BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: ANDY BROWN on 04 September, 2017, 15:20:38

Title: End Float
Post by: ANDY BROWN on 04 September, 2017, 15:20:38
I have an a65 with 12 thou of end float. As soon as the engine fires up it pulls the crank to the timing side. With a DTI on the stator end revving gently it stays this way, only on stopping the engine does it "clunk" back to the left as it literally stops. I stupidly forgot to check end float when the engine was apart for a gearbox problem earlier in the year. The engine has done very little mileage for approx. ten years and has had the timing side bush done just before I bought it last year. I am presuming that the end float was incorrectly set up then. So far I have added about 2k to it with only about 400 miles since I noticed the issue and as it will have the engine stripped totally in a few months I was wondering what the general consensus was regarding still using it? Oil pressure is spot on and from the crank and timing side bush drawings the oil will never be cut off to the rods. I can see the possibility that the oil pump outer casting may touch but my opinion is I would need about 20 thou to have that problem. Am I looking on the bright side or am I leaving myself open to a catastrophe I have over looked! I have the Distinguished gentleman's ride in a few weeks and hoping for a few more jaunts before winter but that's about it really.
Title: Re: End Float
Post by: JulianS on 04 September, 2017, 19:31:58
When the crank is shimmed it will move it towards the timing side with shim/shims being between roller bearing and crank web on drive side. As it is a design feature it is unlikely to touch the pump unless the thrust washer between timing side main bush and crank web is badly worn or was left out when the engine was assembled.

There are no doubt many BSA twins which run OK with excess crank float, but nobody will be able to tell you with any certainty that your bike will be OK.
Title: Re: End Float
Post by: ANDY BROWN on 04 September, 2017, 21:18:25
Cheers for the reply.
I managed to view some of the engineering drawings and even with no shims or cup maximum should in theory be 20 thou of end float. Which is not enough to shut off the rod feed through the timing side bush. However if vibration set in I would imagine the timing side bush could be worn considerably faster. I just wondered if anyone had experience of "leaving it too late" I've surfed as you do and there is a lot of much more experienced people out there as I'm a novice with old Brit bikes. I was a mechanical engineer during most of my working career but every day is a school day as they say.
Title: Re: End Float
Post by: Bess on 05 September, 2017, 18:41:48
Hi Andy,
            I agree with Julian.

Plus you might notice a clunk sound when applying/releasing the clutch and during acceleration or deceleration.

Best wishes...