Triumphrat

lovecuba · 11-20-2012, 12:50 AM

About to button up the cases using an American made Premium RTV Aluminium Silicon made by Valco (Cincinnatti).
How have others laid the bead and where on the mating surfaces of the cases? A 1/8" bead following the centre line of the mate, the bead towards the inner or outer portion of the mate or no bead at all and just a spread of silicon over the entire area of the mating surface?
Ps- I realise now that I could have replaced the timing side bearing with a roller, the ball bearing, as shown will have to do.

Redmoggy · 11-20-2012, 02:42 AM

I used Locktite 518 on mine, and tended to keep the bead on the inside of the bolt holes. Dont forget to seal around the lower mounting bolt lug.

Rod

1963wak · 11-20-2012, 03:27 AM

not wanting to be a bringer of doom but the ball is the weakness in tuned T140s,altho with the balanced crank it might last longer than normal.its the reason triumph detuned (with the ex cam) t140s untill the 3 piece roller came available to them .

lovecuba · 11-20-2012, 04:57 AM

Quote:

Originally Posted by 1963wak

not wanting to be a bringer of doom but the ball is the weakness in tuned T140s,altho with the balanced crank it might last longer than normal.its the reason triumph detuned (with the ex cam) t140s untill the 3 piece roller came available to them .

Thanks for the info Guy's. May re-think the bearing issue! Can you supply a number for the roller bearing please? Does it fit straight in or are modifications to the case required?

Cheers

Muzz.

Ps-have found the TS roller bearing number (thanks again Pete)

1963wak · 11-20-2012, 05:14 AM

its a metric bearing so its cheap, 72 x 30 x 19, 3 piece roller, NSK NUP306ET c3 clearence, no modification, fit inner sleave to crank, roller in case, assemble cases then fit washer on outside.

Miller261 · 11-21-2012, 11:39 AM

ThreeBond works ok too. Using my finger, I smeared a thin and even layer on both case halves, applying to all mating surfaces. This is a popular way to do it. The trick is to get your cases together in the short window before the stuff completely dries. No leaks yet.

Mr.Pete · 11-21-2012, 02:22 PM

Quote:

Originally Posted by 1963wak

its a metric bearing so its cheap, 72 x 30 x 19, 3 piece roller, NSK NUP306ET c3 clearence

If you use a ball-bearing it should have C3 clearance.
A roller-bearing should have CN clearance (normal clearance).

JohnA · 11-21-2012, 02:43 PM

I bought my bearings from Kirby Rowbotham, an engineer who has been tuning and racing Triumph twins for decades. He supplied both timing side roller and drive side roller with C3 clearance. When these arrived I phoned him to check, and he was quite certain that these work best (the drive side was a 'superblend' converted to fit the T140 crank with a hard steel sleeve; the timing side bearingw as the same code as given above by 1963 wak).

My engine runs very nicely without any excessive mechanical noise.

Mr.Pete · 11-21-2012, 03:21 PM

Triumph never used roller bearings looser than "CN".After '76 they were able to use a tighter roller on the drive side.MRJA 1-1/8 J C2 ('76 onward only).

If you have a sleeve pressed into a bearing with an interference fit,it will take up some clearance and you might need a looser bearing.

lovecuba · 11-21-2012, 06:08 PM

Have decided to go with a BL 306 C3 ball bearing. This is a 'heavy duty' bearing which has 11 balls in the race rather than 8 which are found in the 6036 C3.