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ABS/ALB modulator rebuild write up

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Do you have plans for the 93-99 Modulator Rebuild? Thanks for the great service.

If someone is willing to send me a 93-99 modular, I can probably rebuild it, document it, and then provide kits.
That generation of modulators, doesn't have as many issues.
If you exercise it it and maintain it (change the fluid regularly) it should work good for the most part.
 
On my '95 if I don't drive it for a few days the ABS pump cycles once for like 5-10s the first time I step on the brakes after moving. Sounds like this may be a similar condition to the 91-92? With the car down for the winter now would be a perfect time to pull the assembly and rebuild.
 
First, I apologize for not getting to this sooner. I have been really busy and this literally sat on my work-bench for 1 year. I checked the invoice for the o-rings I ordered and it has been exactly a year since I purchased them. I rebuilt the modulator right away. I took pictures as I went, but never got to this point.

Second, this is version 1.00 It was quick, rough, but will guide a skilled person to rebuild their ABS.

Third: This issue with these modulators is contamination. The vented reservoir cap is right in the path of the radiator fan. The underside of this cap is vented. Crap gets forced up and under the cap and contaminates end up in the brake fluid of the ABS reservoir.

Fourth: o-rings should be replaced, but a good cleaning can sometimes bring these modulators back to life. If you have gone to this length to take it apart, change the o-rings.

Fifth: This is a modulator rebuild, not a ALB-ABS rebuild. If you have a pump, accumulator or pressure switch failing, this will not solve your problem.

Sixth: Let me know about any errors, required edits, helpful hints, questions, and I will create a version 2 and so on. (version 2 in progress now)

Seventh: If required, an o-ring kit may be in the works. I would be glad to provide The hard part is done. I am not hiding anything though, all the part numbers and measurements are listed in the write up. knock yourself out, bring those modulators back to life.

UPDATE:
Version 3 is now available:
http://www3.telus.net/public/warshan/Cars/NSX/ABS/ACURA%20NSX%20ABS%20mod%20rebuld_v03.pdf

Great write-up Warren. I happened to come across it while doing some research on flushing the ABS Unit. Are you still sourcing parts for rebuilding 91 ABS units. If so I would be interested in the parts just to have them for what will probably be the inevitable rebuild down the road at some point in time. Thanks, Joe
 
Many thanks to Warren for putting in the time and effort to make these kits available to our community! Every time I started my car my ABS pump would run well over a minute at a time and then cycle within as little as 10 seconds, where it would run another minute trying to pressurize the system. Only after activating the ABS several times would the balky solenoid(s) finally seat properly and allow the pump to stop cycling and even this did not always do the trick. I decided to try this repair and completed the project the other night. While this is a messy and somewhat challenging repair, it is straight forward, Warren's guide is excellent and the o-rings fit perfectly! +1 on the slotted brake line spanner; those lines are very tight and you risk rounding off the nuts without it. Also, you've got to have a 6mm hex drive to remove the bolts from the solenoid retention plate - they are extremely tight as well. Cleaning was easy - I too had bug wings and guts, bits of asphalt and sand all through the system! The most challenging part for me was removing the solenoid cap without damaging the plastic enclosure underneath. Getting the pistons out was also difficult until I relieved some of the trapped brake fluid which then made it much easier. Reassembly goes quickly. Be prepared to add brake fluid to the reservoir when first activating the pump as it draws it down into the modulator very quickly. I did this by starting the car on jack stands and putting it in gear so I could monitor it from outside the car. This helps to eliminate subsequent bleeding by not getting more air in the system. Took it for a test drive and everything works perfectly! Now the pump only runs for 5 seconds every 3rd or 4th time I start the car and after every ABS activation. I highly recommend this kit to anyone that is fairly mechanically inclined and wants to save at least $500 -- Thanks again Warren!
 
I've finally had time to start digging into this. I took it a step further and disassembled the valves because whatever Honda used as lubricant has solidified into a hard crusty material, so they all needed a good cleaning.

There's another o-ring on the stem I'm trying to source, seems to be non-standard. 2mm x 6mm. I've sent an email to a couple US based suppliers for that size in EPDM.

