7 Plate clutch slipping on T140.

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RGM sell a Commando centre machined for the T140 mainshaft or one with just a pilot bore if you prefer to machine to your own spec.
 
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RGM sell a Commando centre machined for the T140 mainshaft or one with just a pilot bore if you prefer to machine to your own spec.
That's interesting. I'll give them a call and make some further enquiries. A friend of mine has a spare Commando clutch that he would sell to me. Thanks Martyn
 

Fast Eddie

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I have a T140 lifter mechanism in the TTI box on the 920.

The T140 lifter mechanism works GREAT with the Commando clutch !
 
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Interesting...I have a T140D with some tuning that's certainly faster than a stock T140...Aerco 7 plate clutch with 650 springs...It doesn't slip at any speed..And it doesn't slip running Valvoline VR1 oil that is not recomended for wet clutches..
 
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Glad to hear that it can work well, Hillbilly, my fully restored ‘70 Bonneville has clutch trouble and I have a Hyde 7 plate I’m in the process of installing. Hope it works, I’m counting on it.
 

Fast Eddie

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Regarding Triumph clutch woes, I have one thing to say:

LPW-Hydraulic-clutch-kit !!
 
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Just asking: why? I've never gone that route and as a long time Trident owner I know many go that route.
 

Fast Eddie

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You can wind the springs in to a point that would be horrid with a cable and still have an easy pull and nice feel.

And it lifts slightly more than stock, which makes it free off so much better. Easy to find neutral at a standstill ? No sweat !
 
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Well, we will see if I can make this work. I’m a lifelong motocrosser and once raced Maico 450s and 490s for 5 seasons straight, and before that CZs for a similar period, so a stiff clutch pull doesn’t faze me, I rather expect it. In my race box I have at least 2 different brands of race clutch springs, I think PM and Barnett— one is coated gold, one is painted red. In fact, I think I have old Alloy Techs too. They all give a fairly stout pull. Anyway, I put my new 7 plate Hyde clutch on my stock ‘70 Bonneville today, with the nuts flush with the tops of the studs and the gold springs, and the pressure plate carefully trued, and a new set of Barnett steel plates. I’m hoping I can back off on the preload somewhat, with these skinny Hyde friction plates and the stout springs, but first it has to not slip— not at all—and go into first cleanly, and not creep at a standstill. If I can achieve all that I’ll be happy.
 
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Fast Eddie

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It should work. Sounds like you going about it the right way.

Just don’t forget that the primary drive oil mixes with the engine oil through the bearing and via the breathing arrangement. So really you should use the same oil in both engine and primary and you really, really should use an oil designed to be compatible with wet clutch.

Don’t wanna start a huge oil thread here, but FWIW I use this stuff, came out close to the top in Comnoz’ oil test and is designed for wet clutches:

https://www.belray.com/product/v-twin-synthetic-engine-oil/
 
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Oh, now that is funny, you can't start talking about oil choices without going 3 more pages. I enjoy reading these debates. I'll start it off by saying, on my street Triumphs, I use Valvoline 20/50 motorcycle oil, JASO MA2, that I buy cheap at Walmart. Natch, since these Triumphs are a 70 and a 79, this also is in the primary/clutch. Same on my Ducatis (80 SSD 900, and 66 250 Mk 3). On my road race Triumph, which has a belt drive and dry clutch, I use Mobil 1 synthetic in the engine, but nothing on the clutch/primary. On my 68 Spitfire, 73 Norton Commando, DBD34 Gold Star, and Metralla I use Valvoline 20/50 motorcycle oil in the engines, and in the clutch F type ATF. Nice and red, so you know what is leaking, and the clutches love it. On my Yamaha 2 stroke modern motocrossers, and my RD 350 (it has one of my old road race engines in it) Yamalube 10-30 or 5-30 in the trans, primary and clutch.
 
