WJ vs. ZJ ABS speed sensors

[albersondh]

Trying to get my ABS working on my ZJ. I have WJ knuckles. Reluctor/tone rings from a 95+ XJ or ZJ have 54 teeth while the WJ has 48 teeth with much deeper grooves and higher teeth. The wheel speed sensors themselves (ZJ vs. WJ) look completley different. I think the WJ uses an optical type sensor (photo transistor?) while the ZJ uses mag-pick up. I think this based off the appearance of the sensors.

- Can someone please verify the differences between WJ and ZJ wheel speed sensors?

[DJJordache]

I don't know yet but I'm about to do this swap also and will be attempting to wire in the WJ sensors to the ZJ ABS system. It worked when I wired the 8.8 sensor into the ZJ system so maybe this will too! <fingers crossed>

[albersondh]

I don't know yet but I'm about to do this swap also and will be attempting to wire in the WJ sensors to the ZJ ABS system. It worked when I wired the 8.8 sensor into the ZJ system so maybe this will too! <fingers crossed>

The fronts wont work. I have WJ knuckles with WJ speed sensors, wired into the ZJ speed sensor harnesses and no worky. ABS light is still on. I thought maybe I just need to reset the ABS CPU so I disconnected the batteries for a few min's, same thing, no worky. The wires in the harness are black and brown from the WJ sensor and the ZJ harness, I solder and shrink tube all my connections. Im running the ZJ tone rings and the space between the sensor and reluctor teeth looks ok.


Some posibilities:

- The WJ uses optical not mag-pick up like the ZJ, so the sensors are not compatable. My money is on this one.

- If the WJ is mag-pick up, some adjustment may be needed to get the correct spacing from the ZJ reluctor ring.

[DJJordache]

dumb question but are you sure the WJ sensors you have are good?

I have not done much testing on this as I'm still in the parts accumulation process of this mod. but should be ready for this swap soon.

I have not looked, but do you think it's possible to somehow mount the ZJ sensors on the WJ knuckles?

[albersondh]

Im going to flip-flop my theory a bit here. After speaking with a brake systems ME friend of mine and doing some searching around I found that there are two types of WSS used in ABS applications and niether of them are optical in any way. On second thought thats a pretty dumb ass idea considering the enviornmental variables, so my initial theory was just dumb.

WSS are active or passive. One is powered and the other is not. The powered WSS's are newer technology and higher resolution (square wave). They can operate accuratley at low vehicle speeds. Passive WSS's get no signal voltage and must make there own return signal VAC and Hz back to the ABS ECU.

- Someone with a WJ please backprobe a WSS with the engine running and see if either of the leads are getting any voltage. If yes, there will be no way to make the WJ WSS's work with the ZJ ABS system without great difficulty.

I suspect the WJ is active and the ZJ in passive. Some good information on the subject found here: http://www.brakeandfrontend.com/Arti...d_sensors.aspx

Skip down to the paragraph that starts with "Active WSS Sensors".

[DJJordache]

that link says it all.... The 99 WJ's were Teves calipers until they upgraded to the akebono calipers. so yeah they are active WSS. BLAH!

I wonder if it might be possible to somehow fit the ZJ sensors into the WJ knuckles (I have not tried it yet) where they could be close enough to still pickup the signal like mounted in the old knuckles.

[albersondh]

that link says it all.... The 99 WJ's were Teves calipers until they upgraded to the akebono calipers. so yeah they are active WSS. BLAH!

I wonder if it might be possible to somehow fit the ZJ sensors into the WJ knuckles (I have not tried it yet) where they could be close enough to still pickup the signal like mounted in the old knuckles.

Im going to make it work. Checked it out and took some pics tonight and Im pretty sure with some minor clearancing in the knuckle and drill/tap, the ZJ sensors will fit and be adustable to the factory air gap (my bs Chiltons doesnt have the gap spec...).

Mocked up the ZJ knuckle with reluctor ring and sensor, the gap is pretty tight.



WJ WSS in WJ knuckle for reference.



This is how the ZJ WSS is going to have to fit in the WJ knuckle. Some clearancing of the knuckle and drill/tap for the locating nub and screw and I think I can get close enough to work.

[DJJordache]

awesome pics! I did not have spare front abs sensors to test fit but like you said with a little tweaking it looks like they should fit fine!

I got my new hub bearings in yesterday and mocked up the knuckle last night and it all clears without having to use spacers behind the caliper bracket, so I'm happy about that. We just need to figure out this ABS sensor mount which looks like it might not be too bad.

While this is not as easy as making the ford 8.8 work with our ABS, I'm up for a challenge!

Luckily I have a couple ZJ FSM's on my work computer so here is the info you were looking for:

[albersondh]

Nice..... That air gap spec range is huge so thats going to make this a breeze. Wish I would have done this with the knuckles off..... Now I have to fight the lazyness that is telling me I can do this (drill/tap) with everything installed... Idealy Ill remove enough materieal to get the WSS positioned correctly with everything installed, then mark my hole to drill/tap, remove the knuckles and put them on the drill press..... Thanks for getting that spec posted.

[DJJordache]

A little trim of the sensor and knuckle should line it up nicely!

maybe I'll try and find some spare sensors to make my swap have the least amount of downtime.

