Considering an OD tranny - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Hugh Mongus · 03-12-2014, 11:35 AM

Can someone explain the how/why regarding the lock up on an OD transmission? Wanting to get away from the TH350 for lower revs on the open road.

brad_man_72 · 03-12-2014, 01:38 PM

The torque converter locks in 3rd and 4th (maybe other gears also) under light-no load and slips like a normal torque converter the rest of the time and when you apply the brakes. It almost feels like you are shifting into another gear when the converter locks.

Not slipping = better mpg.

Hugh Mongus · 03-12-2014, 02:16 PM

Thanks. Is this a hard thing to setup if I were install an OD transmission? I have seen the lock up kits.

cool68 · 03-12-2014, 04:01 PM

search for one that does the work automatically and not have to touch brake or hit a switch. lots of info here and online.

hugger6933 · 03-12-2014, 06:15 PM

Hugh, It is a real simple deal the General used a deal on the S-10's in the real early 80's that was a little [I mean small] vac switch that turned it on[locked up], was mounted on the left fender that and a brake lamp switch type thing to turn it off when you tapped the brake so it worked seamlessly like you never knew it was there. That is about how the aftermarket kits are set up, don't settle for a toggle flip switch. Jim

03-12-2014, 11:35 AM	#1
Hugh Mongus Registered User Join Date: Jan 2014 Location: Tulsa, OK Posts: 360	Considering an OD tranny Can someone explain the how/why regarding the lock up on an OD transmission? Wanting to get away from the TH350 for lower revs on the open road. __________________ -Jason USN Retired

03-12-2014, 01:38 PM	#2
brad_man_72 the boat guy Join Date: Jul 2007 Location: springfield mo Posts: 2,339	Re: Considering an OD tranny The torque converter locks in 3rd and 4th (maybe other gears also) under light-no load and slips like a normal torque converter the rest of the time and when you apply the brakes. It almost feels like you are shifting into another gear when the converter locks. Not slipping = better mpg. __________________ 67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project,

03-12-2014, 02:16 PM	#3
Hugh Mongus Registered User Join Date: Jan 2014 Location: Tulsa, OK Posts: 360	Re: Considering an OD tranny Thanks. Is this a hard thing to setup if I were install an OD transmission? I have seen the lock up kits. __________________ -Jason USN Retired

03-12-2014, 04:01 PM	#4
cool68 Registered User Join Date: Oct 2013 Location: Stockton, CA Posts: 475	Re: Considering an OD tranny search for one that does the work automatically and not have to touch brake or hit a switch. lots of info here and online.

03-12-2014, 06:15 PM	#5
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,263	Re: Considering an OD tranny Hugh, It is a real simple deal the General used a deal on the S-10's in the real early 80's that was a little [I mean small] vac switch that turned it on[locked up], was mounted on the left fender that and a brake lamp switch type thing to turn it off when you tapped the brake so it worked seamlessly like you never knew it was there. That is about how the aftermarket kits are set up, don't settle for a toggle flip switch. Jim

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