Good transmission fluid for a 2006 HD Sportster?

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I'm wondering what a good tranny fluid would be? I hear Mobil 1 75w90 gear oil is a good choice. Is it better then what ever the HD dealer uses? Will it meet my warranty requirments? Thanks for any segestions!!!!
 
I've used it before with good results. Next season I'm trying Redline's MT-90 as it is specifically a transmission fluid and not a "gear lube" although they are likely very close to the same thing.
 
Amsoil makes an excellent 75W-90 product, too!

I guess you could always give one of the synthetics a try: you'll know which one shifts best before very long.

Cheers!
 
I do believe the Sportster has a shared primary & trans sump so I would try Mobil1Vtwin 20w50
 
The primary shares fluid with the tranny, but they are two separate assemblies. The primary houses the sprocket coming off the engine, the chain that transfers power from that sprocket to the clutch, the clutch itself, and the alternator assembly. At the bottom of the primary there is a fluid passage to the transmission. I have used Sport Trans fluid with decent results but I have noticed an improvement in shifting with other fluids.

Since the fluid must provide lubrication for the transmission, I would not use an engine oil since it will quickly shear down. A 75W-90 gear lube or manual transmission lubricant (MTL) is basically the same viscosity as a 20W-50 engine oil yet is made to resist the shearing of the transmission gears. I have seen UOAs of 20W-50 that has sheared to a thin 40-weight oil in less than 3,000 miles when used in a Harley transmission.
 
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The primary shares fluid with the tranny, but they are two separate assemblies. The primary houses the sprocket coming off the engine, the chain that transfers power from that sprocket to the clutch, the clutch itself, and the alternator assembly. At the bottom of the primary there is a fluid passage to the transmission. I have used Sport Trans fluid with decent results but I have noticed an improvement in shifting with other fluids.

Since the fluid must provide lubrication for the transmission, I would not use an engine oil since it will quickly shear down. A 75W-90 gear lube or manual transmission lubricant (MTL) is basically the same viscosity as a 20W-50 engine oil yet is made to resist the shearing of the transmission gears. I have seen UOAs of 20W-50 that has sheared to a thin 40-weight oil in less than 3,000 miles when used in a Harley transmission.




You are probably right about the shearing. But I used to change my oil in my Sportster at 3000 because of that reason. I now have a Dyna Low Rider which has seperate trans & engine & primary sumps and use Mobil1Vtwin20w50 in the engine, redline MTL in the primary and redline shockproof heavy in the trans. ALL work well. The best advice might be to call Redline and ask what they recommend for the Sportster shared sump. They seem to be very knowledgeable.
 
They recommended their 75W-90NS or their MT-90 to me. I've used their 75W-90 and 75W-90NS in the past and will have the MT-90 next season.
 
I don't know that the M1 75W-90 gear lube or any gear lube is suitable for a wet clutch application, certainly in a Big Twin with its seperate trans it would be fine. Also there has been some concern voiced on other forums of using gear lubes in this kind of application doing some damage to the windings in the stator.

I would think using what ever oil you use in the engine would be suitable for the trans/primary. In my Buell as well as my past Sportsters I've use M1 20W-50 in both holes with great results.

David
 
I'm not up to date on the tranny/primary/wet clutch talk.

I'm under the impression that my 2006 1200 Sportster only has 2 fluids, the engine oil and the tranny oil....is that correct? What is a wet clutch? I think someone else answered that for me but I can't find it.

I was just wondering what a good tranny fluid would be besides what the dealer sells as they are a rip off!
 
Does your owners manual not spell out what fluids to use? Or does HD make it so hard to find out because they want you loyal to products they have? I have a friend who found out his dealer is a Ahole on that subject. He (the dealer) flatly refused to put Mobil in the bike for him (this guy won't get his hands dirty), its HD oil or take a hike! Really ticked him off. btw-He said the service guy was hardcore HD, tatoo's, clothing. was a walkingHD billboard and a jerk. Not sure where the dealer is but is in Northern Wis.
 
A wet clutch is a clutch that lives with a fluid supply sloshing around it. Some bikes and most cars have a dry clutch which is just like it sounds-no fluid at all and fluid on a dry clutch is a bad thing. On a wet clutch the plates are designed to work with fluid and the fluid provides some cleaning and cooling function. You are correct about the Sportster having two fluids: engine and primary/transmission.
 
I looked on the redline website and they recommend their 75w90 gear oil for Sportster trans/primary cavity.
 
Looking at the back of Amsoil 20W-50 MCV it states is meets SAE90, API GL-1 gear oil requirements, but is not for shaft drive gears.
 
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