Help me with car reluctant to shift from 2 - 3

[Coelacanth]

For the past few seasons, my '86 GN doesn't seem to want to shift properly. On hard acceleration, it really hangs onto the 2 to 3 shift, and does the same thing under normal acceleration...like it doesn't want to make that usual tire-chirping shift.

Although the car doesn't see many miles per season (our winters are too long, heh) and has only about 90k miles, I felt the tranny deserved some attention. A few weeks ago, I dropped the pan; the fluid was a nice clear red, no metal anywhere, just a bit of blackish sludge attached to the round pan magnet. I replaced the TCC solenoid (though I wasn't having issues with it, I felt I might as well replace it while I had the pan off), and replaced the TV plunger spring. I confirmed that a full throttle pedal press pushed in the TV plunger flush with the cylinder bushing, then replaced the pan and put in fresh Dexron VI.

I adjusted the TV cable precisely as follows:

-Disconnected the cable from throttle bracket;
-Depressed D tab and pulled cable forward;
-Rotated throttle lever to WOT, and held it there while pulling the TV cable sheath to the firewall as far as it would go;
-Released throttle lever, reconnected TV cable;
-Rotated throttle lever to WOT again, the cable sheath slid forward and clicked 3 times.

At idle, the TV cable is firm, no slack. I think 5 notches and a few millimeters more are visible.

After warming up the car & tranny and confirming the fluid level was right, I still have the late/reluctant shifting problem.

Does this sound like a TV cable problem, maybe it has stretched too much? Or does it sound like the tranny needs to have all the pressures tested?

 

[notacarlo]

I have never disconnected the TV cable. Just depress the "d" tab and pull cable to firewall. Get in car and stab the throttle until it clicks and clicks no more. Disconnect ECM power supply, reconnect.

 

[notacarlo]

A Shift delay would indicate that the cable is too far back, but the delay would also be in first.

 

[mikestertwo]

Why did you replace the TV spring? Put the stocker back in.

 

[Coelacanth]

Because it's 33 years old. I was having the shift problem before replacing the spring. (In fact, that problem is what motivated me to do the tranny service.) With millions of compressions over the years, the original spring--which should be 1.90" long--was quite a bit shorter than a new one. I wanted to replace it while I had the pan off as it was probably worn. And indeed it was, see my thread post here, comparing the new one to the worn original spring:

Tranny Work

I'll try readjusting the TV cable as you mentioned, notacarlo. Thanks, I'll update with results soon. The shift delay is also there from 1 - 2, just not as noticeable as the 2 - 3 shift point. I never disconnected the ECM power after adjusting the TV cable, I'll try that as well.

 

[notacarlo]

Yeah, give that adjustment a whack without removing the cable. Your idle will be high on restart until the ecu remembers everything. Give it a minute for warm up then the idle should spin down.

 

[mikestertwo]

Because it's 33 years old. I was having the shift problem before replacing the spring. (In fact, that problem is what motivated me to do the tranny service.) With millions of compressions over the years, the original spring--which should be 1.90" long--was quite a bit shorter than a new one. I wanted to replace it while I had the pan off as it was probably worn. And indeed it was, see my thread post here, comparing the new one to the worn original spring:

The Sonnax spring has too high of a spring rate. It does not work well with a BR valve body in a turbo car. If the stock spring was weak it would give you early shifts, not late shifts. If you had late shifts before with the stock spring....the spring wasn't the problem. Put the stock spring back in.

 

[TexasT]

So, can I get a better description of "reluctant shift"? Is it hanging in second to a higher rpm? Is it trying to shift but doesn't seem to apply the direct clutches and gives a mushy shift?

Because if it is the later I would say you are where a lot of people get to and need an overhaul with some new clutches and steels in the direct at minimum.

Also the 1.90" long tv spring might be too short . I was advised to use one that is 2.01" long so I made one. Little did I know that sonnax sells such a spring for this purpose.

If it has been subjected to spirited driving and some trips to the track I think you got the moneys worth after 90k miles.

 

[Coelacanth]

TexasT, what I'm describing is the engine revs way too high before shifting...it almost doesn't make that 2 - 3 shift. The tranny isn't slipping at all, it just doesn't want to shift at the correct RPM. Everything I've been reading seems to point to this being a TV cable adjustment problem.

