ABS question

[ticker]

I think that my R50 has ABS on the front brakes where as my WD21 only had it in the rear, although I never recall it working. I find the ABS really annoying. Is it possible to disable it easily so I can see the difference? right now if there is the tiniest bit of snow it makes a horrible noise as the ABS kicks in. It doesn't seem to be helping me stop any better and its actually really distracting. Can I just pull the fuse?

Thanks

[alexrex20]

yes, you can just pull the fuse to disable ABS. be sure you "feel the difference" on an empty road or parking lot, because trust me - there is a difference.

 

arguably though, ABS is a hinderance in low-traction situations like mud, snow, wet grass, etc. but is generally a good thing on the street.

[XPLORx4]

Your R50 has 3-channel ABS (right front, left front, rear). ABS is not intended to help you stop faster, although in emergency stops it can help reduce braking distance because the tires aren't skidding. ABS is primarily intended to help you maintain control of the vehicle during braking, especially on slippery surfaces.

 

This is normal. To disable it, you could just pull the fuse, or you could unplug one of the ABS sensors on either the rear trailing arms or the front struts.

[alexrex20]

To disable it, you could just pull the fuse, or you could unplug one of the ABS sensors on either the rear trailing arms or the front struts.

 

 

perhaps nissan made it too easy to unplug the rear ABS sensors. the stick on the beach made real short work of it on the last fishing trip.

 

but to add to my first post: ABS will save your ass 9 times out of 10, unless you're pretty damn good at threshold braking, and can unhesitatingly counter-intuitively let off the brakes once you've locked them up, to allow the tires to regain traction. in theory it sounds pretty simple, but most people find it hard to let off the brakes when they're closing in on that ditch or pole or pickup truck at a speed decidedly higher than they'd like. everyone's reaction is to push harder on the brakes; a reaction catered and encouraged by ABS-equipped brakes.

 

disable your ABS at your own risk.

[Kingman]

It's also a lot safer to have ABS if you have bald tires up front, less gripping force makes it a whole hell of a lot easier to lock them up and wreck.

[ticker]

Good points made. The only vehicle I have ever owned with ABS was the wd21, and as I said I'm pretty certain it was't working. So I guess that I'm not to worried about being used to having it. It's good to know I can pull the plug so to speak on the ABS so I can test it out. There may be something wrong with mine anyway since it makes such a god-awful noise when it kicks in. I let you know how it goes. Its snowing right now so well see how it goes later.

Edited January 13, 2009 by ticker

[tekazgtr1984]

What's the nature of the noise?

[XPLORx4]

What's the nature of the noise?

 

Probably a loud humming/thumping sound.

[tekazgtr1984]

Probably a loud humming/thumping sound.

 

Mine's just a low-pitched mechanincal hum... As far as I know that's normal...?

[alexrex20]

Good points made. The only vehicle I have ever owned with ABS was the wd21, and as I said I'm pretty certain it was't working. So I guess that I'm not to worried about being used to having it. It's good to know I can pull the plug so to speak on the ABS so I can test it out. There may be something wrong with mine anyway since it makes such a god-awful noise when it kicks in. I let you know how it goes. Its snowing right now so well see how it goes later.

 

 

the problem i have with rear-only (1-channel) ABS is that it really never turned on! front brakes do the vast majority of your braking, so if you ever had to slam on the brakes, it's the front brakes that will lock up first. in fact, unless you're in the snow/ice/mud/sand, you can almost be sure that you'll never lock up the rear tires. it is good to have rear ABS, if nothing at all, because rear ABS will at least make you lose control in only one direction. if you were to lock up all four tires, you would lose control and be spinning in circles.

 

so, just because you never felt them work, does not mean they did not work. it just means that you were never so cocky screwed that your rear ABS engaged.

 

 

 

and that noise that you're hearing is the noise that all ABS systems make. the point of an ABS system is to allow the tires to maintain traction by preventing them from locking up. (the coefficient of static friction is greater than that of sliding friction; you have more grip when you're not skidding, obviously.) to do this, the ABS pump will pulse the brakes hundreds of times per second, effectively never giving the tires the chance to really lock up. we as humans could pulse the brakes maybe 2 times per seconds - 3 times if we're lucky. so not only does an ABS system have the ability to infinitely pulse the brakes until traction has been regained, but it can also unerringly complete the task. not all of us have the know-how or self-control to pulse the brakes in an emergency situation.

