Crankcase Joint-Prep and sealing

[b'knighted]

I like that. I'll need hessian rope to keep the oil in a Burman gearbox.

 

[nkt267]

140 grade Morris oil doesn't leak too quickly.Kick starting is a bit heavy in the winter though..John

 

[vibrac]

Glad my thread about silk thread was well received and the tip about running a plug tap down the 1/4 BSF cover screw threads is well worth the trouble. Did you ever wonder why the bottom of the castings in say a inner chaincase were cracked and split? that was the the oil, dirt and old red gasket goo resident in the botton of the threads since the bodging sixties being pressured out by the hydralic force caused by a screw being forced in

 

[Jim Richardson]

I take it this is just sewing silk thread, any particular gauge, or is it something special ?

 

[vibrac]

Just fine silk thread pinched a reel out of me mums sowing basket 40 years ago still got miles on it....

 

[greg brillus]

Best sealant on the market these days by far is Three bond, beauty of it is it's available in grey and black, The Japs designed and use this stuff on their engines for years....how many Jap cars or bikes do you see leaking oil these days.....nil....I always put a smear of it under the heads of the through bolts that pass through from the primary side behind the chain and chain wheel, as this area seems to be a source of oil leaks across the other side off the bottom of the kickstart cover, as primary case oil bleeds along the through studs and drips from the other side...this always risky if you disturb the studs when removing/ installing the kickstart cover.....damn just when you thought it was the valve lifter abuttment seals....remember there's always more to a Vincent than meets the eye..........Greg.

 

[vibrac]

Looks good but they quote 20 types on their site and five on page one what do you use?

 

[greg brillus]

The grey compound is Threebond Pt no 1215 is actually recommended for assembling gearbox's, but works fine on alloy crankcases with a good parting face, and the black is Pt no 1207B is a high temp silicone. These are both non solvent types (don't smell like vinegar) the black type is a bugger to wipe off your fingers.....I use a bead about the size of a match head all around the parting face on one side only, just pryer to finnal assembly, fit a hand full of through bolts fairly quickly to hold it all together with some tension, then with plenty of clean rags at hand...wipe off the excess around the outside, which will be minimal using the amount i described.....if you let it cure off (an hour or two later) you can actually peal off the small extruded length around the inner cases, easy on the gearbox, but use a long bit of rod or whatever on the crank area....thus removing any leftovers that may get into oilways later...this not really necessary, but preferable anyway.....don't forget to put some on the heads of the lower rear throughbolts before installation...cheers.....Greg.

 

[redbloke1956]

The grey compound is Threebond Pt no 1215 is actually recommended for assembling gearbox's, but works fine on alloy crankcases with a good parting face, and the black is Pt no 1207B is a high temp silicone. These are both non solvent types (don't smell like vinegar) the black type is a bugger to wipe off your fingers.....I use a bead about the size of a match head all around the parting face on one side only, just pryer to finnal assembly, fit a hand full of through bolts fairly quickly to hold it all together with some tension, then with plenty of clean rags at hand...wipe off the excess around the outside, which will be minimal using the amount i described.....if you let it cure off (an hour or two later) you can actually peal off the small extruded length around the inner cases, easy on the gearbox, but use a long bit of rod or whatever on the crank area....thus removing any leftovers that may get into oilways later...this not really necessary, but preferable anyway.....don't forget to put some on the heads of the lower rear throughbolts before installation...cheers.....Greg.

Hi Greg, Have you used Blue Hylomar and if so, what characteristic about Threebond 1215 makes it a better product (haven't seen it before)

Kevin

 

[davidd]

I have always used Three Bond 1211. I have used it everywhere on the engine, crank cases, covers, head sealing, and exhaust. It has been quite robust considering how thinly I apply it. I know quite a few racers and hot rodders that will use nothing else. I think other products can be just as good, but the Three Bond products have a good reputation.

It is difficult to comment on the differences, but what I have heard is that 1215 has less propensity to sag. Not an issue for those who use it sparingly. The blowout pressure may be higher, but I have used 1211 on the headjoint with not blowouts.

1216 (or Hondabond HT at the Honda dealer) is designed for rocker boxes and does have a higher blowout pressure. I do not think you can go wrong with any of these products.

http://www.spmc.ru/assets/fs/files/threebond/1200/1216.pdf

http://www.techsilonline.com/getatt...479a-a0c2-7c79dc6bf2ef/TB-1215-Tech-Data.aspx

http://www.spmc.ru/assets/fs/files/threebond/1200/1211.pdf

Tim, the silk thread is a good one!

David