Thoughts on 4WD vehicles and winter weather...

[king nothing]

There's what brake pads are applying, and that doesn't change with switching to 4wd. But now the braking force is getting distributed to all 4 wheels in an even fashion, in the same way that acceleration is spread among all 4 wheels.



I hope I explained it better.

No..... this might be true if you had spools in both axles. All 4 wheels ARE NOT locked together like you seem to think. your brake bias is still heavily toward the front. the braking power of the front brakes is not distributed through the driveline

 

[SonicDTR]

No..... this might be true if you had spools in both axles. All 4 wheels ARE NOT locked together like you seem to think. your brake bias is still heavily toward the front. the braking power of the front brakes is not distributed through the driveline

It would still be transferred to the rears if the front locks up, unless you have a center diff...oke:

 

[DevilSun]

It's always been said that in most cases a 4wd is no better than 2wd in the snow or ice because all it does is help you accelerate faster, but doesn't help you turn or stop.

Copious amounts of logic fail have created this thread

 

[OhIIICobra]

That doesn't disprove that it affects the braking bias. I should clarify.

There's what brake pads are applying, and that doesn't change with switching to 4wd. But now the braking force is getting distributed to all 4 wheels in an even fashion, in the same way that acceleration is spread among all 4 wheels.

So the front pads are applying more force than the rear, but now the 4wd system locks it in so that all braking is shared. I feel this is more important in slick conditions, because there is less need for front bias, as there is less ability to cause weight transfer.

Try driving a truck in 2wd in snow, and hit the brakes. In my experience, the ABS kicks on fast because the front bias is too strong. By switching to 4wd, the front braking is now shared along with the back tires. I've found it allows much better stopping.

I hope I explained it better.

No. When you are in 4WD you simply have more engine braking due to the front axle.

Nothing changes with brake bias.

 

[black92]

Tractorman- Are you trying to say that when 4x4 is engaged, brake bias gets spread out more evenly? So in 2wd, more power is on the two front wheels and when engaged to 4wd, the computer will make the brake bias more even?

I really doubt most vehicles will change the brake bias when 4x4 is engaged. It's pretty much as fiveohstang said and I'll leave it at that.

 

[black92]

No. When you are in 4WD you simply have more engine braking due to the front axle.

Nothing changes with brake bias.

This is what I tried to explain in my first post. Thanks for making more sense

 

[Jroc]

Not in todays world unless you put spools in front and rear diffs.

4WDs come with limited slip diffs to allow for turning and have for years.

Well IDK, but you try to run 4WD in my dads 97 F150 on the pavement, and it doesn't work so good when you turn. :shrug:

 

[Tractorman]

No..... this might be true if you had spools in both axles. All 4 wheels ARE NOT locked together like you seem to think. your brake bias is still heavily toward the front. the braking power of the front brakes is not distributed through the driveline

No, you don't need spools. Why? I think you fail to understand how a 4wd system works. The front and rear axles spin at the same speed. Left and right might spin at different speeds due to a differential, but front to back is equal in a 4wd system.

If you completely disconnected the rear brakes, and were in 4wd drives, and slammed the brakes, the front and rear axles will both stop if the front has enough braking power. I did it plenty on a 4 wheeler when you can just use the front or rear brakes seperately.

It would still be transferred to the rears if the front locks up, unless you have a center diff...oke:

You seems to get where I'm going with this.

Copious amounts of logic fail have created this thread

Care to explain who and why?

No. When you are in 4WD you simply have more engine braking due to the front axle.

Nothing changes with brake bias.

How is there more engine braking? Engine braking comes from the engine. Do you get more engine? No.

The front pads are still applying the majority of the braking force. I'm not saying that changes. But when locked into 4wd (and yes, I know there are differtials, but for our purposes, they don't matter, as all tires are getting equal side to side braking force) then the braking force is spread among front and rear axles, because the transfers case ties them together. If they didn't, then when the front brakes lock up, the rear tires would still spin.

Tractorman- Are you trying to say that when 4x4 is engaged, brake bias gets spread out more evenly? So in 2wd, more power is on the two front wheels and when engaged to 4wd, the computer will make the brake bias more even?

I really doubt most vehicles will change the brake bias when 4x4 is engaged. It's pretty much as fiveohstang said and I'll leave it at that.

No, nothing with the computer changing brake bias. Its a mechanical change.

This is what I tried to explain in my first post. Thanks for making more sense

Thanks for keeping it (mostly) thoughtful discussion.

 

[02 Min Grey GT]

Take a look at the brakes on most vehicles that are not a "sports car". Usaully the front brakes have bigger discs with bigger calipers. Including trucks, I believe. How would switching into 4wd make up for that?!

My truck has rear drum brakes, because the fronts do the majority of the braking whether I am in 2wd or 4wd. OP is clueless it seems.

 

[Tractorman]

Take a look at the brakes on most vehicles that are not a "sports car". Usaully the front brakes have bigger discs with bigger calipers. Including trucks, I believe. How would switching into 4wd make up for that?!

My truck has rear drum brakes, because the fronts do the majority of the braking whether I am in 2wd or 4wd. OP is clueless it seems.

What's your point? Are you saying its possible to lock up the front tires and not the rear when in 4wd? You can't because front and rear axles are locked at the transfer case. If so, explain with some LOGIC instead of acting like a FLAMER.

