Fork set up for trials ATF ?

[mac]

I was going to order some 20 wt fork oil for a cross country set up and just wondered if ATF will work for a trials set up or if I need some 5 or 7 wt also. I use ATF in my Bul but not sure if it is okay in the Hodaka forks.

[Dale]

ATF works great for a lightweight fork oil. You can mix it with 30w non-detergent to thicken it some if desired.

[mac]

Okay, thank you !

[Bullfrog]

My own experience is as follows. I had 10wt fork oil in my Bullfrog trials bike on a 90+ degree day. Damping was virtually non-existent. Forks extended so rapidly after being compressed that the bike was bucking me off on rough up-hills. I went to 20 wt during hot weather after that. Other experiences with Hodie 30mm forks (MX and Cross Country) have proven to me that damping oil weight selection should consider ambient temperatures MORE than anything else. Hot weather calls for more viscous oil, less viscous oil in colder times.
Ed

[Dale]

I agree with Ed's opinion that temperature is a key factor with fork oil selection.

ATF is generally considered to be around 10W. It is the manufacturers recommended fork oil for certain vintage motorcycles (Honda specifically) and it does work well for them, but it is too light for the Hodaka type forks in most cases. I have found Maxima 20W fork oil to be the best for me on my track bikes. For hot weather, I have changed to a mix of this 20W with 30W non-detergent motor oil (NAPA).

For Trials? I'm not sure but my guess is that something between 10 and 20 would work.

[motovate]

Just out of curiosity and not being a Smart A**. By mixing the 30 weight Non D with ATF is the theory to Thin out the 30W ( so more of the ATF) or thicken up the ATF ( so more of the 30W) or just looking for a 50/50 mix???? Seems like it would make a difference.

[Dale]

Just out of curiosity and not being a Smart A**. By mixing the 30 weight Non D with ATF is the theory to Thin out the 30W ( so more of the ATF) or thicken up the ATF ( so more of the 30W) or just looking for a 50/50 mix???? Seems like it would make a difference.

That is a legitimate question... So, if you consider non-synthetic ATF to have a viscosity of 10w and you mix it 50/50 with 30w non-detergent motor oil, you will have 20w. It is that simple. If your target weight is 25w then mix 3 parts of 30w with 1 part 10w.

So why would you use a mixture of ATF and motor oil? Price and availability I guess. Fork oil greater than 20w is hard to find plus it is expensive. And non-detergent motor oil is hard to find other than NAPA 30w. So depending on what weight you desire you need to either source that weight of fork oil or create your own mix. Is there a performance difference? Not that I could ever tell.

[motovate]

Great Thanks. Always wondered why you need "Non Detergent" - 30W. Will regular 30w foam up too much or??

[Bullfrog]

Yes, the operating theory is that non-detergent oil will foam less.
Ed

[motovate]

Thanks - Again being the curious type - I looked on Amazon for 30W M/C Fork Oil and found they had a couple of brands of 30W M/C Fork Oil - not all that cheap but available - all the other weights were available also.

LBM