1985 Corvette automatic 700r4
04-05-2017, 11:04 PM
#1
1st Gear
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1985 Corvette automatic 700r4
What controls the shift points in a 1985 700r4? Does the computer make all the decisions based on speed and throttle position? Does the valve body in the transmission have any control?
I would like to raise the shift points for around town driving. The car shifts into 3rd and 4th gear at very low RPMs, the engine lugs, it's annoying. More throttle raises the shift points, as well as the acceleration to the point that is draws too much attention from the guys in blue.
The only solution is to shift the car manually.
Can anything be done? Or should I just shift manually and shut up? lol
I would like to raise the shift points for around town driving. The car shifts into 3rd and 4th gear at very low RPMs, the engine lugs, it's annoying. More throttle raises the shift points, as well as the acceleration to the point that is draws too much attention from the guys in blue.
The only solution is to shift the car manually.
Can anything be done? Or should I just shift manually and shut up? lol
04-05-2017, 11:40 PM
#2
Melting Slicks
The governor changes shift points, you can buy a Superior trans recalibration kit off ebay. Diff combos react diff, so make small changes n see what happens. Few threads on here so try a search.
04-05-2017, 11:54 PM
#3
Race Director
Make sure your tv cable is adjusted correctly.
04-06-2017, 12:06 AM
#4
Melting Slicks
04-06-2017, 08:53 AM
#5
Burning Brakes
IIRC, the valve body in the tranny controls the shift points based on throttle position and speed. The ECM controls when the converter locks and unlocks.
I have the same issue and am working on getting an EPROM burned to lock the converter later. Early 85 models in an effort to improve fuel milage lock the converter at 15mph and light throttle. Later versions lock above 40mph. Look at your EPROM to find out which you have.
I have the same issue and am working on getting an EPROM burned to lock the converter later. Early 85 models in an effort to improve fuel milage lock the converter at 15mph and light throttle. Later versions lock above 40mph. Look at your EPROM to find out which you have.
04-06-2017, 11:07 PM
#6
IIRC, the valve body in the tranny controls the shift points based on throttle position and speed. The ECM controls when the converter locks and unlocks.
I have the same issue and am working on getting an EPROM burned to lock the converter later. Early 85 models in an effort to improve fuel milage lock the converter at 15mph and light throttle. Later versions lock above 40mph. Look at your EPROM to find out which you have.
I have the same issue and am working on getting an EPROM burned to lock the converter later. Early 85 models in an effort to improve fuel milage lock the converter at 15mph and light throttle. Later versions lock above 40mph. Look at your EPROM to find out which you have.
04-07-2017, 12:21 PM
#7
Burning Brakes
That's the one. There are copies of the .bin file floating around on the web or you can have the person programming it just adjust yours.
04-09-2017, 09:59 PM
#8
I am not electronically knowledgeable. Are you saying that my present eprom can be reprogrammed if I can locate the later version bin file?
04-09-2017, 10:02 PM
#9
Burning Brakes
Yes. The file is available and a custom program can be had. Either programmed onto your existing EPROM or a new one all together.
04-10-2017, 01:20 AM
#10
Race Director
04-10-2017, 03:56 PM
#11
What controls the shift points in a 1985 700r4? Does the computer make all the decisions based on speed and throttle position? Does the valve body in the transmission have any control?
I would like to raise the shift points for around town driving. The car shifts into 3rd and 4th gear at very low RPMs, the engine lugs, it's annoying. More throttle raises the shift points, as well as the acceleration to the point that is draws too much attention from the guys in blue.
The only solution is to shift the car manually.
Can anything be done? Or should I just shift manually and shut up? lol
I would like to raise the shift points for around town driving. The car shifts into 3rd and 4th gear at very low RPMs, the engine lugs, it's annoying. More throttle raises the shift points, as well as the acceleration to the point that is draws too much attention from the guys in blue.
The only solution is to shift the car manually.
Can anything be done? Or should I just shift manually and shut up? lol
Confirm the tv cable is properly adjusted as per the service manual, and see if it improves. It may not. The early C4's did short shift.
If you suspect the governor, pop off the cover, and inspect. Be sure the valve moves freely, and the gear is not "apple cored". If it is, disassemble, clean, and install a new gear.
If you then want to change shift points, you will need a governor recalibration kit, and invest some sweat equity.
04-12-2017, 08:44 PM
#12
04-12-2017, 10:28 PM
#13
Team Owner
04-13-2017, 01:22 AM
#14
Race Director
Shift points are controlled by the governor and the tv cable via line pressure. The ecm controls converter lockup.
