The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: huddie on 28.06. 2008 19:12

Title: oil leaking from the rocker box banjo unions.
Post by: huddie on 28.06. 2008 19:12
I have just tried my A10 along the lane ready for an MOT. There is oil leaking from the banjo unions (enough to make the area around the head smoke!). I'm afraid to over tighten them in case i strip the thread in the rocker cover. Now as this is my first classic and was built from a basket case i'm not sure of the set up of these banjo unions. I have put new fibre washers between the rocker box and the banjo housing but nothing between the housing and the banjo bolts. Is this correct or can you guys put me straight yet again. Many thanks for all your help so far. Regards Huddie
Title: Re: oil leaking from the rocker box banjo unions.
Post by: a10gf on 29.06. 2008 21:26
Hello, I'd say you can tighten quite much on these, as the threads are in the solid steel of the rocker shaft (provided shaft & nut threads ar ok to start with). Washer only on the inside seems to be the norm. When needed, my favorite "avoid overtightening and stop-leak" tool is the Loctite 243 (blue), clean well and apply to the washer and top of nut, tighten normally.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: Brian on 29.06. 2008 23:18
One small thing to look at is the fibre washers. A lot of the ones you buy from automotive places are very poor quality, usually paper thin and as hard as rock. These dont have any ''give" in them and are no better than a steel washer. Try and find ones that are thicker, like a sump plug washer for instance, and softer.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: huddie on 30.06. 2008 08:37
Thanks a10gf and brian.  The fibre washers came with a complete gasket set. they do look on the thick side so first off i will try a good clean up and a bit of "blue". I guess i needed a bit of reassurance that there was nothing missing from my assembly. Thanks again guys, your help and advice is much appreciated.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: BSA_54A10 on 30.06. 2008 11:08
Fiber washers do dry out & go hard with the passage of time.
I for one would try some new copper ones.
Bike Beesa
Trevor
Title: Re: oil leaking from the rocker box banjo unions.
Post by: RichardL on 30.06. 2008 15:59
Huddie,

Apparently, it's not clear if the oil is leaking at the washers or the bolts. Though I have not done this before, it would seem a good idea to lap in the bolts with valve-grinding compound. Now that I've said it, I'm going to do it when mine go together.

Richard
Title: Re: oil leaking from the rocker box banjo unions.
Post by: dpaddock on 01.07. 2008 15:39
a10gf's recommendation is the best and simplest. Use 115 in-lb torque.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: huddie on 02.07. 2008 16:57
Thanks guys for your suggestions, I have a torque wrench that starts at 10Nm. Your recommendation "dpaddock" converts to 13Nm, i think, so i just tried nipping them up to see how tight or otherwise they were. They both moved, alas one just kept on moving while the other nipped up fine.On to the net i go to order a new banjo bolt. Then I think, try swapping them over after looking at the threads, which looked ok. What happens, the one that nipped up ok now turns and the one that kept turning now nips up!. So now it looks like I have a dodgy thread on the exhaust rocker spindle. No wonder it was leaking oil. Will i ever get this bike to the test station?.

Regards Huddie
Title: Re: oil leaking from the rocker box banjo unions.
Post by: a10gf on 02.07. 2008 19:02
Maybe the rocker shafts turn, and nothing wrong with the threads or anything. Try first tightening up the nuts at the other end of the shafts.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: beezalex on 03.07. 2008 17:23
Once you get the stripped bolt/rotating shaft resolved, take the banjos off and flatten them with a good single-cut file.  They often get warped.  Also, I replaced my fiber washers with copper brake washers.  Anneal them with a propane torch before installing.

Good luck.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: RichardL on 03.07. 2008 17:35
Alex (I think),

Those sound like very good ideas, though I can't speak to the effectiveness of the soft copper over firm fiber. It appears I don't have much support for the idea of lapping the tapered bolts to their seats, as the use of Loctite seems preferred. Nevertheless, I think there no harm in lapping (with respect to motorcycle maintenance, that is).

Richard
Title: Re: oil leaking from the rocker box banjo unions.
Post by: a10gf on 04.07. 2008 23:44
Agree, a 'dose' of lapping can only be good, new washers and then tighten well, with no shaft rotation, should do the job without any loctite or other sealant.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: a101960 on 05.07. 2008 15:01
In my experience I have found that the tapered bolts normally seal quite well. I was plagued with a small leak from the banjo unions until I fitted "Doughty" washers I think that the generic term is maybe pressure washer. These washers are stocked by hydraulic component suppliers. The washer has a rubber seal incorporated in it. The washer is squeezed as you tighten up, and the rubber seal expands creating a perfect seal. These washers are designed to seal hydraulic systems where pressures of up to 4000 psi may be encountered.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: huddie on 11.07. 2008 11:39
The saga continues. I thought you all might be interested in what i discovered. The new spindle and banjo bolts duly arrived so I started the replacement. When I tried to undo the domed nut on the opposite end of the old spindle it JUST TURNED!. I looked at the other end as I turned it and nothing moved!. So then i looked at the little bit of the spindle visible between the rocker and the housing where the spring and thrust washer are and it was turning with the nut. You've guessed it the spindle was broken clean in half. Still functioning because both halves were supported by the central part of the rocker casting!. I will take a picture and show it when I have a moment. The old one is out now and the new one in so i will let you now when it is all back together. I hasten to add that as i aquired this bike as a basket case with the rocker assembly as one piece I have never removed any of the rocker components. How on earth did this get broken i ask. Know wonder i couldn't do the banjo bolt up!!. i will let you now how it is when i have it running again.
Regards Huddie.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: a10gf on 11.07. 2008 15:12
Some discoveries just amazes one. This must be a -very- uncommon occurence in the history of the A's. Btw, I was close in my post above, ie the spindle (shaft) rotating, but who in the whole world would ever imagine it was -half- the spindle  *ex*  *lol*

Nice you got it sorted out.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: huddie on 16.07. 2008 12:37
Hi all,    As promised a pic of the offending rocker spindle. The bike is back together and running again. i haven't road tested it yet but in the garage there are no signs of any leaks from the banjos. huge sighs of relief!
Title: Re: oil leaking from the rocker box banjo unions.
Post by: beezalex on 16.07. 2008 19:57
Alex (I think),

Those sound like very good ideas, though I can't speak to the effectiveness of the soft copper over firm fiber. It appears I don't have much support for the idea of lapping the tapered bolts to their seats, as the use of Loctite seems preferred. Nevertheless, I think there no harm in lapping (with respect to motorcycle maintenance, that is).

Richard

Richard, for A10's, I, of course am only referring to flattening the spindle side of the banjo and using copper there.
Title: Re: oil leaking from the rocker box banjo unions.
Post by: RichardL on 16.07. 2008 23:03
Thank you, understood. And, just in case I was misunderstood, I probabaly should have said "I can't speak to the effectiveness of the soft copper instead of firm fiber," so you didn't think I was implying to use copper and fiber together.

Richard