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Dibnah Offline OP
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My mongrel 1972 TR6 has an earlier engine (engine number starts T110, 8 studs) and earlier primary chaincase (no breather). I want to convince myself that there is no oilway connection between the crankcase and the primary chaincase without dismantling. I'm sure I've read (probably on here) that this could be achieved by:

Measuring oil level in the P/C with the traditional dowel (warm engine, bike on centre stand)
Start the bike, leave it on the sidestand for 5 minutes
Put bike back on centre stand, measure oil level in the P/C, if it's noticeably increased then there is an oilway

Is the above a reliable indication?

Some intermittent, slight clutch slippage has returned, this was previously fixed by deglazing the plates. I use Silkolube 20w50 in the engine and primary chaincase, which is labelled as API SF/CC. If no oilway between the primary chaincase and crankcase then I'll try ATF type F.

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Hi Dibna, Pre unit engine has seal behind crank sprocket. Spring on seal faces sprocket. It does not transfer oil to primary case. The spring faces sprocket so low pressure in crank case as pistons rise doesn't suck oil from primary into crank case.

I don't know if Silkolube cases clutch slip or not. ATF F sure works good in primary on the not primary breather motors. I've found you often don't need to take clutch out & clean it. Just change to ATF or wet clutch oil on later bikes, & ride it. Takes about 50-100 miles for the new oil to flush old oil from plates in my experience. I change primary oil again after 100 miles. On later bikes change the motor oil etc including motor sump drain.

Back in the day Triumph recommended 20w in primary. Higher weight in motor.

Your idea of side stand, checking oil would be valid. I know for sure on later bikes, idling motor on side stand transfers oil into primary. I've done that test several times. It takes about 10 miles to get oil back to tank or frame. You can plainly see change on dip stick as well as visually watch oil drop quickly. A fun experiment. Reservoir oil will drop 2", in 15-20 seconds. You can just see it. Then it slows. Why it slows I don't know. I've let my bike idle dozens of times for quick restroom break side of the road.
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Drain primary, remove cover, start engine and see if oil appears from behind the engine sprocket.

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Dibnah Offline OP
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Thanks for the replies. When I bought the bike, I made the mistake of assuming that it was as described, so I assumed that there were oilways between the crankcase and the primary chaincase, but external inspection of the engine, primary chaincase and gearbox indicates that it's all pre-OIF, although the frame is certainly OIF.

I ran the bike last year on the road for a few miles without an outer cover to the primary chaincase, engine oil was not noticeably appearing from behind the engine sprocket, although I didn't peer at it too closely.

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Hi Dibnah,

In your 1st post you say "engine number starts T110, 8 studs".
This is confusing, as I believe both those details suggest a pre-unit (separate engine/gearbox, pre-63 650), though it would be possible but unusual to fit an 8-stud top end to a 63-on unit 650 bottom end. However such a bottom end wouldn't have a T110 engine number.

I've not tried it, but I'm doubtful that a pre-unit would fit into a 72 frame.

So are we dealing with a unit or pre-unit? Cheers.

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Morning Koan,

The mongrel construction of my 650 has been covered on here before: mechanically it's unit, and yet the engine number starts T110 and includes 6T. As Ginge previously pointed out, the 6T was sold with unit engines in the 1960s. I speculate that perhaps the crankcases were a replacement set, with the engine number perhaps being stamped after the cases left the factory

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Hi Dibnah, Ok, unit motor with breather in front of gear box sprocket for sure doesn't mix primary oil with motor oil unless someone modified the breather. So use ATF F in primary. Again spring on seal behind crank sprocket should have spring on sprocket side.

There is a formula for setting clutch spring nuts on 3 spring clutch. Take all the plates out whether you have 12 or the 14 plate (7 plate kit). Clean them. Stack all the plates together friction, steel like stacked in bike. Stack them neatly. Squeeze stack tight with fingers on one hand, measure thickness of stack where squeezed with the other using vernier caliper or 2" micrometer. Ruler won't do. That is your stack height. Record the number.

