Help - 4.10 or 4.56 gears? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

silver7 · 10-31-2009, 11:15 PM

I'm torn between going with 4.10 or 4.56 gears for my 12 inch rear end rebuild. I am working on a frame up restoration of a 71 custom C10 4x4 with 33" tires and a TH350 auto tranny. Any opinions or thoughts will be most appreciated.

Thanks,
Shawn

silver7 · 10-31-2009, 11:16 PM

Oh ya - it will be powered by a 383 stroker.

vectorit · 10-31-2009, 11:40 PM

4.56

Anything less, and your wasting your time and torque.

If you even mention/think/say gas mileage... Then, there is another sand box over there. But since you are talkin real gears, and at the same time talkin tire diameter and transmission. You already know what it takes.

Since you are going TH350, then you need to build it right to withstand the RPM. Plus, you will need to factor in the correct torque converter.

Sorry for sounding harsh, but I have been beat up in past threads. But since you posted something a little more specific, then you got my specific opinion about it.

Longhorn Man · 11-01-2009, 12:11 AM

i found this on the burb board.... putting it on the 4X4 board.

**special-K** · 11-01-2009, 06:55 AM

I`d go with 4.10s.33s aren`t so big that they require deeper gears and 4.10s are deep enough.

The mags are all about making rock crawlers,which in reality isn`t what we drive for the most part.I fretted over gears on my`91 Suburban when lifting and going to 35s.The thing came with 4.10s and the mags had me convinced I needed to change to 4.56s.actually,i was mostly ignorant about the 4L80E and thought I needed to trick it into thinking it was still turning the same gears.I ound out the trans would be ok,so I went ahead with great results staying with 4.10s.The resulting ratio is right about 3.73 now and I can roll in o.d just fine as well as have all the bottom I need.If I had gone to 4.56s my ratio would have actually been right about 4.09:1.
Next,I did a lit and 35s on a`72 K/20 w/4.10s.It ran fine with that combo.
My`72 GMC has 33s and 3.54s.It has all the torque and power it needs.I can chirp second gear.It`s an automatic.

Blazer1970 · 11-01-2009, 07:45 AM

I agree with special-K - 4.10s with 33s.

vtblazer · 11-01-2009, 08:10 AM

Quote:

Originally Posted by Blazer1970

I agree with special-K - 4.10s with 33s.

X 3 on the 4:10's.

With a transmission ending at 1:1 for a final ratio, the 4:10/33's combo will still give you a 'drive-able' set up.

Expect to run around 3,000rpm's on the interstate at speed.

**Stocker** · 11-01-2009, 10:59 AM

Shawn, ya haven't told us (not in this thread, anyway) how you intend to use the truck, so it's kinda hard to say for sure what would be best for you.

For street use -- and especially if it will spend much time on highways -- I would opt for 4:10s. That's what I have in my K20 with 33s and I would certainly not go lower. Now if it's gonna be just around town or off road, 4:56s would be great.... but not for freeway use, not with a TH350.

Mudder · 11-01-2009, 11:22 AM

I am running 4.10's with my 35's/36's and my rpm range on the interstate is right around 3000. 383 stroker.

**kwmech** · 11-01-2009, 11:52 AM

I'm running 4.56 with 33'' tires........BUT I've also got an overdrive that brings the final drive down to 3.31. Go with the 4.11

Dooley · 11-02-2009, 06:45 PM

4.10 gear.

DieselEater · 11-03-2009, 09:10 PM

I'm with VECTORIT.........

Unless you are worried about fuel economy, or traveling on the high-way a lot, then there is no other option!

If you wanted fuel economy then you would have built a 305....

You will wish you had the steeper gears when you are pulling a trailer on a steep hill....

Surely your engine can handle being in the 3-4K RPM range, and occasionally hit 6K when having fun!

A............

silver7 · 11-03-2009, 09:38 PM

All good replies guys, thanks. Sorry for not being more specific. My truck will be a weekly driver and may see a little time off road, but not much. I have a trailer I'll pull a little bit, but mostly I am building this thing to be a bad ass pick-up that looks, drives and sounds the part. I'm not concerned about gas mileage, just raw power and torque. 3K RPM at 60 is acceptable for me.

vtblazer · 11-04-2009, 08:04 AM

Quote:

Originally Posted by Mudder

I am running 4.10's with my 35's/36's and my rpm range on the interstate is right around 3000. 383 stroker.

That's interesting...

I ran 3k @ 65mph with 4:10's & 33's when I had my green blazer.

Clocked it many times via mile markers on the side of the interstate, thought for sure it was correct but we can't both be right...dunno.

Mudder · 11-04-2009, 09:36 AM

I have the 203 TC and have no idea how fast I was running. I'm guessing around the 70 mark. Usually 2800-3000 but seems to be the 3000 more.

