Montesa 301 RR Clutch Issues

[Montesa301]

Morning, 

I’m looking for some help with my Montesa 301 RR 2022 clutch. I’ve had issues with the clutch since purchase a year ago. It’s progressively got worse with juddering, shrieking when hot and now a grinding sound under engine breaking.

 

Ive changed the plates out for Mitani Alluminium discs, fresh HTX 740 and it hasn’t improved or changed at all. 
 

Any advice would be much appreciated.

[lemur]

From a site that sells that expensive lubricant: "ELF HTX 740 is a monograde ultra fluid transmission lubricant specially developed for dry clutch gearboxes coupled to 2-stroke engines. "  I would try something cheaper that you can change out every time you get water in it, nothing will make your wet clutch act up and make noise as bad as having water in the oil.  It's not the steels that are causing a problem it's your cork and/or paper friction plates.

 

[jrsunt]

Get rid of the Elf, it’s great when the bike is cold but can’t handle the heat of a properly used 4rt. Use the same 10w40 that you use in the engine. I also run the Mitani clutch. Try that first, if it doesn’t help then something else isn’t right. 

Edited 8 hours ago by jrsunt

[lemur]

Kubota UDT or similar farm tractor and excavator hydraulic oil 👍  at about 10 bucks per litre works out to ~5 bucks per oil change.  Extensively tested for over 2 decades and 5 Cota'   ... your transmission does not require multiple-grade engine oil, it has far more in common with a farm tractor transmission that contains hydraulics, gears and wet brakes and wet clutches.  If you think your motorcycles transmission oil is under higher stress then a farm tractor or excavator would experience you would be wrong.

 

[jrsunt]

A multigrade oil is not necessary, but something like the Motul 300v is also designed for wet clutches in sports bikes which is perfect for the Mont. None of the light gear oils can handle the 4rt when they are ridden hard, big climbs, steps or prolonged slipping and feathering then the clutch becomes grabby, snatchy and eventually it’s hard to change gear. 

The light/thin oils are perfect for clubman riders, but anything more it’s just not up to the job. 
 

[lemur]

Thankfully nobody is recommending a thin light gear oil in your 4RT transmission 🤔 for any rider.  

UDT is ISO 46 viscosity same as the HTX biggest difference it is half the cost 🤓 so you can change it twice as often.  Replace every 15 hours operation <- that's the factory recommendation how close have you kept to that?

... and if you use power washers on your motorcycle stop doing that.

Edited 3 hours ago by lemur

[jrsunt]

Light oil/thin oil is the problem, the HTX is too thin at 46 viscosity when the bike is working hard. I don’t know the science behind it.
The ONLY reason HTX is recommended in the manual is so the average rider doesn’t have clutch drag when starting up from cold and it will start in gear. Most riders will never have a problem with HTX. 

When we were doing the European and some World Championship events, the clutch would be completely useless by section 2, 10w40 engine oil was the answer

Different level of riders require their clutch to operate differently, mine drags and is a bitch to start in gear when cold, but I know it’ll work properly when i need it to. 

[lemur]

I don't experience clutch drag on cold startup.    4RT won't start at all if the engine oil is below 0C but the transmission will work just fine at ~-7C right up to as hot as you can stand to be riding it.  I do know this, if the clutch makes noise it's time to change the oil and if the old oil comes out opaque or milky, you have lots of water in it.  Water swells the cork or paper fibre material in clutch plates. 

[stou]

Today I juste replaced the metal plates with Apico and used Valvoline Dexron VI AFT oil and the bike is completely different. The best modif I did!

[lemur]

Keep in mind ATF is considered to be less slippery (has a higher coefficient of friction) compared to industrial machine oil lubricants.  What ATF does contain is detergents, friction modifiers, anti-foaming agents and a slew of special chemical additives in ~80% thin machine oil, perfect for a hydraulic torque converter that a 4RT transmission does not have 🤔 If the shifting does get stiff switch to 100% oil.  Steel plates should last a lifetime if you never cook the oil in the frictions.

Edited 25 minutes ago by lemur

[jrsunt]

Lemur, you don’t experience the drag because you are using a similar viscosity to the HTX which works perfectly on a cold engine. If you’ve never experienced the clutch failing due to heat and stress then you haven’t reached the limit. It is a common issue for the expert riders that require the clutch to do more work. 
Montesa301 has asked why he has a particular problem when the bike is hot using new oil and a new clutch plate kit. This problem is experienced when using particular oils