Need some rear end advice!
Thread Starter
|
New Member
Joined: Jun 2012
Posts: 57
From: Crowley, LA
There are some calculators online that will tell you your rpm at speed based on gearing and tire size. I have 3.73's in mine, and with a 235/75/15 (28.88") it runs right at 2,000 rpm at 60 in overdrive and torque convertor locked up.
Your 275/40/20's work out to a few tenths shorter than mine (28.66") While 4.10s wouldn't absolutely kill you on the highway (thanks overdrive! lol), a set of 3.73's would be much more pleasant.
Your 275/40/20's work out to a few tenths shorter than mine (28.66") While 4.10s wouldn't absolutely kill you on the highway (thanks overdrive! lol), a set of 3.73's would be much more pleasant.
Moderator
Joined: Mar 2009
Posts: 8,453
From: Belleville, Michigan
1998 4X4 with 218K miles, original engine, trans & rear axle. The only mods are an Imperial 243012 trans cooler, totally bypassed the trans cooler in the radiator, (keeps fluid temp under 100 degrees) and a severe duty fan clutch. All AC Delco ignition parts and fuel pump, Denso oxygen sensors, tweaked the fuel pressure to 63psi, and camshaft retard is set at zero degrees. Perfect wheel alignment: zero camber and 1/16" toe in. Mobil1 5W20 full synthetic oil. Drop the speed to 60mph, (GPS) with the cruise on, and it will consistently get 24+ mpg. Regular maintenance and good parts is all it takes. With a 4.10 axle, you'd be lucky to get half that mileage. Your 3.08 probably has a hard time spinning the tires from a stop sign on a gravel road, but she'll get great fuel mileage on the highway 
No reason your 3.08 can't get mileage like that, probably even better.
No reason your 3.08 can't get mileage like that, probably even better.
BF Veteran
Joined: Sep 2011
Posts: 2,278
From: Texas
I wish I could get that mileage! With nothing but highway driving I can sometimes scratch 20 mpg. Usually 18. Of course, my 3.73s might hurt a little, and I'm sure the alignment has to be off. All Delco fuel and ignition parts.
Thread Starter
|
New Member
Joined: Jun 2012
Posts: 57
From: Crowley, LA
Wow!!! The BEST ill get 18. And it was like 17.92 mpg. Haha. I am in need of an alignment, though. Just waiting until i have the money to change inner and outter tie rods before i do that. It may be a lil while before i can do that though... Just found out yesterday one of my motor mounts r shot. Hit the gas the wrong way n the motor shifts sideways and spins my fan into the fan shroud.
1998 4X4 with 218K miles, original engine, trans & rear axle. The only mods are an Imperial 243012 trans cooler, totally bypassed the trans cooler in the radiator, (keeps fluid temp under 100 degrees) and a severe duty fan clutch. All AC Delco ignition parts and fuel pump, Denso oxygen sensors, tweaked the fuel pressure to 63psi, and camshaft retard is set at zero degrees. Perfect wheel alignment: zero camber and 1/16" toe in. Mobil1 5W20 full synthetic oil. Drop the speed to 60mph, (GPS) with the cruise on, and it will consistently get 24+ mpg. Regular maintenance and good parts is all it takes. With a 4.10 axle, you'd be lucky to get half that mileage. Your 3.08 probably has a hard time spinning the tires from a stop sign on a gravel road, but she'll get great fuel mileage on the highway No reason your 3.08 can't get mileage like that, probably even better.
No reason your 3.08 can't get mileage like that, probably even better.
Moderator
Joined: Mar 2009
Posts: 8,453
From: Belleville, Michigan
Alex, the motor mount is costing you fuel mileage. It wastes power lifting itself up!
Brian, Remove the entire grille, (5 minutes). It's mounted in front of the AC condenser, all the way to the passenger side, with the lines headed toward the driver side. Then down through the splash shield and connected to the original steel cooler lines. I cut the lines from the trans, just before they turn upward, so the rubber lines have a straight shot at them. The cooler fits perfectly in there, just gotta make a couple of brackets to secure it to the core support and the hood latch bracket. Whole job took maybe 2 hours.
Brian, Remove the entire grille, (5 minutes). It's mounted in front of the AC condenser, all the way to the passenger side, with the lines headed toward the driver side. Then down through the splash shield and connected to the original steel cooler lines. I cut the lines from the trans, just before they turn upward, so the rubber lines have a straight shot at them. The cooler fits perfectly in there, just gotta make a couple of brackets to secure it to the core support and the hood latch bracket. Whole job took maybe 2 hours.
Thread
Thread Starter
Forum
Replies
Last Post
shotnva777
2nd Generation S-series (1995-2005) Tech
46
Oct 12, 2011 09:07 PM
brino1
Steering, Suspension & Drivetrain
5
Feb 25, 2011 08:05 PM
rcravincase
2nd Generation S-series (1995-2005) Tech
1
Sep 13, 2009 07:58 PM
