Anti Lock Brakes upgrade for our cars?

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Re: Anti Lock Brakes upgrade for our cars?

Post by thatfnthing on Thu Feb 14, 2013 11:05 am

geoff528 wrote:typically there are 2 circuits 1 runs the pump this is usually a 40amp maxi fuse and the other if for the module and its only around 25amp fuse. Not exactingly sure how much it draws but wen the pump is activated on most vehicles u see all the dash lights and stuff dim down ... this is with around 100amp alternator and new battery so if u have a low amp alternator u may wont to swap tht out for something better and use the corresponding alternator wire for the new alternator, but if its around 100amp i wouldnt worry about upgrading the alternator or wiring. Hope this Helps Smile

In the Caprice system there are 2 circuits: the computer and the modulator.

The computer draws very little, maybe 1A. It's a computer. More current would kill it. The reason it's on a 15A (not 25A) fuse is because that supply also feeds the airbag controller, the torque converter clutch, the daytime running lights module, the twilight sentinel, the day/night mirror, the audio alarm, the rear defogger control, the fluid warning system, and the entire instrument cluster.

The modulator (which is not a pump -- this is another misconception) draws current directly from the battery via a fusible link. It uses a 30A rated automotive relay, so the draw technically can't be more than 30A, but is usually more like 20A.

As for whether an upgrade is needed to the alternator, that will depend on what other electrical loads the system has. If you have no other high-draw loads (i.e. no a/c, no electric fans, etc.), you can probably get away with a 60A alternator. However, it's always best policy to have the largest amperage alternator you can get in order to ensure every system has sufficient juice available. No such thing as an alternator that is "too large".

Further, making a significant change in alternator amperage will necessitate a larger gauge feed wire -- IIRC our cars typically came with a 12ga feed wire, which will not handle the output of a 100A or higher alternator with a significant load on it. I use a 4ga wire, though 8ga would probably do.

If the lights dim when the ABS kicks in, something is wrong with the system, the wiring is incorrect, or (more likely) the car is underpowered electrically.

Mark
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Re: Anti Lock Brakes upgrade for our cars?

Post by texan01 on Thu Feb 14, 2013 11:58 am

geoff528 wrote:ABS definitely increases stopping distance in snow because if a wheel is sliding it redirects pressure to the other wheels but those other wheels didnt start off with much traction in the first place, this causes another wheel to slide instead of the first 1. Being in canada if u have abs u have to be more careful than u would if u didnt have abs. Thts just in my experience. Not like ur gona be driving in the snow in a classic car LOL

That's opposite from my experience on ice. I'd rather have ABS on ice and snow than not. My 95 Explorer is a champ in slick stuff in terms of stopping, and my '77 is a basket-case of nerves on ice and snow - it pretty much ignores your inputs and goes where it feels like, the Explorer is as loyal as a dog in that respect, the '77 is like a sulking cat. But then again, I live in Texas so my experience is limited to about 3 days a year at the most.

Dirt is another story, you want that wedge of dirt to pile up in front of a stopped wheel so ABS isn't useful off a paved road. Been there and done that a few times!

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Re: Anti Lock Brakes upgrade for our cars?

Post by thatfnthing on Thu Feb 14, 2013 3:29 pm

geoff528 wrote:... because if a wheel is sliding it redirects pressure to the other wheels but those other wheels didnt start off with much traction in the first place, this causes another wheel to slide instead of the first 1.

Yeah, it's actually the EXACT opposite.

It doesn't "redirect pressure" at all. It takes your foot off the brake, but on a wheel-by-wheel basis. The vibe in the pedal you feel is the modulator pushing back at your foot to lighten the load on the wheel it has detected as slipping -- i.e. the one with the lowest tooth count. When the count comes back into line with the others it allows the line pressure to go back to where your foot dictated.

That's why the instructions are always to stomp on it as hard as you can and keep it there -- if you pump the brakes at all, you make the skid far worse, because when it's done modulating the slipping wheel, there's no pressure to "allow" because your foot is no longer pushing the pedal. You're giving it no pressure to work with. It's also why if the ABS system fails, you revert back to normal braking.
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Re: Anti Lock Brakes upgrade for our cars?

Post by pila on Fri Feb 15, 2013 12:38 am

The ABS in the wife's Caddy gave me some heart burn a few times, but I figured she needed the ABS !!

My Elco project has 2 1/4" rear drums (Currie) so the brakes themselves are OK, and I'm not smart enough to do the ABS trick on it ! Very Happy

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Re: Anti Lock Brakes upgrade for our cars?

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