Overdrive Options/Gear Vendor/US Gear/4L80E - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**DANTIP** · 09-28-2009, 10:51 AM

Overdrives are certainly nice for our trucks and I have struggled with my options. My 402/TH400 are in good shape but a PO installed 3:73 gears in place of the 3:08. The combination is fun in town but not as fun on the highway. The Gear Vendor solution is around $3,000 and requires me to mount some electronics and shorten the front-half of the driveshaft. The US Gear solution is around $1,800 and requires a pull-cable for engagement and shortening of the drive-shaft. The GV unit is essentially a compact 2-speed automatic transmission that can be shifted on the fly but doesn't like downshifting). I understand the USG unit can be shifted on the fly up to 35-40 mph but it's like shifting a transmission with no clutch (you have to be smooth and good with the gas pedal). The 4L80E is expensive (total can be $5,000 to $6,000), requires stand-alone electronics, requires a solution for the speedo-cable but is the most driver-friendly of the OD's.

Questions:

Are my assumptions correct ($, required installation changes, operation, etc.)?

Has anyone had really good or really bad experiences with any of these options?

Am I missing a good alternative?

Thanks!

Ackattack · 09-28-2009, 11:44 AM

700R4 and 200R4. Both will have to be built to withstand the power/torque of a 402, but I would imagine they could be done for about the same price as the USG unit.

I put a 700R4 in my 72 GMC behind a TPI 350 with 3.73 gears, and it was great on the highway.

BossHogg69 · 09-28-2009, 12:17 PM

I went from a 454/th400 to a TREMEC TKO 5 spd. I have 3.73's.

The 700R4/200R4 might be cheaper though. I've got about $2200 in my setup and it is nice, but not the cheapest option. I really wanted a 5 spd. You would probably be better off using an overdrive automatic. Less chopping/cutting/fab.

5k seems high for a 4L80E conversion, but I've never done one, so I don't know for sure.

**70cst** · 09-28-2009, 02:25 PM

Would it make sense to go back to a 3:08? My truck also came with a 3:08 but now it has a 3:55 (something like that) and I was wondering if it would pay to go back to a 3:08. By the way...I also have a 402BB/400 set up. Good topic

kamikazekyle05 · 09-28-2009, 04:37 PM

700r4 would prolly be the easiest

texanidiot25 · 09-28-2009, 05:19 PM

200R4 is the easiest in that it's the same length as the TH350/400, and depending on what your looking for, many say better gearing (as it has similar gearing to the 350/400). The 700R4 has a very short 1st gear which is awesome for towing, and torque. But it's longer and requires a bit of work moving the crossmember and shortening the drive shaft. Both can be found with mechanical speedos, and both can be built strong for pretty cheap.

**DANTIP** · 09-28-2009, 05:26 PM

70CST,

Returning to the 3:08 is not a bad option. I would probably order bearings and seals along with the gear set. I have never set-up a differential but I am pretty good at following directions. Any idea what I would have into the conversion if I did the work myself? How much would the labor be for a pro to do everything?

Dan

09-28-2009, 10:51 AM	#1
DANTIP Registered User Join Date: Sep 2001 Location: Fort Wayne, Indiana, USA Posts: 1,890	Overdrive Options/Gear Vendor/US Gear/4L80E Overdrives are certainly nice for our trucks and I have struggled with my options. My 402/TH400 are in good shape but a PO installed 3:73 gears in place of the 3:08. The combination is fun in town but not as fun on the highway. The Gear Vendor solution is around $3,000 and requires me to mount some electronics and shorten the front-half of the driveshaft. The US Gear solution is around $1,800 and requires a pull-cable for engagement and shortening of the drive-shaft. The GV unit is essentially a compact 2-speed automatic transmission that can be shifted on the fly but doesn't like downshifting). I understand the USG unit can be shifted on the fly up to 35-40 mph but it's like shifting a transmission with no clutch (you have to be smooth and good with the gas pedal). The 4L80E is expensive (total can be $5,000 to $6,000), requires stand-alone electronics, requires a solution for the speedo-cable but is the most driver-friendly of the OD's. Questions: Are my assumptions correct ($, required installation changes, operation, etc.)? Has anyone had really good or really bad experiences with any of these options? Am I missing a good alternative? Thanks!

