Switch to 4.10s? - Diesel Forum

bmiliate · 03-21-2005, 07:41 AM

Just installed a BB turbo and expected a noticeable difference in towing on grades, but I'm not seeing it. I can definitely feel the difference unloaded, but not while pulling approximately 7k TT on grades. I'm running a Bully Dog 4-position chip. I tow in the third position - 75hp per Bully Dog. I know it's not imagined, cuz I took the same route to/from Ocotillo and there is one long freeway grade where I know the MPH I can make to the top without excessive EGTs.

Questions:
- Have I traded torque for hp by installing the BB turbo?
- I'm running 285 tires. Would it be overkill to change the gearing to 4.10s - would it make the truck rev too much for daily freeway driving (this is my daiy driver) and kill the mileage?

Thanks for your help.

Brian

**SmokeyWren** · 03-21-2005, 08:54 AM

[ QUOTE ]
- I'm running 285 tires. Would it be overkill to change the gearing to 4.10s - ...

[/ QUOTE ]

4.10 axle ratio with 285 tires would be equivalent to 3.99 axle ratio with stock tires. Not overkill at all.

[ QUOTE ]
...would it make the truck rev too much for daily freeway driving (this is my daiy driver)

[/ QUOTE ]

Stock tires and 3.73 rear end is 2000 RPM at 70 MPH.

285s and 4.10 rear end and a calibrated speedo would be about 2125 RPM at 70 MPH. I don't call that reving "too much".

[ QUOTE ]
...and kill the mileage?

[/ QUOTE ]

If you cared about fuel mileage, you wouldn't be running those big tires. [img]/ubbthreads/images/graemlins/cool.gif[/img]

A 3.99 equivalent ratio might reduce your unloaded mileage a smidgen, but probably not enough you could calculate the difference. And your loaded fuel mileage would probably improve a smidigen.

I think your best bet is to get rid of those big tires and run with Michelin XPS LT235/85R16E. That will give you the best tire mileage, the best fuel mileage, and excellent towing capability. If you don't overload your pickup to much over 10,000 pounds GVW, and if you properly inflate the tires for the load, that's the biggest tire you need.

bmiliate · 03-21-2005, 09:40 AM

SmokeyWren,

Based on your comments, I'll probably switch to the 4.10s and keep the tires - I like the look and guess I'll have to deal with the towing and mileage trade-off.

Best,

Brian

bmiliate · 03-21-2005, 09:43 AM

Thanks, again, for your advice.

Follow-up questions:

- What's a reasonably priced brand for new gears? I like to get on it, but I'm no racer, so I don't abuse the truck.
- Is it worth the extra $$$ to spend on a LSD for the front if I'm in the sand/on the beach 5 times/year?

Thanks,

Brian

**SmokeyWren** · 03-21-2005, 05:52 PM

[ QUOTE ]
- What's a reasonably priced brand for new gears? I like to get on it, but I'm no racer, so I don't abuse the truck.
- Is it worth the extra $$$ to spend on a LSD for the front if I'm in the sand/on the beach 5 times/year?

[/ QUOTE ]

You asked me, and I don't have a clue, so I'll let others respond. [img]/ubbthreads/images/graemlins/warmsmile.gif[/img]