Towing differential

NovaMan · 04-11-2008, 05:12 PM

You guys do more towing than anybody I know, so I figured you'd be the best group of people to ask. What's the best kind of rear differential to use for towing?

Philip Saran · 04-11-2008, 07:42 PM

Pete, it kind of depends on how much weight you tow.
If you read the post about my blown head gasket on a diesel and what
Chris towes with a Dodge 1500/4.7/auto vs bigger diesel truck.

So again it comes down to how much weight do you tow?

I have a 2004 Ford F350 4 dr/4 x 4/long bed 6.0 diesel/4:10 gears, when towing
my travel trailer which weights in at around 7500 lbs loaded it will get 9 to 13 mpg
depending on how many 6% hills I have to climb. My Duster on a 18 ft open trailer
falls into the 5500 lb weight catagory.

I have found out that I can tow the same trailer with a Ford F150 5.4/auto/3:73 rear
gear ratio and be fine (actually good up to 9,000 lbs).

Same goes for a Chevy or GMC V8 with similar 3:73 gear ratio will tow similar
weights to the Ford F150.

Dodge has the problem that there is nothing between a 4.7 V8 that will tow 5500 lbs
and the HEMI or Commins diesel which is needed to tow heavier weights..

NovaMan · 04-13-2008, 01:21 AM

I missed your thread - been absent for a while. I have an '87 Chevy 3/4 ton 4x4 with a warmed-over 350. It came from the factory with 4.10 gears, but my calculations indicate it has been changed to 4.88s. That equates to 3000rpm at 55mph, which I think is a bit much for the highway. I figure if I change gears, that'd be the time to change differential(s) too. I'd be hauling my Nova on an open trailer and some tools and a pit bike or two in the bed. Honestly, I don't know what's in the rear diff right now; it could be a posi, a gov-lok, or an open differential. If I had unlimited funds, I'd run an Ox Locker or an Eaton E-locker, but I can't bear to spend that much money, so my options are a clutch-type Eaton posi, something like a Detroit locker, or a guv-bom-- er, I mean Gov-Lok.

TIA.

NovaMan · 04-13-2008, 02:08 PM

One thing I forgot to mention is that my truck has a manual trans.

Philip Saran · 04-13-2008, 06:11 PM

Pete,

It sounds like you could be just as happy with something like 3:73
or 4:10's at the most for your truck, but that would also mean regearing
the front differential at the same time, unless you pulled the front drive
shaft out and just ran the truck as a 2x4 instead of a 4x4.

I think going down to 3:55 may be too much of a loss of towing power
though.

Does someone else have a opinion??

NovaMan · 04-13-2008, 11:48 PM

I have a friend with a 14-bolt full floater rear with 4.10 gears, so I might swap that in. I'd just keep the t-case in 2H until I got around to changing the front gears. Or I might keep the 14-bolt semi floater and put 3.73s in it.

My immediate concern isn't gear ratio selection, but differential selection. Eaton posi or Detroit Locker? I need to start pricing things out so I can figure out if I can afford gears AND diffs, or just gears.

04-11-2008, 05:12 PM	#1
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Towing differential You guys do more towing than anybody I know, so I figured you'd be the best group of people to ask. What's the best kind of rear differential to use for towing? __________________ ~Pete 1970 Nova

04-11-2008, 07:42 PM	#2
Philip Saran Senior Member Join Date: Oct 2006 Location: Parker, CO. Posts: 728 Likes: 165 Liked 14 Times in 11 Posts	Re: Towing differential Pete, it kind of depends on how much weight you tow. If you read the post about my blown head gasket on a diesel and what Chris towes with a Dodge 1500/4.7/auto vs bigger diesel truck. So again it comes down to how much weight do you tow? I have a 2004 Ford F350 4 dr/4 x 4/long bed 6.0 diesel/4:10 gears, when towing my travel trailer which weights in at around 7500 lbs loaded it will get 9 to 13 mpg depending on how many 6% hills I have to climb. My Duster on a 18 ft open trailer falls into the 5500 lb weight catagory. I have found out that I can tow the same trailer with a Ford F150 5.4/auto/3:73 rear gear ratio and be fine (actually good up to 9,000 lbs). Same goes for a Chevy or GMC V8 with similar 3:73 gear ratio will tow similar weights to the Ford F150. Dodge has the problem that there is nothing between a 4.7 V8 that will tow 5500 lbs and the HEMI or Commins diesel which is needed to tow heavier weights.. __________________ Phil Saran Parker, Colorado Last edited by Philip Saran; 04-11-2008 at 07:44 PM.

04-13-2008, 01:21 AM	#3
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Re: Towing differential I missed your thread - been absent for a while. I have an '87 Chevy 3/4 ton 4x4 with a warmed-over 350. It came from the factory with 4.10 gears, but my calculations indicate it has been changed to 4.88s. That equates to 3000rpm at 55mph, which I think is a bit much for the highway. I figure if I change gears, that'd be the time to change differential(s) too. I'd be hauling my Nova on an open trailer and some tools and a pit bike or two in the bed. Honestly, I don't know what's in the rear diff right now; it could be a posi, a gov-lok, or an open differential. If I had unlimited funds, I'd run an Ox Locker or an Eaton E-locker, but I can't bear to spend that much money, so my options are a clutch-type Eaton posi, something like a Detroit locker, or a guv-bom-- er, I mean Gov-Lok. TIA. __________________ ~Pete 1970 Nova

04-13-2008, 02:08 PM	#4
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Re: Towing differential One thing I forgot to mention is that my truck has a manual trans. __________________ ~Pete 1970 Nova

04-13-2008, 06:11 PM	#5
Philip Saran Senior Member Join Date: Oct 2006 Location: Parker, CO. Posts: 728 Likes: 165 Liked 14 Times in 11 Posts	Re: Towing differential Pete, It sounds like you could be just as happy with something like 3:73 or 4:10's at the most for your truck, but that would also mean regearing the front differential at the same time, unless you pulled the front drive shaft out and just ran the truck as a 2x4 instead of a 4x4. I think going down to 3:55 may be too much of a loss of towing power though. Does someone else have a opinion?? __________________ Phil Saran Parker, Colorado

04-13-2008, 11:48 PM	#6
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Re: Towing differential I have a friend with a 14-bolt full floater rear with 4.10 gears, so I might swap that in. I'd just keep the t-case in 2H until I got around to changing the front gears. Or I might keep the 14-bolt semi floater and put 3.73s in it. My immediate concern isn't gear ratio selection, but differential selection. Eaton posi or Detroit Locker? I need to start pricing things out so I can figure out if I can afford gears AND diffs, or just gears. __________________ ~Pete 1970 Nova