Forum

[scotty]

Hi I have a BNR clutch on my 1994 bullet just got the oil clutch part, if I bought direct could have had the whole belt drive set up same price. Great clutch but, I run 535 piston8.5cr ported head 32mm mikuni and close ratio cogs in box, no slip std one would slip in top at 50kph. Now you can go back to 3rd at 90kph and put the boot in and no slip goes like a train. Like the adjustment to out near the edge instead of the silly plate with 3 bolts cant blame india on that one think the old speed twin had similar to bnr unit mine never sliped and that bike got a hammering.fix once and forget.

[another Allan]

I'm pretty sure that ATF type F is 'grippier' than Dexron. The take-up with Type F is more abrupt, whereas Dexron allows a tiny amount of slip. Under high-torque conditions it may be that this initial slip allows full-blown clutch slip to develop.

I have a Commando Mk3 and use ATF type F in the primary and get no slip and a nice controllable clutch (and lubrication for the sprag, of course which also needs the 'solid' grip provided by the type F.)

[another Allan]

If you decide to change to Type F, you will need to 'decontaminate' your clutch plates of the Dexron. This may not be easy, but a wash in petrol or similar may do it.

If you can't get the Dexron out of the friction plates, you may need to renew them. If you've been having clutch slip they may be worn/glazed anyway, as has been mentioned.

[another Allan]

Oh, and I have ATF type F in my 625 Bullet with standard clutch. I can provoke clutch slip in first but it's ok in the other gears. I plan to fit a 5-plate clutch when I put a 5-speed gearbox in place of the 4-speeder.

[stinkwheel]

I have a plan in a fairly advanced state which involves modifying a spare front plate and using it to replace the clutch cap so I can move the springs further towards the outside of the clutch. This would also have the option of using additional springs in the conventional central position. I reckon the top-hat shape means I'll be able to use standard length springs.



The main sticking point I can see would be a) Wobbling and b) Physically fitting it inside the chaincase.



By advanced state, I mean I've bought the spare plate and done a detailed drawing for my hole centres. I will of course let folks know how it goes.

[Marko]

Surely there must be a way to stop clutch slip? I'm sure that Marks mention of the interceptor clutch would help. FWIW I wouldn't put a triumph or bsa clutch in anything - evil things. Years ago Tony Hayward used to offer conversion kits for clutches, i.e. mainshaft adaptors for different clutch baskets for a load of different british bikes, however the downside is he's very old fashioned and you need to ring him (expect to be on the phone for at least 1/2 hour as he does like to chat!). Do what you must, but don't fit a triumph clutch, trust me.. you'll regret it

[Marko]

Surely there must be a way to stop clutch slip? I'm sure that Marks mention of the interceptor clutch would help. FWIW I wouldn't put a triumph or bsa clutch in anything - evil things. Years ago Tony Hayward used to offer conversion kits for clutches, i.e. mainshaft adaptors for different clutch baskets for a load of different british bikes, however the downside is he's very old fashioned and you need to ring him (expect to be on the phone for at least 1/2 hour as he does like to chat!). Do what you must, but don't fit a triumph clutch, trust me.. you'll regret it

[Paul]

FWIW

I have a race tuned 59 bullet in pre 65 scrambles trim that I used to race. It has a similar state of tune (hot cams, high comp acralite piston, flowed and 32mm Amal etc with close ratio box and different track gearing). I fitted a standard complete new 5 plate clutch assy and it doesn't slip. I use Ford atf in the primary. The 5 plate clutch is up to the job in my opinion.

[kybosusa]

Type F Atf fluid is next to impossible to find over here , is there a different alternative to Dexron that i can use ? I'll take apart the clutch again and inspect the parts affected to pinpoint any defects that may have showed up since install. Will update shortly. Thanks again for the input .

[ric]

Dexron III


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