Anyone have a th400 and 4:10 gears in a half ton swb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**chewychevy67** · 08-06-2018, 01:38 AM

I'm am adding a gv Overdrive to my 2wd th400 67 short box 327 (Maby 300hp) truck. I currently have 3:54 gears and I may be gearing down. I was thinking about 4:10 rears when I add the gv but just asking how other ppl with these in short beds like it. Am I just going to spin when I get into the throttle?

Mike C · 08-06-2018, 12:09 PM

You will be fine. But you may not want that much gear just because you would like fewer RPM on the cruise.

What transmission is in your truck would be good info to know as well.

Coley · 08-06-2018, 12:36 PM

You might want to consider the advantages of switching over to a 4 speed auto with that engine and rear gear.
The 700R or a 4L60 will give you some nice results off the line, on the highway and at the gas pump compared to a Th400.

All good
Coley

**chewychevy67** · 08-06-2018, 02:41 PM

I have a gear vendor Overdrive so my high end will be fine. Tranny is a turbo 400. Just Dont want to be too low at the bottom

Mike C · 08-06-2018, 08:02 PM

I've never owned anything with too much gear down low. Just if you want to go faster!

**chewychevy67** · 08-06-2018, 09:15 PM

I have a 2500 Hd with 4:10s but it's not a tire burner by any means. I guess I just wanted to see if it's street able and even comfortable doing so. With my o/d set up I'm sure top end will be liveable. I just don't want to be spinning out at every stop light with light acceleration.

Mike C · 08-07-2018, 08:35 AM

I have a long bed 402 1/2 ton truck I swapped 4.10 in to move my boat around and it doesn't have any problems.

Run 4.10 in my Jimmy with no problems (35" tires though...) and I have 4.10 in my '69 Camaro. Once again, no problems.

As long as you can get the RPM on the highway down, they will be fine.

RustyBucket · 08-07-2018, 08:44 AM

You need a posi rear or the right rear tire might have a hard(short) life. Depends on how you drive it.

**jocko** · 08-07-2018, 10:17 AM

What is your higher priority, bunouts or reduced highway cruise rpm? Or are both the goal? What is your planned rear tire diameter? I can get you actual comparison numbers when i get home tonight if you want. Generally speaking, adding a gv unit AND a deeper gear is counterproductive. Usually a gv unit is added to an existing deep gear to reduce highway rpm. TH400/3.54 is already a great all around combo, but with a 327, probably lacks in the low end punch - so, anyway, depending on your answer to question 1, can probably help a little more once we know your priorities.

**chewychevy67** · 08-07-2018, 10:59 AM

Rear tire is 29 inches tall. I am not towing and burnouts probably won't be happening in this truck. I just want a little pep on the bottom end and a 3.54 might lack that. I could do 3.73 but everyone I talk to says it won't change much from 3.54. My rear is a positraction as well.

**jocko** · 08-07-2018, 06:53 PM

chewy, numbers below for a 29" rear tire. Note I only accounted for the overdrive in final gear for the GV unit (right chart in each row) - but remember you can split between gears with a GV unit. Bottom end accel remains the same as a stock TH400 with the depicted rear ratios, but you essentially get a 22% o/d for each of the 3 speeds - again, only o/d for 3rd is depicted for comparison.

So, my first car was a 57 Bel Air with a 68 327, Muncie 4-speed, and 3.55 rear end. Very similar to your current combo from the bottom end accel and top end cruising rpm perspectives. It's a good combo to be honest - but as you can see in the upper left chart, your current setup, you're slightly over 3000 rpm at 75 mph.

It's important to remember that the often unmentioned advantage of an overdrive trans, like the 700R4, is that it not only reduces your cruising rpm at highway speeds, but it also has a notably deeper first gear for bottom end accel improvement when compared to a TH350 or TH400 (note your final drive in a 700R4 with 3.54 rear would be 10.83:1 vs your current 8.78:1). BUT - your 55 mph cruising rpm is only 1579 rpm with a 700R4 and 3.54 combo, ok but not ideal - will border on lugging the engine. You're fine at 65 and 75 mph though.

Realistically speaking, with your tires, an overdrive trans would be optimized with a 3.73 rear gear (2nd row, center chart).

Your suggested 4.10 with GV unit is depicted in the bottom right chart. Not a bad combo at all, you get the bottom end acceleration oriented combo of a 4.10 rear while still enjoying relatively low (but not the lower sweet spot of a 700R4/3.73 combo) highway rpm.

Lots of things to consider for most bang for the buck approach though. Personally, I think you'd get the most bottom end accel and lowest (but not too low) highway rpm bang for the buck with the 700R4 and 3.73 combo. And that's probably less expensive than a 4.10 and Gear Vendors swap (or at least comparable in price). A 700R4 will be fine behind your 327.