**special-K** · 11-04-2009, 11:53 PM

33s are not enough above stock to affect gearing much at all.If you can`t haul with 4.10s you have too much weight.With a 305 you might have wanted 4.56s to have the power.A 305 won`t save you gas when it comes to hauling.

**Stocker** · 11-05-2009, 01:34 AM

Quote:

Originally Posted by special-K

33s are not enough above stock to affect gearing much at all.If you can`t haul with 4.10s you have too much weight.

Yes... when I bought my truck, I had 7.50-16 (stock size) Armstrong traction tires mounted, and they were exactly the same height (32.3") as my current 33/12.50-16.5s.

*2tons of fun* · 11-05-2009, 01:46 AM

wtf is a 12" rear?

i am wasting rmp and power with 4.56 and 38"s, i cant image how slow it would be with 33"s.

**special-K** · 11-05-2009, 09:46 AM

Quote:

Originally Posted by 2tons of fun

wtf is a 12" rear?

I totally missed that.Prolly cuz it`s so obvious he meant 12-bolt.

Heck,I haul with 33s/4.10s/even overdrive just fine.I`m talking a truck with a steel Reading work cap with side compartments full of tools,bed full of tools,ladder racks loaded with ladders,walkboards and pump jack poles,and a loaded trailer.I`ve weighed in at just under 10,000# before.and that wasn`t as loaded as I get.that`s with a partially loaded ladder rack and 1,000# of aluminum scrap.when I move from job to job I way a good bit over that.

sailed2japan · 11-05-2009, 03:14 PM

I'm casting another vote for 4.10's. 33" is too short to mandate use of 4.56 gears.

I'm running 285/75r16's (33x11.5) and 3.73's. my truck is a disel, but even so it feels like it would be better with a taller tire or lower gear. Especially on the highway.

**special-K** · 11-05-2009, 09:22 PM

That`s what I have,too...285/75s and a 195 hp diesel.At least,that`s the one I was just referring to in the prior thread.My Suburban has 4.10s/35s/135hp diesel and it does great hauling the same trailer and loaded with tools behind the second seat.

silver7 · 11-06-2009, 11:55 AM

4.10 wins out. I can always go lower if needed. Thanks guys -great information.

10-31-2009, 11:15 PM	#1
silver7 Registered User Join Date: Jul 2009 Location: High Point, NC Posts: 613	Help - 4.10 or 4.56 gears? I'm torn between going with 4.10 or 4.56 gears for my 12 inch rear end rebuild. I am working on a frame up restoration of a 71 custom C10 4x4 with 33" tires and a TH350 auto tranny. Any opinions or thoughts will be most appreciated. Thanks, Shawn

10-31-2009, 11:16 PM	#2
silver7 Registered User Join Date: Jul 2009 Location: High Point, NC Posts: 613	Re: Help - 4.10 or 4.56 gears? Oh ya - it will be powered by a 383 stroker.

10-31-2009, 11:40 PM	#3
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Help - 4.10 or 4.56 gears? 4.56 Anything less, and your wasting your time and torque. If you even mention/think/say gas mileage... Then, there is another sand box over there. But since you are talkin real gears, and at the same time talkin tire diameter and transmission. You already know what it takes. Since you are going TH350, then you need to build it right to withstand the RPM. Plus, you will need to factor in the correct torque converter. Sorry for sounding harsh, but I have been beat up in past threads. But since you posted something a little more specific, then you got my specific opinion about it. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

11-01-2009, 12:11 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Help - 4.10 or 4.56 gears? i found this on the burb board.... putting it on the 4X4 board.

11-01-2009, 06:55 AM	#5
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: Help - 4.10 or 4.56 gears? I`d go with 4.10s.33s aren`t so big that they require deeper gears and 4.10s are deep enough. The mags are all about making rock crawlers,which in reality isn`t what we drive for the most part.I fretted over gears on my`91 Suburban when lifting and going to 35s.The thing came with 4.10s and the mags had me convinced I needed to change to 4.56s.actually,i was mostly ignorant about the 4L80E and thought I needed to trick it into thinking it was still turning the same gears.I ound out the trans would be ok,so I went ahead with great results staying with 4.10s.The resulting ratio is right about 3.73 now and I can roll in o.d just fine as well as have all the bottom I need.If I had gone to 4.56s my ratio would have actually been right about 4.09:1. Next,I did a lit and 35s on a`72 K/20 w/4.10s.It ran fine with that combo. My`72 GMC has 33s and 3.54s.It has all the torque and power it needs.I can chirp second gear.It`s an automatic. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ Last edited by special-K; 11-01-2009 at 12:19 PM.

