Author Topic: Automatic Transmission Issue  (Read 392 times)

Offline ChrisV289

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Automatic Transmission Issue
« on: May 01, 2017, 08:52:21 PM »
My C4 automatic transmission has been having an issue getting into reverse.  When I first start the car and let it warm up I can get into reverse just fine.  After a while though, it does not want to go.  I have to wait for it to eventually kick into reverse and even then I don't feel it really is in reverse since when i step on the gas it does not go any faster, it will, just at a snails pace.  Does the band need adjusting or is it the modulator valve causing my issue? 
Chris
1965 Honey Gold Fastback

Offline ChrisV289

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Re: Automatic Transmission Issue
« Reply #1 on: May 29, 2017, 10:15:28 PM »
Ok so an update and some questions/headache.  I put some Lucas Transmission Fix in and it seemed to go into reverse a little better but when I give it a little gas there is no a vibration and then sometimes it doesn't want to move.  Does this mean the band needs adjusting or the whole transmission should be rebuilt? 
Chris
1965 Honey Gold Fastback

Offline Morsel

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Re: Automatic Transmission Issue
« Reply #2 on: June 23, 2017, 04:19:08 PM »
Ok so an update and some questions/headache.  I put some Lucas Transmission Fix in and it seemed to go into reverse a little better but when I give it a little gas there is no a vibration and then sometimes it doesn't want to move.  Does this mean the band needs adjusting or the whole transmission should be rebuilt?

I don't think it would hurt to adjust the bands prior to taking the whole thing apart, it's not that hard to do if you follow the process. You can find a million post about it on the different forums. I just did it not that long ago and it was easy as long as you have a good torque wrench on hand and to follow all the torque specs as per manual. I found when backing the band adjustment screw out the proper turns, it's a good idea to use a sharpie and mark the screw on the flat side so you don't lose track of the amount of turns, plus it helps to keep it visually in that position once you are tightening the locknuts.

One thing though, once you break the seal on the outer lock nuts to adjust the bands, I would just replace them both with new ones, you'll probably get a leak if you try to use the same ones again. They are cheap and you don't want to have to redo them after you get the adjustment set.

Another thing to check, which I'm sure you probably did, is I've noticed when I first am filling my transmission with fluid, that the car doesn't shift properly until it's correctly filled. There's a process I've used that's worked great for filling the transmission that someone turned me on to that gets the car to shift properly right out of the gate. You fill with transmission fluid about 3/4 of full. Then start the car, and with the foot on the break, run through the gears slowly including park and neutral. After that, slowly add the remaining fluid until the transmission is full, obviously there's a sweet spot, and don't over fill, that's the worse thing, if anything slightly under, then take it for a cruise at slow speeds and let it shift through all the gears smoothly and naturally on it's own, don't hammer the throttle and force a kick down yet. Drive it back home and check the fluid again on a flat surface while idling in park, add fluid if necessary again making sure not to over fill. One thing is if you do over fill it and it's above the full line, you need to syphon out the extra fluid, I've had to do that and it's good to do rather than leaving it over filled. Once you've got the proper fill lever, take it for a cruise and after it shifting through everything properly and driving about another five minute, then you can hammer it and make sure the kick down shifting is working properly.

If all this fails and it's still not shifting properly, probably time for a teardown and a good look over.

Hope that helps a little,

Jason

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Re: Automatic Transmission Issue
« Reply #3 on: June 23, 2017, 09:11:05 PM »
Does the transmission work in all the forward gears OK? The reverse band is usually shared with 1st gear (low).



http://www.newyorkmustangs.com/forums/how-to-service-c4-transmissions-t20090.html

Offline ChrisV289

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Re: Automatic Transmission Issue
« Reply #4 on: October 16, 2017, 08:31:04 PM »
Bringing this up again as the issue is still going on.  Hadn't driven the car during the summer since it is hot here but starting to cool off now.  Reverse works fine when starting it up but then once it warms up it fails to move at all.  I haven't done any adjustments yet.  The transmission I don't believe has ever been serviced at least since we have owned the car since 1992.  Mileage is around 55k we think based on condition of the car.  If I need to pull the transmission out, what is the best way?  Are the steps in the shop manual accurate or are there any suggestions.

Thanks
Chris
1965 Honey Gold Fastback

Offline Bossbill

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Re: Automatic Transmission Issue
« Reply #5 on: October 17, 2017, 01:40:53 PM »
Just be sure to remove the fasteners from the torque convertor before you attempt to remove the transmission from the car! I've seen people try to remove the auto trans without removing the convertor from the flexplate first. What a mess.

 I usually put the car in the air, remove the coil wire, attach a remote starter to the solenoid and bump the starter to get each of the torque convertor-to-flexplate fasteners to line up in the bellhousing inspection plate area. You will know when you have them all as you can then push the convertor back towards the trans and away from the flexplate. Mark the convertor with a paint daub as well as the flex plate (the ring gear) -- mark them both at 6:00.
Then, go back up top and unhook the battery. Removal is similar to the manual trans and your manual is the guide there.
However, never let the bellhousing tip further down than the rear or the convertor will fall out. It's all very messy if the convertor disengages from the trans.

Also, when the trannie is out, grab the convertor, pull sharply and quickly straight back out and quickly flip the convertor onto the floor with the fastener end down. There are many quarts of fluid in this thing. Drain the convertor into your oil pan at your leisure.

When putting the convertor back in,  place it centered over the trans splines, grab the centering portion of the convertor with one hand, slowly spin the convertor and push lightly toward the trans. It should thump at least twice as it goes back in. The convertor will be about 1" back from the trans mating face. Never allow the trans bellhousing to tip down as it could dislodge the convertor.
Position the convertor at 6:00 so it will line up with the flex plate keeping close track of your paint daubs and line up the convertor and flexplate fastener holes.
On trans installation if the trans will not go further towards the engine and the convertor and flexplate are touching, then you do not have the convertor seated. Never force it using the bellhousing bolts! Pull it back, spin the convertor again and push rearward.
Install bellhousing bolts making certain that the bellhousing can be flush against the block face without having to pull it in using the bellhousing bolts!
Yes, I said that twice!
After the bellhousing bolts are in I usually install the one convertor bolt at 6:00, install the starter, hook up the battery and bump the starter for the remaining bolts.
Since Ford starters and wires leading up to them are not energized unless the solenoid is engaged, there is a no risk of shorting.

The rest is in your manual.
Bill V.
3/2/1967 SJ GT350 and other fastbacks