|
01-22-2010, 11:11 PM | #1 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Tranny for towing
I have a C20 crewcab shortbed that I'm putting a 6.2 diesel in with a 700R4 for now...the 6.2 diesel is going to stay in the truck and probably get a turbo...We are getting around a 30 ft travel trailer and going to tow it with the C20...I know the 700R4 probably won't last long towing all this, so my question is...
What would be the best transmission and rear end gears to put behind a turbo 6.2 for towing and gas mileage?...I know that I'm not going to get great gas mileage towing the travel trailer, but I'd like to get decent gas mileage and I also don't want it to be a slug...I want to be able to go 70 in a 70 mph zone...it can be a standard or auto transmission...and I can change the gears in the rearend...it has 4.10s now...just need to know what would be the optimum setup for towing the travel trailer...I won't be towing anything heavier than that, and I'll only be towing that a max of probably 5-6 times a year... thanks guys... |
01-23-2010, 12:03 AM | #2 | |
Registered User
Join Date: Oct 2009
Location: Buhl, Idaho
Posts: 1,438
|
Re: Tranny for towing
Quote:
__________________
86 c30 crew cab dually 454/400 4/6 drop SOLD 1-8-11 1981 chevy K10 short Bed Scottsdale SOLD 10-26-2020 67 GMC Stepside Straight six/3 on the tree "The Peach" 2020 Silverado Double Cab LT Z71 5.3 8 speed Daily Driver K10 build http://67-72chevytrucks.com/vboard/s...d.php?t=671934 The Peach build http://67-72chevytrucks.com/vboard/s...d.php?t=733903 Last edited by Matt Man; 01-23-2010 at 12:04 AM. |
|
01-23-2010, 12:10 AM | #3 |
Registered User
Join Date: Nov 2008
Location: Gwinnett GA
Posts: 1,803
|
Re: Tranny for towing
How heavy is the trailer? Pulling it is only 1/2 the equation... will you be able to stop it from 70? My biased vote is for an SM465 4-speed with a 3.42 axle ratio. Very strong setup, has low gears for around town, and would be about 2600 rpm at 70.
__________________
1982 K10 SWB 1987 V20 - Sold - Doh! |
01-23-2010, 09:32 AM | #4 |
One shot, one kill.
Join Date: Dec 2007
Location: Saratoga Springs NY
Posts: 859
|
Re: Tranny for towing
I'm with 250. I have a 7000 pound utility trailer I pull regularly but with 3:08 gears. 350CID & 465 trans. I can get 15 MPG if I'm easy on the gas. jim
__________________
1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose. |
01-23-2010, 10:02 AM | #5 |
Registered User
Join Date: Feb 2007
Location: Memphis MI
Posts: 1,851
|
Re: Tranny for towing
You 700R4 might suprise you, mine went a long way including towing abuse. Just don't drag race it.
4l80E with a stand-alone controller, out of a 90's diesel. It's a 400 with OD and lockup. Not sure why the 6.2 turbo, why not pick up a complete 6.5T 4L80E out of a later model and swap it in? 400 is fine behind a 6.2, just need the 1 ton control system and a good converter. Manual, NV4500 would win for me. You already have a hydraulic clutch cab.
__________________
1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors |
01-23-2010, 11:47 AM | #6 |
Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
|
Re: Tranny for towing
The SM465 would be the most cost effective route. Yeah it's not a 5 or 6 speed, but the ratios are wide enough to where you can put rear end gears that will get good gas mileage in 4th gear, and the granny gear will still have plenty of ratio to get it moving.
__________________
1977 GMC Sierra Grande |
01-23-2010, 07:20 PM | #7 |
Registered User
Join Date: Jan 2010
Location: Kitchener, Ontario, Canada
Posts: 94
|
Re: Tranny for towing
|
01-23-2010, 04:37 PM | #8 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
I am swapping the 6.2 out of my other truck that I have...so I'm using what I have already...I was think about the 4l80E, but I thought I would need a computer with it...I thought that would be too complicated..maybe i'm wrong...
