Hello everyone...

I have a ZF S-42 in my F-150. It came from my F-250 and has about 150k miles on it. I drove it in the F-250 for a few months (including winter) and then swapped it into my F-150. Ever since the swap, I've felt or noticed that the tranny doesn't shift as well anymore. It's now getting cold here and I've noticed that the tranny really doesn't like to be shifted when cold, which isn't what was happening as badly before I swapped it.

I shouldn't have any clutch/slave issues. I'm thinking it might be related to the tranny fluid change as everything else was unchanged.

When it's cold - I can hardly get it into 2nd if it's moving 2-3+ mph. When it warms up, I can get it into 2nd around 10 mph or less. When it's stopped or going slow enough - it drops right into gear nicely. I don't remember it being this bad and the problem I have is that if I'm going around a tight 90* corner and want to go from 3rd to 2nd, I have to slow down too much to be able to get it into gear. Now I realise this is probably syncro related but it has me confused since it wasn't this bad before.

I've also noticed my 2-3 upshift into 3rd is not as smooth as before either. It's notchy/syncroie when sliding into 3rd is the best way I could describe it. 4th and 5th go in fine, and 1st is ok but I have to be almost stopped to get it into 1st.

I'm hoping it's not simply my tranny being on it's last leg - and hopefully I can improve the situation.

I drained and refilled with mercon ATF and I'm wondering if I should use something else - go synthetic - different lube - what? Any tips?

 

Try bleeding the clutch again and see if that helps.

 

...even though the clutch is operating ok?

 

It might feel like it's operating ok but it may not have enough travel to completely disengage. A bit of air in the line can cause that.

 

Interesting - I'll try that.

Anything to say about the fluids?

 

Plain old Mercon should work fine. Synthetic is probably better but may not notice any difference.

 

Well, I can't help you solve the problem, but when you're trying downshift it to go around a corner, try double-clutching. My Ranger has a similar problem, which I'm working on getting fixed. I really can't downshift to second at all without double-clutching it. (If you aren't familiar with this process, you shift the tranny to neutral, engage the clutch, rev the engine, disengage the clutch, and shift into gear. The amount you rev the engine is dependent on vehicle speed as well as gearing, etc., and comes with practice (or lots of math if you happen to have a tach).)

 

As in having it go into gear w/o having the clutch in? I thought that was called power shifting or something similar. I can shift w/o using the clutch but I havn't tried it on this transmission - it's usually harder/worse than using the clutch in what I've done.

 

No, as in matching the speed of the gears like you'd do in an old crashbox.
Shift to neutral, engage clutch (foot off pedal), rev engine a bit, disengage clutch (press pedal), put into gear. It's the same principal as clutchless shifting, as far as bringing the gears up to speed before engaging them, but you use the clutch both taking it out of gear and putting it into gear (hence double-clutch).

If you can shift without using the clutch, then you have a pretty good idea of where to bring the revs to, otherwise, just practice. When you do it right, the lever will practially fall into gear.

Also note, this is not solving your problem in any way. It just lets you drive more easily until you get around to fixing it.