Hopefully someone can clarify something for me, as the terminology I'm finding on various websites is all over the place, with regards to "shorten" or "lengthen" the TV cable.

When you "shorten" the TV cable, is it correct that you are pulling the TV cable back towards the firewall, which would cause later shifts?

When you "lengthen" the TV cable, does this mean you're moving the TV cable towards the front of the car/throttle lever, which would cause earlier shifts?

A lot of what I've been reading shows pictures but doesn't mention whether "shorter" or "longer" is relative to the throttle lever, the front or rear of the car, or the "D" adjuster tab. Such a simple missing detail in wording can cause a lot of confusion. I think it's also possible that the TV cable might be worn and could have stretched to the point it won't adjust to the correct setting the usual way anymore.

 

[77 cruiser]

Only one correct position for the TV cable. Could a the TV limit be stuck? Gov. spring still on?

 

[TexasT]

X2 on the TV cable adjustment. Wot should also be full tv. The geometry of the throttle arm gives the cable the quicker out at the lower throttle angles. Sounding to me like it is slipping or has a flare going from 2-3. With the rpm going up think the band is releasing and the direct clutch is unable to apply and the free rev occurs.

 

[Gene Van Horn]

Call Dave Husek.

 

[Coelacanth]

So, some additional observations from my test drive yesterday. With the TV cable at it's "correct" adjusted position, the car shifts very late. The gears aren't slipping, though. It just builds up too much RPM before it shifts. After all my research, "lengthening" the TV cable--by moving it towards the front of the car, away from the firewall (to avoid any confusion in terminology)--should make it shift earlier. I pressed in the "D" tab and slid the cable about a notch forward (towards front of car) and test-drove it. Indeed, it was shifting much better--still not QUITE on time, as it used to...but significantly better than with the TV cable set at the "correct" position.

I slid the cable again forward another millimeter or two, and will re-test tonight.

The problem is, if I mat the accelerator pedal, the TV cable will probably click and self-adjust back to it's "correct" position and I'll get late shifts again.

Wouldn't this all seem to indicate the TV cable has worn and stretched over the years (it has never been replaced)?

 

[TexasT]

Could be a worn cable. Just to be clear again. The TV cable is not for shift point adjustment . It gets adjusted to wot and full tv apply and the geometry of the arm on the throttle body applies the tv to get the internal pressure where it needs to be.
www.tvmadeez.com has some pretty good info on how it should work. You are having VB or governor probs with what you are describing. I still think you have a worn set of direct clutches and steels at 90k miles and it is time for an overhaul but it is pretty hard to diagnose over the interwebz. That is just a feeling after torching up a set or ten myself.

 

[Coelacanth]

Yes, I read through that site's articles on the 200-4R and TV adjustment many times, and printed out several of those pictures before dropping the pan and replacing the plunger spring, and verifying that WOT completely depressed the plunger flush with the plunger's bushing. It's a very good, in-depth read.

Since they're inexpensive, I'll buy a new TV cable and compare with the original one. I see many replacements online, because there are tons of GM cars that have 200-4R and 700R4 trannies, carbureted and fuel-injected...is there a particular replacement that's recommended for our GN's?

 

[Pronto]

Highway Stars has them.

 

[Coelacanth]

Thanks Pronto. There are also 2 kinds on RockAuto, an ATP and Pioneer one, but both appear to be too short. 43" is the magic number. Strangely, the Pioneer CA1960 cable shows as being a correct fit for my car, but that must be a mistake.

 

[77 cruiser]

If the cable stretches it would be shifting lower. If the cable did really stretch couldn't you just tighten up a click?
I guess a cable housing could wear & the cable hang up a bit, but you should feel it by pulling on the disconnected cable.

 

[VIN7]

The plunger may be returning to it's resting position, but the valve on the other end of the tv spring could be hanging up. Plus when you change tv spring length and/or rate it will affect the action on the throttle valve. Do you have a pressure gauge?

Check this thread for info about proper positioning of the throttle valve

https://turbobuick.com/threads/setting-base-tv-with-pressure-gauge.430794/page-2

 

[Coelacanth]

Thanks, I've read about the importance of testing and having the correct pressures. A pressure gauge will let you test the pressures, but how would you adjust the pressures? I don't see it mentioned anywhere in that topic you linked, but that was a good read, too.