and about it stopping, I don't see why not...the travel trailer will have trailer brakes, and I'm converting the 14 FF in the rear to discs...it'll have hydraboost brakes, so I don't see why it won't stop...if you see something that says otherwise, please tell me...I want to be able to stop... so I have a few questions... what's a 1 ton control system? what do you mean by hydraulic clutch cab...the cab had an auto in it... what's the better transmission for towing? SM465 or NV4500? What's the cost difference between the two? and also, I might not have been clear about the gas mileage thing...I don't really care the gas mileage I get towing...I know it's going to drop drastically...that's fine...I am going to be running WVO while towing long distances, won't be running WVO around town probably...I only have a 12 mile commute to work...I would like to keep the gas mileage good around town unloaded though...I get 26 mpg in town now...I know I'm not going to keep that going from a 1/2ton swb to a crewcab 3/4 ton swb... rear end gears? I have 4.10s now, if I went with either of the standards, what would be a good gear or will the 4.10s be fine? what is the optimum rpm for the 6.2 diesel to cruise at on the interstate? that'll help determine the gears I'm sure...also, I can cruise at 60 or 65 while towing is fine with me...if that'll help...I've towed cars on car trailers down the highway before, but never towed a travel trailer before...It'll be a new experience for me for sure...I would say the travel trailer probably wieghs as much as a car and car trailer setup, but the wind resistance is going be alot higher with the travel trailer... thanks for all your help guys... Last edited by Stitch; 01-23-2010 at 06:06 PM. |
01-23-2010, 05:44 PM | #9 |
Addicted to Rust
Join Date: Dec 2009
Location: Abbeville SC
Posts: 1,030
|
Re: Tranny for towing
I had a C30 rollback with the granny 4 and a 6.2 and it would pull two cars at 80 + and get decent mileage. Jay
__________________
Current trucks: (48 GMC100 320 inliner) Gone (48 Suburban in pieces) Sold 87 GMC CCSB 5.3 4l60E Daily Driver ECTA National record holder XO/PP We never really grow up, we just learn how to act in public. |
01-23-2010, 05:49 PM | #10 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
when you say granny 4, which transmission is that...and what rear gears were in it if you remember and what kind of mileage did it get...I know that's alot of questions, lol, but I'm wanting to do this once...thanks
|
01-23-2010, 06:26 PM | #11 |
Registered User
Join Date: Nov 2009
Location: goodland,ks
Posts: 217
|
Re: Tranny for towing
granny low is the sm465 4 speed tranny the mosr common 4 speed in gm trucks
hw said hydralic clutch cab because a 87 would of had a hydralic clutch if it was a manual
__________________
mitch 87 chevy short box 4wd tbi 350/built 700r4/np208 3.73s Last edited by munger; 01-23-2010 at 06:28 PM. |
01-23-2010, 07:13 PM | #12 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
thanks for the clarification...
|
01-23-2010, 07:27 PM | #13 |
Registered User
Join Date: Mar 2008
Location: Salt Lake City UT
Posts: 441
|
Re: Tranny for towing
http://www.novak-adapt.com/knowledge/sm465.htm
To reduce your initial outlay, I'd suggest the SM 465 trans. It's rugged, has a deep first gear and is economical to obtain. I've bought two in the past year for about 100 each. However the NV 4500 is my choice if towing frequently and/or using as a DD due to the OD feature and toughness. But it's expensive. I've pulled a couple from wrecked trucks at reasonable cost but folks tend to price them high...especially the 4wd models. However since your truck is an auto, you'll have to rig the hydraulic clutch system. If you're handy it's not much of an issue. |
01-23-2010, 08:00 PM | #14 |
Registered User
Join Date: Aug 2009
Location: taxachusetts
Posts: 138
|
Re: Tranny for towing
sm 465 or nv4500.
__________________
R.I.P gm 1908-1986 1982 chevy k20,350,sm465,np205,10bolt and 14bolt s.f |
01-24-2010, 09:10 AM | #15 |
Registered User
Join Date: Feb 2007
Location: Memphis MI
Posts: 1,851
|
Re: Tranny for towing
TH400 uses vacuum modulation to control shifts. Diesel's don't make vacuum like gassers. TH400's were used behind normally aspirated diesels and some turbo conversions (like 6.2 with Banks) in some 1 ton and delivery van applications, and in military units. These have a vacuum pump and throttle sensing system to modulate the TH400. I have heard there is also an aftermarket system available for the turbo set ups.
