Triumphrat

Snakepit · 07-10-2008, 06:29 PM

My bike is a 78 T140E Bonneville. I've just changed the seal behind the clutch on the sprocket access door 3 times and and not having any luck getting rid of the leak. I've tried putting the seal in both directions so the lip would have a different surface on the shaft but it still leaks. It is definitely engine oil. Nothing leaking from the gearbox ( I changed the 2 seals behind the sprocket as well). It only starts to leak after a 20 minute ride. No oil leaking from the alternator wire hole so I don't think there is excess crankcase pressure. Yes, I've read the tech tip on sealing up Brit primaries. Any help much appreciated...thanks in advance!

TRI-AL · 07-12-2008, 07:01 AM

OK, here you go....had the SAME problem this year (probably for ALL the years I've owned this thing). I changed mine 3 times this summer alone and it only got worse! FINALLY, I degreased the entire area and put it up on it's center stand and lo-and-behold there was fresh oil! BUT it wasn't coming from the primary case as I thought, but from the %&^$# weld where the oiltank goes into the cross member!!!!! When the bike was on it's side stand, the oil flowed to that side and dripped FROM it giving the APPEARANCE that it was the primary leaking! Oil leaks no matter where are a real ()&^% to solve! I'm still in the process of sealing this thing. Slowed down considerably with the help of J.B.Weld and a piece of rag wrapped around it! Winter project to re-weld !

Mecchanica · 07-14-2008, 04:25 PM

Common for the tank tube to crack there. When you weld it, fab up some gussets to reinforce the pivot tube, spread the load. To confirm the location of the leak, put some oil based dye in the primary case and run it. If you get colored oil, then suspect the gasket behind the cover plate or a loose plate screw or a worn spot from the chain.

Snakepit · 07-15-2008, 06:40 PM

found it..case was cracked behind the breather baffle. The rear chain must have picked up something and damaged the case. Not too bad. Just needed some JB weld.

GrandPaulZ · 07-15-2008, 08:12 PM

By the way, on the seal, the lip faces the oil.