I have an FMX behind the 351 Windsor in my 1952 F100. I recently replaced shift shaft seals. Since then, trans won't lock into park. Detents feel normal, but won't lock up trans when placed in park position. Normal for me. One step forward, two steps back.

 

While I know zip about ford transmissions the first thing I would do is disconnect the linkage from the trans and move the selector shaft by hand into the park position. Then rotate a rear wheel and see if it goes into park, if so then just need to adjust the linkage.
If not then the possibly the selector lever or a part of it is not keyed on the selector shaft correctly? The FMX selector looks to be keyed.

 

As droptop said, disconnect linkage. If that doesn't work drop the tranny pan and have a look at the pawl mechanism. If that's the problem it is usually obvious on most any old model trans I have been inside.

 

Linkage not hooked up. Shift arm on side of trans seems to have all correct positions. I have the feeling park mechanism not engaging. I guess I will have to drop pan. Seems like internal problem.

 

I am not an FMX expert but if it is anything like the C4 and AOD then there is a lever inside the trans that moves the park pawl...sounds like the lever may not be in the correct position. Some of those linkages are easy to get on the wrong side of the activating pawl. Good luck.

 

I have a 1967 ford ranger 100 that pops into reverse so I worked on colum for hours trying to fix this problem with these fords popping out of park. I figured out detent was not cut right and I finally got mine to click into park like a normal shifter. Colum should lock it and need to know you can't blame it on trans or put parking brake on to fix this old problem. This is the 2nd ford I had that did this and it's not because you need to grind shifter or detent is wore out. Mine locks in by hearing it click into park now and I'm not hooked to trans. If any one is interested I'm going to be making new detent that works for anyone that wants one. Does anyone know if there is one to buy ? If not I will make them and heat treat them and show a video that this works great! If I get enough responses I will make a few up.

 

I think that Danny is right on about this! I also have an FMX. And it has jumped out of Park and into Reverse all by itself, and the problem is as far as I could tell a weak Park detent lock on the steering column. I have a 56 F-100, with the factory, original, automatic transmission shift column. On mine there is an "index plate" behind the steering wheel, which has a slot that the shift column interlock mechanism is supposed to lock into when in Park. The problem on mine was over the years of use, and people not bothering to pull the shifter before moving it out of Park, the metal slot the park lock mechanism would hook into got sort of wallowed out, and then there was not much metal left to lock it into Park anymore. Two ways to fix it, is to either remove the steering wheel and column and weld or braze it back to it's orignal size. Or what I did was take a small flat piece of steel, drilled a hole where the shifter lock would rest in Park, and then drill two smaller holes to bolt it in back of the index plate. When I mounted mine, I used the #6 screws that mounts the PRNDL indicator to the front of the index plate. Works great!
Danny, I would like to see yours. I am sure it will help others out!

 

FMX , if I knew a few people want a detent ,I would start making them and heat treat them. Also I would show how to install on video. Any interest e-mail chevyandme@comcast.net my wore out colum works great now. Let me know if anyone already makes them right.

 

FMX: Misc. 1968/89 FoMoCo Passenger Cars; 1973/77 F350 with 300 I-6.

 

If your column is suppose to lock into park you must fix that first. Your transmission should also click to each gear without linkage hooked to column. When your column locks into to park with a click noise then column is ready for adjustable linkage to be hooked up to trans and do no go under car or truck unless you know what your doing.

 

Where on the steering column is this index plate located?

Upper pic: 1954/55 / Lower pic: 1956.

 

If your column has a slot in it for every shift position? Then your linkage is not set right or not the right one. You should be able to adjust linkage. Don't be playing around by yourself with this. Is your trans and column a match to make it proper? If it's jumping out of park on that 56? First of all unhook linkage to trans by a professional so you don't get hurt. Shift the column and see if it locks. If it doesn't lock you need that part to make it lock before you rejoin linkage. If you want to know what part locks it, google each part number and you will find that part that locks column into park.

 

Hi Bill,

The index plate (i doubt it's the official name, just a descriptive term) I am referring to is the vertically long plate at the end of the steering column. The 7209 shift tube slides into it, and the 3511 flange bolts over it. Sorry if I created any confusion.

 

Thanks Danny, I appreciate the advice, but with the piece I made, I now get a solid lock in Park. Problem solved!
But I am sure others could benefit from your solution for their same years of trucks.

 

. I'm sure by looking at at the older 60s cars detent I can make a detent work on all them. If you did yours I will not worry about producing any. Thanks👍