C4 Auto selecting gears...

CortinaChris · 3 Weeks Ago

Super quick question if I may..... when cold, the C4 auto on my 66 straight 6 doesn't always instantly select?!?!?!
If you select drive, it will sit there, then rev the engine, and on the downward rev, it will select, and off you go.... once you've been into 3rd a couple of times, it's fine for the rest of the drive. (same for reverse, which makes getting her out of the drive 'interesting' at times)
Any ideas? How does the box 'know' to select, is it vacuum, electronic? What might have failed?
She is a rolling restoration, so something I can do, or test, without dropping the box would be the ideal

Look forward to hearing from you all, restoring/running a Mustang in the UK is proving interesting and fun!
Christopher

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Faith No More · 3 Weeks Ago

Check your fluids, my friend. Low transmission oil can cause this/similar issues.

Bigfred_63 · 3 Weeks Ago

If I'm not mistaken its run of hydraulic pressure correct me if I'm wrong tho..... but like the guy above me said it could be low fluid or the wormholes or passageways in your valve body could be partially gummed up or have some unwanted crud in them or a check ball could maybe be sticking for a few secs.... idk just decided to give you my 2 cents hope I helped a little bit and good luck

havoc65 · 3 Weeks Ago

Hi there, Id start by changing the fluid and replace the filter. I had this same problem in my 65 and doing this fixed it. There could be a whole host of things wrong but you can change your fluid in a hour for $30 so its a good place to start.

Ivy66GT · 3 Weeks Ago

First, I agree that low fluid might be the problem or something gunking up the control valves.

We in the USA are accustomed to cheap gas and oil. Last time I checked ATF in Bucks costs something like $5 a quart so there won't be any such thing as a $30 fluid change for Christopher.

Also, there is no true filter in a C4. There is a screen which can be cleaned with petrol which is also a lot closer to $10/gallon for him than it is to our $2.50.

PaulS · 3 Weeks Ago

Quote:

Originally Posted by CortinaChris

Super quick question if I may..... when cold, the C4 auto on my 66 straight 6 doesn't always instantly select?!?!?!
If you select drive, it will sit there, then rev the engine, and on the downward rev, it will select, and off you go.... once you've been into 3rd a couple of times, it's fine for the rest of the drive. (same for reverse, which makes getting her out of the drive 'interesting' at times)
Any ideas? How does the box 'know' to select, is it vacuum, electronic? What might have failed?
She is a rolling restoration, so something I can do, or test, without dropping the box would be the ideal

Look forward to hearing from you all, restoring/running a Mustang in the UK is proving interesting and fun!
Christopher

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Christopher,
If there are a lot of miles on your C4 you are likely suffering from "morning sickness". This "delayed engagement" is caused by hard and or cracked piston apply seals in the two clutch packs.
Low fluid may cause the same effects but as long as it is not burnt you can just add to it. Clogged filters on the C4 are rare but not impossible. If type F fluid is expensive there are a couple good alternatives that are very expensive here in the states but they might be cheaper where you are. Those alternatives are AmsOil type F synthetic, and B&M "Trick Shift". Check out the prices in your area and select the least expensive if you are going to change the fluid. Remember to adjust the bands too (although it is not causing your problem).
I believe that a rebuild is going to be in your future though.

CortinaChris · 2 Weeks Ago

Thankyou all for your excellent advice!!!
Topped up the ATF Fluid as suggested (though worrying she too a litre to get to the full level, just over a Quart, which is a concern as I see it's only 2.5 Quarts to fill the box!!!) and now she engages like a dream even from stone cold!! Can't thankyou all enough!!!
Was surprised that it fills through the DipStick though, and that the exhaust is directly below, have a slightly pink patio now and the smell was 'interesting (even with a funnel, some managed to 'get away')
So, as the stick itself also recommended, did it whilst then engine was at normal temperature (a 20 min drive) and running in park, though wanted to ask, are a few bubbles whilst checking 'normal'?
I got Comma (a UK derivative of Mobil i think) AQF ATF Fluid, claims it meets Ford ESP-M2C-33F/G requirements and want to check that is the right 'viscosity'?
Can't get hold of Castrol type F over here, but seeing what that is/did I believe this to be the UK equivalent?!?!

Oh, and thankyou for your compassion on fluid costs....
5 litre's of ATF Fluid (5.283441 Quarts) £15 ($25)
1 UK Gallon of fuel (1.2009499 US Gallon) £4.16 ($6.95)

Christopher