Re-gearing from 3.73 to 4.10?

[tedujam]

Anyone have a good explanation or link for what's involved (and costs)?


This is for a 2009 E350 with a Ujor 4x4 coil conversion.

[carringb]

That's such a small, nearly imperceivable, change that it won't be worth it. Even on paper, it only increase the GCWR by 1,000 pounds. Basically, axle shafts have to be pulled (which means pulling the knuckles up front), R & R the ring and pinion.

Depending on local labor rates, assume ~$700 per axle. More if you upgrade to lockers at the same time.

What size tires do you have? V10 or V8? I'm not saying you shouldn't swap gears, but if you're going to do it, might as well do it right.

[tedujam]

Originally Posted by carringb

That's such a small, nearly imperceivable, change that it won't be worth it. Even on paper, it only increase the GCWR by 1,000 pounds. Basically, axle shafts have to be pulled (which means pulling the knuckles up front), R & R the ring and pinion.

Depending on local labor rates, assume ~$700 per axle. More if you upgrade to lockers at the same time.

What size tires do you have? V10 or V8? I'm not saying you shouldn't swap gears, but if you're going to do it, might as well do it right.

I'm going from a 31" wheel/rim setup to 33-35". I was told I really need to bump my gears, but I'm really not excited about spending any more $$ anyway.

[RememberTheFallen]

Originally Posted by tedujam

I'm going from a 31" wheel/rim setup to 33-35". I was told I really need to bump my gears, but I'm really not excited about spending any more $$ anyway.

I think the engine would matter a lot. 5.4 would certainly need an upgrade but a 6.0 diesel might not even notice it.

[SheepShagger]

Originally Posted by tedujam

I'm going from a 31" wheel/rim setup to 33-35". I was told I really need to bump my gears, but I'm really not excited about spending any more $$ anyway.

What engine? I’ve got 6.0 diesel with 35s and 4.10s, I’d much prefer to have 3.73, but the cost of swapping 2 axles isn’t worth it. But if you have 5.4 v8 I can see the need, You may even want to go higher than 4.10s.
But personally I’d put the wheels tires on first, then decide, you may be fine with it.

[carringb]

Yup. Put the tires on first. The difference between 33" and 35" is enough to decide between 4.30 and 4.56 gears

[tedujam]

It's 5.4 V8

[carringb]

Your 4r70 transmission won't last long with taller tires if you don't re-gear, if you go taller than a 32". This would be equivalent to having 3.55 gears now, which is about as tall as you want to go.

That said... you could get by for a while if you're careful, especially backing. If you get on a steep slope, and you're over-geared, just use "2WD-low" so you aren't spinning the torque converter too much. But the longer you drive with taller tires, and stock gears, the sooner you'll have to replace the tranny. Reverse is a taller ratio than first (more like 1.5) so that's why backing can be an issue.

[tedujam]

Thanks for all the feedback. I'm now looking at BFG Mud Terrain 255/75R17s or Nitto Terra Grappler 285/70R17s. Neither of them are bigger than 32.7 inches, so it sounds like I should just stick with my 3.73 gearing.

[REF]

2 very different tires....the Nitto Ridge Grapplers are more comparable to the BFG A/T than the M/T, although they are a hybrid, I’d say go with the Nitto’s between the 2, better for mixed use and quieter on hwy, M/T tires are really lousy on anything other that mud and loud on hwy. I’ve been happy with the Goodyear Duratracs