Can I do it?: Taller Rear End??

mannytranny402 · September 15, 2002

I have a duramax with the 6 speed. I would like it to cruise faster at a little lower RPM. Im sure that it has plenty of power to do this, but what should I look out for? I believe it has a 3.73 or something like that on it now. Thanks for the help...

CMNTMXR81 · September 15, 2002

Sure, as long as you do the front at the same time if you have 4wd.

3.73's are the biggest available with D-Max, but with a manual trans I don't know what gear you actually have.

MarkD · September 15, 2002

What RPM are you turning in 6th gear? What do you want to turn?

mannytranny402 · September 15, 2002

When I drive in 6th gear at 85, it runs at like 2450. It feels like it needs a 7th gear. It has plenty of power at that speed. I wont be towing anything very heavy, prob never more than 5k. Would this affect the gas mileage for better or worse? I would like it to run at 2400 at 90 or so.

silverado3500 · September 17, 2002

You could consider having transmission regeared by a transmission shop, but I would recommend leaving it stock, at least until the 100,000 warranty runs out. If you even change the air filter to something other than stock, :urgent: GM WILL VOID THE WARRANTY :urgent:

Colorado Kid · September 19, 2002

As far as I know no taller gearing exists for the 11.5" rear end.

I know what you mean, when not towing it does feel like it could easily handle a gear above 6th. In fact I've been surpriaed to find the shifter already in 6th a few times...feeling like I wanted to shift up.

Bigger tires accomplish much of the same effect, some are running 285/75R16, a few are even running 305s

A Gear Vendors Overdrive unit would work, if you want to spend $$$$ just to turn the engine slower.

Any fuel economy improvement would be small...not reason enough to do it in my opinion.

When I've got the 5th wheel on the gearing is just right, so I;m not going to change it. In particular I don't want first gear and reverse to be any higher for campgraound manuvers.