11-01-2009, 07:45 AM	#6
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Re: Help - 4.10 or 4.56 gears? I agree with special-K - 4.10s with 33s. __________________ Tim

11-01-2009, 10:59 AM	#8
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,561	Re: Help - 4.10 or 4.56 gears? Shawn, ya haven't told us (not in this thread, anyway) how you intend to use the truck, so it's kinda hard to say for sure what would be best for you. For street use -- and especially if it will spend much time on highways -- I would opt for 4:10s. That's what I have in my K20 with 33s and I would certainly not go lower. Now if it's gonna be just around town or off road, 4:56s would be great.... but not for freeway use, not with a TH350. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

11-01-2009, 11:22 AM	#9
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: Help - 4.10 or 4.56 gears? I am running 4.10's with my 35's/36's and my rpm range on the interstate is right around 3000. 383 stroker.

11-01-2009, 11:52 AM	#10
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,455	Re: Help - 4.10 or 4.56 gears? I'm running 4.56 with 33'' tires........BUT I've also got an overdrive that brings the final drive down to 3.31. Go with the 4.11

11-02-2009, 06:45 PM	#11
Dooley Registered User Join Date: Mar 2005 Location: North Coast Posts: 1,012	Re: Help - 4.10 or 4.56 gears? 4.10 gear.

11-03-2009, 09:10 PM	#12
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: Help - 4.10 or 4.56 gears? I'm with VECTORIT......... Unless you are worried about fuel economy, or traveling on the high-way a lot, then there is no other option! If you wanted fuel economy then you would have built a 305.... You will wish you had the steeper gears when you are pulling a trailer on a steep hill.... Surely your engine can handle being in the 3-4K RPM range, and occasionally hit 6K when having fun! A............ __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959 Last edited by DieselEater; 11-03-2009 at 09:14 PM. Reason: add to message...

11-03-2009, 09:38 PM	#13
silver7 Registered User Join Date: Jul 2009 Location: High Point, NC Posts: 613	Re: Help - 4.10 or 4.56 gears? All good replies guys, thanks. Sorry for not being more specific. My truck will be a weekly driver and may see a little time off road, but not much. I have a trailer I'll pull a little bit, but mostly I am building this thing to be a bad ass pick-up that looks, drives and sounds the part. I'm not concerned about gas mileage, just raw power and torque. 3K RPM at 60 is acceptable for me.

11-04-2009, 09:36 AM	#15
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: Help - 4.10 or 4.56 gears? I have the 203 TC and have no idea how fast I was running. I'm guessing around the 70 mark. Usually 2800-3000 but seems to be the 3000 more.

11-04-2009, 11:53 PM	#16
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: Help - 4.10 or 4.56 gears? 33s are not enough above stock to affect gearing much at all.If you can`t haul with 4.10s you have too much weight.With a 305 you might have wanted 4.56s to have the power.A 305 won`t save you gas when it comes to hauling. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

11-05-2009, 01:46 AM	#18
2tons of fun Account Suspended Join Date: Jan 2009 Location: galt ca, Posts: 749	Re: Help - 4.10 or 4.56 gears? wtf is a 12" rear? i am wasting rmp and power with 4.56 and 38"s, i cant image how slow it would be with 33"s.



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11-05-2009, 03:14 PM	#20
sailed2japan Jonny Join Date: Apr 2008 Location: Outside the Box, Austin,TX Posts: 741	Re: Help - 4.10 or 4.56 gears? I'm casting another vote for 4.10's. 33" is too short to mandate use of 4.56 gears. I'm running 285/75r16's (33x11.5) and 3.73's. my truck is a disel, but even so it feels like it would be better with a taller tire or lower gear. Especially on the highway. __________________ 1966 C30, Cummins, stacks, and a flat bed in progress... "Honor.....simply put, A veteran - whether active duty, retired, national guard or reserve is someone who, at one time in his life, wrote a blank check made payable to 'The United States of America', for an amount of 'up to and including his life.' That is Honor, and there are way too many people in this country who no longer understand it." -AEC Hundley USNR Last edited by sailed2japan; 11-05-2009 at 03:16 PM.

11-05-2009, 09:22 PM	#21
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: Help - 4.10 or 4.56 gears? That`s what I have,too...285/75s and a 195 hp diesel.At least,that`s the one I was just referring to in the prior thread.My Suburban has 4.10s/35s/135hp diesel and it does great hauling the same trailer and loaded with tools behind the second seat. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

11-06-2009, 11:55 AM	#22
silver7 Registered User Join Date: Jul 2009 Location: High Point, NC Posts: 613	Re: Help - 4.10 or 4.56 gears? 4.10 wins out. I can always go lower if needed. Thanks guys -great information.

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