Day 7 in the Big Brother house...

[MalcW]

The frame on my 650 was starting to look tatty where someone in the past had done some painting that has been coming adrift, leaving the grey primer on show. I've been rubbing sections back to metal and re-doing them with good old Tekaloid. The idea was to not strip the bike down too much, but...

Malc

[chappers1962]

Got the bike roadworthy just before lockdown, did 500 miles and now isolating - gutted, but for a good cause. Bike runs well, but rear suspension was bottoming out. Luckily, ordered new springs from the spares scheme the last day they were open. Fitted and with some extra weight (the wife), tested them going up and down the drive - result they work!

Next, had a problem with very little gap between the fork shrouds and my new (expensively painted) tank. Cause of the problem was wear where the steering lock and frame meet - not much but, enough to give me heart palpitations every time the steering went into full lock. Solution was to fabricate a small bracket out of aluminium (soft so would be sacrificial and therefore wouldn't cause more wear on the frame). Painted, then glued on some rubber (spare from the battery liner), then fitted to the steering lock lug using the existing (convenient) hole.

Nice gap now between the forks and the petrol tank, steering circle not compromised much (can still do a u-turn on our narrow street - in front of my house so still self isolating), plus the extra bonus of a nice cushioned full lock.

[pkr87]

My isolation job is to put the 350ccs engine back together and into the 16m.The bike has been running with a 500ccs engine for ages, after the big end of the 350 cried enough. I fitted a new big end about 5 years ago and "I'll finish the job when I've got time". Biggest part of the job so far is " where in that mess in the shed are the other bits"? Found most of them but one pushrod is still hiding somewhere. At least the shed is looking tidier and I have found all sorts of car bits I had forgotten about.

[Stan Palmer]

Gardening suspended as the bonfire is now unreasonably large.
Switched back to my chaincase sealing project, on a Triumph rigid. Originally assembled with a greased paper gasket: it leaked badly. Redone with Three Bond and no gasket. Left to cure for three days. It took an hour for the first drip to get through, closely followed by several others at different places. I figured it would be empty within a week.
Did a search on this site for alloy chaincase leaks. I think the AMC type must be much better than Triumph ones as there seem to be few complaints. So back to googling I found the following remedies:
1) Take both halves off and flatten by grinding on glass plate and filing if necessary. Probably the best solution but I am not keen as it's a lot of work to get the inner cover off, removing clutch, battery case, rotor etc. Also not that easy to make it flat by the methods indicated.
2) Use composite gasket with sealant both sides. By this I think they mean the thick cardboard gasket with a plastic coating both sides. I actually have a piece in stock, unfortunately already cut out some rocker gaskets so it's not big enough now.
3) Form a thick silicone gasket (good quality bathroom sealant) by greasing a flat piece of plywood. The silicone is applied to the outer cover, which is then lightly pressed to the greased surface and allowed to cure. It should lift off cleanly leaving a 1 to 2mm gasket on the outer cover.
4) The same as 3) but apply the grease to the inner cover instead of the plywood sheet. Put the silicone on the outer cover as before, then put on the bike but only tighten enough to close the gap to 1-2mm. Allow to set and then tighten up.

To me option 4 seems the simplest and likely to work as the gasket is profiled to both surfaces. A bit tricky to assemble and I am not sure about droop as the surfaces will be vertical. I guess I could lay the bike down.
Before I proceed are there any improved ideas out there ?
Stan

[ajscomboman]

I'd suggest not using bathroom (sanitary silicone) it's quite thin and runny compared to neutral cure window sealant. Something like a clear 7T neutral sealant should be fine.

[spookefoote1956]

I'd suggest not using bathroom (sanitary silicone) it's quite thin and runny compared to neutral cure widow sealant. Something like a clear 7T neutral sealant should be fine.

Dead right, stay away from the bathroom stuff.

[Stan Palmer]

That's good information. It was the runny nature of bathroom sealant that was bothering me.
Stan

[39speedtwin]

I had the same problem with a leaking primary on my pre-war speed twin, eventually I had to smooth both surfaces with emery paper on a surface plate. It worked only required a thicker gasket and a smear of grease, no leaks.

[Stan Palmer]

I have that as my last option. There is time, think we will be in lockdown for quite a while yet. The T100 doesn't leak, the Tbird does. Sod's law the awkward one has an alternator. Another alternative is to fully prepare spare cases (I have those) and swap them out as a clean build. I only got them running so I can transfer them to another shed and free up the workshop.
Stan

[Dave T_LAPSED]

Hi guys from sunny lockdown France (where you have to fill in a letter of authority if you want to go out!).

When instant silicone gasket first came out you had to assemble the pieces with a thin gap, probably 1/16" in those pre-decimal days, and leave it to go off overnight thus ensuring a film all around the joint. Common practice nowadays seems to be to nip it up nearly straight away thus squashing the bulk out of the joint.

The best seal for a large joint, I think, would be use some proprietary "instant gasket" for mechanical use, not kitchen silicone, and leave it, as you said to set, then don't overtighten the casing. Does that sound reasonable?

Stay safe! Dave.