The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: Roadrocket649 on 09.05. 2011 09:01
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Bike BSA A10 Super Rocket 1958
With the urge to get the bike out in the good weather, and unable to locate any SAE 30 fork oil, I put SAE40 Castrol XXL40 Oil in the forks
I had a sever juddering under braking
I believe it is the fork bushes, but before I dismantle them, I thought I would check with you GURU's
Any thoughts?
Roadrocket649
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Hi RoadRocket649,
My pennies worth before far more experienced people than me give their input.....
I had exactly the same problem, severe juddering from the front brake when trying to slow down and lack of braking effeciency. The problem was found to be the front brake drum had warped slightly and required skimming true. Once done, the juddering disappeared and the front brake was back to normal (pitiful instead of non-existent *smiley4*).
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I agree with Brucie64, had the same on my Flash and skimming cured it, now got on the RGF and had the hub skimmed on Friday, cost me £19 UK but depends upon how much they have to set up the lathe or whatever, often the result of respocking but will be other causes as well , as you mention worn bushes, slack headstock bearings
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90% drum, 5% bushes, 5% head stock. Both mine do it, get around to that one day. Brakes only slow you down *eek*
Cheers
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I agree I don,t think the type of oil used will make any difference.
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That oil would make the forks hard.
Where did you chaps get your skimming done?
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For a while now I have been meaning to ask what the thickness of a new drum is and what the maximum amount of skimming that can be done before the drum is rendered useless. Does anyone have any such measurements?
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I don't think the thickness is an issue on our old iron hubs LJ other than the possible need for oversize linings on the shoes.
The shop that have done mine did mention that some of the modern stuff have a hard metal liner in an alloy hub and often they cannot be skimmed.
Andy mine are done by the local engineering firm (Woods Berwick upon Tweed ) they also do truck brakes I believe.
a Quick Google came up with http://www.motorcyclewebsite.com/home/a0_R/a0_Ro (http://www.motorcyclewebsite.com/home/a0_R/a0_Ro), you will know if there any good
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I don't think would cause juddering but why not drain the oil out and see if the juddering stops.
Sid
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Hi Everyone
About 18months ago I used Leicester Wheel and Brake Restorations Rob Coley mobile 07947 822940, I had a complete rebuild and refurbishment done.
I think he does a hub skim and over size brake linnings on a complete wheel its worth a ring.
He is based North side of Leicester 5mins from the A46.
Regards
Nick
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Take the bike to an mot station with brake testing rollers, when the front or back brake is put on gently if the needle on the gauge moves up and down then tis the brake drum, I replaced staunchions and bushes on mine and it did not make any difference, but when I had it mot'd on the rollers brake tester it showed up, previous to then they used an old dial with a winding handle which did not show anything amiss.
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Hi Guys
Just to say many thanks for your advice.
It was not the fork bushes, but the inner hub was ?proud? by about 0.010? in one place, as some of you guys suggested (NickSR, BSA-Bill, Brucie64, Muskrat and others)
I bought oversize shoes, and had the inner hub skimmed, and the shoes turned down to match
The job was done by an engineer in the West Sussex BSA Owners club
Judder Gone!
Many thanks for your help ? it had not occurred to me
Roadrocket649
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Hi everyone,
I'm resurrecting this old thread hoping for some advice. My 59 GF is back on the road and I'm now working through the little gripes to make it nicer to ride. One of the issues I have is the front brake juddering. The head races, wheel bearings and bushes/stanchions are all good but I've checked the drum with a dial gauge and there's about 0.10mm ovality - is this within tolerance, or should I get it skimmed? *????*
Cheers
Tim
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should I get it skimmed? *????*
Cheers
Tim
I trued my own drum by sticking strips of 80 grit sticky backed emery paper to the shoes and slowly turning the wheel until it was trued up.
https://www.ebay.co.uk/itm/3M-Adhesive-Backed-Sanding-Discs-40-80-or-120-Grit-5-125-mm-For-Drills-PF/201590623048?hash=item2eefbccb48:m:mNYlO1uEj-Nyp41_TnJlfYg
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I'm a little sceptical that coarse emery paper will remove any appreciable amount from a well-seasoned, work-hardened steel brake drum. *conf*
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I'm a little sceptical that coarse emery paper will remove any appreciable amount from a well-seasoned, work-hardened steel brake drum. *conf*
It worked on my iron drum.
