S13 ABS retrofit

[Def]

I think the small weight penalty is more than worth the advantages of having ABS as a safety net for getting a little overzealous with the braking or getting surprised out on the track(once flatspotted some tires when a Mini braked HARD about 500 yards before T10a as I was closing in at probably 20 mph faster than them - definitely a code brown moment). It's better to carry around the little bit of ABS weight vs. flat spotting some expensive tires IMO.

So the stock S13 ABS system is a 3 channel(2 front, 1 rear) setup with the rear speed sensor in the diff housing. A few answers will probably help with retrofitting options.

1. Did any easily available Nissan cars of the 90's era that would probably retrofit easily use a 4 channel setup?

2. Any way to get independent rear wheelspeed sensors?

3. What's needed up front hardware-wise beyond S13 ABS/S14 ABS spindles and wheelspeed sensors?

4. If a 3 channel setup is used, is there anyway around a stock ABS diff housing and ABS driveshaft?

5. How heavy is the actuator/computer unit?

[Def]

Did a little searching...

For number 1, all Z32s had 4 channel ABS fitted. It also looks like later(late 90's) Infiniti G20's also had a 4 channel setup. I'm thinking that'd also mean B14's would have it(guessing there).

The Z32s at least use wheel speed sensors mounted onto the ears you see on many rear diff covers by each output shaft. Not sure if the rings can be retrofitted to other output shafts(my S15 output shafts don't have this IIRC).

Number 3, front spindles - do the wheelspeed sensors just read off the back of the front studs?

On number 4, did a little searching and didn't find out what kind of ring the sensor is reading.

[jmauld]

Number 3: There's a toothed ring that the sensors are reading. It's a much higher resolution than reading the front studs.

[djsilver]

The ABS control unit and bracketry weigh in the neighborhood of 30lbs. You may have seen Logr's thread where he mention that he mounted it on the floor to keep it low and back in the car. I looked into this about 2 years ago and everyone said it wasn't worth it. As time goes on it sounds more useful but I feel dumber now. I recently hauled off a wrecked SE/HICAS/ABS hatch shell to the recycler with all the ABS stuff still in it..., I remember trying to sell the ABS controller on Flea-Bay with no takers. Pretty much all the wheel speed sensors use a toothed wheel and a pulse counter. If you know the number of teeth on the setup you want to use you could easily get some toothed wheels machined to fit whatever you have. As far as swapping something from another vehicle... I've read that the ABS control module algorithms are setup for the dynamics of the specific vehicle. That means you'd want one from a car with similar characteristics to get reasonable results. If you've got cubic money you can buy aftermarket ABS/traction controllers from folks like Race-Logic...,

Remember that Jason Rhoades (JRZ on most forums) won an SCCA Solo National Championship in STS against all the spec Civics for that class. He did it with the heaviest version of the 240sx; an SE/HICAS/ABS hatchback.

[jbennett58]

Very glad to see this thread started.I have already been down this road and did not get the desired results so went back to drawing board.On first attempt looked for easy to get cheap rear wheel drive unit and had to be independent of other systems on vehicle.Answer:chevy astro van,rear wheel drive,pull apart was full of them and could get everthing I thought I needed for $50,why not.Abs unit self contained,independent but large and heavy so i mounted in trunk,made all new brake lines and bled system -good pedal and still had same braking w/o electrical controls-step one a success.Now for the speed sensors,fronts were easy,turned astro front brake rotors over and knocked tone rings off,they pressed perfectly onto my hubs,that was lucky.Astro speed sensors are plastic and slip over spindle ,Whats not to like?Hole in middle to small,no problem,file out to right size for press fit on 240 spindle,so far so good.Broke out snap-on vantage(graphing multi meter)checked for signal perfect,now to the rear.The astro is 3 channel and uses the speed sensor for speedometer through a signal modifier,welded tone ring to drive shaft,mounted speed sensor to trans housing,it worked.Bottom line is it worked but was unpredictable,could never get rear and front to match,but it did work,had to go back to drawing board and removed whole system after several months of trying to fine tune.
New plan,1995 m3 system,after freind blew m3 motor he bought a wreck for parts(he also is my co-driver)and gave me all the parts i need .yesterday is when it started removed the abs from m3 we will see how it goes from here.

[Matt93SE]

All Maximas use a 4 channel ABS system too, FYI. rings for the rear are mounted to the hubs, and the rings for the fronts are on the axles. sensors bolt through the hubs just like they do on the S/Z chassis rear diff.

What about maybe an E30 bimmer? did they have ABS? I just joined up with a few guys with an E30 LeMons car. They have another 325 parts car we're getting ready to gut for the engine and spares- if it has ABS, they'd probably be wiling to part with it for cheap.

[logr]

I still have an extra ABS unit so I could weigh it but I think it and the puter were shy of 25 lbs. I mounted them both to the floor behind the rear seat. You want the puter light where you can see it so you know if something is wrong. Even if you have a dash light, you have to see the puter light to diagnose.

On my car, weight isn't as much of an issue as to where it is. I am over 240 lbs heavier on the front than the rear so adding 25 bls to the rear isn't that bad of a thing to me.

The ABS diff can be found relatively easily. Lots of JDM had it. My first half cut had every thing I needed. Either driveshaft will work. It is a bit of a pain to get the non ABS one in because of the center mount but it will work. I have had a non ABS JDM one in my hatch for 2 years.

I looked at doing 4 channel from a Z32. It might be doable but I don't have an issue with rears locking like fronts so it didn't seem worth it. If the teeth on the Z32 fronts are the same as S13's then using a Z32 puter and controller seems like it would work if there isn't some unforseen issue like the puter tied into something else on the car or the sensor using a different signal. Seems to me that the sensor mounts were on the sub frame, not the diff but I'm not sure.

