Towing differential

[NovaMan]

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]

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]

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]

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

[Philip Saran]

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]

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.

[james schaechter]

I had a 1985 Heavy 3/4 with 4.10s (2wd) and T-400 warmed up 350 and it towed an open like it wasn't there. I didn't get great mileage, but it didn't change much towing or not. If you have a deal on a 4.10, I would go for it. If you start buying stuff new parts , it gets pretty $$$. I am guessing you have a 4 speed with granny low then.
If you start changing a bunch of things, you might be better off looking for a different truck. I have had several stick shift 4x4 3/4 tons (mid 90s GM). You can find them priced right. My brother has my old 1997 truck and it is awesome. It is an ext cab vortec 350 5 speed with 3.73s. It still pulls our 24ft enclosed at times and pulls it no problem. It has over 200k on it. Original engine and we just replaced the clutch. If yo usold your truck and bought one of these, I bet it would only cost a couple thou different. I would tow in 4th at 55 mph and 5th at 65 mph or above.Make sure you look for the heavy 2500 so it has the good HD trans. the med duty one has a small clutch and an integral bellhousing. They also ride nicer with the independent front susp instead of the straight axle. It might be worth getting a calc out the $$$ and do some research. you might find some deals.
By the way, many of the 1/2 ton SUV types like a Yukon for example have the power. I have a friend who towed a 26 ft enclosed with one when we he first got back into racing. I was expecting probelms with braking or suspension. With load bars, it handled well, stopped well (4 wheel discs). the weak point was actually the pinion bearing. Not strong enough for the weight on a long tow and he knocked 2 of them out before he upgraded to a 3/4 ton. JIm.

[Chris1529]

I don't think I would worry too much about the differential as long as it is in good shape. I don't know too many people that run detroit locker on the street though. I towed an open trailer with a 1/2 ton Ford 4x4 (351W Automatic) with an 8.8" rear and stock limited slip. The pinion bearing eventually came out of it.
The rest of the parts looked like new.

[NovaMan]

Originally Posted by james schaechter

I had a 1985 Heavy 3/4 with 4.10s (2wd) and T-400 warmed up 350 and it towed an open like it wasn't there.

Cool. Did it have a 14-bolt full-floater or semi-floater?

Originally Posted by james schaechter

I am guessing you have a 4 speed with granny low then.

Yessir. With the 4.88 gears, the trans in Low, and the t-case in 4L, I could start the truck going, hop out and walk faster than it moves.