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Hi everyone,
I'm resurrecting this old thread hoping for some advice. My 59 GF is back on the road and I'm now working through the little gripes to make it nicer to ride. One of the issues I have is the front brake juddering. The head races, wheel bearings and bushes/stanchions are all good but I've checked the drum with a dial gauge and there's about 0.10mm ovality - is this within tolerance, or should I get it skimmed? *????*
Cheers
Tim
Just my opinion but 0.1mm is just 004” so pretty round. Maybe check there is a chamfer on the on the leading shoe before looking at skimming.
I’ve managed to get good brakes without skimming just by making sure the leading shoe contacts the drum first, I’ve got pretty out of round drums on both my bikes, and not had juddering yet.
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I'm a little sceptical that coarse emery paper will remove any appreciable amount from a well-seasoned, work-hardened steel brake drum. *conf*
It worked on my iron drum.
Good to hear that this worked for you Roy.
Ive been suggesting this method for awhile after it worked to fix my SR 2ls brake judder. Since then the Emory method has improved the front brakes on the Vincent and the 650ss.
The more common method of drum trueing, skimming in a lathe, also works well, however the emery removes the bare minimum of material. Sometimes the lathe operator might chop off a little more than necessary.
The other benefit to the emery method is its DIY, some cost savings.
Glen
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Thanks everyone,
I'm going to try chamfering the leading shoe first and see if that works. I'll get back to you and let you know how I get on.
Cheers
Tim
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You use the brakes *eek*
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Hi everyone
I finally got around to chamfering the leading edge of the brake shoes and it's transformed them - no juddering and they work! I love a cheap fix.
thanks for the advice.
Cheers
Tim
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Good one Tim.
No reason not to go here. https://sites.google.com/site/shoalhavenclassicmc/home
Lots of trophy's on offer (they took me ages to make).
Cheers
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I'm a little sceptical that coarse emery paper will remove any appreciable amount from a well-seasoned, work-hardened steel brake drum. *conf*
Abrading ferrous metals is kind of what it’s made for.
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Which is true, in the sense that "abrading" could describe the use of emery etc in engineering to clean the metal's surface of rust and mill-scale, remove burrs etc etc.
Unless M-S has got somehow "softer" or emery cloth upped it's performance to new heights over the decades that still holds true. What it never did was to appreciably change the dimensions etc of the parts it was used on, hence it's use on finished machined pieces etc.
Chuck up a test piece in a lathe and use emery/sandpaper/whatever for a period and see how much it's altered dimensionally.
Good luck to anyone who thinks emery etc would clear a ten thou ovality from a drum with a few passes. I suspect they'd run out of emery or arm muscles long before they reached the target of a true drum..
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So, could the emery be working by smoothing out the different diameters so the brake shoes are sliding without juddering?
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Musky said
No reason not to go here. https://sites.google.com/site/shoalhavenclassicmc/home
Lots of trophy's on offer (they took me ages to make).
Musky
is there a prize for 'The best not very original, totally wrong colour, oil leaking A10 with unmatched engine/frame numbers'? - I might be in with a chance!
Cheers
Tim
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G'day Tim.
You'll have stiff competition from my A7 plunger.
Cheers
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10 thousandth with emery paper?
Sure, monks carve rocks with paint brushes too.
I wouldn't want to do it, but the phrase "forever and a day" does come to mind. ;)
Lee
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My SR had the judders bad. I probably spent a couple of hours grand total to get the drum trued with the Emery.
That didn't seem like a long time to solve an annoying and dangerous problem.
Didnt have to pull off tire, drive the wheel to some shop in town to turn drum, wait one week, pick up and remount tire. I've gone thru all of that a couple of times with other bikes.
In that context, 2 hours with the Emery strips is pretty quick.
And free. Almost.
Glen