A traction control system is easy with a small sensor by each rear axle.
I kind of like the idea of keeping these systems separate for (issues) sake.
I have one but I call it my right foot. I admit it is made of lead though.

Is it worth it?
IMHO, It is the best single improvement next to A6's or me not overdriving.
I have no more smoke or flat spots ever. I can get 100 runs on A6's.
Acceleration is not really an issue so I seem to get to corners a bit faster than I think I am going to. ABS saves the day. I'm not really a fan of ABS on the street but on the track, I like it very much.

[djsilver]

What about maybe an E30 bimmer? did they have ABS? I just joined up with a few guys with an E30 LeMons car. They have another 325 parts car we're getting ready to gut for the engine and spares- if it has ABS, they'd probably be wiling to part with it for cheap.

We just sold a 1992 E30 318iC (convertible) and it had ABS. I don't know about the older ones, as the 92 vert was a hold over for the E30 and also came with the M42 DOHC four cylinder when all earlier versions had the SOHC motor (M20?)

[racepar1]

The only benefit I see here is that the ABS would just help mask your driving mistakes. Why not save the weight and just concentrate on not screwing up? Flat spotting a set of tires every couple years is a pretty poor reason to go through all the trouble of making this work IMO. I have actually thought about this myself, but I would want as modern of a unit as possible. I mean what's the point of changing out a mid-90's 3-channel ABS system for a mid-90's 4-channel ABS system? It's STILL a mid-90's ABS system.

[logr]

The idea wasn't changing it out for me. It was installing one.

If you can drive a stiffly sprung, very powerful SM or greater car without tire smoke now and then, you are a much better driver than I or anyone I know. Good job.

Personally, I need all the help I can get. One of the Z06 guys that I recently beat at a 2 day combined event, trophied in SS at Nats this year. I hadn't beat him since he bought the Z06. I added ABS and did. Of course there could be many reasons but ABS may be one.

Not sure tire smoke is always driving mistakes, for my money. Bumps, sand, etc. on the track is just one thing that could cause it. Overdriving is definately a reason as well.

It works for me, maybe not others.

[djsilver]

The only benefit I see here is that the ABS would just help mask your driving mistakes. Why not save the weight and just concentrate on not screwing up? Flat spotting a set of tires every couple years is a pretty poor reason to go through all the trouble of making this work IMO.

For roadracing I agree in any case except maybe rain. Autocross is a different animal and we do lots of intentional overdriving that wouldn't be appreciated or useful on a road course. On a 60 second course, if you can jamb it into a corner a little hotter than you should, trail-brake the p*ss out of it, ABS lets the outside front tire work without smoking the inside front tire and you gain two tenths on your competition it can be the difference between 1st and 15th at the end of the day. A lot of autocross is about upsetting the car on purpose to get it through the cones but still be able to control it. I've watched people like John Thomas (13 time national champ) make a car look like it's floating, dancing and changing lanes without changing direction. I've seen him smoke tires plenty but he has sponsors to pay for them..,

[BeerBringer]

An BMW E30 ABS system would be old and slow (just as the S13 is).
If you are looking at other options than Nissan you should look into later model sportscars.

Late model Porsches is suppose to have great ABS...but I guess it will be a real PITA to fit.

[racepar1]

I am a firm believer that ABS, TCS, ASM, Or anything similar are all band-aids for poor drivers. If you learn to use the controls that of your car properly you do not need any of them, be it rain or autocross or whatever. To tell you all the truth, no I do not have any problems with smoking tires. I'll smoke one every once in a while, but I have yet to flat spot a tire on a racetrack. MAYBE in an autocross setting I could see it being more useful (autocross guys are whacky creatures), but on a road course I see absolutely no need for ABS.

[jmauld]

Autocross is a completely different beast from road racing. Not to take away from driving on a track, but when you get 4-5 looks at a course before going to completely different venue, you don't have a lot of opportunity to get it right. Add to that the presence of a clock that actually makes you want to drive at 100% and you'll quickly see the need for ABS.

ABS is almost a requirement when you're autocrossing on tires that can be ruined by one small mistake, and cost $1300.

Using ABS to save your ass in the case of a mistake, doesn't make you less of a driver.

If you don't see the need for ABS, then just don't post in this thread.

[GSXRJJordan]

I tried to post in this thread last night, but I guess it didn't get up there.

I agree with Racepar in the sense that for straight-line braking or similar, ABS might add consistency but it's possible that it wouldn't help you (read: an experienced driver, very comfortable in the car) as much on a road course. Where I draw the line is going from my S14 or similar to my Dad's C5 Z06 - I have slightly larger rubber on my car, but can't get nearly as wild on the brakes (Z32 all around, Z32 M/C) coming into the corner as I can on the Z06 ~ it's the best braking control I've ever driven (very similar in feel to the GT3 Porsche, lets you get a little sideways and definitely change direction/slide, but prevents you from coming all the way around) and totally changes your mental approach to an unfamiliar corner. I can see where this would be worth it's weight on an Autocross course, but worth the most in the canyons or on a sandy/dusty/wet road course.

If I could find a way to retrofit this type of system into my car, I would jump on it. From an engineering prospective, I don't see why it couldn't be done - the computer is self contained, and rings could be manufactured to match the stock sensors. I'm going to ask Mike Essa (Tech Trix Motorsports) what the early-model Porsche guys do, hopefully he'll have a late-model retrofit solution.