Need some info on the ABS system

[JoshT]

I am using an Explorer as a donor for an older street truck. The brakes I'm putting on the project are overkill for the weight of the truck, and I'm a little worried that it will be entirely too easy to lock up the brakes (4 wheel disks). The project truck came stock without any type of ABS, but I can easily add all the sensors needed for the Explorer's 4 wheel ABS system and would like to try to add it. So my questions:

I see in the EVTM that the ABS module is connected by 1 wire to the GEM. Does the ABS module get information from the GEM, or is it supplying information to the GEM? In other words, can the ABS system work properly without being connected to the GEM?

Explorer in question is a '98 Eddie Bauer 5.0L 2wd.

My gut tells me that it will, but want second (and 3rd or more) opinions, on whether or not it would work. I am not interested in opinions on whether or not I need abs, but I know that won't prevent them from being given.

 

[SoNic67]

That wire from pin 11 is to send the signal to GEM "ABS ACTIV". That is used by GEM to dis-engage the Auto 4x4 when ABS is active (as in braking hard and wheels locking). This is important if vehicle is in 4x4 mode, not useful for 2x4 or AWD. I would say that your GEM doesn't need that information if you don't have a 4x4 project.

Other models will pick up the speed information from ABS module too (VSS out, pin 19) but your project most likely doesn't need that.

 

[JoshT]

Thanks. That's what I needed to know.

The project is an 86 Ranger, 2wd, reg cab and short bed with the following.
- V8 and trans swap (331 and manual eventually)
- 95-97 Ranger steering knuckles (can accept front speed sensors)
- DJM Dream Beams
- 13" cobra brakes (will eventually get performance rotors and pads)
- 31 spline 8.8 w/ LS, disk and anti-wrap bars
- edelbrock IAS shocks.
- large aftermarket front sway bar, B2 1" rear sway bar
- B2 tank (better weight distribution.
- 17" Mach 1 wheels (for now) tire size TBD

Thread not about truck, but that's what I want to put the abs in. Light truck, too much power ( eventually), and very strong brakes (for it). Worried it'll be too easy to lock them up.

Right now I'm trying to determine best way to wire. Either full electrical swap from explorer, or aftermarket body harness and swap in the explorer systems (efi, abs, etc.). The former is cheaper and systems are already integrated, but its a pain to adapt since I'm keeping the rangers lighting and controls (ignition, light, wipers, etc.). The latter is more expensive, but simpler to wire which means it gets done quicker.

Either way I've got a big wiring task since I also have to extend the engine harness to put the ECU in-cab.

 

[SoNic67]

Makes sense to have ABS on that...
Good luck!

 

[pugulis]

What's the weight difference between the explorer and the ranger? The reason I ask is if the difference is too great, the ABS won't work properly. As you brake, the computer is sensing wheel speed and stopping the wheels from locking. The amount it pulsates to keep the wheels from locking is based on the weight of the vehicle. Also, you realize you'll have to replace everything in the system to make it function properly, not just the adding the sensors. You'll need the hubs, calipers, master cylinder, and possibly the booster. You'll also have to make sure the vacuum to the booster is the same. And I don't know about explorers, but on some vehicles the brake lines are routed differently for ABS. Good luck.

 

[JoshT]

Yes, I have thought about the weight issue and it is not as close as I would like. I figure that I will try the components I have on hand. If they do not work I will swap out the ABS components from similar Ranger (reg cab, short bed, 2wd) parts. I really question whether it cares about vehicle weight. On a truck how is the system to know if the bed is empty or loaded with a literal ton of trash?

As long as I have the ABS module and sensors in place, wired properly, and bled correctly it should work. The ABS system doesn't touch the hubs, calipers, master cylinder or booster. All it does is control the line pressure to the calipers. If the other components mattered that much then you wouldn't be able to get away with big brake kits or brake conversions on any abs equipped vehicle, but they are done successfully all the time.

 

[pugulis]

The ABS system doesn't touch the hubs, calipers, master cylinder or booster. All it does is control the line pressure to the calipers. If the other components mattered that much then you wouldn't be able to get away with big brake kits or brake conversions on any abs equipped vehicle, but they are done successfully all the time.

Well the master cylinder is most definitely different. It only has 2 lines coming out and a single fluid chamber. Plus, they are sealed more than a standard master cylinder (screw on cap instead of clip on) which would make me think there is more pressure going on. But I'm not sure about the booster or pressure. As for the rest, they always ask if it's an ABS vehicle (even on the larger brake kits). The wheel sensors need to read off something. Either the hub or axle assembly will have a special component with teeth on it. And the sensors themselves are connected to the caliper assembly. The ABS also has a vehicle speed sensor (independent of the wheel sensors). Even if the parts look exactly the same, I wouldn't want to take the chance. You don't want to screw up the braking system. It may seem fine at slow speeds, but the last thing you want is to find out that it doesn't work right while doing 65.

