Can an Oil cause fork juddering on braking?

[Roadrocket649]

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

[Brucie64]

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  ).

[bsa-bill]

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

[muskrat]

90% drum, 5% bushes, 5% head stock. Both mine do it, get around to that one day. Brakes only slow you down 
Cheers

[Goldy]

I agree I don,t think the type of oil used will make any difference.

[A10Boy]

That oil would make the forks hard.

Where did you chaps get your skimming done?

[LJ.]

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?

[bsa-bill]

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, you will know if there any good

[Sidcar]

I don't think would cause juddering but why not drain the oil out and see if the juddering stops.


Sid

[NickSR]

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

[Rich]

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.

[Roadrocket649]

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

[TimK]

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

[RoyC]

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

[Rex]

I'm a little sceptical that coarse emery paper will remove any appreciable amount from a well-seasoned, work-hardened steel brake drum.