Triumph primary drive/clutch

To whom it may concern,
I have been hired to do some work on a 1970 Triumph TR6C, one of the owners complaints is the excessive clutch drag. I have disassembled the clutch and found everything to be OK. On the Norton side of this forum many members recommend the use of ATF, and I was wondering if that is an acceptable thing to do with this Triumph. I did a quick seach on the subject and I found that some Triumph models vent their crankcases through the primary so that evidently there would be a mixing of oils, any info regarding this would be appreciated.
Second question is in regards to belt primary drive kits for Triumph, can anyone recommend one and provide a souce. If Triumphs vent through the primary case how does this effect the belt drive?

George Baker
geo46er@yahoo.com

hi george,as you mentioned some late model triumphs do vent the crankcases through the primary,so a mix of atf and engine oil i dont think would be desireable,look for holes in the crank cases level with the bottom run of the primary chain to see if your tr6 is one of these models,regarding belt drives google tony hayward,hes in uk,he does belt drives that will run in oil

Anyone converting a post-69 Triumph big twin to a dry primary needs to install a crank main seal, fill in the three tiny drilled oil transfer holes just behind the crank, and arrange alternate crankcase venting.

Some belt drive kit suppliers claim you can run thier belts in oil, the arguments for & against this are still raging (as are all arguments involving any kind of oil).

geo46er said:

one of the owners complaints is the excessive clutch drag.

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There shouldn't be excessive clutch drag, so there's a problem somewhere.

geo46er said:

I did a quick seach on the subject and I found that some Triumph models vent their crankcases through the primary

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All '70-on models do that. (Look for the breather stub at the upper rear of the primary case)

The oil in the primary case is simply to lube the primary chain, and converting to belt drive will not help with a dragging clutch in any way at all.
Drag on these bikes is caused by either by mechanical wear, distorted plates, worn or wrongly assembled release mechanism, or spring tension not being adjusted correctly.

Most belt drives include a new clutch, or most of a new clutch, so you could see an improvement. Seems like a clumsy way to address a dragging clutch problem though..

Hi again,
When I received the bike I could not break the clutch free by holding the lever in and kicking the kickstart lever. I pulled the cover to inspect and found that the pressure plate is lifting evenly and seemingly a significant height. The clutch basket and clutch center slots were not worn (grooved) hardly at all. I did find that the clutch plates were in fact stuck together quite tightly and needed to be pried apart. The plates appeared to be in good condition, not worn, burnt , or warped. After washing the clutch plates, reassembling, and refilling with the specified amount of motor oil (350cc) the clutch would break free easily (using previously described method). However, after a single test ride the clutch was again sticking and was reluctant to release. On the next test ride I resorted to an old trick that I had used with a 76 Bonneville I had owned many years ago, After starting I would run along side jump on and slip it in gear (rolling down hill is easier) then while holding the lever in a couple blips on the throttle and the clutch would break free. This was something I only had to do once per year at spring start up, this of course is unacceptable to have to do every time the bike is to be ridden, and even after getting the clutch to release there is enough drag to cause the neutral to first shift to grind unacceptably. I cured my Commando of such behavior by installing a primary belt kit and running a completely dry clutch (best modification I have done to it). I would recommend the change to primary belt to the owner of this Triumph except that I don't want to have to re-engineer the engine breather system in order to do it. All clutches, dry, wet, or semi wet, drag to an extent, from what I have read and experienced the older British bikes tend to do this too much IMHO.

GB

geo46er said:

refilling with the specified amount of motor oil (350cc)

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The book "initial fill amount" for a 'breather' primary case was reduced to 150cc.


However, if the clutch friction plates are old, they may have developed "sticky-plate syndrome" and nothing short of replacement is likely to cure that.

Cleaning the plates and trying the 150cc sounds to be woth a try. In theory, little or no oil should be on the plates.

Is it feasible to try a thinner grade of oil in engine and primary?

A new set of plates is worth a try too- much cheaper than a belt kit.

Triton Thrasher said:

Is it feasible to try a thinner grade of oil in engine and primary?

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I run my T140 on the recommended 20w/50, the clutch frees off easily, usually within one or two easy kicks, and it doesn't suffer from drag.

L.A.B. said:

Triton Thrasher said:

Is it feasible to try a thinner grade of oil in engine and primary?

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I run my T140 on the recommended 20w/50, the clutch frees off easily, usually within one or two easy kicks, and it doesn't suffer from drag.

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What grade of oil is geo46er using?

Blankety Push-Rod ? . Remove and check ends , particularly Left , for blueing , burrs , distortion , etc .

70 is first yer for chaincase breather , doubles volume compressed by pistons on downstoke, so Halves
Pressure Fluctuation . So were told .Also Told NO Friction Modified Oils . The Thicker engine oil typically drags a bit when cold.

Was a fancy ' T ' Thrust Race pushrod / clutch end thingo available aftermarket , to Eliminate BLUEING from honda boys (oops )
HOLDING IN CLUTCH at lights. This Is Bad Manners , and will not be tollerated .The ' blue' was red (hot) and the End softened ,
and wore , sortened , and siezed . To the bearing , The 1/4 (or is it 3/16) BALL ( as in just one) between the little hat in the centre of the clutch,
and the push-rod.Typically welds to pushrod and Galls .

So now you know !

Important to check ' centering ' of actuateing Lever . ( Much as rockers over Valves ) I presume it should End Travle at or about Square ,
( Max Leverage whilst holding in clutch , to cause aforesaid injuries :mrgreen: )

Differant conditions ( Thicknesses) of Clutch Plates lead to this too . . . New plates throw it all out if it was set up precise previously ,
when replaceing ' consumed ' ones .

NOW , we never had this bother with Pre-Units ( ) CORK ones gave infinately better take-up ,
would schorch if slipped excessively under power , but enabled you to hold the front wheel up under
power whilst ' getting under way ' . :shock: letting it in , progressively .

1970 is one of the ' Better years ' , should run 32 mm carbs , AND Ports . Won Castrol 6-Hour in Aus,
Vs the ' New ' 750 Honda. Next year they madem fit ' unworn ' footrests previous to the start .
A Determined Effort in the first 1/2 hour wouldve worn em enough to repeat the exercise , if
theyed intentionally groundeed it ashard as possible as long as possible in the bends !?

A Commado couldve got it once too . . but for time lost after looseing front brake pads .

Worst thing on the English 70 is the tank paint , No ' Wings ', Tweek it up a bit
Dont be pedantic with originality,First year of the fancy ' shuffle valve ' two way
damped forks too , I think .
Worth Flushing and reoiling there too .Tey get right grotty inside if neglected .

A little too much oil in the primary initially will result in a bit of slip, not any freeing off issues (or precious little if any).

Sounds like the actuation is suspect. Pushrod and lifter ramp in the gearbox case need to be looked at. Belt drive won't cure a worn actuation.

Mick