C4 Rebuild Fluid Question

cr_bobcat

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So this is my first time ever opening up a transmission. I have have it broken down into the major components right now (haven't disassembled the pump or the clutch packs). Just got the case/snout/bell back from getting sent through the parts washer at a local shop. I believe that I have all the guts (or will so shortly as I wait for the last few bits to get delivered.) So I'm currently in the phase where I make sure I have everything I'm going to need sitting on my bench next to the transmission when I'm ready to start operating.

That being said, should this rebuild stick to the Type F fluid? I know the new guts are modern so is there a reason to move to a synthetic because of the kevlar? Am I risking anything by sticking with Type F?

This noob is looking for any sage advise out there. I think I'm safe with the Type F, but it's better to ask before I start assembly...
 

ludwig

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If the name of the maker starts with F, use type F. Just to be on the safe side. Do NOT use type GM.
 

cr_bobcat

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Thanks ludwig, will do. I planned on using Type F but then was curious as to whether or not that would be the right path with modern internals.
 

ludwig

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Woo hoo!! Another hick. I mean 'Iowan'. Like me. Des Moines TRHS '69.

Frankly, I don't know what the exact difference is, but I burn up something in a Mercury a couple decades ago by NOT using type F. So I do it anyway. I don't know if it's the weight or the viscosity or some particular lube additive or high temp thing. I just do.

Many of the other guys know a lot more than I do and they WILL have an opinion.
 

cr_bobcat

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I'm actually a transplant from Ohio. Grew up 20 min from the Ford engine plant in Lima. Still redneck all the same though :beer:
 

cr_bobcat

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If there's no real advantage to switching, I may just keep it as Type F just so I don't get confused. I just wasn't sure if there was some advantage to switching or not. This is a daily driver that I don't necessarily get on that hard so if there's no compelling reason to change, I'll just leaver her be...
 

ludwig

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From Wikipedia:

All ATFs contain friction modifiers, except for those ATFs specified for some Ford transmissions and the John Deere J-21A specification;[6] the Ford ESP (or ESW) - M2C-33 F specification Type F ATF (Ford-O-Matic) and Ford ESP (or ESW) - M2C-33 G specification Type G ATF (1980s Ford Europe and Japan)[7] specifically excludes the addition of friction modifiers.

It's a mystery to me why the friction modifiers are **excluded** in type F, but they want a particular performance characteristic across the transmission lines, so what the heck?
 

bubba22349

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Originally the type F fuild gave a quicker firmer shift then the old Dextron I (since the Dex is designed to slip) using Type F also made the older transes last longer. I don't know about the friction abilitys of newer type Dextron III fuilds except that the newer Fords have been using it for many years now. I think the Honda's used fuild like the old Type F too, about 7 years ago my daughters 1998 Honda Accord had its trans finished off a bit sooner when a budget oil change place used Dextron in it instead of Honda spec fuild. Good luck :nod:
 

ludwig

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That's what I was getting at earlier. Thanks for the explanation. I suspected it was something like that; higher density fluid for a firmer shift.
 

bubba22349

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Yes for sure in fact in the late 60's,& into the 1970's many of the GM racers would also use the type F fuild in their Power Guides, Turbo 350's 400's to make them shift harder. But like I said before I don't really know what the current tech specs are.
 

Crosley

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I 'm not an expert on oils, but I have been in the automotive field for 40+ yrs . Worked on , with & against automatic transmissions since my first one in 1974

Type F was developed by Ford to correct a shift noise in transmissions. The friction material they used at the time would make a screech noise during a shift. Ford also used frictions in the old cast iron cruise-O trans that had a brass - bronze material instead of a fiber based product. Many of the early fiber friction material contain asbestos.

GM fluid in the early days was heavy content of whale oil. The whale oil use was out lawed in 1970 If I remember correctly. You could not mix the old type F and GM fluids. A mess was the result.

Modern fluids are all mixable , modern friction materials work with all oils. Modern synthetic oils are designed to allow more slippage at a microscopic level because of the Pulse Width Modulated strategy used during shifts in these 6 , 7, 8 , 9 speed automatics. The friction pack is actually pulsed on at high rate to smooth out the shifts , kinda make them seamless.

In the high horsepower (2500 - 4000) race - performance transmissions I work on, various oils are used. Amsoil compressor oil, John Deere Hygard oil , there are others. Various weights are used. 10 weight, 20 weight or a race team may have a mixture of each weight they use. Lucas Marine trans fluid is a very good fluid for high HP use
 

cr_bobcat

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Well that answers the mail for me. I'm not down with whale oil. I'm strictly in the camp for lubricants made from freshly clubbed baby seals....
 

Crosley

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ludwig":1ir1p5md said:
Brilliant. Thanks. That explains a lot. Also why you don't want to mix GM and F fluid.


My statement is not to mix OLD type F and OLD GM fluids of decades ago. The OLD whale oil fluid and OLD type F would make a mess , gumm up, turn to goo...

That is the OLD wives tale of NOT mixing GM and Ford fluids still lingers on incorrectly today on the interweb

As I posted further down in the statement ALL modern trans fluids are mixable, dyno oils or syn oils... I have not seen any problems mixing modern trans fluids
 

ludwig

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Well ,Crosley,

Even old wives need to be taken to the dance once in a while. Get to see something new for a change.
 

Crosley

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ludwig":3bgqua4v said:
Well ,Crosley,

Even old wives need to be taken to the dance once in a while. Get to see something new for a change.


Well, I am not a wordsmith. Sometimes getting the info from brain to my fingers (can not type) and then on to the computer screen is a challenge and some times not clearly eggsplained
 

ludwig

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I was just funnin'. But that was interesting to know about whale oil and type F and why they should not be mixed.

Like I said way up at the top, most of the guys know a lot more about this than I do, and you are one of them.
 
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