convertor lockup???
Thread Starter
Instructor
Joined: Jun 2007
Posts: 100
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The reason I asked is I had a hypertech chip in the ECM and I was getting lockup at 42 mph. I took it out because once the cooling fan came on it wouldn't go off and put the stock chip back in and now I am getting lockup at 35 mph. I don't remember what it did prior to installing the hypertech chip but I guess it was 35 mph. Thanks for the input one and all.
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
At normal operating temperature, my stock '85 locks at 68 kph or 42 mph consistently. I jumpered a toggle switch into the power wire at the brake switch, which when the toggle switch is open - it replicates the brake switch being activated (no brake lights on, of course) unlocking the TC until I switch it back on with the toggle. Works nice on cruises and in areas where the speed limit is right around the lock up speed.
Le Mans Master
Joined: Oct 2004
Posts: 7,705
Likes: 485
From: Everett WA
C4 of Year Finalist (appearance mods) 2019
At normal operating temperature, my stock '85 locks at 68 kph or 42 mph consistently. I jumpered a toggle switch into the power wire at the brake switch, which when the toggle switch is open - it replicates the brake switch being activated (no brake lights on, of course) unlocking the TC until I switch it back on with the toggle. Works nice on cruises and in areas where the speed limit is right around the lock up speed.
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
I sure hope that you are monitoring your trans fluid temp. When the tc is not locked up it is constantly generating more and more heat due to friction. If you hold that tc in an unlocked position for an hour of driving your going to drive the trans fluid up quite a bit. Just my .02
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Team Owner
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Haven't we all ready talked about this before????
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
Le Mans Master
Joined: May 2007
Posts: 8,448
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From: Valparaiso
yes,i know that feeling but what if you buy a non lockup? i know they waste gas
they are locked all the time ? strange,i know the feeling but i dont know exactly
when it locks or unlocks ...for example if im cruising and there is an uphill,does it unlock?
if im going faster im unlocked ? lol ...its confusing !
they are locked all the time ? strange,i know the feeling but i dont know exactly
when it locks or unlocks ...for example if im cruising and there is an uphill,does it unlock?
if im going faster im unlocked ? lol ...its confusing !
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
Using your 3rd gear selector is another option, if that's your preference. I don't think this is the only topic on the forum that has been "talked about" before...did I miss a ruling about that?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
No .
A non lockup convertor is just like a convertor installed in millions of trans before pollution / economy became a concern .It just means that the trans is never running at engine revs; there is alway a percentage slippage.The lockup feature is for economy only.
As above , running unlocked no different to any non lock up trans ;TH400 /Glide / TH350 .The heat is from slippage ; not friction.
The PROBLEM with T700/4L60 is that it does not have full fluid flow to the cooler unless it is in lockup mode hense the stated concerns about overheating of trans when running unlocked.
A non lockup convertor is just like a convertor installed in millions of trans before pollution / economy became a concern .It just means that the trans is never running at engine revs; there is alway a percentage slippage.The lockup feature is for economy only.
The PROBLEM with T700/4L60 is that it does not have full fluid flow to the cooler unless it is in lockup mode hense the stated concerns about overheating of trans when running unlocked.
Le Mans Master
Joined: Oct 2004
Posts: 7,705
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From: Everett WA
C4 of Year Finalist (appearance mods) 2019
I never realized that flow to the built in trans cooler within the radiator doesn not occur unless the tc is locked.
Can you explain this in a bit more detail. How is the fluid flow to the cooler controlled.
My situation is that my tc does not lock up until 48mph in 4th. In my daily commute I unfortunately spend much of the time at speeds lower than this and the trans temp just continues it's steady rise in temp. To the point where the water temp = 190 but the trans fluid temp is 40 degrees higher.... however once I hit 48 and the tc locks up the temp will hold (at what ever temp is was at that point) and not rise any further and infact over enough time it will fall to within 10-15 degrees (f) of the water temp.
PS I thought slippage and friction were essentially the same thing.
Last edited by Mr. Peabody; Sep 3, 2009 at 04:15 PM.
Safety Car
Joined: Sep 2001
Posts: 4,134
Likes: 531
From: Glenbeulah Wi
Wow thank you for that.
I never realized that flow to the built in trans cooler within the radiator doesn not occur unless the tc is locked.
Can you explain this in a bit more detail. How is the fluid flow to the cooler controlled.
My situation is that my tc does not lock up until 48mph in 4th. In my daily commute I unfortunately spend much of the time at speeds lower than this and the trans temp just continues it's steady rise in temp. To the point where the water temp = 190 but the trans fluid temp is 40 degrees higher.... however once I hit 48 and the tc locks up the temp will hold (at what ever temp is was at that point) and not rise any further and infact over enough time it will fall to within 10-15 degrees (f) of the water temp.
PS I thought slippage and friction were essentially the same thing.
I never realized that flow to the built in trans cooler within the radiator doesn not occur unless the tc is locked.
Can you explain this in a bit more detail. How is the fluid flow to the cooler controlled.
My situation is that my tc does not lock up until 48mph in 4th. In my daily commute I unfortunately spend much of the time at speeds lower than this and the trans temp just continues it's steady rise in temp. To the point where the water temp = 190 but the trans fluid temp is 40 degrees higher.... however once I hit 48 and the tc locks up the temp will hold (at what ever temp is was at that point) and not rise any further and infact over enough time it will fall to within 10-15 degrees (f) of the water temp.
PS I thought slippage and friction were essentially the same thing.
The older 700 did not have full flow to the oil cooler until they were in lock-up 1985 and earlier. If you have a 1986 or newer that issue was resolved and you will have full flow to the oil cooler when it is not in lock-up.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
So on that basis all the stories/myths / rumours of burning up your (post '87) trans if running unlocked are unfounded ?
Bad for fuel economy; yes but not bad for trans.
Safety Car
Joined: Sep 2001
Posts: 4,134
Likes: 531
From: Glenbeulah Wi
An overdrive transmission puts more torque load on the convertor at any speed when it is running in overdrive (as compared to an older style 1:1 nonoverdrive transmission). This torque load creates slip and heat so the general rule of thumb for an overdrive transmission is to use lock-up when in overdrive to keep the oil temperature lower. If the oil temperature when in overdrive nonlock-up can be kept under 200 degrees the transmission will not have any issues with the nonlock-up torque convertor.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
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From: Tampa Florida
My situation is that my tc does not lock up until 48mph in 4th. .... however once I hit 48 and the tc locks up the temp will hold (at what ever temp is was at that point) and not rise any further and infact over enough time it will fall to within 10-15 degrees (f) of the water temp.
48mph in 4th. This is exactly how my tranny acts - it stays "locked up" until I hit the throttle hard again (goosin' it) or hit the brakes. '89:
PCM4less chip mod, ~3,000 stall ( http://www.kmjent.com/cart/product.p...3&cat=0&page=1 ) an additional trans cooler ( http://www.summitracing.com/parts/SU...A/?image=large ) in place, insulated ( http://www.summitracing.com/parts/DEI-010408/) oil return line ....my tranny return oil rarely hits 200 F
The above combo works pretty good IMO
Race Director
Joined: Jun 2004
Posts: 13,924
Likes: 700
From: WI
Just to add to this, I went with a non-lockup trans for this last rebuild. I have run it for hours and hours unlocked without any heat issues. Typical temp is 150° with a Derale pan, and B&M cooler.