09-28-2009, 11:44 AM	#2
Ackattack Senior Member Join Date: Aug 2002 Location: Valley Center KS Posts: 3,525	Re: Overdrive Options/Gear Vendor/US Gear/4L80E 700R4 and 200R4. Both will have to be built to withstand the power/torque of a 402, but I would imagine they could be done for about the same price as the USG unit. I put a 700R4 in my 72 GMC behind a TPI 350 with 3.73 gears, and it was great on the highway. __________________ Project Bruiser: 68 Pro-Touring C-10 5.3L / 4L60E Project Ironhide: 97 GMC Crew Cab 4x4 Cummins SOLD: '69 GMC 1/2T SWB TBI'd: Project No Buck Assembly Manual Index Sign up Thread!!! Factory Service Manual Index

09-28-2009, 12:17 PM	#3
BossHogg69 motor exploder Join Date: Mar 2009 Location: Pittsburgh, PA Posts: 2,346	Re: Overdrive Options/Gear Vendor/US Gear/4L80E I went from a 454/th400 to a TREMEC TKO 5 spd. I have 3.73's. The 700R4/200R4 might be cheaper though. I've got about $2200 in my setup and it is nice, but not the cheapest option. I really wanted a 5 spd. You would probably be better off using an overdrive automatic. Less chopping/cutting/fab. 5k seems high for a 4L80E conversion, but I've never done one, so I don't know for sure. __________________ Adam 1969 Chevy CST/10 stepside, DART Big M/TREMEC Magnum Extreme/3.73's w/Detroit Truetrac 1965 Chevy Bel Air Wagon (daily driver), 327/TH350,10 bolt w/3.08's 1961 Chevy Bel Air Sport Coupe, ZZ454/M21/9" rear w/3.50's & Detroit Truetrac 2005 GMC 1500 ccsb 2wd, 6.0L/4L65e/3.73 G80 2006 GMC 2500HD ccsb 4x4, DMax LBZ/Allison 6spd/4.56's w/Detroit TrueTrac Use the SEARCH function on this forum - it is your friend!!

09-28-2009, 02:25 PM	#4
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,375	Re: Overdrive Options/Gear Vendor/US Gear/4L80E Would it make sense to go back to a 3:08? My truck also came with a 3:08 but now it has a 3:55 (something like that) and I was wondering if it would pay to go back to a 3:08. By the way...I also have a 402BB/400 set up. Good topic __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder! Last edited by 70cst; 09-28-2009 at 02:25 PM.

09-28-2009, 04:37 PM	#5
kamikazekyle05 Registered User Join Date: Nov 2007 Location: Vernon, Texas Posts: 331	Re: Overdrive Options/Gear Vendor/US Gear/4L80E 700r4 would prolly be the easiest

09-28-2009, 05:19 PM	#6
texanidiot25 Eat My Rust Join Date: Jan 2007 Location: Cypress, Texas Posts: 3,362	Re: Overdrive Options/Gear Vendor/US Gear/4L80E 200R4 is the easiest in that it's the same length as the TH350/400, and depending on what your looking for, many say better gearing (as it has similar gearing to the 350/400). The 700R4 has a very short 1st gear which is awesome for towing, and torque. But it's longer and requires a bit of work moving the crossmember and shortening the drive shaft. Both can be found with mechanical speedos, and both can be built strong for pretty cheap.

09-28-2009, 05:26 PM	#7
DANTIP Registered User Join Date: Sep 2001 Location: Fort Wayne, Indiana, USA Posts: 1,890	Re: Overdrive Options/Gear Vendor/US Gear/4L80E 70CST, Returning to the 3:08 is not a bad option. I would probably order bearings and seals along with the gear set. I have never set-up a differential but I am pretty good at following directions. Any idea what I would have into the conversion if I did the work myself? How much would the labor be for a pro to do everything? Dan



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