Hey everyone, thanks for reading. I'm new to posting ,but have been reading the forums for a while now. Background: Love ford trucks, my dad had a 79 f100 custom 302/c4 combo when I was growing up. It is the only truck he ever bought brand new. I have had a few newer fords, 95 f150 and a 2006 f150, Both were good trucks. over the last three years I've been without a truck, traveling for my job and needing the family vehicle. About a year ago I ran across a 79 F150 Ranger with a 351w and c4 trans. The po was going to scrap it. I got for junk yard price and brought it home. Blown head gasket, fixed it, sloppy steering, fixed, leaking steering pump, fixed, bad radiator, fixed... anyway, every time I drive it, it does not stay in the gear I put it. Example: If I put it in reverse and go to back up, most of the time it will drop down to drive or even low, without me touching the gear selector. If I drive it and say stop and make a turn sometimes then it will drop from drive to low. And always if I get it warmed up good and put it in reverse the whole truck will shake until it drops it into another gear. I was told fluid, changed it and put new screen filter in. nothing on the old filter, no shavings or chunks, fluid did not look burnt or smell burnt. Told to adjust the bands, did so according to shop manual. An older fellow told me maybe it was the mounts, changed both motor mounts and transmission mounts. when I get the truck up to drive it does not try to change gears and runs perfect going down the road. but I'm tired of holding that shifter in place with one hand and steering with the other trying to back up or getting on the highway..... Has anyone experienced this or know a fix. I seek your collective knowledge. Thanks

 

Are you saying that the gearshift lever is moving, causing the problem? Or is the gearshift staying put and the trans is "mystery shifting" on it's own?
If the gearshift lever is moving, the problem is more than likely either the gearshift detent is loose or worn, the spring is broken or the little tooth on the gearshift that engages the detent is worn.

BTW, welcome to FTE. Lots of good people here.

 

Yes Sir its the gear shift lever. It has a new shift column collar. I also replaced the pin and the grommet? on the end of the lever. If its the spring where could I find one of those at? and the lever looked ok when I changed the collar.

 

There'e a detente in the tranny that you should feel as you change gear selector. There is also a guide under the gear indicator on the column that should force you to pull back on the lever to get in to PR2 or 1.

 

Oops! double post.

 

The detent plate is held in place by two screws, I've seen the screws work loose before allowing the gear shift to "flop around".
Click on the link, that will open an illustration from the Ford parts catalog of your steering column.
The shift detent plate is 7A216 and the spring is7B071

 

I had the same problem with my daughters truck. There is a thread from me when I had the problem. I swapped out the column. I then repaired the column when she was the shift tube broke on the replacement. Anyway, I rebuilt the original column with the part mike says to replace and a shifter that I had from a parts truck. I cleaned and lubed everything. Not sure which one was the problem, but now it works fine.

 

Thanks folks, I'll check those parts this week end. I can feel it engage in the tranny, so I'm thinking it has to be in the column, luckily when I bought the truck he had a lot of extra parts including a different column, so hopefully I already have the parts. So far I haven't had to buy anything other than the ps pump and radiator. everything else was in the bed in boxes like the po just gave up.

 

Checked the extra column I have, wrong year. oh well guess I'll get into the column and check all the parts and see what's bad and what's not. Thanks benbuilder for the info of other threads, there are several on here. Thanks mikeo0o0o0 and beartracks for the info of what to look for. The diagram mike is a huge help.

 

Well I put in a new spring and detent on the column and it no longer does what it did, but......I got a new problem. I went out this morning and went to leave and when I put the truck in reverse I started backing up and POW. Sounded kind of like a u-joint popping and then NO MORE REVERSE!?!. I have all other gears. It is a c4. Any suggestions?

 

Oh, and if any one has a diagram of the back side of the 79 fuse block. The only one I have just shows the fuses but there are more wires on the back.

 

Found the wiring diagram! Still haven't checked the tranny yet. No garage and raining here all day.

 

Anyone know or recommend a good rebuild kit for the c4. I think my reverse band went out and if I have it out I'd rather rebuild the whole thing.

 

Okay, no reverse but I have low. I thought on a c4 reverse and low would go out together if it was the band. I'm stumped. Any suggestions on what would make reverse go but not low?

 

Well I did rebuild the tranny. Got to test drive around 6 miles and it ran perfect all gears there and shifted great. And then I went to go out about 30 minutes later and put it in reverse and the truck was shaking like it did before reverse went out. Put it in drive and NO drive. No forward gears really, it seems to engage but will not pull the truck. Reverse will work. Fluid not burnt and full. Pulled the valve body and checked it, seemed ok. Was wondering if any one can steer me in the right direction on what to check. I plan on pulling it back out this weekend. Thanks for any suggestions.