Crankshaft end float

Singles, twins and fours.
Post Reply
ann-marie.scott
Posts: 19
Joined: Fri Jul 29, 2022 11:40 pm
Contact:

Crankshaft end float

Post by ann-marie.scott »

The original publications recommend .002" end float. Dragonfly is recommending .005". Why the change?
User avatar
Roger Gwynn
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 1113
Joined: Tue May 28, 2013 11:34 am
Location: Norwich, UK
Contact:

Re: Crankshaft end float

Post by Roger Gwynn »

Which bike would be involved here, it makes answering your question a little easier.
Roger Gwynn, Membership Secretary, curator of the Machine Register and the works drawings. Director of Draganfly Motorcycles, Craven Equipment and Supreme Motorcycles mostly retired.
ann-marie.scott
Posts: 19
Joined: Fri Jul 29, 2022 11:40 pm
Contact:

Re: Crankshaft end float

Post by ann-marie.scott »

I am restoring a 1958 Ariel Square 4..
User avatar
Roger Gwynn
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 1113
Joined: Tue May 28, 2013 11:34 am
Location: Norwich, UK
Contact:

Re: Crankshaft end float

Post by Roger Gwynn »

The Draganfly web site says "The crankshaft end float should be .003” to .004” on the front crank and .005” to .006” on the rear. Ariels only ever listed shims to increase the end float, not to decrease it; these may occasionally be found fitted outside the timing side main bush." This is what is quoted in the Waller book. Checking the later 1956 owner's guide I see that Ariel say .002-.004 for both cranks. It should be a small amount to ensure that the cranks are not nipped up but as little as possible.
Roger Gwynn, Membership Secretary, curator of the Machine Register and the works drawings. Director of Draganfly Motorcycles, Craven Equipment and Supreme Motorcycles mostly retired.
ann-marie.scott
Posts: 19
Joined: Fri Jul 29, 2022 11:40 pm
Contact:

Re: Crankshaft end float

Post by ann-marie.scott »

My concern stems from twin cylinder BSAs who's oiling system is similar to the Ariel's; .006" is way too much, starves the left hand rod.
will_curry
Holder of a Silver Anorak
Holder of a Silver Anorak
Posts: 959
Joined: Thu Oct 08, 2015 12:56 am
Contact:

Re: Crankshaft end float

Post by will_curry »

Big difference between BSA (including Huntmasters) and Ariel 500s and Fours is that the
former have decent sludge traps which the latter don't and the latter have oil seal washers
on the outside of the timing side bushes which the former don't. BSA didn't get round to
fitting them until the A70 twins. 6 thou end float on a roller bearing A65 is indeed an
impatient disaster.
ann-marie.scott
Posts: 19
Joined: Fri Jul 29, 2022 11:40 pm
Contact:

Re: Crankshaft end float

Post by ann-marie.scott »

The term oil seal washer is a tad odd; is there supposed to be any rubber on them? Mine, which appear to be original, are just plain steel. Did I mention that this is a bike in a box, disassembled in 1978?
will_curry
Holder of a Silver Anorak
Holder of a Silver Anorak
Posts: 959
Joined: Thu Oct 08, 2015 12:56 am
Contact:

Re: Crankshaft end float

Post by will_curry »

No rubber. As you say, just plain steel but I think they only fit one way round.
ann-marie.scott
Posts: 19
Joined: Fri Jul 29, 2022 11:40 pm
Contact:

Re: Crankshaft end float

Post by ann-marie.scott »

The inside of the seal is beveled but it will fit either way.
User avatar
paul.jameson
Holder of a Golden Anorak
Holder of a Golden Anorak
Posts: 2933
Joined: Wed Oct 12, 2011 3:04 pm
Location: Herefordshire
Contact:

Re: Crankshaft end float

Post by paul.jameson »

The bevelled side goes inwards, towards the main length of the crank. The bevel is to cope with the tiny radius at the change of crank section.
Paul Jameson
35 LG (project), 37 RH500, 52 ex ISDT KHA, 54 KH(A), 75 Healey 1000/4.
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist (but not Machine Registrar), Gauges and Clocks Spares Organiser.
Post Reply

Who is online

Users browsing this forum: Ahrefs [Bot] and 1 guest