A new Triumph set of friction & steel stacked would have been average nominal 1.400" thick.
"
A used stack is often thinner. Say 1.340" So .060" thinner than nominal. So set spring nuts to dome is flush with end of studs. Then go .060" deeper using depth gauge on the Vernier caliper. (one full turn of nut is about .038"). That gives factory spring tension as if plates were new.

Spring binding is not part of this, due to the spring cup/pressure plate is to the right side of bike farther compared to studs for spring nuts. So your not adding tension, just bringing tension to specs. This works really well. I will allow using even very worn plates & they grip fine so long as they still have some friction pad remaining.

I've used the 1.400" nominal many times on both 6 & 7 plate kits. Works great. If you don't have verneir calipers, you need some. Cheap digital ones on ebay are fine for this type work. Fitting bearings etc you need better, but they'll serve you well for most uses. Accurate to about .001-.0015".

A fast easy way to drain primary is siphon oil out filler hole. 9" long 1/4" brass or aluminum tube. A few feet of 1/4" clear plastic hose. Stick tube into filler hole behind chain. Work it to bottom. It goes easy, not fight. You feel the bottom. Suck clear hose to start siphon. Takes 15-25 minutes depending on oil temp. I do this all the time. Never drain from chain adjuster plug. It's often even slower. Plus threads for plug are temperamental. Damaged easily. I avoid taking it out when possible.

Don


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Dibnah Offline OP
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Thanks Don,

I have previously adjusted the clutch as per your postings, plate stack was around 1.400" when last measured, as I recall. I should keep written records.

I'll let you know how I get on

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Hi, Dibnah, Good. I expect the ATF will be big help.
Don


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Dibnah Offline OP
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The siphon worked well, thanks Don, although I used a variation with a handpump from a disposable soap dispenser.

150cc of Type F ATF into the chaincase, Type F is available in the UK from Eurocarparts for £5 a litre. Checked pushrod adjustment (cable disconnected at handlebar end), 1/2 turn back from the "stop", test run and the clutch cable failed at the handlebar lever frown Replacement 60-0565 D565 , outer cable 47", inner 51", my bike has the 1972 US bars (probably!) , new cable = same length as the previous cable. However, the previous cable has a "pear" nipple at the gearbox cover end, the new cable is more of a "end-on" barrel with a shoulder (photos), perhaps an angular pear! New cable fitted after fettling nipple with a small file.

The mysteries of the origins of my mongrel 650 (1972 "hi-frame", 8 stud barrels, unit construction engine) continue to mystify: several different 1/2" AF sockets have never been a good fit for the clutch pushrod nut, closest fit has been a 1/4" BSF (3/16" Whitworth) ring spanner with a deep offset. I've finally bought a 3/8" UNF nut (although not a Triumph part), which is far too big. Under close inspection, the fitted nut is in reasonable condition and measures 29/64" across flats (approx 0.45 of an inch), the screw is 1/4" OD and 20 TPI. Is this possibly cycle thread?

To get to the point (please!), did pre-unit Triumphs use cycle thread screws/nuts for the clutch pushrod adjustment?

I can re-use existing, but it would be useful to have some understanding of what I'm working with.

Left hand clutch cable = previously fitted but broke, RH = new, but doesn't fit at the gearbox cover end "out of the box"

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AFAICT the clutch adjuster screw was only 1/4" 'til 1965, then 3/8" (UNF) thereafter. BUT it was 26 tpi, cycle thread, with the same thin nut as used on the tappets of that era 60-4264

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Dibnah Offline OP
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Thanks TinkererToo, I've re-visit the TPI

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Hi Dibnah,

Can’t answer all your mysteries, but perhaps a little to offer.

¼ X 20 tpi can be UNC and Whitworth.

Though the same OD and TPI, UNC and Whitworth are not a perfect fit.
UNC has 60 deg angles, Whitworth has 55 deg.


