Technical C-6 trans slips out of Park

Hey there, I’m hoping someone can help me out here. I did a forum search and came up empty, so here I am. I’ve got a C-6 transmission with a Lokar shifter in my ’58 Ranch Wagon. A couple times it has slipped out of Park and into Reverse while I’ve had the engine running. One time it did it while I was outside the car and rolled out of the garage. Luckily no one/nothing was in the way. I checked the linkage and nothing seemed wrong…at least to my inexperienced eyes. Anyone ever have this happen to them? If so, does anyone have a fix? Thanks in advance for any and all help!

 

Sounds like readjust your linkage. Remove the shift linkage and make sure the park paw is locking into park solid. Then adjust linkage around that.

 

Thanks carkiller. That sounds like something I can try and tackle this weekend.

 

Ford had a problem with late '60's-early '70's C-6's doing this. If I remember right, some people even were hurt. Don't remember if Ford did a re-call. Do remember my uncle's new '73 Ford pick-up. It jumped into reverse while he was letting it warm up on morning. Backed straight across the street, up the neighbors driveway and into her Maverick. Ford fixed both cars.

 

Once you get the shift arm on the trans fully into park, adjust the linkage rod to drop into the hole in the trans arm. Should be OK then, unless something is wrong inside the trans.

 

i remember that as well come top think of it. Just another reminder to have a working park brake and use it.

 

If the parking brake (or E brake) is not working get it fixed soon,I usually have it working before the vehicle hits the road and use it.

 

I believe this particular C-6 is out of 1970 Thunderbird, so the defect/recall issue would apply.

 

Agree about the parking brake. It was engaged when it rolled out. Looks like I've got some P-brake adjustments to do also...

 

Need to research the original Ford issue and see if it was the linkage or an internal transmission problem. I am not aware of any internal modifications to the transmission to address this so would think it was a linkage issue, but would be worth checking out.

 

It does seem like they can roll backwards with them on easier then forward.

 

The Ford recall fix was to apply a silver sticker to the lower dashboard cautioning the consumer to shut it off in park, no prolonged idling recommended.

I guess that's traditional for a manufacturer's fix.

 

Recall on this. Old guy (now 90) who worked for my dad had a 78 F250 that he traded in because " that damn truck tried to kill me twice". This was one of the early recalls by Ford. Before this, they did n fact let them kill the customers.

 

I wonder if rebuilding the valvebody and replacing the check balls would solve the problem?

 

Both the C6 and C4 would do that, raises hell inside a shop or a parking lot.

 

Back in those days we put Fords in the air if we wanted to run them for any length of time. It was a very common problem.

 

Make sure the lever ( weather floor shift or column ) locks in also don't depend on the detent in the transmission, I try to make sure my truck with a slightly troublesome c4 is rolling very slightly when I put it in park and when the park dog drops into the notch in the shaft or drum or where ever that "notch " is inside the truck rocks a little bit also my dad taught me when I was a kid to put my foot on the brake pedal when applying the parking brake to push the shoes out to make it easyer to get good pressure from the p brake cam

 

The factory Ford issue was in the column shifter, not the transmission. It would seem like it was in park, but it wouldn't be latched into the notch. A little vibration and it would slip down into reverse.

Got myself into the habit of pulling on the shifter to make sure it was latched before getting out.

Could be the same issue with the aftermarket shifter. Make sure the transmission is actually in park when the shifter is in the P position, and that it is latching in and can't easily pop out.

 

Ford recall
https://autos.yahoo.com/news/rememb...tting-chevy-historical-context-190037788.html

 

My old 70s trucks wouldn't go all the way into park when the cab mounts went bad. Never had one jump out of park though, just had to re adjust the linkage

 

someone at one time tried to put transmission in park while it was still roll7ng and has damaged parking pawl,very common problem.

 

Relic Stew nailed it. It is the detent plate in the column. VERY common in late 50s early 60s fords. Here is a link to the aftermarket fix for Squarebirds.

http://www.squarebirds.org/detent_thunderbird.htm

Maybe someone can wittle out a new plate for you based on your original.

Edit: Upon further review of the original post. He has a Lokar shifter, so it won't be the detent plate in the column.

 

I had 2 of them do that to me on an alignment rack around 1977 or 1978. Once while the ramps were up, the garage door stopped the car, no damage to anything.

The 2nd was when I was putting the ramps up, I had the car door open and was standing next to the car. I had to hit the dirt and the car door brushed right over me. The open garage door jamb stopped the car.

After that we were a lot more careful with Fords and Mercurys while doing alignments. On level ground, they were okay, any incline could make them pop out of park.

Bob

 

Looking into the valve body will not fix the problem. It is a linkage problem. The check balls have nothing to do with park, that is in the manual valve of the valve body, and movement of the manual valve is congtrolled by the shifter. The park pawl is the only thing in the transmission that has anything to do with park. Just try to readjust the shifter

 

I have two stories about this. My nephew had a 70 torino, got pulled over by the hiway patrol, he left his car running and was standing outside with the cop. It jumped into reverse, about hitting them both. Yep you guessed it another ticket was issued. We had a 73 ford pick up where i worked. The sticker was right there on the dash.

 

had it happen to my grandma with her 72 LTD , after the 3rd time they bought a OLds .