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Clutch Squeak


andilicious
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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

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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!

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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.

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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!

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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 by thats_a_five
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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 drag
Thin 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........... @100oC
GRO Gear Extreme 75W*......... 20.............. 5.2
Elf HTX740.syn........................ 21.4............. 7
Valvoline Dextron VI ATF syn.. 29.5........... 6.0
Motul ATF VI*..........................30,5...........6.10
Mobile 1 Dextron VI…………. 29.5…..…. 5.3
Royal Purple Max ATF........... 35.0............. 7.5
Valvoline +4........................... 34.13.......... 7.55
Allison Transynd syn ATF ..... 53.9............ 9.75
Elf HTX735.............................114............17.8
Amsoil 75W-90 syn**……….. 130……. 15.6
Amsoil 80W-140 syn**…….... 256……. 26.4
Silkolene Medium 85W-90... 150-340..... 15
Silkolene Light 75W-80......... 100-180..... 15
Silkolene Comp 80W-90........ 100-145.... 15
Silkolene Pro SRG 75............ 100-180..... 11
* info from Trials Central posts.
** Hypoid gear oil - do not use in a wet clutch

I 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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