Spanner sizes:

The UNC would usually be 7/16 AF (0.4375”)

The later BS hex size for Whitworth would be 0.445” AF
This seems the most likely candidate for your existing nut.

My guess is it is ¼ 20 tpi Whitworth with a 0.445” AF hex.

This does surprise me as I didn’t think Whitworth was used much in the 60’s, other than cylinder base studs into the case.

Are you sure of the 20 tpi? It is difficult to gauge over a short length. I’d much rather that be 26 tpi (in which case it would be BSF or BSCY).

The pre-units didn’t have an adjuster in that location, they just had a top hat bush. Their adjustment was done on the gearbox end of the pushrod.

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Dibnah Offline OP
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My error, 26 TPI, that will teach me for trying to gauge a thread using a hacksaw blade. I'll have to buy a thread gauge, yet another one.

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Yes, a problem with hacksaw blades is they come in different tpi, and the numbers get rubbed off the side!

I reckon that is 1/4 X 26 tpi cycle thread BSCY. It has the correct AF too.

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Thanks Koan, it is just possible that ageing eyesight also contributed to my error.

I should add that running the engine with the bike on the sidestand did not increase the oil level in the primary chaincase, so it's likely that there is a good seal between the PC and the crankcase.

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Hi Dibnah, I'm yet again confused on exactly what you motor is. Please post side views of motor both sides. Some full motor views & closer views of primary area & trans cover area. All this stuff matters. We don't want to give incorrect info. Many changes through the years.
Don


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Dibnah Offline OP
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I've been confused about this bike for a long time Don.

A couple of photos from a few years ago, the clutch cable entry to the gearbox cover now has a boot, and the bike is no longer shiny.

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

I'm going to have to re-visit "does oil transfer between the crankcase and the chaincase?" I've checked my notes from when I ran the bike with the outer primary chaincase removed (last year), the notes record that I could see oil being produced from somewhere, but of course I couldn't see behind the engine sprocket, so it's possible that it's general splatter.

I'll probably drain the ATF and refill with engine oil, as I can't risk ATF contaminating the crankcase, even though the "extended idle on the sidestand" test did not increase the oil level in the primary chaincase. If the primary chaincase has to come apart again then a dry clutch beckons.

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Hi Dibnah, That looks like a '68 case. What is the wire/hose?? Comin up from behind cylinder area. Normally the alternator wire comes out next to the breather tube in front of rear sprocket.

What is hooked to the breather tube in front of rear sprocket. Lots of changes on this motor, I understand your concerns. A little ATF in motor oil is not a disaster, but you certainly don't want it to mix.

Sure motor oil in early primary works just fine. I've tried Torco T4 20-50 was ok, Mobil1 vtwin 20-50(Good). Bike Master 20-50 (good).What are you using in motor now? I've used various brands types ATF that's not what you want though.

Back in the 70s I used Castrol GTX 20-50 in later motor. I was perfectly fine with clutch, original cork plates. Mobil1 vtwin works very good with both original cork plates or modern plates. It seemed like T4 20-50 didn't free quite as well cold as Mobil1 V-twin. Bike master freed & worked good like Mobil1 vtwin with modern friction plates. Didn't try it on cork. This is non synthetic oil.

Just this very day I freed clutch on the '69 Bonnie cold & started it, Hyde 7 plate. Has Mercedes 134A ATF which is basically ATF Dexron II. Blind folded I couldn't tell the difference between this oil, Mobil1 vtwin, Bike master 20-50.

End of day, if you set up & adjust the clutch properly any of these oils free perfectly & don't slip. I don't see any difference in chain wear with motor oil or ATF.

That's why I say just use same oil in your motor assuming it's wet clutch approved.

