Tires and gear

[Kenyi]

Hi all,

So, I’ve been slowly buying parts for a U-joint leaf conversion so far, I have got transfer case and tail housing
front and rear axle “the front axle is getting rebuild following bknudtsen and shaft threads ” :Thumbsup:
both axles have 3.73 gears and I’m debating of what size of tires to get 33” or 35”
and what would be the best gear choice to the tires.
For the moment, I do not tow anything no plans for that either.
I been having this 4x4 conversion planned for a while and it’s been going really
slowly my other interests is to travel the world and to combine both one needs
to take a toll and that has been the van conversion.
Me and wifey have been having a blast whit the 2wd van otherwise travelling around the west coast.
but more frequently we been ending up hitting this road signs like this

​

that want us to go more forward with the conversion.

• So, for you guys that have a conversion. What size of tires and gears do you guys have on your 4x4
Are you satisfied whit your choice or would you have done it different today?

• Do you off-road a lot how hard do you push the van whit your set up?

• Would you have opted for ARB air lockers on the rear or do you have ARB air locker on your van?


Thanks.

PS I've searched for regear treads and all that I don't know what I'm doing wrong because the search results are poor.

 

[expedition4x4]

I am doing same as you (slow build) but did the axles first. It really depends on engine but I am doing a 7.3 power stroke with 35's and geared the axles to 4.30's with ARB lockers.


Sent from my iPhone using Tapatalk

 

[4x4pair]

If you're not going to tow anything you could always stick with the 3.73 gears and save yourself some money. If you're going to run 35's, it's about 200 rpm lower at 70mph from stock. If you're running 33's, it's about a 65 rpm difference from stock. I'm running 35's with 4.10's and it does fine by itself (towing I wish it was 4.56's but there's always a compromise somewhere).
Also, if you haven't already, you could consider Eaton E-Lockers. They're much less problematic than ARB's and are just as strong if you get the newer 4 pinion design.

 

[Backcountry Pursuit]

I'm on 35 with 4.30. It is pretty much stock shift points and rpms at that point. There are some really cool tire size/gear ratio calculators online. Punch in scenarios to see what the results are. I'm very happy with my set up at present.

Also, I found a sterling 10.5 with factory limited slip and 4.30. I don't have a ton of miles yet, but the two trenches I leave in dirt when I light up the rear tells me it works well.

 

[Kenyi]

Thanks guys

@ expedition4x4 - Slow sometimes is good you get better understanding of what you are getting in to the van is kind of my hobby, it’s a E350 7.3 2001. From what I hear ARB lockers are one of the good ones.

@ 4x4pair -I think I need to re-gear if I’m going with bigger tires. About the Eaton E Locker, I’m going to read more about them.

@ Backcountry Pursuit - Thanks for the advice of the gear calculator I’m learning while I’m going it maybe sound obvious for others about the calculator that’s life you learn.

I got some results when I punched the numbers of different tire size and I got some numbers that’s good.

View attachment 403555
View attachment 403556
This calc can be used to find a new gear ratio.

Bigger tires can help you crawl up those slick rocks, look cool, and rob you of power. One way to compensate for this is to swap out your differential gears. The left side of the calculator requires all three entries. The right side will show the results. The New Gear box will show the ideal gear ratio (getting as close to stock as possible). If you want a bit more power, for rock crawling, go with something closer to the Lo Gear number. Also, the Effective Ratio box shows your adjusted gear ratio if you choose to keep your original gears.

 

[ujoint]

For a 7.3 with 35s the 4.10s will be good as long as the van isn't loaded heavily or towing a lot. If you're keeping the stock rear axle then the ARB is your only locker option. 3.73s with 35s will stress the engine more causing higher EGTs and tranny temps.

Ratio also depends on where its primarily driven. Mountainous terrain, give it some gear.

 

[Haf-E]

33 inch tires are cheaper and often last longer than 35 inch tires which are more expensive.

Gearing also depends on if it is a low or high top and if you are planning on bolting on a lot of things - kayaks / bikes etc.

You can always swap in the rear axle sooner and add a locker to get the feel for what you are planning. harder if it requires a wheel / bolt circle change though. I have one friend who did the F&R axle swap years before he got the transfer case and fuel tank modified - so that is even an option to consider.

 

[Kenyi]

@- Chris Steuber. Thanks for reply I know you’re busy. I will do the 4.10 re-gear then I don’t think its heavy loaded I got pretty much what everybody else have bed frame, drawers with kitchen stuff, camping gear and tools. On the hitch, I just carry 2 MTB on a Thule hitch rack. I’m not keeping the stock axle going to replace it with a Sterling 10.5 from a F250/F350. 05-07 info that I got according your web site. I hope I’m doing everything right please correct/advise me if I’m doing something wrong. After that a purchase from U-joint offroad for the rest of all the parts that I’m going to need for a 6” conversion.

@-Half-E Thanks for the info rethinking ill probably follow your advice and start whit 33” if I’m happy whit them I’ll stick to it if not I’ll try the 35” when the 33'' wear out hahahaha. The conversion is going to be made in 2 stages so probably front and rear are going to be done at the same time