Gears vs. tires vs. turbo?

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I have a BJ73 with 3b NA diesel. It currently sits on stock size tires (29?) . It runs fine for me on the highway up to 120K or so. I am going to put lunchbox type lockers front and rear and larger tires. I'm thinking 33's. Currently my rear pinion bearing is worn out and needs replacing. I'm thinking about doing lower gears at the same time as the lockers in order to work well with the larger tires. Can the 3B push the 73 down the road at 100K without a turbo on 33's if geared down a bit? Any suggestion on Gears? I think stock is 4.10 but not sure here.
 
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Does your bj73 have a tachometer? you must notice that now you are almost "stock" with the 29 " should you check how many rpm @ 120 km / h? (or mph?) for a 3B, I think you should at least have about 4.56 gears for those 33 "

:)
 

joekatana

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I have a BJ73 with 3b NA diesel. It currently sits on stock size tires (29?) . It runs fine for me on the highway up to 120K or so. I am going to put lunchbox type lockers front and rear and larger tires. I'm thinking 33's. Currently my rear pinion bearing is worn out and needs replacing. I'm thinking about doing lower gears at the same time as the lockers in order to work well with the larger tires. Can the 3B push the 73 down the road at 100K without a turbo on 33's if geared down a bit? Any suggestion on Gears? I think stock is 4.10 but not sure here.
You could put 4.88's in it but with 33's I would recommend installing a Turbo , it will completely change the ride. Also if you go for the 33's please consider "skinny" tires like a 255/85/16 or a 33/10.5/15 depending on your wheelsize.
 

FJBen

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Yep tall skinny’s work great, less drag on the vehicle. Lots of hills and mountain driving? Joe is absolutely right, turbo 33s for sure. The 4.88s won’t hurt at all, higher rpms on the highway as well.
 
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I don't have a tach. so I don't know what my RPMs are. It's not lacking for power with these tires. It reminds me of 4 cylinder naturally aspirated diesel pickups I drove overseas but more torque down low. She runs 100-110k no problem. Pretty wound out at 120 which is the fastest I've driven it. In normal driving around town I'll start out in second gear. Everybody seems to like to tall skinny or tires I'm guessing there issues with 12.5 rubbing on turns. I like the the way the 1050's look, but I know the 1250s would be better off road. I've got factory 15 inch chrome 5 spokes now. I may try to get some steel rims from a wrecking yard off Tacoma's or tundras. I was leaning toward 4.56.
 
Joined
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Messages
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I don't have a tach. so I don't know what my RPMs are. It's not lacking for power with these tires. It reminds me of 4 cylinder naturally aspirated diesel pickups I drove overseas but more torque down low. She runs 100-110k no problem. Pretty wound out at 120 which is the fastest I've driven it. In normal driving around town I'll start out in second gear. Everybody seems to like to tall skinny or tires I'm guessing there issues with 12.5 rubbing on turns. I like the the way the 1050's look, but I know the 1250s would be better off road. I've got factory 15 inch chrome 5 spokes now. I may try to get some steel rims from a wrecking yard off Tacoma's or tundras. I was leaning toward 4.56.
. I'll get out the calculator and look at the 488 too. I do want to be able to drive 70 miles per hour on the interstate.
 

FJBen

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Currently with 29” tires your Rpm s are

100kph = 2500
120kph = 3100

33” tires. (I used 32.5 as it’s closer to actual)

100kph
4.11 = 2250
4.56 = 2450
4.88 = 2650

120kph
4.11 = 3000
4.56 = 2950
4.88 = 3200

I would choose 4.56 personally. However, it’s still working that engine a little harder. I have 33’s and the 13BT and 4.11s and I think it works great. The turbo makes a huge difference. If I were higher in altitude or more mountain passes I would change mine to 4.56 to help get some more power back.
 
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