hello Mates, Finaly I got my car
My first Vette, I was waiting for 24 years!!!!
So the first thing I did is put the car on the Garage and check it from nose to tail. The car has only 51k miles and only few stupid thing on the interior are the bad points.
But the Gearbox.... When I start the car run good without any problem. Only when I change from P to R and D the change is so hard and knocky. I made about half mile and the traction just desappear, engine running but no traction. I stop the car and change to 3 gear. The car, was running fine. I drove for 10 miles and no problem at all, running in 3 position. When I put D no traction, Revers run Ok, 1 ok, 2 ok, 3 ok but no Direct.
The Corvette is 84 crossfire with all original on it.
Sorry about my English but I try...

 

Hi,

I have a similar problem. No traction on D or double D. All other gears works fine.
I will browse the forum to see if I can get some help somewhere. I will start a thread about it eventually.

Cheers

Dag

 

4th gear band servo is not activating or operating as it should.

 

You lost or burnt out the 3-4 clutch assembly.

Rebuild time.

 

If the 3/4 clutch pack were bad, you wouldn't have 3rd either.

Either the servo is 'stuck' or the TV cable needs to be adjusted.

Make sure your trans isn't low on fluid.

Some times the valves hang up. A full flush might help too.

 

87 vette 81 big girl,

What is a "4th gear band servo"? Where is the fourth gear? I've only noticed three and the overdrive. Is the overdrive considered to be the fourth gear? If so I guess I will have a look att the TV cable.

Cheers

Dag

 

I'm a bit confused about the gear numbering. I have 1, 2, D and DD. I thought that D was the third gear and DD was still the third but with overdrive. Therefore I thought something is wrong with the "third gear". And if the third gear is slipping in D, so it will in DD.

Cheers

Dag

 

"D" is drive or 3rd gear.
Direct drive,
1 : 1 transmission ratio.

"DD" or the D with the circle around it is Overdrive 4th gear range position.
The input shaft - turbine shaft turns slower than the Output mainshaft- tailshaft where the driveshaft connects too.
Or the output shaft spins faster than the input shaft.

Brian

 

2-4 band is a Single wide band used in all 700R4 & 4L60e transmissions.

One single servo cover on the front passenger side of the trans case.
Cover held in place with a round wire style snap ring.

There are 2 servos in 1.
Hence the 2-4 servo.

2nd gear servo is the inner servo inside of the trans case.

4th gear servo is toward the outside of the trans case- cover.

4th gear is done by activating the 3-4 clutch & 2-4 band, forward clutch, power flow through front planetary gearset, reaction sun gear shell, & rear reaction planetary gearset.

Be a good idea to check "TV" - throttle valve adjustment on your 700R4 trans - YES.

Brian

 

Thanks for the explanation Brian,

So I suppose I might confuse people if I refer to the D with the circle around it as DD since the single D is direct drive which in fact could be shortened as DD.

Cheers

Dag

 

It's unfortunate, but that's what your looking at. New bands and clutch assys from Redline will make the trans almost new again.

 

Thanks for the tip! Wish I had time and room to do it myself. Guess it's not rocket science and I would save a fortune.

Cheers

Dag

 

Hello again Brian,

Yesterday evening I couldn't contain myself. Just had to check the TV wire. I took a photo of the original position, adjusted and took a new photo. Only had my phone there so pic quality isn't that good.



Before adjustment



After adjustment

As you can see the wire was thightened a bit. This really affected the gear shifting. I shifts later and I like it a lot. I get a "tuned up" feeling. Having only two gears and then the slip to compare with I think it sometimes shifts too late though. Since the wire, according to adjustment procedure, was not properly adjusted I wonder if I could have prevented the breakdown if I knew this when I bought the car. I have only driven it for 3000 km.

If TV adjustment is so d-n critical, it's strange that it isn't red painted or marked "danger" or something since it is so easy to change. I mean, who doesn't peek and poke a bit here and there just to see that things aren't falling off.

Cheers

Dag

 

Likely was adjusted correct before.

Here is what you do to correctly adjust the TV cable on your 700R4 Corvette transmission.........

There is a gold or silver lock release on the TV cable where it snps into the upper bracket on the TPI system.

With a small screwdriver,
Push in or depress the hinged lock.
Keep pushing down on the lock,
Push the protruding jacket or nose of the TV cable all the way back towards the firewall.
Let go of the lock.