End of day I don't really see a real advantage converting to dry clutch. If normal primary chain & clutch is set up properly they work great. Chain wear doesn't seem to be an issue. Personally I feel Aerco 7 plate kit+1 & 6 more new smooth steel plates. Keep the original steel pressure plate. 650 springs. So long as basket & cush hub is not worn it just works perfectly. I've been tracking wear between friction pads of Hyde & Aerco. I'm finding Aerco lasts longer. You don't need to crank down springs or anything. Allows using 650 springs on T140. 500 springs are just too soft & will slip.

I've never tried the Emgo kit. I got 6 friction plates. They were so thick with original steel plates the last steel plate was in danger off falling off with clutch pulled. I didn't know at the time I needed the thinner Emgo steel plates. Took it back & installed Hyde 7 plate.
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Thanks for the detailed reply Don, as always.

The black cable is a black sleeved cable assembly for a pair of green cables (I can't easily see a marker stripe), I assume from the alternator, which connect to another pair of wires, which are yellow. I can't easily see where the yellow wires terminate, they head towards the battery area, I assume the regulator is there somewhere.

The black cable assembly runs through what appears to be a non-factory hole through the top of the engine casing.

The spigot for the engine breather can be seen near to the gearbox sprocket. I have previously tried to fit a flexible hose to monitor how much oil the breather spews out, but I struggle to get my hand up there.

The few miles I rode with a dry clutch last year were a revelation (no PC outer case fitted); the clutch was light yet precise, and the rattling added to the general aural ambience. It's the cost that's the major deterrent, I can't see how to do it for less than £500, which buys a lot of petrol. A few years ago, you could buy a reasonable used bike in the UK for £500.

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Hard to reach hose hook up. I have LONG needle nose pliers for just this job.


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My recent A10 Road Rocket hot rod build has a 5 disc 4 spring Triumph style clutch with orange friction discs from Low Brow Cycle. The discs friction area was narrowed by me despite some doubters on the forum. The oil is 10/30 Motul wet clutch ...The bike has the power of a 650 Triumph, the clutch action is light with no slippage or drag and frees up instantly. Of course as usual I use Magura or Brembo type levers and perches and not that awkward feeling crap fitted to Most Brit bikes. If you have a primary not sharing engine oil you may want to try the not too expensive Motul
The Areco 7 plate on my T140 has a decent feel with no slip or drag...However with Mobil1 V twin 20/50 it takes a few pokes to free the clutch after the bike sitting for a few days.in fact the non Jaso rated 20/50 Valvoline VR1 conventional was equal in terms of clutch function.
My 96 Ducati 900 has a dry clutch with the famous clutch rattle in neutral...I dont care for the noise and have dampened it with an aftermarket clutch basket...


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Hi Desco, The breather hose is 3/8”. Long needle nose as was suggested makes it not very hard task. Squirt carb cleaner spray on tube & in end of hose. Push hose on quickly. Hold it a minute or so. Cleaner will dissipate & hose stays on with no clamp. Original hose was thin wall plastic unlike material. I use 3/8 fuel line. Of course right next to sprocket you have to zip tie it to frame.

Get longer piece such you can blow into hose with your mouth. Remove plugs & turn motor via rear wheel. I made a test sheet to test cam breather valve.

PM me your email & I’ll scan it & send it to you.

Plus… you can remove primary filler plug. Blow into motor vent in open position on cam disc. Motor should be sealed. No air out of primary. If you hear air the primary has been modified to allow oil mix.

On the cam breather motors this sounds nuts but primary is vented through clutch push rod bore in main shaft. So into transmission. The transmission is vented through a small hole drilled in upper front corner of trans outer cover. A tiny venting may pass through clutch cable & shift quadrant pivot shaft, but not much.

What about the frame vent up behind head tube? How are you dealing with that? Often a bit of oil runs up back bone on hard down hill breaking. Have you experienced that?

Normally that oil runs down frame vent hose & into T & into primary case & pumped back to frame.

The alternator wire next to chain & routed under motor had similar routing problems of its own. Drilling hole & going up might not be bad plan. Never seen that but why not?

You have some puzzles going on.
Don


1973 Tiger 750

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