Another option, and a fairly bulletproof one - IF you don't feel you need MORE bottom end accel than you currently have, would be to simply add a GV unit to your current setup. Top row, far right chart. Very good highway cruising rpm range - and you're only changing a single thing from your current setup, i.e. adding the GV.

Bottom row middle chart is what you'd want to avoid if you don't want to accidentally chirp the tires at every stoplight. Note the 12.55:1 final drive in 1st gear of the 700R4/4.10 combo.

Anyway, food for thought, hope this helps.

**chewychevy67** · 08-07-2018, 08:30 PM

That is very interesting. Thanks for doing that for me.

azle · 08-08-2018, 12:40 PM

I have 4:10 behind a th350 and a healthy SBC, it's fun to drive 0 to 80 is quick if you can get it to hook up.... The Hwy sucks! At 65mph I'm running about 3500rpm. The GV will be an asset for sure. make sure the GV is tight if your running any kind of H.P. Have fun I do!!

Azle

87Skier · 08-08-2018, 05:56 PM

I have factory 4.11 gears, Turbo400, and running 31" tires. Makes my old, tired engine feel pretty good off the line for 6000 lb Suburban. Does around 3000 rpm on the interstate, so you will running a few more.

It really depends on what type of truck you want. If it's an in town and occasional highway driver, I would say go for the 4.10/4.11's.

**chewychevy67** · 08-08-2018, 07:14 PM

It's going to be an in town and occasionally driven on the highway. The only thing in my future that may give me alot of problems is I would like to do the power tour someday. But even if my truck is at 2300 with the overdrive I'm ok with that. Will keep me from speeding.

08-06-2018, 01:38 AM	#1
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Anyone have a th400 and 4:10 gears in a half ton swb I'm am adding a gv Overdrive to my 2wd th400 67 short box 327 (Maby 300hp) truck. I currently have 3:54 gears and I may be gearing down. I was thinking about 4:10 rears when I add the gv but just asking how other ppl with these in short beds like it. Am I just going to spin when I get into the throttle? Last edited by chewychevy67; 08-06-2018 at 02:16 AM.

08-06-2018, 12:09 PM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	Re: Anyone have a th400 and 4:10 gears in a half ton swb You will be fine. But you may not want that much gear just because you would like fewer RPM on the cruise. What transmission is in your truck would be good info to know as well. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-06-2018, 12:36 PM	#3
Coley Registered User Join Date: Oct 2011 Location: Victoria, B.C Posts: 3,794	Re: Anyone have a th400 and 4:10 gears in a half ton swb You might want to consider the advantages of switching over to a 4 speed auto with that engine and rear gear. The 700R or a 4L60 will give you some nice results off the line, on the highway and at the gas pump compared to a Th400. All good 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

08-06-2018, 02:41 PM	#4
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Re: Anyone have a th400 and 4:10 gears in a half ton swb I have a gear vendor Overdrive so my high end will be fine. Tranny is a turbo 400. Just Dont want to be too low at the bottom Last edited by chewychevy67; 08-06-2018 at 02:47 PM.

08-06-2018, 08:02 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	Re: Anyone have a th400 and 4:10 gears in a half ton swb I've never owned anything with too much gear down low. Just if you want to go faster! __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-06-2018, 09:15 PM	#6
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Re: Anyone have a th400 and 4:10 gears in a half ton swb I have a 2500 Hd with 4:10s but it's not a tire burner by any means. I guess I just wanted to see if it's street able and even comfortable doing so. With my o/d set up I'm sure top end will be liveable. I just don't want to be spinning out at every stop light with light acceleration.

08-07-2018, 08:35 AM	#7
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	Re: Anyone have a th400 and 4:10 gears in a half ton swb I have a long bed 402 1/2 ton truck I swapped 4.10 in to move my boat around and it doesn't have any problems. Run 4.10 in my Jimmy with no problems (35" tires though...) and I have 4.10 in my '69 Camaro. Once again, no problems. As long as you can get the RPM on the highway down, they will be fine. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-07-2018, 08:44 AM	#8
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,055	Re: Anyone have a th400 and 4:10 gears in a half ton swb You need a posi rear or the right rear tire might have a hard(short) life. Depends on how you drive it. __________________ 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!!

08-07-2018, 10:17 AM	#9
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: Anyone have a th400 and 4:10 gears in a half ton swb What is your higher priority, bunouts or reduced highway cruise rpm? Or are both the goal? What is your planned rear tire diameter? I can get you actual comparison numbers when i get home tonight if you want. Generally speaking, adding a gv unit AND a deeper gear is counterproductive. Usually a gv unit is added to an existing deep gear to reduce highway rpm. TH400/3.54 is already a great all around combo, but with a 327, probably lacks in the low end punch - so, anyway, depending on your answer to question 1, can probably help a little more once we know your priorities.

