Trans swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Ends · 07-04-2014, 03:19 PM

Hey guys it has been a while since I've had the time to get on the forums, but I have a question. I've been wondering if any one has had the pleasure of swapping a 4L80e for a T56 trans? I've always wanted the 6 speed and if I can't figure this issue with the automatic then I'll have a good excuse for the swap. I got the 95 motor and 4L80 in the truck and have been wiring it all running driving but am having trouble getting it to shift I have not had time to get the brake switch wired in and can't find the wiring for it and have heard that the switch controls the torque converter locking. The truck doesn't shift out of 1st gear.

Ends · 07-05-2014, 11:56 AM

im sorry i miss-informed it is in 2nd gear limp mode, and everything but the brake switch is wired in correctly, would that cause me to drop into limp mode? Also when i hook up the computer to the truck im not getting anything from the VSS, im not going to just throw the part at it if its not bad so is there a way to test the input and output VSS?

sKnNyPpY · 07-05-2014, 12:38 PM

I have no idea but that is some GORGEOUS fabrication. You need a clear hood and bed!

Ends · 07-06-2014, 10:16 PM

Quote:

Originally Posted by sKnNyPpY

I have no idea but that is some GORGEOUS fabrication. You need a clear hood and bed!

Thanks Man is your user name related to the band? if so thats sick if not all the same.

sKnNyPpY · 07-06-2014, 10:20 PM

Yes sir...Brap On!

Oldtruckfanatic · 07-06-2014, 10:55 PM

OK, the brake switch just unlocks the converter when you step on the pedal while its locked up. Your VSS is imperative to the vehicle shifting. No speed signal means no shifting. Also usually limp mode is 3rd gear on the later transmissions I'm not sure which year you have though. usually when I have speed sensor and shifting issues on a known good electronic overdrive transmission I find the issue to be related to grounding.

Oldtruckfanatic · 07-06-2014, 11:08 PM

By the way...that truck.is bada$$

Ends · 07-10-2014, 12:24 AM

Quote:

Originally Posted by Oldtruckfanatic

OK, the brake switch just unlocks the converter when you step on the pedal while its locked up. Your VSS is imperative to the vehicle shifting. No speed signal means no shifting. Also usually limp mode is 3rd gear on the later transmissions I'm not sure which year you have though. usually when I have speed sensor and shifting issues on a known good electronic overdrive transmission I find the issue to be related to grounding.

there is no problem with any grounds checked and rechecked them, i know that the usual on the 95 4l80s is the VSS but i have checked all the common problems they have im not the type to throw money at parts i find the problem. the Limp mode is 2nd gear, so i have P,R,N, and 2nd (OD/D). the computer throws no codes at all.

RManson · 07-11-2014, 12:16 AM

I have a T56 Magnum in my '68 and it's a BLAST! Even in stop and go traffic in LA, it's always worth it. With a 29-inch or so tire and 3.73 gears, 70 mph in 5th is around 2300 and 6th is around 1700, give or take.

bs46488 · 07-11-2014, 07:47 PM

I was trying to write something of value to help answer your question, but all the drool on my keyboard has made it start to malfunction.

07-04-2014, 03:19 PM	#1
Ends Registered User Join Date: Jan 2011 Location: Colorado Springs CO. Posts: 35	Trans swap Hey guys it has been a while since I've had the time to get on the forums, but I have a question. I've been wondering if any one has had the pleasure of swapping a 4L80e for a T56 trans? I've always wanted the 6 speed and if I can't figure this issue with the automatic then I'll have a good excuse for the swap. I got the 95 motor and 4L80 in the truck and have been wiring it all running driving but am having trouble getting it to shift I have not had time to get the brake switch wired in and can't find the wiring for it and have heard that the switch controls the torque converter locking. The truck doesn't shift out of 1st gear. Attached Images __________________ LAYDIIREST member 1970 C10 stepside full tube Chassis, supercharged 454 and much more, 95 motor and trans swap, pro street SLAMMED! 1951 Fleetline custom chopped, channeled, narrowed.

07-05-2014, 11:56 AM	#2
Ends Registered User Join Date: Jan 2011 Location: Colorado Springs CO. Posts: 35	Re: Trans swap im sorry i miss-informed it is in 2nd gear limp mode, and everything but the brake switch is wired in correctly, would that cause me to drop into limp mode? Also when i hook up the computer to the truck im not getting anything from the VSS, im not going to just throw the part at it if its not bad so is there a way to test the input and output VSS? __________________ LAYDIIREST member 1970 C10 stepside full tube Chassis, supercharged 454 and much more, 95 motor and trans swap, pro street SLAMMED! 1951 Fleetline custom chopped, channeled, narrowed.

07-05-2014, 12:38 PM	#3
sKnNyPpY Registered User Join Date: Sep 2012 Location: Columbia, SC Posts: 549	Re: Trans swap I have no idea but that is some GORGEOUS fabrication. You need a clear hood and bed! __________________ Life is too long to go slow... 71 GMC 1500 Super Custom LWB 350/350 AC(replaced w/vintage air)/PS/PB 2.5 CPP Spindle, 1" CPP Drop Spring, CPP Front and Rear Sway Bars/DJM Flip, new General Spring KC 5 spring pack, HEI /IntReg Alt 20x8.5 OldSkools 5" BS, 275/45 Falkens

07-06-2014, 10:20 PM	#5
sKnNyPpY Registered User Join Date: Sep 2012 Location: Columbia, SC Posts: 549	Re: Trans swap Yes sir...Brap On! __________________ Life is too long to go slow... 71 GMC 1500 Super Custom LWB 350/350 AC(replaced w/vintage air)/PS/PB 2.5 CPP Spindle, 1" CPP Drop Spring, CPP Front and Rear Sway Bars/DJM Flip, new General Spring KC 5 spring pack, HEI /IntReg Alt 20x8.5 OldSkools 5" BS, 275/45 Falkens

07-06-2014, 10:55 PM	#6
Oldtruckfanatic Truck junkie Join Date: May 2006 Location: Reno NV Posts: 697	Re: Trans swap OK, the brake switch just unlocks the converter when you step on the pedal while its locked up. Your VSS is imperative to the vehicle shifting. No speed signal means no shifting. Also usually limp mode is 3rd gear on the later transmissions I'm not sure which year you have though. usually when I have speed sensor and shifting issues on a known good electronic overdrive transmission I find the issue to be related to grounding.

07-06-2014, 11:08 PM	#7
Oldtruckfanatic Truck junkie Join Date: May 2006 Location: Reno NV Posts: 697	Re: Trans swap By the way...that truck.is bada$$

07-11-2014, 12:16 AM	#9
RManson Registered User Join Date: Jun 2011 Location: United States Posts: 158	Re: Trans swap I have a T56 Magnum in my '68 and it's a BLAST! Even in stop and go traffic in LA, it's always worth it. With a 29-inch or so tire and 3.73 gears, 70 mph in 5th is around 2300 and 6th is around 1700, give or take.

07-11-2014, 07:47 PM	#10
bs46488 Registered User Join Date: May 2014 Location: San Diego, CA Posts: 547	Re: Trans swap I was trying to write something of value to help answer your question, but all the drool on my keyboard has made it start to malfunction.



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