 

but back to the noise: the noise and vibration in the pedal is feedback from the ABS pump doing its thing - pulsing hundreds of times per second.

[tekazgtr1984]

I still think Nissan really dropped the ball by not making rear discs... With two-channel rear ABS. Bah!

[XPLORx4]

front brakes do the vast majority of your braking, so if you ever had to slam on the brakes, it's the front brakes that will lock up first. in fact, unless you're in the snow/ice/mud/sand, you can almost be sure that you'll never lock up the rear tires.

 

Actually, you have that backwards. When braking, the weight shifts forward, increasing the weight, pressure, contact patch, and therefore, the traction of the front tires, decreasing the weight, pressure, contact patch, and traction of the rear tires. With heavy braking applied to the rear tires which now have reduced weight and traction, the rear tires will lock up much more easily than the front.

 

Have you ever ridden a mountain bike and squeezed the front and rear brakes tightly (without sending yourself over the handlebars)? Which tire locks up first? (Hint: it's not the front.)

[tekazgtr1984]

Have you ever ridden a mountain bike and squeezed the front and rear brakes tightly (without sending yourself over the handlebars)? Which tire locks up first? (Hint: it's not the front.)

 

If one's smart enough not to mix up the levers...

[alexrex20]

Actually, you have that backwards. When braking, the weight shifts forward, increasing the weight, pressure, contact patch, and therefore, the traction of the front tires, decreasing the weight, pressure, contact patch, and traction of the rear tires. With heavy braking applied to the rear tires which now have reduced weight and traction, the rear tires will lock up much more easily than the front.

 

Have you ever ridden a mountain bike and squeezed the front and rear brakes tightly (without sending yourself over the handlebars)? Which tire locks up first? (Hint: it's not the front.)

 

it's a bit naive and irresponsible to compare a truck to a mountain bike. the bike has individually controlled brakes, where the truck's brakes aren't infinitely variable.

 

moreover, our trucks have rear drum brakes which by application receive only a small percentage of braking pressure. regardless of weight transfer, on a disc/drum setup the front will always be doing more work. forget your bike, slam on your truck brakes and see which lockup first.

[XPLORx4]

it's a bit naive and irresponsible to compare a truck to a mountain bike. the bike has individually controlled brakes, where the truck's brakes aren't infinitely variable.

 

moreover, our trucks have rear drum brakes which by application receive only a small percentage of braking pressure. regardless of weight transfer, on a disc/drum setup the front will always be doing more work. forget your bike, slam on your truck brakes and see which lockup first.

 

Naive? Irresponsible? Wow. The example was only intended to be an illustration of the effect of weight transfer on braking.

 

Where did you get your facts from? Do you have any references that explain how rear drum brakes "by application receive a small percentage of braking pressure"? While it is true that the front brakes always do more work than the rear, they do this because of the forward weight transfer inherent to braking, not because of the brake configuration. Even vehicles with 4-wheel disc brakes or 4-wheel drums (older cars) have the same issues: front brakes work harder than the rear. Only if the [non-ABS] braking system and chassis are paired and tuned properly will the appropriate tires lock to provide predictable handing.

 

BTW, what did you mean with this statement?

it is good to have rear ABS, if nothing at all, because rear ABS will at least make you lose control in only one direction. if you were to lock up all four tires, you would lose control and be spinning in circles.

Edited January 14, 2009 by XPLORx4

[alexrex20]

Naive? Irresponsible? Wow. The example was only intended to be an illustration of the effect of weight transfer on braking.

 

Where did you get your facts from? Do you have any references that explain how rear drum brakes "by application receive a small percentage of braking pressure"? While it is true that the front brakes always do more work than the rear, they do this because of the forward weight transfer inherent to braking, not because of the brake configuration. Even vehicles with 4-wheel disc brakes or 4-wheel drums (older cars) have the same issues: front brakes work harder than the rear. Only if the [non-ABS] braking system and chassis are paired and tuned properly will the appropriate tires lock to provide predictable handing.