04-14-2017, 04:06 PM
#15
04-17-2017, 07:03 PM
#16
my 1985
I did not like the way my 1985 which was bought in 1992 with 700R4 shifted so I changed it the cheap way. I have installed a wire to a dash placed switch that inhibits the torque converter from functioning. Leave my torque converter off for in the city driving. I told my wife when she goes to the grocery store to just drive in second gear, speed limit is just 30 mph. I will put the torque converter in use when I get on a highway.
04-17-2017, 08:58 PM
#17
Team Owner
I did not like the way my 1985 which was bought in 1992 with 700R4 shifted so I changed it the cheap way. I have installed a wire to a dash placed switch that inhibits the torque converter from functioning. Leave my torque converter off for in the city driving. I told my wife when she goes to the grocery store to just drive in second gear, speed limit is just 30 mph. I will put the torque converter in use when I get on a highway.
04-17-2017, 10:15 PM
#18
op, I had a 1985 up until last November and I got to the very bottom, the root of your problem. I felt the same I hated the way it felt like it was stack shifting.
it is in fact not shifting early.
it is engaging the torque converter almost instantly after entering into second third & overdrive.
it was done like this to meet mile per gallon requirements.
however the complaints were loud, and GM did release an updated prom chip for the 1985.
it is in fact not shifting early.
it is engaging the torque converter almost instantly after entering into second third & overdrive.
it was done like this to meet mile per gallon requirements.
however the complaints were loud, and GM did release an updated prom chip for the 1985.
Your problem will be solved by simply buying this chip spending a couple of hours pulling your Computer out and swapping the prom chip.again, just for clarity, your transmission shift points are just fine.It is the early engagement of the torque converter that is controlled by the ECM and it feels like it's shifting to early into the next gear. It's not. But it feels like it is.
there is the off chance that a previous owner messed with the governor. Which is a mechanical device that controls your shift points of the transmission itself. But chances are very slim that happened. Chances are you're just experiencing the early lugging as the stock 1985 ecm engages the tourqe converter too soon.
hlm 3200 is what u r after.
https://www.corvetteforum.com/forums/c4-tech-performance/3830279-1985-corvette-early-tc-lockup-shorted-ecu.html
there is the off chance that a previous owner messed with the governor. Which is a mechanical device that controls your shift points of the transmission itself. But chances are very slim that happened. Chances are you're just experiencing the early lugging as the stock 1985 ecm engages the tourqe converter too soon.
hlm 3200 is what u r after.
https://www.corvetteforum.com/forums/c4-tech-performance/3830279-1985-corvette-early-tc-lockup-shorted-ecu.html
Last edited by VikingTrad3r; 04-17-2017 at 10:16 PM.
04-18-2017, 06:47 AM
#19
Melting Slicks
op, I had a 1985 up until last November and I got to the very bottom, the root of your problem. I felt the same I hated the way it felt like it was stack shifting.
it is in fact not shifting early.
it is engaging the torque converter almost instantly after entering into second third & overdrive.
it was done like this to meet mile per gallon requirements.
however the complaints were loud, and GM did release an updated prom chip for the 1985.
it is in fact not shifting early.
it is engaging the torque converter almost instantly after entering into second third & overdrive.
it was done like this to meet mile per gallon requirements.
however the complaints were loud, and GM did release an updated prom chip for the 1985.
Your problem will be solved by simply buying this chip spending a couple of hours pulling your Computer out and swapping the prom chip.again, just for clarity, your transmission shift points are just fine.It is the early engagement of the torque converter that is controlled by the ECM and it feels like it's shifting to early into the next gear. It's not. But it feels like it is.
there is the off chance that a previous owner messed with the governor. Which is a mechanical device that controls your shift points of the transmission itself. But chances are very slim that happened. Chances are you're just experiencing the early lugging as the stock 1985 ecm engages the tourqe converter too soon.
hlm 3200 is what u r after.
https://www.corvetteforum.com/forums...orted-ecu.html
there is the off chance that a previous owner messed with the governor. Which is a mechanical device that controls your shift points of the transmission itself. But chances are very slim that happened. Chances are you're just experiencing the early lugging as the stock 1985 ecm engages the tourqe converter too soon.
hlm 3200 is what u r after.
https://www.corvetteforum.com/forums...orted-ecu.html
It was an added bonus when i fitted a hyper tech chip, see the link below. It has the changed converter lock up speeds making it better to drive.
Not that i recommend the chips, it did not really make any noticable difference in engine performance ....
http://www.parts123.com/corvettecent...050f&ukey=6056
http://www.parts123.com/corvettecent...050f&ukey=6053
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