[albersondh]

Bad news. I pulled the L side WSS to do my initial mock up. I went to pop the knuckles off for drilling/clearancing, luckily I started on R side and I checked things out before pulling the knuckles. The WSS's are the same for both sides on the WJ and ZJ and there is no way to make the ZJ WSS fit on the R side. You would have to hog out a lot of matierial in a critical area. The oly alternatives I can think of would be to check compatability of the WJ ABS CPU to the ZJ harness, then use the WJ sensors. Or find an alternative to the ZJ WSS with the same coil resistance, approximatley the same magnetic force, and of course a profile that would allow correct fitment and alignment in the WJ knuckle. Im not giving up just yet but my focus is on the 8.8 swap at the moment so Ill get back to this in the future.

[DJJordache]

plan B what about the Rears on the D35 or 44a?
a quick google image search yielded:
http://www.naxja.org/forum/showthread.php?t=998638
where he put the d35 sensors on his 44.... anyways look at one of the sensors and it looks like it is almost a mirror of the front one you have pictured. The wire comes off of it in a slightly different direction but should not be an issue.


I didn't keep my stock d35 sensors to see for sure but you still have yours if your going to swap in a 8.8. did you see how I kept the ABS on the 8.8?

[albersondh]

plan B what about the Rears on the D35 or 44a?
a quick google image search yielded:
http://www.naxja.org/forum/showthread.php?t=998638
where he put the d35 sensors on his 44.... anyways look at one of the sensors and it looks like it is almost a mirror of the front one you have pictured. The wire comes off of it in a slightly different direction but should not be an issue.


I didn't keep my stock d35 sensors to see for sure but you still have yours if your going to swap in a 8.8. did you see how I kept the ABS on the 8.8?

Yea I read your 8.8 ABS very nice and that was in the plan for me. The 44A is still intact but since the ABS is inop due to the fronts not working, the 44A wont mind if I snag a WSS for testing, and its about to go away anyhow.... Ill take a look at this over the weekend and report back. I didnt even think about looking at those WSS's, thanks.

[DJJordache]

BUMP! have you gotten a chance to check if the rears might work? I might be heading to the junk yard to get some if I get some time this weekend

[albersondh]

I blew up the tranny in my 08 WRX so all ZJ stuff has been on hold while I get this POS back together.... My next move is the 8.8 swap and Ill be messing with the brake stuff at that time.

[DJJordache]

I blew up the tranny in my 08 WRX so all ZJ stuff has been on hold while I get this POS back together.... My next move is the 8.8 swap and Ill be messing with the brake stuff at that time.

thanks for the update. I have not done anything with mine elther... It's 1000 degrees outside and have been to busy to get to the yards on the weekend to get some rear sensors for testing.

and the other part of me is saying screw this D30 stuff and go 60 or 609 one ton front

[downtowncb]

go 60 or 609 one ton front

FTW. I really want to build a 609 front but I made the rook mistake of investing a ton of money in my Rubicon 44 (basically a D30) before I knew any better. Ugh, decisions...

[DJJordache]

BUMP! I got the ZJ sensors mounted in the WJ knuckles last saturday. I didn't do the whole install yet (hopefully this saturday) but I plugged them in and tested for the ABS light and it went off just like normal.
so this should work and the system should not know the difference=)
yes the air gap looks large but it's the same as the WJ sensors were and still tests out fine when plugged into the stock system.

[albersondh]

Your running CV's? Thats great I hope it works, if it does Im copying you. That gap does look pretty big Im suprised its close enough to get a signal.

[DJJordache]

the gap in that pic is larger than the end result...... but after a long wrenching day yesterday I still have some adjustments to make.... AKA the ABS light came on, but not right away. So I'm betting after a few small asjustments I'll be in business =) but not this weekend! I'll try and do some adjusting during my lunch break at work. Just a little closer and I should be set! but at least now I have OTK steering and the much bigger brakes

Edit: just FYI the stock abs mounting screw is M6 x1.0

[jr4x4]

hey guys sorry to to jump in. looks good! i am wondering about the gap clearance. i snaped my sensor bolt off in my knuckle & long story short after tapping the sensor sat crooked with a bigger gap than normal. my abs light went off but when using my brakes to slow down my brake pedal vibrated & fluttered from bad signal. in the end the sensor gap had to be almost perfect to not set off my abs. again sorry to jump in but wanted to tell you what happen;d so maybe you can figure it out before you have everything back together.

[Stealth Crawler ZJ]

BUMP! I got the ZJ sensors mounted in the WJ knuckles last saturday. I didn't do the whole install yet (hopefully this saturday) but I plugged them in and tested for the ABS light and it went off just like normal.
so this should work and the system should not know the difference=)
yes the air gap looks large but it's the same as the WJ sensors were and still tests out fine when plugged into the stock system.

I realize it’s a dead Thread but do y’all have working photos of the finished product?

[DJJordache]

it did not work out.... the air gap was not correct and it caused the ABS to freak out and be DANGEROUS. it would freak out the system sometimes and almost lock up one corner and cause hard steering that way. almost had some close calls because of it.
abort mission.... I pulled ABS relays and fuses, been years now and all works great with NON ABS. the ABS in the ZJ's sucks anyway