1968 chevy c20 3/4 ton custom camper 4l80 trans swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jbuky · 07-31-2017, 02:02 AM

so im having some shift issues. Im using the tci ez tcu on my 4l80 e trans. got all the settings correct or for the sake of argument lets say i set it up perfect for my aplication. however i think i am only getting first and second gear after that it says its shifting but it performs like the tcc (torque converter) has locked. What could cause that? The internet said the 4l80 takes 3.5 gallons but it drank more like 4 gallons of cam2 tranny fluid. Is it over filled? aftermarket dipstick says not. My motor is a 350 gm crate motor. edlebrock intake and carburator. bla bla bla it lined up with my 4l80 using 3 existing holes. we drilled and tapped 2 more. it fits. we only needed to remove 2 inches from the drive shaft and then buy a 4l80 trans yoke th400 yoke fit inside but outside gauge is smaller. you need a 4l80 yoke. moved the the tranny mount acourdingly, i dont know what my rear end ratio is. we just swapped drum for disk in the frond only and it needs alignment. bad. but for the most part the swap was a totall success but truck is running 35000 rpm at 60 mph and feals like it wants to shift but it says it allreadty has on the tcu live readout screen. im supposed to go from a three speed to a 4 speed with overdrive. wtf i was thinking id be cruising down the freeway at 75 busting 22000 rpm or lower. whats a good place to start looking for a solution please help im desperate.

Jbuky · 07-31-2017, 02:07 AM

hi

Coley · 07-31-2017, 03:07 PM

...hang in there.
Some guys who know more about this will weigh in when they get a chance.
Welcome to the forum by the way!

Coley

Jbuky · 08-01-2017, 12:06 AM

thank you for the hearty welcome i seriously appreciste that. as for my problem, it was solved when we pushed in the wiring harness all the way, lol fml . it was only partially plugged in but the tranny has a limp home setting so that if the tranny becomes unplugged or the tcu fails, it can limp home instead of burn itself out. it works perfect now. soposedly thats one of many fail safes that make the 4l80 transmision bullet proof. so if anybody has any questions i can show them what i did. i got full conversion almost problem free now my tranny is electric and it has over drive. it is going to make me money as a work truck. and its old so its got style and patina. lol im so glad its working!!!!

RustyBucket · 08-01-2017, 09:49 AM

Is this a great site or WHAT?? You registered, made 2 posts and BAM !!! your transmission is working great.

Seriously, this site is a great source of info about these trucks. Post some pictures of your truck please. The first '67-'72 I had was a '68 C-20 CST beater that I paid $300 for in the early 80's. Drove it to work and play for 10+ years with very little maintenance.... and sold it to a neighbor for $600.

Jbuky · 08-01-2017, 12:55 PM

haha right? this site is awesome

ya ill get some pictures up. i love the 68 so much, pre smog, and just down right reliable.

07-31-2017, 02:02 AM	#1
Jbuky Registered User Join Date: Jul 2017 Location: Costa mesa,ll california Posts: 4	1968 chevy c20 3/4 ton custom camper 4l80 trans swap so im having some shift issues. Im using the tci ez tcu on my 4l80 e trans. got all the settings correct or for the sake of argument lets say i set it up perfect for my aplication. however i think i am only getting first and second gear after that it says its shifting but it performs like the tcc (torque converter) has locked. What could cause that? The internet said the 4l80 takes 3.5 gallons but it drank more like 4 gallons of cam2 tranny fluid. Is it over filled? aftermarket dipstick says not. My motor is a 350 gm crate motor. edlebrock intake and carburator. bla bla bla it lined up with my 4l80 using 3 existing holes. we drilled and tapped 2 more. it fits. we only needed to remove 2 inches from the drive shaft and then buy a 4l80 trans yoke th400 yoke fit inside but outside gauge is smaller. you need a 4l80 yoke. moved the the tranny mount acourdingly, i dont know what my rear end ratio is. we just swapped drum for disk in the frond only and it needs alignment. bad. but for the most part the swap was a totall success but truck is running 35000 rpm at 60 mph and feals like it wants to shift but it says it allreadty has on the tcu live readout screen. im supposed to go from a three speed to a 4 speed with overdrive. wtf i was thinking id be cruising down the freeway at 75 busting 22000 rpm or lower. whats a good place to start looking for a solution please help im desperate.

07-31-2017, 02:07 AM	#2
Jbuky Registered User Join Date: Jul 2017 Location: Costa mesa,ll california Posts: 4	Re: 1968 chevy c20 3/4 ton custom camper 4l80 trans swap hi

07-31-2017, 03:07 PM	#3
Coley Registered User Join Date: Oct 2011 Location: Victoria, B.C Posts: 3,794	Re: 1968 chevy c20 3/4 ton custom camper 4l80 trans swap ...hang in there. Some guys who know more about this will weigh in when they get a chance. Welcome to the forum by the way! Coley __________________ ....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500

08-01-2017, 12:06 AM	#4
Jbuky Registered User Join Date: Jul 2017 Location: Costa mesa,ll california Posts: 4	Re: 1968 chevy c20 3/4 ton custom camper 4l80 trans swap thank you for the hearty welcome i seriously appreciste that. as for my problem, it was solved when we pushed in the wiring harness all the way, lol fml . it was only partially plugged in but the tranny has a limp home setting so that if the tranny becomes unplugged or the tcu fails, it can limp home instead of burn itself out. it works perfect now. soposedly thats one of many fail safes that make the 4l80 transmision bullet proof. so if anybody has any questions i can show them what i did. i got full conversion almost problem free now my tranny is electric and it has over drive. it is going to make me money as a work truck. and its old so its got style and patina. lol im so glad its working!!!!

08-01-2017, 09:49 AM	#5
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: 1968 chevy c20 3/4 ton custom camper 4l80 trans swap Is this a great site or WHAT?? You registered, made 2 posts and BAM !!! your transmission is working great. Seriously, this site is a great source of info about these trucks. Post some pictures of your truck please. The first '67-'72 I had was a '68 C-20 CST beater that I paid $300 for in the early 80's. Drove it to work and play for 10+ years with very little maintenance.... and sold it to a neighbor for $600. __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!

08-01-2017, 12:55 PM	#6
Jbuky Registered User Join Date: Jul 2017 Location: Costa mesa,ll california Posts: 4	Re: 1968 chevy c20 3/4 ton custom camper 4l80 trans swap haha right? this site is awesome ya ill get some pictures up. i love the 68 so much, pre smog, and just down right reliable.



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