To lock up 0r not to lock up - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**hotrodmtodd** · 12-03-2010, 12:07 PM

Will it damage a 700r4 to run it without a lock up switch? Son needs to get back to college tomorrow 100 miles away, and I dont have it hooked up yet. Running out of vehicles to let him take. Anybody have a quick way to hook it up temporary if it is not a good idea to run it without it? Read the FAQs but everything sounds more involved than we have time for today. Please help if you can. Thanks, Mike

406 Q-ship · 12-03-2010, 12:20 PM

If the engine runs at or above the torque converter stall speed (unlocked) on the freeway, then it will not hurt anything. It will just be like running an old TH350/400 with a slightly looser stall converter. My 1974 has not had the lock-up hooked up for the last few years and all is still fine.

If you want to do a quick and dirty hook up, use a toogle switch so your son can throw the switch on the highway. Just remember to turn it off around town or in stop and go traffic.

Jacfourteen · 12-03-2010, 01:07 PM

X2 on the above, if you toggle it and forget to unlock it when you stop it will stall out like a manual tranny does if you don't push in the clutch.

**hotrodmtodd** · 12-03-2010, 01:11 PM

Thank you SO much. I just need to get him back to school and we will gather parts and try to get it right on Christmas break. If it doesnt work, AAA can ride him the rest of the way. hehe

dan76 · 12-03-2010, 01:25 PM

I've wired the lock out through the brake light switch so when it's activated it's deactivated when the brakes are applied. This is a good technique if other folks are driving the vehicle and they aren't savvy enough to flip the toggle switch prior to stopping.

Pop's C-10 · 12-03-2010, 01:30 PM

How would this be wired up..i'm plaining a 2004r swap & looking for tha lowbuck way of doing it..

AusTx68 · 12-03-2010, 06:21 PM

I've read that it may cause the tranny to overheat but I've also see a lot of people running them for years without a problem. I ran without one for the first 300 miles then added it later. No issues.

k5hart · 12-03-2010, 08:43 PM

I never lock mine up and its been fine for years. Same with my previous longbed. I also have it wired to a brake light switch made for cruise control and have a toggle switch in the console to turn it off. This reminds me I need to figure out why its not activating anymore.

**americanmusc1e** · 12-03-2010, 11:05 PM

I've driven mine unlocked no problem.... but if you have a stall converter too much bigger than stock you could run into a problem..... if your not sure drive it in 3rd gear, it won't burn up in third gear unlocked.... may be a little noisier though

*stich626* · 12-03-2010, 11:10 PM

not locking it up and running in o/d will overheat the tranny, if you push it..
and a truck is a brick in the wind..
even with the stock stall speed..

12-03-2010, 12:07 PM	#1
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 913	To lock up 0r not to lock up Will it damage a 700r4 to run it without a lock up switch? Son needs to get back to college tomorrow 100 miles away, and I dont have it hooked up yet. Running out of vehicles to let him take. Anybody have a quick way to hook it up temporary if it is not a good idea to run it without it? Read the FAQs but everything sounds more involved than we have time for today. Please help if you can. Thanks, Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

12-03-2010, 12:20 PM	#2
406 Q-ship Registered User Join Date: Oct 2010 Location: Largo Florida Posts: 632	Re: To lock up 0r not to lock up If the engine runs at or above the torque converter stall speed (unlocked) on the freeway, then it will not hurt anything. It will just be like running an old TH350/400 with a slightly looser stall converter. My 1974 has not had the lock-up hooked up for the last few years and all is still fine. If you want to do a quick and dirty hook up, use a toogle switch so your son can throw the switch on the highway. Just remember to turn it off around town or in stop and go traffic. __________________ Lifes journey is not to arrive at the gate well preserved, it is to slide in sideways all used up and wore out yelling.....God what'a ride! Where patience fails, force prevails Stapp's Ironical Paradox "The universal aptitude for ineptitude makes any human accomplishment an incredible miracle." Last edited by 406 Q-ship; 12-03-2010 at 12:20 PM.

12-03-2010, 01:07 PM	#3
Jacfourteen Big Red - Now its a SWB! Join Date: Jun 2009 Location: Oroville, Ca Posts: 1,624	Re: To lock up 0r not to lock up X2 on the above, if you toggle it and forget to unlock it when you stop it will stall out like a manual tranny does if you don't push in the clutch. __________________ 68 3/4 ton (Project)-350 Small Block, .030 over, 10:1 comp, 3998993 heads, C3BX edelbrock intake, comp cams XE268, Holley 670 SA, long tube headers, dual flow 40's, E-fan, Alum rad, currently under the knife getting shortened and bagged build thread 41 3/4 ton (wife's)-flatbed, fully restored to original 01 Tahoe LT 4WD (my daily driver)-Magnaflow Muffler, Rollin on 22's 02 Ford Mustang Convertable (Wife's Car)-Flowmaster 50, Clear corners, Intake, sittin on 18's

12-03-2010, 01:11 PM	#4
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 913	Re: To lock up 0r not to lock up Thank you SO much. I just need to get him back to school and we will gather parts and try to get it right on Christmas break. If it doesnt work, AAA can ride him the rest of the way. hehe __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

12-03-2010, 01:25 PM	#5
dan76 Registered User Join Date: Mar 2008 Location: Salt Lake City UT Posts: 441	Re: To lock up 0r not to lock up I've wired the lock out through the brake light switch so when it's activated it's deactivated when the brakes are applied. This is a good technique if other folks are driving the vehicle and they aren't savvy enough to flip the toggle switch prior to stopping.

12-03-2010, 01:30 PM	#6
Pop's C-10 Registered User Join Date: Jul 2010 Location: memphis Posts: 2,537	Re: To lock up 0r not to lock up How would this be wired up..i'm plaining a 2004r swap & looking for tha lowbuck way of doing it..

12-03-2010, 06:21 PM	#7
AusTx68 Registered User Join Date: Nov 2008 Location: Italy Posts: 1,278	Re: To lock up 0r not to lock up I've read that it may cause the tranny to overheat but I've also see a lot of people running them for years without a problem. I ran without one for the first 300 miles then added it later. No issues. __________________ '68 C-10 SWB 383 Stroker (Sold 3/2/2013) '87 R2500 LWB 454 TBI converted to Carb

12-03-2010, 08:43 PM	#8
k5hart Registered User Join Date: Nov 2002 Location: Charleston, South Carolina Posts: 1,370	Re: To lock up 0r not to lock up I never lock mine up and its been fine for years. Same with my previous longbed. I also have it wired to a brake light switch made for cruise control and have a toggle switch in the console to turn it off. This reminds me I need to figure out why its not activating anymore. __________________ 2006 Silverado CCSB, 1939 Ford Sedan, 1962 BelAir Wagon, 1976 Vega Panel Charleston, South Carolina

12-03-2010, 11:05 PM	#9
americanmusc1e Senior Member Join Date: Jan 2009 Location: Austin, TX Posts: 1,079	Re: To lock up 0r not to lock up I've driven mine unlocked no problem.... but if you have a stall converter too much bigger than stock you could run into a problem..... if your not sure drive it in 3rd gear, it won't burn up in third gear unlocked.... may be a little noisier though __________________ -- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted

12-03-2010, 11:10 PM	#10
stich626 Account Suspended Join Date: Sep 2010 Location: hingham ma Posts: 1,721	Re: To lock up 0r not to lock up not locking it up and running in o/d will overheat the tranny, if you push it.. and a truck is a brick in the wind.. even with the stock stall speed..



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