ABS issues

[NSXGB]

Been years since I did mine (with the correct modulator), I would say the best bet would be to check out buying as a kit from SOS or Mita. Not sure if Christian at ATR does a kit, probably worth a try too. Unfortunately, exchange rates are not in your favour.
Well worth doing though, one of my favourite upgrades.

EDIT: Parts list here: http://www.nsxcb.co.uk/showthread.ph...2646#post72646

[britlude]

all straight forward, the most awkward pipe is ABS to front passenger side wheel....

S2000 modulator if you don't mind losing TCS, it's physically the same unit, with just one wire position change in the main connector...

adapter harnesses should be plug n play, maybe a tweak for the dash light depending on the original car configuration... and some need an extra connection for the ABS computer reset wire.

think Mita does a kit, SOS does one too, (obvs spec RHD) or party pack order from amayama and the like, but you still need the aftermarket harness adapter.. not sure if Christian at ATR does a kit, tho i know he got a delivery of NSX spec modulators recently

[duncan]

Historically marque specialists re-gassed Citroen spheres. Currently eBay lists new Citroen spheres from £30 up, it would most likely need a thread adapter (I’ve no idea which threads are used Honda & Citroen) but worth a deeper dive?

[Papalazarou]

Historically marque specialists re-gassed Citroen spheres. Currently eBay lists new Citroen spheres from £30 up, it would most likely need a thread adapter (I’ve no idea which threads are used Honda & Citroen) but worth a deeper dive?

That’s a good call Duncan. I wonder how viable that is. I guess it’s all down to the spec. I am really enjoying this thread.

Cheers.

[duncan]

Citroens (of old) used LHM hydraulic which always came with a warning not use in other non Citroen applications. Delving into the web to find out why . .
Seals for conventional brake fluid are a natural rubber blend which is not resistant to hydrocarbon fluids, like LHM. However, seals for LHM will be a nitrile rubber blend which resists oil based (hydrocarbon) fluids and will also resist conventional brake fluids.
Thus it would appear that save for the thread and sealing flare detail Citroen spheres could be considered.
Perhaps someone with a spare Honda sphere from a converted system could measure the thread?

[Kaz-kzukNA1]

Slow to join the conversation and you may have already decided on the future direction so going to just touch on the basic.


If nothing done to your existing ABS and just completely failed, I wouldn’t bother repairing it.
ABS light will result in MOT failure.
Can be disabled though.

However, since you mentioned that the pump was replaced (mechanical pump + electrical motor = expensive), then it’s worth at least doing some tests before upgrading.

You also mentioned that ‘it’s all been rebuilt recently’.

Don’t know what kind of overhaul was done but there are several procedures only available in Japanese workshop manual so may have missed something and contributing to your issue.


For the upgrade, you can find example here; http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=30

For your reference, as of June/23, Honda has stopped taking any new order for the NSX upgraded modulator.
Don’t think it will be discontinued but no future schedule at this stage.

Waited for months and even for years for the delivery of multiple orders because every time when the expected delivery date got closer, Honda/manufacture postponed it due to manufacturing failure.

Finally, got all three delivered last month but that’s it.
No more new order for the upgraded modulator accepted by Honda.

So, if doing the upgrade, the used S2000 AP1 modulator is one of the proven option for now unless you can source the NSX specific modulator from somewhere else.


Will leave the testing procedure for now but could you clarify the following?

Q1. When you triggered the ABS on purposely, did you feel kick-back at the brake pedal and if yes, was it weak or strong kick-back?

You already owned so many NSX that I assumed that you have some idea on what to expect from the kick-back.


This is the famous website that many refers to for flushing the modulator. http://danoland.com/nsxgarage/brakes/abs/abs.htm


Above link can only flush half of the ABS so not complete but good for understanding the procedure and the connector/relay location.


With the above method, you will be able to manually operate the ABS pump.
Also, you will know how to manually activate each solenoid.

These become handy when testing the abs pump and the accumulator.
Also, whether any high pressure fluid left inside the accumulator or not without the use of OEM ABS T-wrench


I’m aware that you got intermittent ABS light so while the accumulator could be not 100% healthy, it still has some life left with enough nitrogen gas left behind the bladder.
Otherwise, you would always trigger the ABS light after started moving the car and the ABS pump operated more than 120sec.


While it can help, please be aware that one can introduce new issue by applying hard braking on slippery surface to ‘exercise’ the ABS.

This is still recommended by many in order to prevent the sticky/leaky solenoid.
I used to recommend the same.

However, I no longer recommend it and instead, asking the owners to manually flush the accumulator and activate the solenoid in specific way at least once a year.


Most likely your 1st accumulator with your previous NSX was fine and just had so much air inside due to overly ‘exercising the ABS’ or the leaky solenoid issue.

Flushing the accumulator properly and air bleeding the modulator/piston chamber would have fixed it since your solenoids and the pump were not replaced.






If you are happy to remove the accumulator, you can check for the pin hole/puncture of it.

With the heathy accumulator, you can only insert centre punch, allen key, etc just for a few cm from the top, like less than 3cm.
Tiny opening so narrow tool required.


With the punctured bladder or loss of nitrogen gas at the accumulator, the tool can go all the way close to the bottom of the sphere/accumulator, i.e. the diameter of the sphere.


Years ago, I read somewhere on Prime about recharging/regas of the accumulator so probably can be done but it’s under extremely high pressure so may struggle with the delivery method.


Ultimately, best upgrading to the latest one body ABS modulator but you can buy some time if your existing ABS has some life left.


Kaz

[Papalazarou]

Thanks Kaz,

I drove the car today to see exactly how it reacted to different braking input.
Driving from cold and applying a small amount of braking force, triggered the chirping and the pedal to feel as if the ABS had been triggered when it had not; so kick-back and the feeling of the pedal falling through its travel.
At low to medium speeds the chirping would kick in regularly when not using the brakes.
At higher speeds with higher braking force, the brakes worked fine, but would chirp and kick when I backed off the brakes but was still applying some pressure.
Overall the kick was quite strong, but most disconcerting was the clunk as the pedal would fall through it’s travel as though I had lost traction.
The picture is the invoice for the seals replaced at the time of the rebuild.
Apparently when everything had been rebuilt/replaced, the previous owner reported that the ABS was improved, but still displayed the above characteristics at times.