The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: jhg1958 on 06.06. 2020 13:25
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Just taken my 1961 A10 forks apart. The good news is that they are straight, the bad news is that they have some marks in them. Does anyone know what these marks are and if they matter?
I was planning to fill them in with aridity and get some fine wet and dry to dress them down. I have done this before with Japanese bikes and it has cut down the oil loss and damaged oil seals.
John
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Do you mean Araldite?
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If they’re in an area a seal operates, they do matter – they’re relatively deep. What caused them? I’ve no idea – they’re unevenly spaced and uni-directional – maybe the stanchion got caught up in some machinery where it shouldn’t have been. If you plan on filling them, I’d drill each a little deeper (but not right through!) to give the filler some purchase, rather like a dentist does. Devcon plastic steel would be my choice.
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Maybe someone was easing it through a press (with a damaged face) to straighten it?
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GOOD superglue is the trick. The thin stuff will wick right onto the metal 'pores'. 'Zap or 'Hot-Stuff'. Build it up and rub it down.
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Wouldn't a good soldering job work better than Araldite? Araldite softens over time particularly in oil....
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Check whether the seal lip actually runs across the damaged area; are they on the 1 1/4" machined surface. or above it.?
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The marks are on the oil seal part. The other has some corrosion too. I am slowly coming around to the thought of buying new ones. I have looked at getting them rechromed but I fear that would be more expensive than replacing them.
I have a bolt missing from one of the split clamps at the bottom of the forks and another that does not look right. I suspect these are high tensile and cannot be replaced with a normal bolt.
I was hoping this part of the rebuild would not cost so much but
Stanchions £84
Seals £7.50
Seal holders £41
bushes £27
Springs £62
and Nacelle £93
*sad2* *sad2*
John
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I replaced my stanchion bolts with stainless bolts with domed nuts, cant see why they would need to be hi tensile just for clamping, understandable for the shocks perhaps...
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Other way around IMO. The yoke bolts need to be a fine thread (BSCY is ideal) to apply the clamping force, while the rear shock mount bolts are in shear, and as long as they stay put they'll work OK.
I recently had this very problem with a set of yoke bolts on a Panther; the PO had replaced the bolts with nice shiny stainless M8 jobbies and then wondered why the front end always felt slightly "floppy" from then on..
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mmmm I put stainless bolts and nuts on bottom yoke with a thick brass washer and lock washer over 30 years ago and no problems
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Trick I saw that apparently is use on nicks on helicopter blades is to lay nicks on the flat, coat with superglue and sprinkle bicarb on. Sets instantly rock hard and can be rubbed down. I was sceptical but tried it and it works. No idea why.
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I am slowly coming around to the thought of buying new ones
John if you plan to keep the bike and the $ are OK then that would be a good way to go. much less mucking around and a long-term solution. i've finally just replaced some well-pitted forks and it was money well spent and not too hard a job.
I had wondered if very tired bushes could cause those marks under braking (uninformed speculation) so note your wise plan to replace bushes also.
coat with superglue and sprinkle bicarb on
i've build up plastic surfaces with this methods and it works ok. it doesn't take a lot of force tho. it may work well for pitting tho i haven't tried it for that.
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Yes I plan to keep the bike. I am already on a trajectory of vastly over capitalising this bike with a very expensive rebuild. Labour of love and as expensive as a wife.
I missed some on eBay yesterday. However. They looked cleaned(wet and dry?) This might be ok for the seal but could be a problem with the bushes.
I wondered about the damage being due to the bushes. They are not a bad fit. But there are two sets of these marks not opposite each other. There must have been some bending forces on the forks to get them to dig in. Also there is no sign of damage on the edge of the bush.
John
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a trajectory of vastly over capitalising this bike
that's the life of a BSA owner- money flows in the top, oil drips out the bottom. it makes us better people somehow.
personally I'd favour new (straight) stanchions, bushes and obviously seals. maybe get by with existing seal-holders, springs and nacelle if you can?
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It could be worse; a horse, or a boat; by comparison I think we get off lightly!