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Here is a further report on my new 7 plate clutch. I have installed and used the 7 plate Hyde clutch on my '70 Bonneville, and it works very very well, with no slipping. I used a set of new Barnett gold springs (same pressure as stock Triumph 650 springs) with the studs flush with the top of the nuts, and a new set of Barnett steel plates, which I have always liked best for stock Triumph clutches. As I think as I said above, I am using Valvoline 20-50 conventional motorcycle oil, a JASO MA2 motorcycle oil meant for motorcycles with wet clutches. It does not free off when cold or from a stop quite as nicely as I would like, but my guess is, that is down to the Barnett plates, which come with a sandblasted surface and so are quite grippy--I have experienced this before with them. Next, I will try to take some preload off the springs --to the bottom of the slots--to see if that changes things. In the mean time, I think it is better to kick it through cold with the clutch in to free it off, than it is to have it slip on the road.

I have no idea what is causing the problems others are experiencing, but I am not experiencing that. My guess is, if one starts with all new parts including steel plates and springs, and the clutch basket and hub are absolutely not grooved from wear, and the web and rubbers in the hub are good, maybe the results will be better.

On the the question of which 20-50 motorcycle oil to use, I don't go for the very high end oils in my road bikes, since I generally don't ride long distances or at high rpms; I have a number of bikes that are mostly stock mild configurations, and I live in Alaska where the temperatures are mild and the riding season is very short, and so I may put only 500-1000 miles on any particular bike in a season, and then the oil gets changed the next season again. Having read the oil thread, I certainly can see the benefits of higher quality oils for a different use, in a different climate out West. On my race bikes, I always used the best I could get, and this latest information would change my choice.
 
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Ive thought similar that it may well be better to do frequent changes than to use a better oil longer if you are in a mild climate.
Even with new engine these old air cooled boat anchors foul the oil a lot faster than a modern motor . Only my Trident has a
full flow filter on the pressure side.
 
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Yup, once you fix the slipping clutch it doesn't sound like a motor boat, or (for the older US readers who will know what I mean) an early 50's straight 8 Buick with the "slush-o-matic" transmission.
 
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An update.
Regarding the clutch slip on my T140, I have at last ordered a "Commando clutch centre modified for Triumph main shaft," from RGM for my T140 with a view to fitting a Commando clutch. Unfortunately, having built the clutch centre into the chain wheel, and offering it up to the g/box main shaft, I've found that the clutch basket sits too far back (towards the gearbox) so much so that the chainwheel slightly rubs on the primary chain case cover plate that sits behind the chainwheel, and the teeth on the clutch basket sit approximately 0.090" behind (closer to the gearbox) the teeth on the crank shaft sprocket and that is without the 1 x 0.0010" shim that was previously fitted behind the crank shaft sprocket. If I were to line up the c/shaft sprocket with the clutch chain wheel, I'd have to machine meat off the c/shaft sprockets shoulder and then I think the chain would rub on the rear of the chain case.

So it would seem that the taper has not been machine in the clutch centre at the correct position. I am of course disappointed about this. As far as I can see, there isn't a way to alter the position of the modified Commando clutch centre as it is pre determined by the taper.

RGM do sell a Commando clutch centre with just a pilot hole in it. Maybe my next step is to exchange the one I purchased for one of these and get an engineering company to cut a taper in to suit my bike.

I'll give Roger a call next week and see where I go from there.
 

Fast Eddie

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You’re heading down the road of a lot of work there matey. Fine if it’s a project that you want to do, but if not, it just shouldn’t be necessary. The T140 clutch should work...

The posts above talk about new Barnet plain plates, maybe give them a try?

And forgive me if this has already been mentioned, but you are using an oil compatible with a wet clutch?
 
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Reggie,
I think you are doing the right thing as at best the Triumph clutch is borderline, & at worst totally inadequate being basically a 650 clutch. A long time ago I fitted a Hemmings belt drive to my TR7 & had the same issue with the taper being machined incorrectly, but in that case the clutch sat too far out. Once I had remachined it the clutch fitted. There were however too many other problems & I got a refund from Hemmings who didn't seem all that interested. For the £400 it cost I didn't expect to be used as a development engineer.

Martyn.
 
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