replace the circlip because they actually crush into place hence do away with shimming too, is that right??
Jules, when I placed a top bush, with a retaining cup/widgett resting on the top of each fork leg in turn and holding the widgett down tightly I could still move the bushes up and down slightly with a finger of my other hand - so they wouldn't have been tight between the top of a bush and an oil seal. One widgett needed 0.010" shim, the other 0.020". This was achieved by trial and error to take up all the free play but making sure the widgetts were still tight on the top of each fork leg. Maybe it was the quality of the F---d widgetts I bought because they were definitely bigger in diameter than the fork leg threads. No way would they have gone past the threads in an oil seal holder. Hence my over exuberance with a file *eek*, but with the oil seal holder screwed down and then (with *bright idea* must be a technique worthy of a mention in any good engineering manual) I vigorously shook each assembled fork and I didn't detect anything rattling inside *clap* - so presuming a tight assembly.
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got it, thanks....still seems odd to me though that it needed a circlip to hold the bush down before, but now it doesn't, how does the widget achieve the same function? surely its just the screwing down of the seal holder onto the widget which in turn loads the bush, so why do you need a circlip on A10 at all, when screwing down the seal holder achieves the same end?? OR does it?? cheers
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Jules - there is a gap between bush and seal. The widget fills in that gap so the seal holder retains the bush instead of the circlip.
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Jules, you are right. The problem is that the widget will be a simple pressing, and in an ideal world each would be perfect. These days any so called new stock may not be quite as perfect as it should be, and luckily Roger realised his set needed a shim to clamp the bush, which itself may not have been as perfect as it should have been.
Ideally, the widget should be deep enough to bridge the distance between the top of the bush and the bottom of the seal when the oil seal holder is finally tightened down, and collapse slightly to exert force to hold bush and seal in place. The thickness of the seal also has to be considered, some are marginally too shallow.
Swarfy.
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Photo is cross section of A65 type damper rod fork and shows the position of the widget. Ignore the damper valve and position of bleed holes shown, they dont apply to the A10.
Fit is not always perfect, there can be some slight variation in depth of seat in the slider for top bush and also in the thickness of the lip on the top bush.
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These days any so called new stock may not be quite as perfect as it should be,
Swarfy.
Too right Swarfy!
When I bought and picked up my bits to overhaul my A10s fork legs I also bought a rear 42T sprocket stamped 'Made in the UK' to replace the one on my bike because its teeth had lost their chunky roundness and I decided on an imported rubber sealed bearing to go with it because the difference in price was £8.33 for an imported bearing or £25.00 for a UK made one. When I got home I tried the fit of the bearing in the sprocket, not to actually fit it but just out of curiosity - like you do and to my surprise it just fell in the hole. Assuming the imported bearing was at fault it was a phone call and a drive back to Monty's Classic Motorcycles. Luckily I took both sprocket and bearing with me. When I arrived Monty had already fitted the same type of bearing in the same type of sprocket, as a test. He told me he had to press it in. I turned the sprocket I had taken with me, with the bearing in hole, upside down on the counter and the bearing dropped out. Puzzled, Monty got another bearing and tried that in the sprocket, it was loose. So it was the sprocket that was made in the UK that was at fault. Monty's comment was, with a *eek* look, 'Imported bearing fine, UK made sprocket not'. He also said he doesn't get too many problems like this with Triumph parts (which he tends to concentrate on more) and the reason is that all the drawings for Triumphs have been saved but when BSA closed down the workmen went in and trashed everything and the engineering drawings were burnt. How true? I tend to believe Monty, maybe somebody on here will know for definite. If it is the case it may help to explain why we have so many problems with re-manufactured parts.
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My new sprocket experience was a bit different - the bearing/sprocket fit was so tight the bearing just would not fit. Tried bearing in a new old stock sprocket and it fitted perfectly.
Such significant variations in the sprockets are a quality control issue for the manufacturer.
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Roger - Can’t see that lack of drawings is the reason. If you are making a part but don’t have the drawing, you don’t just makes holes any size – you find out what the hole is for and make the size accordingly.
Problem is more likely due to the UK fast becoming a 3rd world country. All the engineering we once had has been relocated to the EU, assisted by massive EU grants and sweetners.
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JulianS same here with bearing , brother had to take a bit out of new sprocket , bearing ok in original one
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Roger - Can’t see that lack of drawings is the reason. If you are making a part but don’t have the drawing, you don’t just makes holes any size – you find out what the hole is for and make the size accordingly.
Problem is more likely due to the UK fast becoming a 3rd world country. All the engineering we once had has been relocated to the EU, assisted by massive EU grants and sweetners.
I think the reasoning behind it is that the various manufacturers are taking measurements from parts to make more parts, as opposed to following the original engineering drawings with one lot of specifications. Just my take on it.
(Edit): Regarding the replacement parts for my fork overhaul and new rear sprocket, to sum it up: Oil seal holders did not fit fork leg threads, A65 fork widgetts that can be used in place of circlip did not fit without some modifying and the sprocket bearing hole was the wrong size for the bearing - says it all!
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Just reporting back on my recent fork overhaul, as promised.
I took my G/Flash off its work platform earlier this evening, where it's been for a month and took it for a good test ride. I'm pleased and relieved to say everything felt smooth and correct, so I've returned home a happy bunny *smile*. The forks operated smoothly with no knocks or unusual noises, even though I tried to find as many bumps as possible to test them (it's sods law how scarce they become when you want one to ride over). So my conclusion is that the A50/A65 fork bush retainers (widgetts) in place of the awkward circlips seem to work perfectly and is a quick and easy way to secure the top bushes in place - as long as you buy ones that are made to the correct size. In my case buying ones that were not quite correct resulted in me having to spend time with a file because they were slightly too big in diameter to fit into the oil seal holders. If I didn't have to do that they would have been a piece of cake to fit as they just need to be slipped onto the stanchion between the oil seal holder and top bush (and that would take only a couple of seconds) before screwing everything together.
I also took the opportunity to change the rear sprocket for a new one, removed the gearbox inner cover to check if anything was amiss inside and swapped the cover with one I obtained last year to which I had fitted a new mainshaft bearing and bushes. Also removed the old paint from the front fork legs, trousers, front mudguard, its fixings, the front hub cover and both brake back plates, rear mudguard and number plate, replacing all the nuts, bolts and washers I had to remove with stainless steel ones.
So now hoping for some decent weather!