 

[JoshT]

Well the master cylinder is most definitely different. It only has 2 lines coming out and a single fluid chamber. Plus, they are sealed more than a standard master cylinder (screw on cap instead of clip on) which would make me think there is more pressure going on. But I'm not sure about the booster or pressure. As for the rest, they always ask if it's an ABS vehicle (even on the larger brake kits). The wheel sensors need to read off something. Either the hub or axle assembly will have a special component with teeth on it. And the sensors themselves are connected to the caliper assembly. The ABS also has a vehicle speed sensor (independent of the wheel sensors). Even if the parts look exactly the same, I wouldn't want to take the chance. You don't want to screw up the braking system. It may seem fine at slow speeds, but the last thing you want is to find out that it doesn't work right while doing 65.

Typing this on phone so bear with me.

All RBVs only came with 2 port master cylinders, even the older cast units had one on my '84. Those older units were as sealed as newer style (if not more so) if properly maintained. By '86 they already had the newer style single chamber units. That said since I am using the Explorer rear axle with disks, I also swapped the master cylinder from the donor. While the Explorer booster will not fit due to bolt pattern, I did swap it out for a '94 4.0L booster which is nearly the same size and much bigger than the stock '86 one.

You may be correct about the front wheel speed sensor, if we were talking about a 4WD/AWD Explorer. The 2WD Explorers are set-up like a 2WD Ranger with the sensor in the knuckle and a tone ring on the back of the rotor for it to read. My 97 Ranger knuckles have mount points for the sensor, and the mub adapters are machined to accept the tone ring. The VSS for the abs is the same one used for everything else, and it is located in the pumpkin of the rear axle. The rear axle from the explorer is being installed so it's covered.

The nice thing about abs is that if abs fails it turns off, and system acts like non-ABS. A bigger chance/risk is the 13" brake kit or swapping in rear disk. The biggest risk is a failing hose or loose fitting, and those have nothing to do with ABS. I have got places I can test before hitting the road.

 

[SoNic67]

Yes, I have thought about the weight issue and it is not as close as I would like.

Weight has nothing to do with ABS. ABS will pulsate the system with some fixed frequency of 10-15 Hz, until it detects enough wheel rotation - it is a closed loop regulation.

As proof, many cheaper cars, with ABS (mandatory since 2007), don't have anymore weight distribution valve on rear brake lines, expecting the ABS to keep the wheels from locking when trunk is empty.

 

[JoshT]

That's how I thought the system worked, glad to have the confirmation. It also uses an acceleration sensor to get momentum and compare it to the wheel speeds, if the truck is stopped or nearly so we wouldn't want the abs working the whole time our foot is on the brake.

The main reason I even considered weight to be a potential issue is because I saw it pop up in a lot of my Google search results for ABS swap, but then I got a lot of results for abs as well. -P) I knew that it really didn't make sense from what I understood of the system operation. It seemed to me that if anything having similarly designed braking systems would be more of a compatibility issue, but even that could be adapted to make it work. Since Ranger and Explorer brake systems are almost the same that wasn't an issue. That left sensor mounting (solved) and if the system could operate standalone, which I now know it can.

SoNic67, thanks for your help. I have gotta ask where are you getting your information? I don't mean to be rude, but I searched for this stuff and couldn't find it. You, however, seem to be finding it with ease or know it from training. Regardless as I said, appreciate the help.

 

[colintrax]

Where in Ga do ya live? I wanna see this when it's done

FYI, my 91 4cyl ranger weighs just shy of 2,800lbs. My 97 6cyl OHV explorer with a few weight adding mods weighs right in at 5,000lbs

 

[JoshT]

Macon/Warner Robins area

It's got a ways to go yet. Just got hold of a fuel tank cross member the other week so next step is get it located, mounted, and tank installed. Then position and install Explorer cross member for upper shock mount. After that it's mostly plumbing, wiring, interior and exterior reassembly. Hopefully I can remember where everything goes.

If I had a good place to work on it, I'd be willing to say that it would run this year, but everything is being done outside in my back yard so progress depends on the weather. I don't get too motivated to do anything during the heat of summer. Once I see an end in sight, or am making regular progress, I'll probably start build threads everywhere.

 

[SoNic67]

You need to know how to google this days Either Bosch or Teves ABS system was used in a boat load of cars/brands, including Ford. I think that in Explorer is version Teves 4.0.
But ABS principles are the same.
One example for the Bosch 5.3 version (with EBD - proportioning for rear axle):
avto-skan.ru/uploads/bl_bosch_abs_5_3.pdf
http://www.aa1car.com/library/abs98.htm
Another for Teves ver 20 (also with EVPS - proportioning for rear axle):
http://www.aa1car.com/library/abs_teves_mk20.htm
And the one channel ABS (only for rear) found in some early Rangers and Explorers:
http://www.aa1car.com/library/abs_kelseyhayes_rwal.htm

Bleeding ABS:
http://www.aa1car.com/library/abs_bleeding.htm