 

 

it should be common knowledge (especially to someone as learned as you) that the rear brakes receive less brake pressure than the front via a proportioning valve (or some other device of the same purpose). the front brakes do more work, so they receive more pressure. they receive more pressure, so they are the first to lockup. if you don't want to disable your ABS to see if i'm right, so be it. that doesn't change the fact that your front brakes will lockup first. and you're right: it is the same with all braking systems, whether they're disc/disc or disc/drum or drum/drum. there's a reason why the front brakes are (usually) larger than the rears in a disc/disc setup, or the fronts are disc and the rear are drums. the physics of dynamic weight transfer dictate such.

 

not only do the fronts do more of the work and receive more pressure, but in our specific case (with a disc/drum setup), the drums themselves cannot even provide as much clamping force as discs. so even if your brakes were rear-biased, your front brakes will still be doing more work. and will lockup first.

 

 

BTW, what did you mean with this statement?

if you have no ABS, and lockup all 4 tires, there's a good chance that you will spin wildly and uncontrollably, because all 4 tires will have zero traction. if you at least have rear ABS, even if you lockup your front tires, you will still track reasonably straight because your rear tires will not lose traction. of course, you will have no steering ability, but at least the rear tires will still have traction and allow you to continue forward in a straight line. both instances would be considered a loss of control, albeit the latter notably less so.

[Simon]

Alex is correct in this case. The proportioning valve shifts braking power to the front for more stopping force there. This is decreased in a case where you're carrying a heavy load, or trailering.

 

The rear ABS equipped WD21's don't seem to give the driver the typical feel of ABS. I've never felt it kick in, on either of my trucks, but I know it's equipped. I've also never locked up the rear brakes, except when in 4wd, which automatically disables the rear ABS.

[Kingman]

I've never been able to lock up the rear brakes on my WD21, only the fronts. Even with new rear pads, the only time they lock up is if I pull the e-brake. The front's lock up, but only after a lot of force at the pedal.

[Pezzy]

Ticker, as Simon mentioned, I too have never felt the ABS in his WD21, but in the R50, it scares the crap out of me, more than the fact that I am sliding.

 

My old truck (mazda B2200) only had ABS in the back, and I never felt it. So it comes as a shock when the ABS kicks in on my pathy, feels like it shakes the entire truck.

[ticker]

Ticker, as Simon mentioned, I too have never felt the ABS in his WD21, but in the R50, it scares the crap out of me, more than the fact that I am sliding.

 

My old truck (mazda B2200) only had ABS in the back, and I never felt it. So it comes as a shock when the ABS kicks in on my pathy, feels like it shakes the entire truck.

Thats exactly what it feels like, and the noise mine make just sounds wrong. Kind of grindy and slow and loud!, as opposed to the stutter of other ABS I have felt. I'm going so slow when it kicks in that I feel like it is more detrimental then anything else. I guess I don't like the vehicle making a decision for me. The R50 is so much smoother and quiter then the Wd21, I'm already feeling like i'm not as in touch with the outside world, this just adds to that feeling of isolation.

[tekazgtr1984]

I find the ABS a little more sensitive too, when compared to other vehicles I've driven. I would assume it's just the way it was designed so I'm uncertain if much can be done to modify or change this system. Compared to my '93 Blazer, the ABS on the R50 is a lot more sensitive.

[nissandoms47]

Ha,you guys should go drive an audi in the snow.

[tekazgtr1984]

Ha,you guys should go drive an audi in the snow.

 

Does a VW Jetta 1.8T come close?

[alexrex20]

I find the ABS a little more sensitive too, when compared to other vehicles I've driven. I would assume it's just the way it was designed so I'm uncertain if much can be done to modify or change this system. Compared to my '93 Blazer, the ABS on the R50 is a lot more sensitive.

 

 

larger tires will make ABS more sensitive. remember, ABS uses wheel speed to determine whether or not a tire has locked up. the larger the tire, the more exaggerated the speed differential will be among the 4 tires, during the same amount of slip compared to stock tires. effectively, it will take a smaller amount of lockup to trigger the ABS.

[ticker]

Ha,you guys should go drive an audi in the snow.

oddly enough that is the other vehicle that I have driven with ABS that actually kicked in. I remember not liking the feeling then either, but it was definitely more refined. Audi Allroad, It was one of my favorite vehicles that I had driven, and I considered buying one instead of the R50, but was scared off by maintenance costs.