4Rt Gearbox Oil Continued.

[sportsawyer]

As ELF HTX740 became unavailable in the USA, I was very interested in trying the GRO Gear Extrem 75 because of the close viscosity match to the ELF oil. But there's no current USA importer of GRO oil. I also checked Canada for both, no luck. And no dealers seemed particulary interested in getting either the ELF or GRO. Having it sent via air from the UK also seems to be a problem, and none of the dealers I checked with would send to the USA.

So I started looking for something else. Wanting to get the closest viscosity (to HTX740) of available oils, I tried the Valvoline Dexron VI full synthetic mentioned above. It worked well when hot, but was sometimes a little sticky and had more drag when cooler. I also started getting some strange engagement... but I think that was mainly due to a well-worn Mitani clutch in my 2005 4RT.

So I went with the Jitsie dimpled steel plate set I had laying around and new OEM clutch friction plates -- 2 each 22201-KY2-000 cork and 4 each 22201-NN4-B00 new type paper -- with the Valvoline Dexron VI.

This has suited me very well. No sticking or drag, with very smooth and predictable engagement.

I just did the first change on my MRT260, and that's about the end of HTX740 I had. So I'll probably change to dimpled steels with Dexron VI on that bike with the next change.

The Valvoline Dexron VI is readily available for only about $8 / quart in the USA at O'Reilly stores.

Edited May 22, 2014 by sportsawyer

[andilicious]

Hi Guys,

Just to chip in, I use Putoline GP10 in my 4RT and its spot on. I get the usual bit of drag until its warmed up but then its fine.

I have been advised to stay away from ATF in trials gearboxes, but to be honest I used it on my enduro bikes religiously and found it to be good enough that I never had to think about it.

I was also advised to stay away from the 75w light gear oils in the 4RT as they tend to make the clutch more of a switch, whereas the thicker ones (such as GP10) keep it smooth. Thats only what I'v been told though as I never bothered with any other oils once the GP10 felt good.

Andy

[lee_28]

I've had my 4rt for 2 years now, used ATF from the get go. no problems, no dragging not even when cold!

[shyted]

Interesting to see about the plates by sportsawyer.By chance ,have any of you read the clutch fix for Beta in that part of this forum. If not go and cast your eye's on it.Come the time for a peep at " what's going on in there" i'll be looking at the plates in great detail . Been down this rout with my 280 Andorra Gas Gas and took a while to find a good reliable set up that uses gearbox oil and not hydraulic fluid . That included laboariously cleaning all the gum and excessive friction material from the friction plates and countless types of oil . The oil i've got in the Mont now is doing the job,however it's not cheap.That's not to say it's to exspensive as i am a believer in good in good out,and would rather pay the £28 per ltr than be on the verge of a gearbox rebuild.Just my view there as i'm a right fussy so and so.

So keep the info coming

Edited May 27, 2014 by shyted

[dadof2]

I see some people have been comparing the oils viscosities at 40 degrees C. Much of the time a trials engine and gearbox will be running at 75 degrees C and over.

[billyt]

Interesting PDF. ELF says its for DRY CLUTCHES MMMMM

Elf.pdf

[mags]

I saw that sheet on an Elf site and queried it with the Aussie Importer. He said " Still the oil to use according to factory! My 2014 service/owner's manual says HTX740.

Its still available here in Australia… I pay $32 a bottle (1 litre).

Mags

[shyted]

I saw that sheet on an Elf site and queried it with the Aussie Importer. He said " Still the oil to use according to factory! My 2014 service/owner's manual says HTX740.

Its still available here in Australia… I pay $32 a bottle (1 litre).

Mags

Ha ! Like to bet the designated usage could change when not a soul can buy HTX740 ! As Billyt states "why are they using Elf when REPSOL is directly associated and sponsor Honda/Montesa"? You have to admit every one, he has a bloody good point there .Would say mags ,so do you . So it may say that in the manual this year ,but if you can't get it ,what then ?Hope you see where i'm coming from saying that.Maybe next year they will state a Repsol product for the gearbox.

An extra MMMMMMMMM on the dry clutch application too billyt !

[mags]

Shyted,

Now there is a paradox! If they change it to Repsol (although in my 2014 manual it does say to use Repsol for the engine oil) we have no Repsol in Australia (that I've seen) so I'd be in the same situation like those that can't get Elf for gearbox… I couldn't get Repsol for gearbox, so i would use Elf!

As for the Elf and its friction additives and not being used in immersed clutches… if the additives allow slip maybe that what Montesa wants??? Doesn't slip on full clutch engagement but may slip slightly on take-up giving more progression on clutch take-up??? Just a thought?

