Triumph Bonneville T140 - Primary Case Oil Leak and Primary Chain Tensioning

[@ThreenaddiesRexMegistus]

I made what appears to be a permanent fix to that gear shaft leak. Never did get much success with the O-ring. I shortened the bush by 5mm and installed a proper oil seal which seems to have done the trick. The other bad one is usually the seal behind the clutch basket. So a new seal and proper clean and reinstalling the cover plate with Hylomar did the trick. Bonnie barely loses a drop these days - until next time, that is! The other thing I like to think helps is installing a flapper type GM crank breather valve. 👍🏻

[@StuartPiper-ir1zz]

Very helpful and shares my thoughts on crap Triumph design issues!

[@bodganeering]

They’re not much better now… 😂 Thanks.

[@steved5518]

Typically not needed to remove the left foot rest. Just loosen and let it drop. Otherwise much effort in getting the bolt matched up with the nut on blind side.

[@easdaleholland9050]

The tool you made from a bolt to adjust the primary chain what size was it, I couldn't quite catch it on the film

[@bodganeering]

I think it was 5/16”, or 8mm in funny money.

[@robthoreson8384]

Do you have any good fixes for the primary adjustment screw plug? Mine doesn't seem to grab onto the threads in the case well. I've dabbed a good smear of hylomar blue on the threads of the plug and front and back of the fiber washer. I still seem to have leaks right onto my left side pipe after a bit.

[@bodganeering]

A new thicker fibre washer could be worth a try. I'd be trying the same with Hylomar TBH but another option is a few wraps of PTFE tape (Teflon Tape) on the threads of the plug. Are your threads in good condition on the case? As they are difficult to align when in the frame they are often cross threaded by previous owners over the years. No a great design.

[@robthoreson8384]

@@bodganeering I'm afraid that my threads in the case are probably not in good condition. I do have some PTFE tape I could try to use as well.

[@ThreenaddiesRexMegistus]

That leak has given me hours of quality time trying to fix it. It’s not like you can just pull the whole lot out once the engine is in the frame. It’s a real ba…d even when you’ve got the engine out. I’ve tried all manner of seals and degreased threads, even did the Hylomar thing. Ended up draining the primary, hosing it all out with carb cleaner then spraying with Permatex spray sealant - so far, so good. One day I’m going to get rid of that ridiculous tensioner setup. Probably easily replaced with all-thread or a long-thread cap screw and a Doughty washer. Wish I’d done last time I had the engine out and thought I’d fixed it.

[@pattoallen1981]

Put the gasket on the bike not the cover mine got caught up and moved I picked it up before I tighned it down

[@TheReverb1]

Hello; my 79 does not leak except for that spindle when I do long trips. I changed that O ring several times; never stopped anything...the factory knew that so they discontinued the useless O ring and put a seal there. I bought the seal but did not fit in the bush! so I think they changed the bush or enlarged the ID. Is not simple to remove that bush without damage the cover so still I have the stupid useless O ring. (I use these bikes a lot; may be for a guy that does 1000-2000km a year the O ring could be efficient) ---Regarding the adjuster; way better to retrofit the later adjuster. Have an external bolt so is not needed that stupid adapter. Front abutment is other but still is possible to use the "fork" abutment without removing it (not possible with the engine assembled) Hope that helps

[@Cobra427Veight]

Can you add a slightly fatter oring or another trick is to wrap the oring groove with 3-4 turns of Teflon tape then fit the oring , maybe chamfer the inside to help lead the oring in without cutting it .cheers .

[@TheReverb1]

@@Cobra427Veight Yes; I did that several times (O ring + Tflon) did not worked for me. Thanks