Next from underneath the hood yet,
Grab the throttle body Cam where the TV cable connects & the accelerator or gas pedal cable connects likewise,
Fully open the throttle body slowly till you hit the fixed external stop.

Let go and You are done adjusting the TV - throttle valve cable for your C4 700R4 trans.

Road test your Corvette.

If you still dont' have 3rd or 4th gear,

Unable to hit 130 - 150 mph flat out in less than 1 US mile............

Its time to remove your 700R4 trans & rebuild it.
3-4 clutch frictions & steels are burnt out & gone to rest.

Brian R.

 

Some guys adjust TV cables by shift feel as You do........

Its 100 % a Bullchit practice..........

Want shift feel,
rebuild & blueprint your trans right as I did with my 700 R4.

Air was perfect today............

Horsepower day...........

at 50 MPH & punched the gas.....forced a downshift from 4th to 2nd.

I lit up the rear 1990 ZR-1 11X17 & 315/35ZR17 Goodyear GS-C tires, smoked them & car got sideways on me.

That is real shift feel.

 

Brian,

Well, I doubt that the cable was adjusted properly before and I also think that might have something to do with the assumed breakdown.

I found the adjustment procedure here on the forum and carried it out as you describe. The lock you mention is the square formed button like thing between the the two silver colored metal parts in the bracket. You don't need a screwdriver, a finger will do nicely. I pushed the nose in, released the button and then WOT. Doing that, the nose moved towards the throttle cam making a couple of cracking sounds.
I think I got it right.

The car goes throug first and second gear to about 70 MPH and then there is no more pull since it can't get the third gear in.

Everthing indicates I have to spend a lot of money...

Cheers

Dag

 

I didn't adjust by feel but I forgot to say I followed the proper procedure. Sorry!
I think I'm facing an overhaul and if so, I will have it reinforced. The 3-4 clutch will be replaced by better stuff and the stall will be raised a couple of hundred rpm's.

Cheers

Dag

 

Do the rebuild yourself & save$$.

I have had people come up to me in person & say that I adjusted my TV cable wrong..........let me adjust it for you.

lol

few years back.

I told them i was going to rip there arm off & beat them with it.

they believed me & left.

 

Brian,

A shop I called told me they spend about 5 to 6 hours to get the gearbox in and out of the car and guessed it would take me about two days on my garage floor with no lift if I did it myself. That scared me a bit. Also I have to support the engine while tranny is out which means I can't move the car. He would charge me about 700 bucks to do it for me.
Right now I don't have time to do it myself (turning 50 in two days and have a lot to prepare) so in that case it will have to be a winter project. That means no more Corvetting this season
I was also told that replacement parts often have a bad fit and needs customizing. Scares me even more.
I know I can save money doing it myself but I'm not sure I can handle it right now.

By the way - how crucial is the TV cable adjustment? Could you really ruin a tranny if it's not properly adjusted? I understand you can alter the shift points. But ruin the gearbox?

Cheers

Dag

 

It was not so long ago I had to rebuild my original 700R4 in my 87.
It seemed like a very daunting task to me also.
I asked many questions on C4 also.
I am a mechanic so removing & reinstalling a transmission is pretty easy task anyhow.
If you read back about 1 year on C4,
CORVETTEMIKE2004 & his black 1989 Corvette Roadster, used to be a stick on top of this main tech page & has been moved,
Mike home rebuilt his C4 700R4 himself.
He did an excellent job.
I helped along with many others for tech support & morale support also.
Mike also home fashioned many tools himself to get the job done.
Many fantastic photographs & write ups by Mike there.
Mike got fed up with the Politics here on C4.
Said Fick this chit Brian to me 1 day.
He bought a Harley & rode off into the desert sunset.........really he did.
Mike will be back, about the time you are ready to rebuild your Corvette 7004.
He had to go beat up some American jerks in person for a while....lol
I will help you when ready.

How important is the 700R4 TV- throttle valve cable adjustment ???

If the current president of the USA came up to You after you freshly rebuilt your 700R4 & blueprinted it & stated you did not know chit & get out of the way & I will adjust it for you...............

Tell him too that You will rip his right arm off & beat him with it also......LOL

TV cable adjustment is that important.
Controls line pressure rise & correct shift points w/ the centrifugal governor.

Many quality aftermarket 700R4 parts.
Research & ask questions.
I will answer your questions.

Brian R.