F type or GM type ATF in the primary

Yellow_Cad · Jan 27, 2009

Can anyone please explain why F type ATF is considered so much better than GM type for this lube the primary chain but don't get in the clutch duty of the primary case lube? It seems like there are all sorts of stories to attest this but no explanation as to why.

RennieK · Jan 27, 2009

I think it's something to do with the seals. It seems to me GM ATF will eat the seals or rubber parts in a ford transmission. Maybe someone will confirm?

chopped850 · Jan 27, 2009

I just dumped in 200cc's of Type F. It has better conditioners and other stuff for keeping the clutch plates and seals happy. The other stuff is for the newer transmission with selinoids. I have been running Type F ATF in all my 2 stroke ATV's and dirtbike transmissions without issues. It's not recommended to run it in an engine where the transmission and engine share the same oil.

bill · Jan 27, 2009

I have been rebuilding transmission for over 35 years so here go's. there was 2 types of fluid years ago(50s-60s) type A and F, type F was formulated for ford because they used bronze friction plates while every one else used organic (asbestos) friction materiel and type A. in the later years (70s-80s) dexron came on the market and even ford recommended it when they stopped using the bronze plates. Now we have a larger mix with Mercon 5 Chrysler's +3 and +4 and full synthetics.

windy

RennieK · Jan 27, 2009

So Bill, what type lube do you use in your primary?

If you have the stock 850 bronze plates would you use type F?

For barnett and old style fiber plates would you use type dexron?

or are you saying no matter what your clutch plates are, use the red stuff.

bill · Jan 27, 2009

I run my primary dry because of the belt drive :mrgreen: . If I still had a chain I would run type F with bronze. with surflex depending on how I wanted the clutch to grab dexron SHOULD give a smoother apply but you probably would not notice a whole lot of difference with type F.
It was an old racers trick to run type F as it was rummerd to make the frictions lock up better.
With my belt I run 5 surflex plates. I don't like the weight of the bronze clutch or how it reacts to running dry. IHMO the more weight you remove from the primary the easier it is on the gearbox.
If I was to do it over I would overdrive the primary and bring the final drive down accordingly to make it even easier on the box along kick starting.
I would also HIGHLY recommend a dyno dave push rod seal no matter a dry or wet primary as the clutch plates ( no matter which plates ) do NOT like gear oil.

windy

nidyanazo · Jan 27, 2009

I thought the primary drive called for 20w50 oil?
No?

Corona850 · Jan 27, 2009

nidyanazo said:
I thought the primary drive called for 20w50 oil?
No?

The manual does, yes. But ... modern oils are too slippy and the clutch will likely slip with a modern 20/50. See this norvil link ...

http://www.norvilmotorcycle.co.uk/techtalk27.htm

The manual also call for 20W50 engine oil but many folks (including Norvil) say use straight 50.

tpeever · Jan 27, 2009

I use straight 30W in my primary with bronze clutch plates. No slippage in 4 years that I have had the bike.

batrider · Jan 28, 2009

Norvil big deal. You can read all kinds of opinions on the 'net and that is all they are.

BrianK · Jan 28, 2009

Can't miss an opportunity to plug my favorite - Redline MTL in the primary case. Pricey, but worth it I think.

debby · Jan 28, 2009

Corona850 said:
nidyanazo said:

I thought the primary drive called for 20w50 oil?
No?

Click to expand...

The manual does, yes. But ... modern oils are too slippy and the clutch will likely slip with a modern 20/50. See this norvil link ...

http://www.norvilmotorcycle.co.uk/techtalk27.htm

The manual also call for 20W50 engine oil but many folks (including Norvil) say use straight 50.

I used to use 20W50 in the primary and it worked ok with no slippage, but I had some clutch drag. I switched to ATF and the drag went away. It's worse about leaking though. Straight 50 might be good for the engine but not for the primary.

20W50 won't make your clutch slip. 5W30 probably would, as it has the anti-wear additives that cause the clutch slippage. Look at the API rating on the bottle.

Debby

Corona850 · Jan 28, 2009

debby said:
20W50 won't make your clutch slip. 5W30 probably would, as it has the anti-wear additives that cause the clutch slippage.
Debby

It did on mine!!
Bought the bike off ebay and had to take it to the DMV for inspection. It's about a 5 mile trip and I barely made it home because the clutch was slipping so badly when hot.
Called Phil Radford at Fair Spares and bought a new set of Barnett plates. Phil told me to use ATF. He also suggested Torco oil (for the engine), but that's too expensive for my tastes so I use Valvoline VR1 50W in the engine. I hope one wouldn't even consider putting 50W in the chaincase; I certainly never suggested that.

But 20/50 will cause slip, and drag too. Quote below from Mobil's website

Mobil 1 website said:
So how is Mobil 1 for passenger cars different from Mobil 1 for motorcycles?

.... In general, Mobil 1 motorcycle oils have:

Additive packages balanced differently for motorcycle engine and transmission operation. For passenger vehicles, fuel economy and emission system protection are higher priorities. These require low phosphorus systems and the use of friction modifiers. Motorcycle oils do not require friction modifiers for fuel economy and for better clutch friction less/no friction modifier is optimum. Motorcycle oils allow the use of higher levels of antiwear additives such as ZDDP (phosphorous).

The bit about 'better clutch friction' is a reference to the tendancy to cause slip in wet clutches with 'ordinary' 20/50.

BillT · Jan 28, 2009

Another advantage to using ATF in the primary is its easy to tell if your crank seal starts leaking, as the primary oil will turn from red to brown.

Having a Mk I 850, my primary has the one cover bolt and large O-ring seal. I put a light coat of Permatex Aviation Form-a-gasket on the O-ring, no more weeping.

Like Debbie, I also use VR-1 in the engine. Cheap, high zinc content, and widely available.

gw88 · Jan 28, 2009

Interesting thread on primary oil. Just replaced the original bronze clutch with a new Barnett due to age and slipping. Heard somewhere that the Barnett works well with 10W or 15W fork oil. Anyone else tried this? Comments appreciated. :?:

Jason Curtiss · Jan 28, 2009

I've been using 20w-50 in Triumph and Norton primarys for some 25 years - no problems to report yet. And ten years prior, I can't remember what I used, but it wasn't ATF of any kind.

F type or GM type ATF in the primary

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