 

[SonicDTR]

You can test this concept by putting your vehicle in 4wd, finding a loose surface and locking up the e-brake...I believe you'll find that all 4 tires lock up if the rears lock up(not all e-brakes work that well...)

 

[Silver2003Cobra]

4wd shifts the brake bias because the front brakes that do most of the stopping are now stopping the rear at the same time, since the 4wd ties them together.

4wd doesn't handle any better in the snow. If it did, I wouldn't see more trucks and SUV's in the ditch compared to cars. 4wd is good for getting retards going too fast for conditions. When you hit ice, it doesn't matter if you have 4wd or 2, physics will over ride it all.

For those drinking hatorade: http://www.4x4abc.com/jeep101/safe.html Or search the interweb on your own.

there's a few mis-conceptions here.. unless your center differential (transfer case etc) is locked, either the front end or rear end will be getting all the power (same thing that happens on a hotchkiss rearend, the one that slips gets all the power) not many people drive around with the transfer case locked..

now for why a 4x4 is better in incliment weather, they aren't.. UNLESS you have the tires that can take advantage of the extra traction. If your running around on the stock tires, no your not going to get much of an advantage.. but on my 4x4's I run BFG All Terrains.. and YES it's MUCH better in the snow, icy roads etc than any highway oriented tire, both in acceleration and stopping.. (and turning, since I can floor it, and have the front wheels pulling the vehicle sideways if needed)

 

[02 Min Grey GT]

You can test this concept by putting your vehicle in 4wd, finding a loose surface and locking up the e-brake...I believe you'll find that all 4 tires lock up if the rears lock up(not all e-brakes work that well...)

My e-brake has been removed because it kept locking up (my truck is a 1988). However, it only locked up one tire. It would work the same whether the truck is in 4wd or not. I don't even think "e-brakes" are connected to all four wheels anyway, are they? They are really more of a parking brake than an emergency brake.

 

[Silver2003Cobra]

You can test this concept by putting your vehicle in 4wd, finding a loose surface and locking up the e-brake...I believe you'll find that all 4 tires lock up if the rears lock up(not all e-brakes work that well...)

only if you have 2 things on your vehicle.. #1 the transfer case is locked, and you have a locker or limited slip on the front axle (99.99999% of all 4x4's dont have this)

 

[02 Min Grey GT]

What's your point? Are you saying its possible to lock up the front tires and not the rear when in 4wd? You can't because front and rear axles are locked at the transfer case. If so, explain with some LOGIC instead of acting like a FLAMER.

Yes, I would say that in a situation with limited traction (not just slamming on the brakes on dry pavement) you could not only lock up the front tires with locking up the rears, but you could actually lock up only one tire, regardless of which axle it is on.

The transfer case, axles, differentials, etc. only have to do with where the power is being sent, not the braking force. If you can't LOGICALLY comprehend that, then you are beyond the help of anyone on this board.

 

[SonicDTR]

only if you have 2 things on your vehicle.. #1 the transfer case is locked, and you have a locker or limited slip on the front axle (99.99999% of all 4x4's dont have this)

Even with an open diff, one of the front tires would lock up, if you locked up both rear...or vice-versa.

All of this is assuming the t-case is in fact locked, and no center diff involved.

*edit* I'll make a video to illustrate this...gimme a min...*edit2* see video in my below post...

 

[Jroc]

there's a few mis-conceptions here.. unless your center differential (transfer case etc) is locked, either the front end or rear end will be getting all the power (same thing that happens on a hotchkiss rearend, the one that slips gets all the power) not many people drive around with the transfer case locked..

now for why a 4x4 is better in incliment weather, they aren't.. UNLESS you have the tires that can take advantage of the extra traction. If your running around on the stock tires, no your not going to get much of an advantage.. but on my 4x4's I run BFG All Terrains.. and YES it's MUCH better in the snow, icy roads etc than any highway oriented tire, both in acceleration and stopping.. (and turning, since I can floor it, and have the front wheels pulling the vehicle sideways if needed)

BFG All Terrain T/A's are the shiznit. Great tire. Pretty much all my friends with 4wd trucks that aren't running some insane tires run them, as does my mom on her 08 F150.

 

[SonicDTR]

Here, this should illustrate what I said earlier...let me know if you all would like any other examples.

The truck is a traxxas mini e-revo brushless. It is full shaft driven out of the transmission, NO center diff, and front and rear diffs are both open differentials...

[youtube_browser]hPk7noZrNrA[/youtube_browser]

 

[OhIIICobra]

How is there more engine braking? Engine braking comes from the engine. Do you get more engine? No.

:rollseyes


You're really confused. :lol1:

You get more (~50%) engine braking due to the increased rotational mass of all the 4WD components in the front axle being physically connected to the drivetrain through the transfer case and responding when you lift the throttle vs just the ass end of the vehicle responding in 2WD. Manual transmissions benefit more.

If you lock in the hubs on any old 4x4 put it in 4L, romp on it and quickly let off you will experience a very pronounced increase in engine braking vs. 2WD.

 

[OhIIICobra]

This is what I tried to explain in my first post. Thanks for making more sense

Yeah, evidently he still fails to comprehend though. :shrug: