I decided to re-gear

[2014 Warthog]

I think we are saying the same thing. If you add the rotations made by both front wheels and compare it with rotations made by both rear wheels, and come up with a significant delta you will have binding. What I don't quite grasp yet, is how this delta/binding is not additive over time/distance and what would be considered significant. I feel there must be some part of the system that relieves tension beyond the tires slipping. Otherwise, even very slight turns would eventually add up to a bind. Maybe I'm over thinking it and the reality is that it would take a bunch of miles of gradual turns to come up with a noticeable delta front to rear.

Just to clarify, I'm talking about dry even pavement here. The tires obviously slip on slick uneven terrain without issue.

Oooh I see, yeah. With gradual turns the lugs on the tires can bend a little bit each relieving the stress gradually over the turn, but you are wearing the tires out a little faster having more side stress put on the lugs that way. But a tight turn requires way too much differential movement and the lugs cant bend that far and finally just start skidding/squealing/hopping instead.

Even on in 2wd, the tires wear from the differential in distance traveled while cornering just from the width of the tire itself! I.e. The outter part of the tire travels less than the inner part on the tire inside of the turn. My soft rubber AT tires leave nice "prints" in the driveway if I am turning sharply on it due to them slightly slipping/rubbing on the cement

 

[Bilbo]

Absolutely the direction of the turn matters. Let's say you were making all left turns on a mile drive. Your front left tire would travel the least distance and the right rear would travel the most distance. Now if we reversed it and made all right turns for a mile the right front would travel the least distance and the left rear would travel the greatest. Let me put some numbers out here:

-Going through a one mile left turn that makes a 90 degree direction change.
-285 tires (for ease of math let's say 33" tire or 103.67" circumference = 8.64'.)

Roughly, your outside right rear tire would travel around 5 feet further than your inside left front tire. That's over a half a revolution. Conversely going the other direction the tires would swap.

In reality, your tires will scrub, you will lose or gain due to bumps or potholes, etc and everything will be fine. This example is a really gentle turn on an interstate but the rotational differences are there. ...

I'm also confused about this. When I look at the photos in http://www.toyota-4runner.org/5th-gen-t4rs/133871-using-part-time-4wd-dry-pavement-te-sr5.html it appears that on a right turn, the front left travels farther than the rear left, and the front right travels farther than the rear right. The same would be true when turning left. On average, the front axle wheels travel farther than the rear axle wheels regardless of direction of the turn.

As you've said, the effect may be trivial. I never saw a problem leaving my SR5 in 4WD when driving open highways that alternated between dry and snowy sections.

 

[wfo9]

I'm also confused about this. When I look at the photos in http://www.toyota-4runner.org/5th-gen-t4rs/133871-using-part-time-4wd-dry-pavement-te-sr5.html it appears that on a right turn, the front left travels farther than the rear left, and the front right travels farther than the rear right. The same would be true when turning left. On average, the front axle wheels travel farther than the rear axle wheels regardless of direction of the turn.

As you've said, the effect may be trivial. I never saw a problem leaving my SR5 in 4WD when driving open highways that alternated between dry and snowy sections.

Yea, the direction of the turn is irrelevant to binding.

I'm not sure what [MENTION=66316]1engineer[/MENTION] was sipping on yesterday. I think he was actually talking about his experiment with marking the tires with chalk, but that is not really related to binding with open diffs.

I drove in 4wd yesterday on dry pavement and did not notice any binding at all. I just switched back to 2h for intersections where I needed to make a 90* turn. Besides intersections, most 35+ mph roads only require the steering wheel to go about 5-10* off center.

I thought about it a bit more yesterday as I was ripping turns on my mountain bike, and although not quite the same on 4 wheels, some of the same physics are at play. I think the reality is that most of a turn at speed is done with contact patch/camber change alone. Plus, there is more slipping of the tire lugs than one would think.

Back to [MENTION=78273]Jeremy556[/MENTION]'s statement. You are fine as long as moving at some speed. He said 20mph. That might be pushing it a tad. To be 100% safe, I think if you can take the turn at 35mph you won't bind at all.

 

[1engineer]

Yea, the direction of the turn is irrelevant to binding.

I'm not sure what [MENTION=66316]1engineer[/MENTION] was sipping on yesterday. I think he was actually talking about his experiment with marking the tires with chalk, but that is not really related to binding with open diffs.

I drove in 4wd yesterday on dry pavement and did not notice any binding at all. I just switched back to 2h for intersections where I needed to make a 90* turn. Besides intersections, most 35+ mph roads only require the steering wheel to go about 5-10* off center.

I thought about it a bit more yesterday as I was ripping turns on my mountain bike, and although not quite the same on 4 wheels, some of the same physics are at play. I think the reality is that most of a turn at speed is done with contact patch/camber change alone. Plus, there is more slipping of the tire lugs than one would think.

Back to [MENTION=78273]Jeremy556[/MENTION]'s statement. You are fine as long as moving at some speed. He said 20mph. That might be pushing it a tad. To be 100% safe, I think if you can take the turn at 35mph you won't bind at all.

I was completely backwards. That's what happens when you are doing three things at once.

 

[TheWraith]

when you re-gear for 4.56 what do you do to adjust the speedo ???

 

[Jeremy556]

when you re-gear for 4.56 what do you do to adjust the speedo ???

No. For whatever reason, the dash ignores the speedo input from the transmission, and uses the wheel speed sensors for speedometer and odometer.

 

[TheWraith]

No. For whatever reason, the dash ignores the speedo input from the transmission, and uses the wheel speed sensors for speedometer and odometer.

no thats awesome ... so I can even go 4.88 ??? and not have any issues with the speedo being off ...

 

[bimrunner]

No. For whatever reason, the dash ignores the speedo input from the transmission, and uses the wheel speed sensors for speedometer and odometer.

Interesting. However, I'm off by about 7% give or take. This has been confirmed for me through comparison driving (wife following etc and sat (stand alone nav unit) and the dumb little radar signs showing your speed versus the speed limit). I agree it has nothing to do with the gearing. It does have to do with tire size. Since most of us run larger tires when we re-gear, it would make sense that our speedo is off (a reading on the speed sensor would be off due to less revolutions/second on a larger wheel). Just trying to make sure it is clear for others out there what to expect. Happy to be corrected though.

 

[bimrunner]

no thats awesome ... so I can even go 4.88 ??? and not have any issues with the speedo being off ...

Once they are available from Yukon. As of the last time I looked, only Nitro gears in 4.56 were offered. That should be good up to about 35s. Some go as high as 37s on that but really 4.88 would be better for 37s. It is just a lot of work to go to 37s.

 

[TheWraith]

Once they are available from Yukon. As of the last time I looked, only Nitro gears in 4.56 were offered. That should be good up to about 35s. Some go as high as 37s on that but really 4.88 would be better for 37s. It is just a lot of work to go to 37s.

Ive had 4.88's before on my tundra and loved the extra pepped it gave it even with the 16.5x12 weld wheels on 33x12 tires ...

So 4.56 is the way to go huh ??? Ohh well I dont plan on pushing anything bigger than 33's ... might just stay with 4.56

 

[bimrunner]

Ive had 4.88's before on my tundra and loved the extra pepped it gave it even with the 16.5x12 weld wheels on 33x12 tires ...

So 4.56 is the way to go huh ??? Ohh well I dont plan on pushing anything bigger than 33's ... might just stay with 4.56

4.56 with 33s and the speedo is so close you can call it accurate. It is maybe off by a 3.5% but you really won't notice that difference unless you are going 100MPH... It does feel much more responsive with 33s. Noticed a big difference when I went to 34s (more like a slight improvement over stock). I'd guess you'd be way low at 4.88 with 33s.

 

[Jeremy556]

Once they are available from Yukon. As of the last time I looked, only Nitro gears in 4.56 were offered. That should be good up to about 35s. Some go as high as 37s on that but really 4.88 would be better for 37s. It is just a lot of work to go to 37s.

Nitro released 4.88 gears for the 8.2 in August.
Nitro Gear 4.56 Ring & Pinions for 2010+ FJ Cruiser, 4runner, Prado 150*Rear - New Products - Nitro Gear & Axle

 

[bimrunner]

Nitro released 4.88 gears for the 8.2 in August.
Nitro Gear 4.56 Ring & Pinions for 2010+ FJ Cruiser, 4runner, Prado 150*Rear - New Products - Nitro Gear & Axle

Excellent! I probably will go to 4.88 in the rear when I SAS. Depending on what size I can go up to for tires will probably determine it for me.

 

[nevada]

Yea, the direction of the turn is irrelevant to binding.

I'm not sure what [MENTION=66316]1engineer[/MENTION] was sipping on yesterday. I think he was actually talking about his experiment with marking the tires with chalk, but that is not really related to binding with open diffs.

I drove in 4wd yesterday on dry pavement and did not notice any binding at all. I just switched back to 2h for intersections where I needed to make a 90* turn. Besides intersections, most 35+ mph roads only require the steering wheel to go about 5-10* off center.

I thought about it a bit more yesterday as I was ripping turns on my mountain bike, and although not quite the same on 4 wheels, some of the same physics are at play. I think the reality is that most of a turn at speed is done with contact patch/camber change alone. Plus, there is more slipping of the tire lugs than one would think.

Back to [MENTION=78273]Jeremy556[/MENTION]'s statement. You are fine as long as moving at some speed. He said 20mph. That might be pushing it a tad. To be 100% safe, I think if you can take the turn at 35mph you won't bind at all.

im a bit late here, it looks like maybe you've got it all figured out.
but here is a vid that explains things nicely.





it shows how in a curve, all 4 tires are going a different speed.

 

[wfo9]

Finally got out last weekend and played a little off-road. It was much improved capability overall. The lockers worked fantastic. I did find one off camber situation where a-trac was a much better choice as fully locked just caused me to pitch the rear too much, but besides that it was awesome to just slowly crawl up steep stuff. Overall, I think you get more bang for the buck out of tires and suspension (since we already have a-trac), but the selectable locker plus the better crawl speed sure are sweet icing on the cake. I think my next mod is long travel in the rear. Below are a few pics of the fun.

I did not get any pictures of the steep climbs, but it sure was a goat in the rocks. Still got stuck when my rear lower link mount would catch something.

 

[fattire]

It's a total mountain goat! It will be interesting to see how the LT helps (or doesn't?) with some of the obstacles we got hung up on.

I may just start with adding links to what I have and see where that gets me.

 

[wfo9]

It's a total mountain goat! It will be interesting to see how the LT helps (or doesn't?) with some of the obstacles we got hung up on.

I may just start with adding links to what I have and see where that gets me.

Hey wheeling buddy,

I think the key for those steep ledges is hitting it with a better angle of attack, Which is scary without better down travel. At least that is my going theory at the moment. Your down travel is much better than mine in the rear, but I'm not sure if dropping my swaybar will help much with my springs....

Here are a few pics of [MENTION=809]fattire[/MENTION]s rig. We had a good time. You will see that his articulation is much better than mine.