Quote Originally Posted by Timmy View Post
Hey Ross, you've mentioned this a few times now and I was curious... Why do you feel it struggled to maintain 75mph with 4.88's? I'm guessing at 75mph you were around 2900 RPM in sixth gear? (based on that tool I published and punching in your measured tire size.) I'm very surprised that at 2900 RPM it was struggling at 75 Mph? I actually would have thought the exact opposite would happen with the 4.56 gears? 4.56 Gears appears to be hitting 75 Mph at 2700 RPM so I would have thought it would be more of a struggle say if you hit an uphill section? I mean, technically, isn't this like saying you couldn't hit 75Mph by downshifting to 5th because the RPM's went to 3200?

Not doubting your personal experience as I fully trust you when you say 4.88's were not as good as 4.56's on the highway, but I'm wondering if you could elaborate more on why you feel the 4.88's struggled so much?
When i say "struggled" thats probably not the best word. The Jeep was fine getting to those speeds, but the pressure i had to hold on the pedal to get there was uncomfortable, keeping the truck at 2600 rpm is not her sweet spot for cruising. So if i wanted to do 75 for a long distance with 4.88s, I had to really hold the pedal down farther than normal. She didnt comfortably cruise at 75. Or 70 for that matter.

2900 rpm to do 75mph is a LOT of rpm to me. I dont think the truck wants to spin at that level for an extended trip either. Or maybe i dont like to hear the engine working harder than it should in a cruising situation.

With 4.10, I would cruise at 75 at about 2k rpm. She was a road trip killer. Now she isnt quite the same cruiser she was, but the overall acceleration is better.

Now I cruise at 70 at around 2200 rpm. Or somewhere around there. I thought 4.88 was unlivable. Could i get to high speed? yes. Did I have to flog BB to get there? also yes. In NJ people do 80 mph on every highway. If your not up there, you are a slug.