Question about "Park" in auto transmission

[minifridge1138]

When an automatic transmission is in "park" some kind of a pin physically locks the wheels so the car can not roll.

Can someone elaborate on how that actually happens?

I only ask because my 700R4 is stuck in drive. No matter what position the gear shift is in, the car is in "drive". The only thing that works, is the car can't roll when in "park". It has been suggested that my problem is that the linkage is no longer attached to the valve that controls the valve body. I would like to know if it is possible for park to lock the wheels IF the valve body is not moving.

Thanks!

 

[6880 Mike]

The parking detent is not at the wheels; it's in the transmission. It does not physically lock the wheels --it locks the transmission.

 

[SR'71]

Park locks the fly wheel. A stop engages the teeth of the fly wheel. Like an anti-starter motor.

 

[minifridge1138]

Ok, thanks for the information.

My transmission still locks the fly-wheel when i put it in park, but it is still in drive (Neutral, reverse, park, they are all drive).

So I'm trying to figure out if my problem is something simple (disconnected linkage) that I can fix myself or something complicated (broken forward clutch).

So my question is, if the 'S' clip that attaches the linkage to the valve body comes loose (i.e. car is always in "D") is it possible for park to still lock the flywheel?

 

[SR'71]

I don't know the vette auto linkage. I think, from feeling other auto shift levers, you should be able to feel a dead shifter. Its easy to go under the car and look to see if the linkage is intact. I only answered to what Park does to lock the car.

 

[minifridge1138]

It still feels completely normal.
It just won't get out of drive.

Externally, all of the linkages work.

Anything that has come apart, has done so inside the transmission.

I'm just trying to figure out if it can come apart from the valve body but still be attached to the detent cable.

 

[TimAT]

In a 700R4, there is a small rod that's "S" shaped and connects the detents to the valve. Here is a picture of a 400sorry I don't have a picture of a 700)

If you look just to the right of the light color tube you can see the shift lever where it connects to the valve- A 400 uses a pin in a groove on the valve, but you should get the idea. Look at the flat plate with the "Y" on the end- then just a little aft. That's it. The long rod running down the upper side in that picture is the parking linkage rod.

It's possible for 2 things to happen.
1 The small rod got bent.
2 (most likely) The nut that holds the detent plate on the selector shaft came loose.

 

[gmjunkie]

Park locks the fly wheel. A stop engages the teeth of the fly wheel. Like an anti-starter motor.

Dude,The Park Paw doesn't engage anywhere close to the flywheel!!

2 (most likely) The nut that holds the detent plate on the selector shaft came loose.

Yes,!! Nut has worked loose on the selector shaft allowing the finger on the Plate to come out of the slot to the valve shaft to the valve body, or the finger has broken off the Selector Plate and still allowing the park paw to engage!!(Latter is my Guess!!) Been There,Done That!

PS Lower Rt Hand Corner of Scan 2!! Sorry Minifridge,It's Internal!!
But it is possible for you to repair it your self without removing the transmission!!

 

[minifridge1138]

Hey everyone, thanks for your help.

Good to see you Junk. I know you were away for awhile. It's great to have you back.

 

[Victory Red C6]

Park locks the fly wheel. A stop engages the teeth of the fly wheel. Like an anti-starter motor.

How can park lock the flywheel? If that were the case you would not be able to start your car when the transmissin is in park. Also if the engine were running and the transmission was shifted into park, I would imagine that it would tear some stuff up by placing a locking pin into the rotating flywheel. There is no possible way for park to lock the flywheel. Check out the link to learn about an automatic transmission. Amazing the world and everything in the world is at your finger tips with a few simple keystrokes and yet....

http://auto.howstuffworks.com/automatic-transmission5.htm

 

[geekinavette]

What Junk said! On both counts!

("flywheel" that's just downright funny!)

Bill

 

[minifridge1138]

Ok, dropped the pan and took a look.

The small metal arm that attaches the valve to the selector has come out. There is no bolt on that arm. There was a hole in the selector and the arm has a 90* bend and slips into the hole. There is a small metal clip that keeps the arm from falling out (I don't know why there isn't just a cotter pin or a nut).

That clip is broken.

So the question is:
Where can I get a new retainer clip?

Is it something I can get from a dealer?

Thanks!

 

[gmjunkie]

Ok, dropped the pan and took a look.

The small metal arm that attaches the valve to the selector has come out. There is no bolt on that arm. There was a hole in the selector and the arm has a 90* bend and slips into the hole. There is a small metal clip that keeps the arm from falling out (I don't know why there isn't just a cotter pin or a nut).

That clip is broken.

So the question is:
Where can I get a new retainer clip?

Is it something I can get from a dealer?

Thanks!

The small C clip can found at most auto parts stores or a hardware store!!

 

[LVMYVT76]

Go to a friendly transmission shop, they usually will have a bunch extra parts that they scavage off of other transmissions just laying around.

 

[minifridge1138]

this is not a c-clip. I was looking at pictures of 700r4 trans in later vettes and the arm on the valve was "S" shaped with no clip. So I am looking for a part they didn't use for very long. (I can guess why)

 

[gmjunkie]

this is not a c-clip. I was looking at pictures of 700r4 trans in later vettes and the arm on the valve was "S" shaped with no clip. So I am looking for a part they didn't use for very long. (I can guess why)

Probly had 1 of these small push on spring clips!! There in all sizesmbeen used on carburetor's,linkages and heater and A/C servos for years!! I get'm at my local True-Value Hardware!!
This one is allot smaller than it looks,it pushes over a 1/6-3/32nds inch shaft!!

 

[minifridge1138]

Actually that is not the clip, either.

I found what I was looking for at Napa. It is called a Rod End Clip. It was in an old faded box labeled "GM Clips." The salesman said that box had been there longer than him (he looked like he had been there a long time).
I wasn't sure what size I needed, so I bought 1 of each (they only had 3 different kinds).
Hopefully one of them will fit.

When I get done, I'll post a pic of one of the spares just to show you all what I have been talking about.

Thanks everyone!