Mags

Edited May 28, 2014 by mags

[chuck4788]

Shyted,

Now there is a paradox! If they change it to Repsol (although in my 2014 manual it does say to use Repsol for the engine oil) we have no Repsol in Australia (that I've seen) so I'd be in the same situation like those that can't get Elf for gearbox… I couldn't get Repsol for gearbox, so i would use Elf!

As for the Elf and its friction additives and not being used in immersed clutches… if the additives allow slip maybe that what Montesa wants??? Doesn't slip on full clutch engagement but may slip slightly on take-up giving more progression on clutch take-up??? Just a thought?

Mags

Good point

My experience has been:

1. Modern car crankcase lube oils are risky to use in a wet clutch because anti friction additives can cause clutch slippage. But JASO-MA oils ar OK. ATF oils are gear oils for wet clutches.
2. Montesa recommends Elf HTX740, which is a very thin synthetic gear oil. Elf cautions to not use this oil in a wet clutch. EBC and others recommend not using synthetic oils in wet clutches. Go figure!!
3. Dextron ATF provides much smoother clutch engagement than "F" ATF.
4. Synthetic ATFs are much thinner at typical ambient temps than Dino based ATFs (see chart below).
5. Thicker oils cause more drag, thinner less drag and faster hookup.
6. Cork friction discs provide the smoothest engagement, paper the grabbiest. EBC claims smooth engagement with their sintered cork and Carbon Fiber frictions.
7. CR250 frictions provide better clutch action for 315Rs and 4RTs. Probably because they are all cork compared to Montesa using a mix of cork and paper plates/

I tried a Valvoline synthetic Dextron VI ATF in my 315R with good results. A little more drag when cold, slightly longer range of engagement, and smoother lockup. But how much was new oil versus old oil, or different brand? The increase in drag was fixed with a bit of adjustment at the lever.

I have also used Mobil 1 with a wet clutch with slippage problems. But Shell Rotella T and T6 provide good clutch action, but are thicker than the syn ATF.

[shyted]

Hello chuck4788.Great info there pal.Clutch slip is not the problem ,drag is,but as you say it may be why they use HTX . For me both problems defeat the object of a clutch for a machine designed for our purpose. If i was drag racing i would want initial slip and then lock up . I'm sure some drag racer will put me straight for that comment ,just repeating pisch i've read.

As for ATF , it is an oil designed for an hydraulic environment but nowt to say it can't be used for what we need.My self i prefer gearbox oil.I don't doubt that the HTX isn't a gearbox oil ,but i think it's qualities are really short lived,and further more with the experience on my Mont very rapid drop off in the oils performance.

I agree with what your saying about the plates,and possibly thats where part of the problem lies.

It's a bloody toss up with the information . It would be interesting to talk to the like's of EBC's R&D department to find out where they get they're results from.

I think the problem lies when the clutch is disengaged and the oil wont let the plates seperate,therefor causing the drag.The colder the oil the worse the problem.That's why i let my bike warm up for a good 5mins before i even contemplate riding. Even when the bike was new it sufferd from drag.

I blead the clutch and adjusted it (brand new bike here) no different . Now i've changed the oil and type, when the bikes warmed up it's no problem.

But i'm interested with what every one now seem's to be saying about the clutch plates.

Keep it coming men,and ladies.

[ian640]

Why not just use the Elf oil recommended in the 4RT manual? It's readily available in the UK at least.

[shyted]

If you want to use it ,use it .I've stated the reasons above why i don't . So have you used Repsol 10w30 in the motor ian640 ?

It states that in the manual also.I use Castrol probably one of the finest oils in the world.

Edited May 29, 2014 by shyted

[ian640]

So have you used Repsol 10w30 in the motor ian640 ?

No, haven't found a supplier for that. I habitually use Splatshop who stock the Elf. I've used the Castrol as well in the engine

I've assumed (rightly or wrongly) that Honda-Montesa would know what they're doing when specifying the oils.

[dadof2]

There are at least two reasons why some synthetic or semi synthetic engine oils in particular should not be used in wet clutches.

Firstly some contain High temp, high shear (HTHS) additives which prevent the clutch engaging fully, leading to extended slip periods after engagement.

Secondly some of the cleaning / dispersant additives dissolve the adhesive that bonds the linings to the plates.

When buying car engine oils you do not know what exactly is in them, but as both Castrol and Mobil produce wet clutch (motorcycle) varieties of their synthetic engine oils its a fair bet they are designed to avoid the problems I mentioned.