January 30, 201412 yr Hi All, I noticed my clutch squeaking under load last time out. Anyone know a cause of this? I assume the plates are worn and need replacing? Cheers, Andy
January 30, 201412 yr A clutch squeak is actually chatter, it's just so fast that it comes across as a howl or chirp So it's slip grip slip grip, cause could be more than one thing Try a different oil first If tear down is needed measure plate thickness, maybe they are glazed and only need a deglaze
January 30, 201412 yr Author Its had new oil in about 2 hours prior to this done by the shop I got it from, not sure what it was though. I think I'm gonna drain it and run it on ATF anyway like my enduro bike so one oil suits all gearbox's! I'm opening it up to remove two of the clutch springs so I can have a look at the plates while I'm in there!
January 30, 201412 yr My '11 280 chirps when cold, running elf htx. Once warm I can do my usual clutch pings for bigger steps and she's fine
January 30, 201412 yr I don't now about the chirping but I do know you will really enjoy the clutch after removing the 2 springs.
January 30, 201412 yr enjoy the clutch after removing the 2 springs. I presume this is either 2 clutch springs so long as there are opposite ? and what effect does it achieve ... ? cheers Greg
January 30, 201412 yr Yes, any 2 springs opposite to each other. The '05 4RT has a reputation of a clutch that is more "on-off' than is desirable for good trials riding. Removing 2 springs make it much lighter for the left hand index finger, thus much more progressive and easier to slip the clutch.
January 31, 201412 yr Author Does anyone have a recommendation on which ATF to use? I have used whatever was the cheapest in my local motor factors for the KTM and changed it literally after every 2nd ride so about 5-6 hours use and never had a problem with it. I will try a 'box full of this one anyway but if someone can recommend a good choice I'll go with that when this one runs out!
January 31, 201412 yr Montesa recommends ELF HTX740. I just got my 4RT last year and am not sure oil what is in the gearbox so I have a bottle of the this oil on order (not usually sold in US). I think the bike may have Motul oil and once I removed that 2 springs the clutch was very progressive. I will be interested to see how the ELF performs.On another forum (don't know if it's OK to post here) there are some people who have spent time "Improving the 2005+ Montesa 4RT" and they recommend using 520cc's or Silkolene 10w40 Off Road engine oil (the ELF oil is not available in the states). They say "Determined by experimentation: One should avoid light clutch-transmission oils or the clutch will be more grabby." I have not tested this so I provide this only as information for your consideration, not a recommendation.Ride on! Edited February 1, 201412 yr by thats_a_five
January 31, 201412 yr And ATF oil makes it even more grabby than light transmission oils, so I'm told... I'll be testing the Mitani clutch with aluminium plates shortly, it should improve the clutch action...
February 2, 201412 yr I posted the following in another thread on Monty clutches, although it is for a 315R the plates in the 4RT are the same size: Besides the dimple disc, that Montesa finally switched to, oil has a big effect on clutch operation. Montesa specs a very thin Elf HTX740 synthetic gear oil, but it is expensive, and for me difficult to locate. My research.Thick oil slow hookup and increases dragThin oil faster hookup and less drag.Regular ATF or Ford type vs Dextron type; Dextron has smoother lock up, regular ATF quicker lock up.Thick and thin above refers to the oil's viscosity at 40C.Gear Oils................................ @40oC........... @100oCGRO Gear Extreme 75W*......... 20.............. 5.2Elf HTX740.syn........................ 21.4............. 7Valvoline Dextron VI ATF syn.. 29.5........... 6.0Motul ATF VI*..........................30,5...........6.10Mobile 1 Dextron VI…………. 29.5…..…. 5.3Royal Purple Max ATF........... 35.0............. 7.5Valvoline +4........................... 34.13.......... 7.55Allison Transynd syn ATF ..... 53.9............ 9.75Elf HTX735.............................114............17.8Amsoil 75W-90 syn**……….. 130……. 15.6Amsoil 80W-140 syn**…….... 256……. 26.4Silkolene Medium 85W-90... 150-340..... 15Silkolene Light 75W-80......... 100-180..... 15Silkolene Comp 80W-90........ 100-145.... 15Silkolene Pro SRG 75............ 100-180..... 11* info from Trials Central posts.** Hypoid gear oil - do not use in a wet clutchI have CR250 plates and discs (dimpled) in my 315R and switched to Valvoline Dextron VI ATF syn and have the best clutch action of any bike I have owned, and much smoother clutch action than with the Elf oil. My friend's '05 4RT clutch, with OEM plates, is very grabby with lots of chatter while slipping. Apico sells the same clutch kit for both bikes. He has tried different plates and it still chatters, I think he should try a different oil.
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