straight six
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
4.56 or 4.88 gears will give a lot of grunt, but will kill MPG. I don't know how fast you drive on the highway, but here's some food for thought:
65 MPH with a ZF (.80 OD according to most charts) and 33" tires will net the following RPM.
3.50 = 1850
3.73 = 1975
4.10 = 2175
4.56 = 2400
4.88 = 2580
If you will be off the highway most of the time, and off road enough to make the 4.56 or 4.88 gears worth the cost, both in purchase price and MPG hit on the highway, they will give the best performance.
For mixed driving, I'd still say 3.73-4.10 is a good compromise. They will keep the 300 in the middle of it's peak torque range, allowing for a good mix of power and MPG. These will also leave 4th usable when a little extra power is needed at highway speed. The 4.56 and 4.88 will make 4th almost out of the question above about 60 MPH.
Again, it depends on your intended use of the rig, and the rig's weight. Your rig looks to be a bit lighter than than a long wheelbase truck, which also factored into my original suggestion.
65 MPH with a ZF (.80 OD according to most charts) and 33" tires will net the following RPM.
3.50 = 1850
3.73 = 1975
4.10 = 2175
4.56 = 2400
4.88 = 2580
If you will be off the highway most of the time, and off road enough to make the 4.56 or 4.88 gears worth the cost, both in purchase price and MPG hit on the highway, they will give the best performance.
For mixed driving, I'd still say 3.73-4.10 is a good compromise. They will keep the 300 in the middle of it's peak torque range, allowing for a good mix of power and MPG. These will also leave 4th usable when a little extra power is needed at highway speed. The 4.56 and 4.88 will make 4th almost out of the question above about 60 MPH.
Again, it depends on your intended use of the rig, and the rig's weight. Your rig looks to be a bit lighter than than a long wheelbase truck, which also factored into my original suggestion.
Post Fiend
Joined: Jan 2007
Posts: 7,021
Likes: 5
From: Almost Heaven
The 300 doesn't do well with low gears. Not if you drive the highway often. I say for 33's just stick to 3.73's, no lower. Once you hit 35'' and above, fuel milage and power doesn't matter anyway, you gear it as low as you want.
The biggest mistake I've ever done regaurding my truck is installing 4.11 for 31'' tires.
The biggest mistake I've ever done regaurding my truck is installing 4.11 for 31'' tires.
Postmaster
Joined: Jun 2007
Posts: 3,856
Likes: 1
From: Lebanon
thanks RW, Billy! right now, the pilot bearing(?) has me stopped. do i fight with it, or just leave it in. the last (and only) clutch i did, i didn't replace throwout bearing, much to my later regret
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Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
Is it a bearing, or just a brass bushing? If it's a bushing, and it doesn't look worn, leave it be.
A bearing, on the other hand, needs to be checked for feel. If even slightly rough, replace it. If it feels good, and can be greased, add the grease and go on.
A bearing, on the other hand, needs to be checked for feel. If even slightly rough, replace it. If it feels good, and can be greased, add the grease and go on.
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
How does it feel when you try to turn the inner piece?
On my RX7 the bearing has exposed needles, and they all felt good, but a bit dry. I simply smeared some grease into the needles, and worked it around.
It also uses a small seal, and that didn't come with my clutch kit, so I left the old bearing and seal in place. I figured adding grease and keeping dirt/dust/grit out would make the old one last longer than the new one without any way to keep out the crud.
On my RX7 the bearing has exposed needles, and they all felt good, but a bit dry. I simply smeared some grease into the needles, and worked it around.
It also uses a small seal, and that didn't come with my clutch kit, so I left the old bearing and seal in place. I figured adding grease and keeping dirt/dust/grit out would make the old one last longer than the new one without any way to keep out the crud.
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
If it ain't broke, don't fix it. In other words, if it works, it works. If you start having transmission issues, then find a C6 to replace it.