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+--- Thread: Comfortable hwy rpm (/showthread.php?tid=3796)
Comfortable hwy rpm - nevrenufhp - 07-17-2012
The SD I have is seemingly a put together mass of wrecking yard parts. I dont think it has the right rear gears. What are you guys comfortable with, in rpm, on the freeway? I hit 3k at roughly 61mph. I was thinking of dropping in a set of 2.47 gears from a 380 I saw.
RE: Comfortable hwy rpm - larsalan - 07-17-2012
So what are your gears now? Likely 3.07, should be stamped on the diff case on the lower corner under all the soot and road grease. I love these 2.88 + my rear tires are 8% greater diameter than stock. Way more room in the power band now from 50-90mph.
RE: Comfortable hwy rpm - dude99 - 07-17-2012
I have 2.47 gears in mine and love them. cruise around 2000ish I think. I'll have to pay more attention next time I'm out.
RE: Comfortable hwy rpm - nevrenufhp - 07-17-2012
According to an online gearing calc, I have the 3.46 gears. I just hate to take my next road trip with such steep gears. That's 11 hours of screaming at 3k-3100 rpm. I think I'll try to break the bank and get the freeway gears. I did the 3rd member in my pickup last year. It went from 3.55 to 2.75, and makes the freeway much nicer. Got the mpg back up to 13.7.
RE: Comfortable hwy rpm - larsalan - 07-18-2012
3100k is not so much screaming. I thought peak torques come from 2800-3100. Or so they say, and we are revving the 617 easily to 4500 during normal/aggressive acceleration.
I think I paid like under $50 for mine, just a bit of work pulling, cleaning, installing, gear oiling.
But love them.
DV has a bunch of nice photos to help you
http://www.peachparts.com/wikka/W123Differential
and a list of options
http://www.superturbodiesel.com/std/thread-2570.html
Make sure and not stretch/rip the brake lines whilst you lower all that subframe
RE: Comfortable hwy rpm - winmutt - 07-18-2012
3.46 is too high. 2,88 is perfect. I want 2,88 for my 603 with the 5 speed.
RE: Comfortable hwy rpm - Simpler=Better - 07-18-2012
I used to turn around 3,400 at 65ish, sounds "normal" if uncomfortable to me