Early diesels with the 4l80E have a stand-alone controller that senses throttle input and controls the trans. 6.5 NA applications, late 6.2, and some early 6.5 turbo packages, again in 1 tons and heavy vans. This is a great rig for a swap if you can find one. The key is to get one before all the electonically controlled functions went together, so it must be a diesel pre-Duramax set up.
__________________
1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors |
01-24-2010, 12:35 PM | #16 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
D13, thanks for the information...
what would be the optimum rpm to cruise on the highway at 65 mph be... and what would be the correct gear ratio for the rear end to put the engine at that rpm using a 4l80E and an SM465? thanks for all the help so far guys...I'm definitely going to get this truck right with the help here...thanks again... |
01-26-2010, 12:10 AM | #17 |
Registered User
Join Date: Jun 2009
Location: Wyoming, MN
Posts: 13
|
Re: Tranny for towing
Depending on cash a th400 with a gearvendors overdrive would be nice. And then 4.10 in the rear. You can tow in od with a gear vendor unlike the 4l80e
|
01-26-2010, 12:50 AM | #18 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
what does a gear vendors OD cost...and that would work, because I have to get my driveshaft shortened anyways...
|
01-26-2010, 02:04 AM | #19 |
Registered User
Join Date: Jun 2009
Location: Wyoming, MN
Posts: 13
|
Re: Tranny for towing
Ohh they are pricey. They go on ebay for about 1500 rebuilt or 26 to 28 new.
|
01-26-2010, 12:21 PM | #20 |
Registered User
Join Date: Jun 2009
Location: Wyoming, MN
Posts: 13
|
Re: Tranny for towing
But another bright side is the gear vendor will also split every gear in the tranny. http://www.gearvendors.com/
Last edited by jrp267; 01-26-2010 at 12:21 PM. |
01-26-2010, 11:48 AM | #21 |
Registered User
Join Date: Jan 2010
Location: Oran, IA
Posts: 78
|
Re: Tranny for towing
I would say SM465, but mine doesn't tow like I thought it would. The gears are WAY too far apart. You pretty much have to hit the governor before shifting and then it is almost lugging too hard to pull through.
I'm going to make a 30 mile (each way) trip pulling a '28 gooseneck this weekend, will let y'all know how it goes. A turbo 6.2 would probly be ok. But my 700R4 6.2 burban seemed like it could accelerate a lot easier than my SM465 C20 (the stick is still way more fun tho)
__________________
'87 GMC K2500 Factory 6.2 Diesel, 4 speed. Converted to 350 (has cracked block) converting back to 6.2 '82 [COLOR="Sienna"]Cadillac Coupe Deville 350 DIESEL '93 Chev S10 2.8L 5 speed '98 GMC K1500 Z71 ext cab shortbox 6.5 DIESEL '96 Ford F250 7.3 Powerstroke |
01-26-2010, 11:16 PM | #22 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
what about a built 700r4
|
01-26-2010, 11:38 PM | #23 |
Registered User
Join Date: Nov 2009
Location: goodland,ks
Posts: 217
|
Re: Tranny for towing
to pull good with power and mileageyou need a 20% overdrive like 0.80 not .70 or 1:1 idk where you can find a tranny like that
my dad has a 06 gmc 1500 ccsb it has a 4l60e and always jumps in and out of third and fourth when towing to low of rpms in od to high in direct and its basically a 700r4 so its not good for towing
__________________
mitch 87 chevy short box 4wd tbi 350/built 700r4/np208 3.73s |
01-27-2010, 07:04 PM | #24 |
Account Suspended
Join Date: Jul 2008
Location: Where I come from, it's cornbread and chicken...
Posts: 3,122
|
Re: Tranny for towing
the gears will keep it in the power band where it needs to be...I'm not asking of the ratio is good in the 700r4...
I'm asking if a built 700r4 will tow what I'm asking...that's all...thanks |
01-27-2010, 07:57 PM | #25 |
Registered User
Join Date: Jun 2009
Location: Wyoming, MN
Posts: 13
|
Re: Tranny for towing
I have seen some very well built 700 r tow heavy but they cost as much built as anything else. so its an option.
|
Bookmarks |
|
|