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Thread: Dexron Transmission fluid in forks

  1. #1
    Dale Rudolph
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    Dexron Transmission fluid in forks

    I have an old Honda CT-90 trail bike and will be changing the fork oil.
    The Clymers manual recommends Dexron transmission fluid or 10wt. fork oil.

    The Clymers manual was written about 35 years ago, so may be out of date.
    I have some Dexron 3 fluid, but notice that there is now a Dexron 1, 2 ,3 and 4 being sold.

    Does anyone know if any Dexron fluid would work or what the differences are between the 1,2,3,and 4 types that are sold now.
    I also have some 20wt. fork oil from my K75, is there really that much difference between 10wt. and 20wt. in the forks?
    Thanks for any information.

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    Administrator 20774's Avatar
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    Snowbum has a good page on his website showing properties of a variety of fork fluids.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    Registered User dieselyoda's Avatar
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    The original ATF's were just a single grade oil.

    Very early on, late '70's to very early '80's, ATF's were a single weight SAE 10 with a dye added. They were virtually interchangeable from cars all the way to heavy equipment.

    I can't answer your question directly related to Dexron as it's a trade name.

    All of the ATF's we see around now have become pretty sophisticated with their additive packages and the trade names become important.
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  4. #4
    Dale Rudolph
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    So I guess the answer is that Dexron in the late 60's and early 70's when Clymers came out, is not the Dexron made now and may not be suitable for use in forks.
    I think I'll just get some 10wt. fork oil to be on the safe side.

    I did go through Snowbum's website but did not find an answer there.

    Thanks for your help.

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    Quote Originally Posted by Rudyjo View Post
    So I guess the answer is that Dexron in the late 60's and early 70's when Clymers came out, is not the Dexron made now and may not be suitable for use in forks.
    I think I'll just get some 10wt. fork oil to be on the safe side.

    I did go through Snowbum's website but did not find an answer there.

    Thanks for your help.
    Don't feel alone. Snowbum's site is as difficult to get information from as any I have seen!

    Information is useless if one can't find it using normal searching techniques, let alone the "if this, then that" or if not that, then see my page..." and on and on. I give up most of the time.


    There may be a wealth of info there, but it seems so disorganized that you get lost in the maze of articles, not to mention the pics that I don't want to see.

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    Back then, I think ATF was simply a light weight hydraulic oil and for most purposes (like trail bikes) it wasn't an issue. Only those who raced actually cared about fork oils and differing weights.

    Now, probably the best thing to do is purchase a brand name fork oil - Belray is one of the most popular.

    I question the 10w though, because most people settle on 5w or 7.5w.

    Be sure to clean out the forks as well before putting in the new oil.

  7. #7
    Outlander Omega Man's Avatar
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    Well all that aside, where is the picture of the CT90???? they are a great bike
    I'd stay with the recommendation on the ATF or go to something like the Bel Ray. Kevin at Kevin's Cycle- http://www.kevinscycleracing.com/ has been around a long time and would be a good resource for fluids and what-not for the older gem you have.
    Good luck, they are a lot of fun.
    OM
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  8. #8
    Dale Rudolph
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    Quote Originally Posted by Omega Man View Post
    Well all that aside, where is the picture of the CT90???? they are a great bike
    I'd stay with the recommendation on the ATF or go to something like the Bel Ray. Kevin at Kevin's Cycle- http://www.kevinscycleracing.com/ has been around a long time and would be a good resource for fluids and what-not for the older gem you have.
    Good luck, they are a lot of fun.
    OM
    They are a great project bike. I picked this up at a yard sale a month ago, it was supposed to be a project for the winter but has been so much fun to work on, it's almost done.
    I took everything off of it and re-painted it and cleaned up the rims and chrome parts. Parts are easy to get.
    I'll have to start looking for another to keep me busy through the winter, unless I get done with it in a couple of weeks.
    Will get some before and after pictures posted soon.

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    Quote Originally Posted by Omega Man View Post
    Well all that aside, where is the picture of the CT90???? they are a great bike
    ...
    Not the OP, but here's mine...

    DSC01701.JPG

    It's a 1971 that I got from my brother who used it a lot up in the Colorado mountains. It's been cleaned up a bit since the pic but needs some work. It smokes pretty bad so probably needs a ring and/or valve job. Probably need some fork work too. I've been meaning to tackle it but just haven't gotten a round tuit yet.

    My RS is in the background.
    1983 R100RS (Sold)
    2004 R1150RT
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    Quote Originally Posted by markaz View Post
    Not the OP, but here's mine...

    DSC01701.JPG

    It's a 1971 that I got from my brother who used it a lot up in the Colorado mountains. It's been cleaned up a bit since the pic but needs some work. It smokes pretty bad so probably needs a ring and/or valve job. Probably need some fork work too. I've been meaning to tackle it but just haven't gotten a round tuit yet.

    My RS is in the background.
    WOW! Brings back memories. I worked at a Honda/BMW dealer while in High School when Honda introduced these.

  11. #11
    Dale Rudolph
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    Markaz: The one I have is a 1975, looks just like yours, same colors.
    The difference is that the 1975 has turn signals built into the taillight and handlebars.
    Probably the best place to get parts is at www.dratv.com, they have just about every part for them including all the original stickers and placards.

    I lucked out finding mine for $400, sold by the original owner, had been kept inside all it's life. It runs very well. Even has the extra gas tank that goes on the rear fender.
    There was really no reason to take it apart, but a new coat of paint works wonders for it.
    You can get an almost perfect match to the original yellow paint at Napa auto parts, it's an automotive paint called School Bus Yellow.

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    As I remember, they sold some other attachments that catered to hunters. I think that is why they came out with this style - for hunters. I definitely remember a "holster" that held a shotgun or rifle.

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    Quote Originally Posted by Rudyjo View Post
    Markaz: The one I have is a 1975, looks just like yours, same colors.
    The difference is that the 1975 has turn signals built into the taillight and handlebars.
    Probably the best place to get parts is at www.dratv.com, they have just about every part for them including all the original stickers and placards. ...
    Rudy, thanks for the pointer. I'll check it out.
    1983 R100RS (Sold)
    2004 R1150RT
    BMW MOA 181289
    ABC 13558

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    There is a new Dexron 6 and it is very low viscosity and synthetic. probably a 5 or less weight. Being syn it will have a wide viscosity index, meaning the viscosity will not change much with temperature. There is still type A fluid around. It will be the thickest. Then dexron 3. Finally dex 6. from thickest to thinnest. The possibility of fork tuning does exist if using tranny fluids without having to travel to your motorcycle store.

    Rod

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    Outlander Omega Man's Avatar
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    Quote Originally Posted by ragtoplvr View Post
    There is a new Dexron 6 and it is very low viscosity and synthetic. probably a 5 or less weight. Being syn it will have a wide viscosity index, meaning the viscosity will not change much with temperature. There is still type A fluid around. It will be the thickest. Then dexron 3. Finally dex 6. from thickest to thinnest. The possibility of fork tuning does exist if using tranny fluids without having to travel to your motorcycle store.

    Rod
    Hey! you left out Type F
    I still have some in cardboard cans
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