My '86 automatic shifts into hi-gear right at 42mph. Is there any way to program it to shift lower, say 35 or so?

 

You are saying your 1986 700R4 Transmission shifts in 4th gear @42 mph part throttle - light throttle driving...Correct?

That is perfectly normal operation.
Why do you want it to shift into high gear at 35mph?

Are you looking for better fuel economy?
You could change out the Corvette governor weights to lighter ones.
And you could go inside of the valvebody and change out the 3-4 upshift valve springs.

Not really worth the extra effort unless you are very bull headed like I am........make up your mind and you just have to have it that way.

Corvette engineers did an excellent job calibrating the C4 700R4 Valvebodies for daily and high performance usage driving.
If you don't believe that, drive another Non Corvette 80's or early 90's GM vehicle that has a 700R4 trans...

You will be sadly disapointed........slushbox feeling comes to mind driving a non C4 Auto Vette.

Brian

 

I also have a 2003 with a 6-speed and for driving around town I try to get it into 6th as soon as possible. Even at 35 around town. Most city speed limits are 35. I would like my '86 to shift into the highest gear at 35. Gas milage? Sure! My '86 has over 210/k on it and I can't remember the last time I "nailed" it. So high speed shifts are not a problem, just low speed.

 

You are a Mobil Economy Run type of Driver.
Thats Ok too.

You don't miss nailing the gas and passing that kid in his Honda Civic?

I take great pride and joy wiping that dirty ear to ear grin those guys have when at a stoplight next to him in my 87 Vert.

Torque wins. Kid in Honda loses.

What kind of gas mileage do yo get in your 86?

For the effort, you may not have very significant gains in MPG making your trans shift into 4th gear @ 35mph.

Brian

 

........ Torque converter clutch operation is programmable vs MPH in the computer ... however , the shift points of the transmission are controlled by the governor weights and to a minor extent by the TV cable ... under light throttle and steady load conditions my 700R4 shifts into 4th gear at 37mph ... the TCC locks up at 43mph and unlocks at 40 ... So , Yes both can be adjusted to suit your driving style ............

 

I have an 86 also. I believe it will shift earlier then 42 miles per hour. At 42 MPH is when the torque converter locks up.

 

Part throttle upshifts are controlled mainly by the springs in the governer. Full throttle shifts are determined mainly by the weights. However, they both play a factor in full and part throttle shifts. Buy yourself a B&M governer kit and mix and match parts. I did this when I was running a 700r4 and spent hours dialing in part and full throttle shifts. Oh, also make sure your tv cable is adjusted properly before going through all this. Willie

 

how do you get it to shift higher, and release 4th earlier? mine stays in 4th all the way to 1100 rpm before it downshifts.

 

In town, around 23 on the road around 28 or so. It went down to around 19 and 25 until I put new injectors in!

 

To shift higher, you will need lighter weights and/or lighter springs. Not sure how that affects downshifts.

 

how high can i get it to shift into 4th? it's going into it at around the 42 mph mark.

 

If you use light weights and springs, the governer will need to spin quicker for centrifical force to open the valve to allow the shift. You can make it shift really high if you want. Unfortunately, it affects the rest of the gears shifts as well as wot. To be honest, that is one reason I finally got a 4l60e. I could set the wot shift points for the track and part throttle shift points in every gear with a laptop. Willie

 

There are spring loaded up shift valves OR SHIFT TRAIN VALVES inside of the valvebody on a 700R4.

They Control or Make the hydraulic actuated gear changes.
The "BRAIN of the transmission"

The springs are color coded and have unique spring tension rates.

Much like different spec engine valvesprings for a hydraulic flat tappet, solid flat tappet, or full race solid roller camshaft.

Every different application 700R4 GM vehicles have these springs matched to the original GM transmission engineers specifications.
One reason all C4 Corvette 700R4 transmission Valvebodies are unique to any other GM vehicle.
A real nice compromise between daily light footed driving to the grocery store.
Or Heavy full throttle usage.

These upshift spool valve springs are seldom changed out by most transmission builders.
They leave them alone or have no knowledge of how to recalibrate properly for performance style use.

Only The most knowledgeable will change them out to suite a particular performance application.

Dana @ Probuilt transmissions knows all about these SHIFT TRAIN VALVES/ upshift spool valvesprings.

They are also available through Trans Star transmissions & PATC transmissions.

If you don't know what you are exactly doing, you are better off leaving those upshift spool valve springs alone in your C4 Vette 700r4 transmission.

Brian