part throttle shift points raised

[Roland Black]

I have a recent Art Carr 700R4 tranny and 9" TC (1300 miles ago). I went out driving today, and at first the Syclone was shifting normally under part throttle driving. All of a sudden, I had to get much higher in the mph and rpm before the tranny would shift. Example......... shifts to 2nd now around 25 mph and 4000 rpm, shifts to 3rd around 50+ mph and again high rpm. I didn't have enough room to try for 4th gear TV cable adjustment didn't appear to make any difference, loose, tight or in between.

Weeks ago I removed the govenor and replaced the smaller weight to bring up the WOT shift point from 5000 to 5500. First try got me to 5450, and I decided that was close enough. When test driving the vehicle after this, part throttle was exactly as it was before the weight change..... yea!

As the govenor was the last thing touched, I removed it. All was intact (weights, springs). The center piston (doubtfull thats what it's called) was sluggish, so I cleaned the whole unit thoroughly with spray brake cleaner, and dried it. Once I was comfortable that it moved freely up and down, it was re-installed. On a test drive, I still must drive through local neighborhoods like a madman. I can see no difference.

I'm planning on pulling the govenor again, and trying a stiffer spring. Am I correct in my understanding that it is the spring connected to the heavy weight that I want to change for part throttle conditions?

Anyone have any ideas as to why the part throttle shift points suddenly changed? Thanks in advance,

 

[MeanBuicks]

Sounds to me as if you've got a sticky TV valve in the valve body. That could trick the valve body into thinking that you're applying more throttle than you actually are.

It's a fairly common malady for these transmissions to experience.

 

[Roland Black]

Thanks for the input Greg. I just purchased a couple cases of tranny fluid and a new filter kit. I'll change the filter, add fluid and pull off the return line......... crank it up and keep adding fluid while it's running, trying to flush out the system.

I'm no auto tranny expert by any means, but your explanation makes sense to me! Thanks!

 

[MeanBuicks]

While you're in there...

you may as well check the TV system.

The TV plunger and sleeve assembly (activated by the cable) is removable from underneath, without having to remove the valve body. Pull the retaining roll pin with needle nose pliers or dykes.

Pull the plunger and sleeve out and then fish out the plunger spring. Now you should be able to determine whether or not the TV valve is sticking in the valve body. It lives all the way down the end of this bore and will not come out w/o vb removal.

Using a screw driver or scribe, push on the TV valve and see if it moves in and returns back. There is a small return spring in the end of the TV valve. If you can't move it, than it's stuck and the valve body should come off at this point for repair.

 

[Roland Black]

hey Greg;

I have the tranny pan off, and the insides look pretty good! Very clean and hardly anything left in the bottom of the pan.

To the TV valve.........
The tv cable attaches to the 700R4 from the top (vertically) and the TV "stuff" runs horizontally inside the tranny. There is a lever at the reaward of the tranny/assembly that attaches to the TV cable itself. The most rearward plunger and spring (partly visible) move freely.

If I follow you correctly, if I remove the visible portions I mentioned above, by then pushing gently with a screwdriver, I should be able to test the actual tv valve that I cannot see? If it moves in-out freely, all is well. If not, then I get to really make a mess?????

Sorry if this sounds rather lame, But I'm at the point where I normally don't tread, and would rather ask stupid questions than do stupid things!

Thanks again,

 

[MeanBuicks]

Originally posted by Roland Black
If I follow you correctly, if I remove the visible portions I mentioned above, by then pushing gently with a screwdriver, I should be able to test the actual tv valve that I cannot see? If it moves in-out freely, all is well. If not, then I get to really make a mess?????

I believe you're on the right track there!

I did miss one important thing here though. You are working on a 700 and I had 200 on the brain. The one difference here between the two is the fact that the Hydramatic engineers working on the 700 didn't see a need to install a TV valve return spring like the 200-4R; go figure. It's fairly common for rebuilders to add one during the overhaul process as we do at TCI.

That being the case, you may do better to substitute the screwdriver for a small magnet like the telescoping type attached to the end of an antenna-looking stick. That way you can move the valve in and out to see if it's sticking.

 

[Roland Black]

Whew...... ok, pull...... don't push.

I used a small magnet attached to a coat hanger to get in there. All my stronger magnets will not fit. "IF" the TV valve is suppose to come out by doing this ...... it doesn't. There is a view hole roughly half way, and I cannot get the tv valve even up to the view hole............ at times it does feel like there is slight movement, but I can't truly be sure. <------ if there is movement, it is slight.

Should this valve now come out freely if all is correct? Or, should it just move in there mildly to and fro (even tho I'm not sure it's even doing that)?

Still appreciating the help here,

 

[MeanBuicks]

No, that valve will not come out. It's retained by a second roll pin from the top of the valve body. It should freely move back and forth about .200".

 

[Roland Black]

I just got back from Napa, and got one of their bendy type magnets. I'm heading down to see if I can fiqure out some way of verify movement without having to remove the valve body.

I do believe you've got me outa the woods here Greg, one way or another. Much thanks,

 

[Roland Black]

hey Greg;

I do believe you hit the nail on the head!

With my new bendy magnet, I finally managed to get the tv valve to freely go back and forth. I then buttoned it up with new filter, and flushed 12 qrts of fluid thru the system. I then filled it with Redline and took it out for a test drive. It drives like it's got a new tranny............ oops, it does have a new tranny!

THANK YOU for leading me thru this experience. You DA MAN!

 

[MeanBuicks]

Great to hear that!

Glad to help.