700R4 lockup speeds?
09-01-2014, 03:52 AM
#1
Le Mans Master
Thread Starter
700R4 lockup speeds?
Well I have the 700R4 trans seams to shift OK, but it does not go into converter lockup till 75 MPH. then when It drops below 75 it disconnects. The RPMs 2,200 @ 75 mph when it does lockup it drops to 1,850 rpms
I don't drive 75 MPH so how can I get the lock up to kick in around 55 or 60?
I don't drive 75 MPH so how can I get the lock up to kick in around 55 or 60?
09-01-2014, 04:38 AM
#2
Race Director
As far as I know all Corvettes with 700r4s are programmed to lock up the torque converter at 40 MPH. I know that mine will lock up at 40 MPH in any gear (I have tested that).
You can monitor lockup by putting a voltmeter on pin F of the ALDL connector and reference it to ground (pin A). It will read 12 volts when it's NOT locked and zero volts when it IS locked. You can use a test light for this. Just keep in mind that the light will be on when it's NOT locked and will go out when it IS locked.
You can monitor lockup by putting a voltmeter on pin F of the ALDL connector and reference it to ground (pin A). It will read 12 volts when it's NOT locked and zero volts when it IS locked. You can use a test light for this. Just keep in mind that the light will be on when it's NOT locked and will go out when it IS locked.
09-01-2014, 05:29 AM
#3
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I don't drive 75 MPH so how can I get the lock up to kick in around 55 or 60?
Also, if you install a switch with that test light you can force TCC lockup manually, in any gear except 1st.
09-02-2014, 04:45 AM
#4
Le Mans Master
Thread Starter
As I mentioned it does lock up but only at 75 mph. So how do you get it to lockup say at 60 mph without a switch?
09-02-2014, 05:04 AM
#5
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Any chance your brake switch is stuck on? Most vehicles unlock the convertor when the brakes are activated. Have no idea if this applies at speeds above 75 mph or not -
Just a thought -
Jake
Just a thought -
Jake
09-02-2014, 02:36 PM
#6
Instructor
An easy fix is to have the converter lock up whenever the transmission shifts into 4 gear regardless of speed. It will stop the annoying lock/unlock problem.
Here is a great article with pics to show how easy it is to do.
http://www.superchevy.com/how-to/53562/
I did this but added a toggle switch so I can leave the lock-up off when I want.
Here is a great article with pics to show how easy it is to do.
http://www.superchevy.com/how-to/53562/
I did this but added a toggle switch so I can leave the lock-up off when I want.
09-02-2014, 09:28 PM
#7
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So how do you get it to lockup say at 60 mph without a switch?
For example the "chip" may have been reprogrammed. The ECM may not be seeing proper speed or some other parameter. If not a custom chip then an ECM scan would be in order to find out why the ECM is not locking the TCC at the proper speed.
09-03-2014, 02:17 AM
#8
Le Mans Master
Thread Starter
Will it lock if you drive up to say 50mph and hold steady speed on a flat road? If not there is a defec somewhere.
For example the "chip" may have been reprogrammed. The ECM may not be seeing proper speed or some other parameter. If not a custom chip then an ECM scan would be in order to find out why the ECM is not locking the TCC at the proper speed.
For example the "chip" may have been reprogrammed. The ECM may not be seeing proper speed or some other parameter. If not a custom chip then an ECM scan would be in order to find out why the ECM is not locking the TCC at the proper speed.