08-07-2018, 10:59 AM	#10
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Re: Anyone have a th400 and 4:10 gears in a half ton swb Rear tire is 29 inches tall. I am not towing and burnouts probably won't be happening in this truck. I just want a little pep on the bottom end and a 3.54 might lack that. I could do 3.73 but everyone I talk to says it won't change much from 3.54. My rear is a positraction as well.

08-07-2018, 06:53 PM	#11
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: Anyone have a th400 and 4:10 gears in a half ton swb chewy, numbers below for a 29" rear tire. Note I only accounted for the overdrive in final gear for the GV unit (right chart in each row) - but remember you can split between gears with a GV unit. Bottom end accel remains the same as a stock TH400 with the depicted rear ratios, but you essentially get a 22% o/d for each of the 3 speeds - again, only o/d for 3rd is depicted for comparison. So, my first car was a 57 Bel Air with a 68 327, Muncie 4-speed, and 3.55 rear end. Very similar to your current combo from the bottom end accel and top end cruising rpm perspectives. It's a good combo to be honest - but as you can see in the upper left chart, your current setup, you're slightly over 3000 rpm at 75 mph. It's important to remember that the often unmentioned advantage of an overdrive trans, like the 700R4, is that it not only reduces your cruising rpm at highway speeds, but it also has a notably deeper first gear for bottom end accel improvement when compared to a TH350 or TH400 (note your final drive in a 700R4 with 3.54 rear would be 10.83:1 vs your current 8.78:1). BUT - your 55 mph cruising rpm is only 1579 rpm with a 700R4 and 3.54 combo, ok but not ideal - will border on lugging the engine. You're fine at 65 and 75 mph though. Realistically speaking, with your tires, an overdrive trans would be optimized with a 3.73 rear gear (2nd row, center chart). Your suggested 4.10 with GV unit is depicted in the bottom right chart. Not a bad combo at all, you get the bottom end acceleration oriented combo of a 4.10 rear while still enjoying relatively low (but not the lower sweet spot of a 700R4/3.73 combo) highway rpm. Lots of things to consider for most bang for the buck approach though. Personally, I think you'd get the most bottom end accel and lowest (but not too low) highway rpm bang for the buck with the 700R4 and 3.73 combo. And that's probably less expensive than a 4.10 and Gear Vendors swap (or at least comparable in price). A 700R4 will be fine behind your 327. Another option, and a fairly bulletproof one - IF you don't feel you need MORE bottom end accel than you currently have, would be to simply add a GV unit to your current setup. Top row, far right chart. Very good highway cruising rpm range - and you're only changing a single thing from your current setup, i.e. adding the GV. Bottom row middle chart is what you'd want to avoid if you don't want to accidentally chirp the tires at every stoplight. Note the 12.55:1 final drive in 1st gear of the 700R4/4.10 combo. Anyway, food for thought, hope this helps. Attached Images

08-07-2018, 08:30 PM	#12
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Re: Anyone have a th400 and 4:10 gears in a half ton swb That is very interesting. Thanks for doing that for me.

08-08-2018, 12:40 PM	#13
azle Registered User Join Date: Feb 2017 Location: Fort Worth Texas Posts: 69	Re: Anyone have a th400 and 4:10 gears in a half ton swb I have 4:10 behind a th350 and a healthy SBC, it's fun to drive 0 to 80 is quick if you can get it to hook up.... The Hwy sucks! At 65mph I'm running about 3500rpm. The GV will be an asset for sure. make sure the GV is tight if your running any kind of H.P. Have fun I do!! Azle

08-08-2018, 05:56 PM	#14
87Skier Registered User Join Date: Mar 2014 Location: Corvallis, OR Posts: 715	Re: Anyone have a th400 and 4:10 gears in a half ton swb I have factory 4.11 gears, Turbo400, and running 31" tires. Makes my old, tired engine feel pretty good off the line for 6000 lb Suburban. Does around 3000 rpm on the interstate, so you will running a few more. It really depends on what type of truck you want. If it's an in town and occasional highway driver, I would say go for the 4.10/4.11's. __________________ 1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205 1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears 1996 Chevy Suburban K1500 350/4L60E

08-08-2018, 07:14 PM	#15
chewychevy67 Senior Member Join Date: Jan 2010 Location: Here Posts: 5,557	Re: Anyone have a th400 and 4:10 gears in a half ton swb It's going to be an in town and occasionally driven on the highway. The only thing in my future that may give me alot of problems is I would like to do the power tour someday. But even if my truck is at 2300 with the overdrive I'm ok with that. Will keep me from speeding.



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