Rocker Box Leaked - No Wonder!

[alanp]

As some of you may know already, I am under strict orders from the wife to not drip oil on the drive. I've got a dry belt primary drive now but there is still one leak left, the leak from the rocker box, which had to be tackled.
Usually there was just a little smear of oil on the head from the rocker box, no real problem, it didn't turn into drips. However, I tightened up all of the screws/nuts securing the rocker box and hey presto it got worse....What the heck? Talking to an A10 friend of mine last night, he said his rocker box leak got worse after tightening the fixings like I did, but he couldn't face the hassle of stripping it down and fixing it.
Today I decided I had to bite the bullet and take the rocker box off to see what was going on.
The photos below explain it all. Somehow tightening (over?) the fixings had squashed the gaskets out from their seats. The locations of the errant parts of the gasket were of course not readily apparent until the strip down. On one photo the pencil shows where the gasket had leaked and on the other it's pretty obvious.
Now 4 of the fixings are associated with fixing the engine top to the frame, so there is a tendency (well for me anyway) to make sure they are tight.  
Hope this helps someone.
Alan
ps apologies for the way I spelt 'squashed' on the photo titles

[Topdad]

Alan, lightning spares in altringham sell there own gaskets a bit thicker and wider to help sort this out hope that'll help keep the peace regards Bob Hebdon.

[bsa-bill]

I doubled up on the gaskets this time ( in the knowledge the head will be to torque down in time), too soon to say whether it's a good idea or not.

[muskrat]

Don't talk to me about rocker box leaks !! I can't seal the cafe's for love nor money. I make my own gaskets and have tried 0.4mm and 0.8mm with all sorts of goo and without. I even tried copper ! Lapped both surfaces on glass with wet & dry (guides out). I'm about to try another box.
The '51 on the other hand is oil tight. Different head steady.
Good luck with yours.
Cheers

[chaterlea25]

Hi Alan and All,
Somewhere back along on the forum I showed photos of the "modified" head steady that I made
I cannot find it now I think due to the increased number of sections ????
Anyway I fited a rubber bush which is pressed in between 2 tubes, to this is welded the 2 arms which bolt to the frame
(weld before inserting rubber bush) the inner tube bolts between the brackets on the rockerbox

It is my belief that the engine vibrations cause some movement between the rocker box and head??
the bush reduces this so as the gaskets are not sawn to bits!!
The proof of my experiment is that the rockerbox/head joint on my SR is still good after 10 years and prob 15k miles
I will try to find the photos over the weekend

HTH
John O R

[muskrat]

I found the post John. http://www.a7a10.net/forum/index.php/topic,2912.0.html
I haven't made one yet but it's up there on the list.
Thanks again for posting.
Cheers

[Steve.Carter]

Hi all

This is my first post although I been reading all your threads for a long time now and I must say you all seem very friendly and helpful. I have picked up a lot of advice from here so I'm glad now to be able to say thank you very much.

 I have had lots of trouble trying to seal my rocker box on my Ariel  Huntmaster basically the same engine as the A10. It seemed that the gaskets I was was using couldn't cope with the heat around the exhausts and became very brittle and started to leak after around 1000 miles. I tried to make my own gaskets  from all sorts of different materials, I have even tried leather!! after a few miles the smell of burning made me think I had ran over a rabbet My solution in the end was Siliconised Glass Cloth. It's a material used for making insulation jackets and capable of withstanding high temperatures.  I made the gasket using the rocker box as a pattern and then smeared the head and rocker box with a very thin film of silicone, and waited for it to dry and then bolted it all up. No leaks now after 5000 miles.

Steve Carter Hampshire England       

[alanp]

Thanks John, makes sence since the rocker box joint does transmits the engine vibration forces to the frame to some extent even though the 4 top bolts on the head steady screw down into the head. I hadn't thought of that. I'll see if I can replicate the device you made, or on the same lines.
Steve, what is siliconised glass cloth and where can I get some?
Thanks chaps
Alan

[t20racerman]

Hi Alan and All,
Somewhere back along on the forum I showed photos of the "modified" head steady that I made
I cannot find it now I think due to the increased number of sections ????
Anyway I fited a rubber bush which is pressed in between 2 tubes, to this is welded the 2 arms which bolt to the frame
(weld before inserting rubber bush) the inner tube bolts between the brackets on the rockerbox

It is my belief that the engine vibrations cause some movement between the rocker box and head??
the bush reduces this so as the gaskets are not sawn to bits!!
The proof of my experiment is that the rockerbox/head joint on my SR is still good after 10 years and prob 15k miles
I will try to find the photos over the weekend

HTH

I like this idea a lot - proven to work too. Many people not used to rubber mountings (other than Norton or Harley ones) think that they will move a lot - but not so if you use the right ones. My Suzuki T20 race bike continually cracked the frame due to the high frequency vibration (and general stress too) and I rubber mounted the engine using TZ350 Yamaha mounting bushes and a great deal of welding/ turning up bits etc. (details on 'T20 racing page' here: http://www.t20suzuki.com.
Anyway, on starting the bike and revving it up I was really disappointed at how little the engine moved now it was rubber mounted - it was invisible to the eye and only JUST feel-able with a finger across the mount and engine bolt. What a waste of time I thought 

However, it cut out the high rev tingle I noticed when on track, and in the 5 years since, I've not had ANY cracks in the frame. Clearly then, a head steady like this design would be ideal - it would still do its job of stopping the head/frame vibrating with respect to each other, but would damp out the amplitude of any overall vibrations too.
This will definitely be something I try on my bike... when I've finished building it up that is!

[Steve.Carter]

what is siliconised glass cloth and where can I get some?
Thanks chaps
Alan

We use Siliconised Glass Cloth in our business for making insulation jackets, we throw away offcuts of the material everyday so if anyone would like a few pieces  to try I could put some in the post, maybe just a SAE  industrialsewnproducts.com

Steve

[chaterlea25]

Hi All,
Cheers Muskrat, when I put in "head steady" into the search all it came up with was this thread?????

I read through most of T20's adventures with his Suzy! very interesting

If a proprietry (bought) bonded bush could be used and pressed into the outer sleeve it may be a better solution???
Anyway did a hundred miles all along the coast and back this afternoon on the SR
Life just couldnt be better

HTH
John O R

[muskrat]

G'day Steve, welcome to the forum, say g'day and intro yourself in bikes,pictures and members.
 That SGC sounds interesting. I'll try anything twice. Had a look on the net down here and the only place I found has sheets of G7 3' x 4' x 0.015" for $150AU min buy $250AU. Your offer is great, of corse I would cover postage + packaging. Will PM you.
Those covers of yours look the part. So much better than the asbestos I used 30 years ago. Hasn't killed me yet.
Cheers

[muskrat]

G'day John,
               use the search on the left side of page under your avatar.
Cheers

[chaterlea25]

Live and learn 
Cheers Muskrat

John

[cableguide]

Hi all,

Newcomer here and second post. Hope you dont mind my 2penneth.

One thing to bear in mind is torque order. Im sure I was told once the correct way to tighten any alloy casing is from the centre outwards so the fasteners flatten and push out the alloy like pushing flat a banana.

I do this with hallite gaskets and blue hylomar and have always been astonished how oil tight the rocker box can become.
cg