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This ABS system is so basic I'm surprised nobody has stepped up to the plate for overhaul services. Maybe it's a liability issue? If anyone has a spare '91 valve they'd like to sell to me (that upgraded to SOS etc..). I'll see what I can do in order to reproduce the non o-ring rubber portions, or the entire stem and secondary piston. I'll be putting all four of mine back in service since I never had fluid exchange between the pedal side and the solenoid side.

Just about everything with the exception of the accumulator should be easily rebuildable. Even the motor when that becomes unavailable for those who want their NSX to remain 100% stock.
 

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I've finally had time to start digging into this. I took it a step further and disassembled the valves because whatever Honda used as lubricant has solidified into a hard crusty material, so they all needed a good cleaning.

There's another o-ring on the stem I'm trying to source, seems to be non-standard. 2mm x 6mm. I've sent an email to a couple US based suppliers for that size in EPDM.This ABS system is so basic I'm surprised nobody has stepped up to the plate for overhaul services. Maybe it's a liability issue? If anyone has a spare '91 valve they'd like to sell to me (that upgraded to SOS etc..). I'll see what I can do in order to reproduce the non o-ring rubber portions, or the entire stem and secondary piston. I'll be putting all four of mine back in service since I never had fluid exchange between the pedal side and the solenoid side.

Just about everything with the exception of the accumulator should be easily rebuildable. Even the motor when that becomes unavailable for those who want their NSX to remain 100% stock.
Thanks for the additional tear down and detail.
The only issue I have ever really seen on the valve side is the seal can break down due to something in the brake fluid making the valve useless. That side of the modulator typically stays pretty clean.
If you cannot get that 2x6mm o-ring send me a PM and maybe I can get Daemar Inc. to supply. They have world wide supply, but are not fast.
 
I've finally had time to start digging into this. I took it a step further and disassembled the valves because whatever Honda used as lubricant has solidified into a hard crusty material, so they all needed a good cleaning.

There's another o-ring on the stem I'm trying to source, seems to be non-standard. 2mm x 6mm. I've sent an email to a couple US based suppliers for that size in EPDM.

attachment.php



This ABS system is so basic I'm surprised nobody has stepped up to the plate for overhaul services. Maybe it's a liability issue? If anyone has a spare '91 valve they'd like to sell to me (that upgraded to SOS etc..). I'll see what I can do in order to reproduce the non o-ring rubber portions, or the entire stem and secondary piston. I'll be putting all four of mine back in service since I never had fluid exchange between the pedal side and the solenoid side.

Just about everything with the exception of the accumulator should be easily rebuildable. Even the motor when that becomes unavailable for those who want their NSX to remain 100% stock.

Good info
 
I've finally had time to start digging into this. I took it a step further and disassembled the valves because whatever Honda used as lubricant has solidified into a hard crusty material, so they all needed a good cleaning.

There's another o-ring on the stem I'm trying to source, seems to be non-standard. 2mm x 6mm. I've sent an email to a couple US based suppliers for that size in EPDM.

attachment.php



This ABS system is so basic I'm surprised nobody has stepped up to the plate for overhaul services. Maybe it's a liability issue? If anyone has a spare '91 valve they'd like to sell to me (that upgraded to SOS etc..). I'll see what I can do in order to reproduce the non o-ring rubber portions, or the entire stem and secondary piston. I'll be putting all four of mine back in service since I never had fluid exchange between the pedal side and the solenoid side.

Just about everything with the exception of the accumulator should be easily rebuildable. Even the motor when that becomes unavailable for those who want their NSX to remain 100% stock.

How do you plan to reproduce the rubber portion of the solenoid?
On my car the pressure would not build up due to a leak in one of the solenoids.
BTW, how do you pull them apart?
As I have a spare set, I'd like to see what can be done?
 
How do you plan to reproduce the rubber portion of the solenoid?
On my car the pressure would not build up due to a leak in one of the solenoids.
BTW, how do you pull them apart?
As I have a spare set, I'd like to see what can be done?


There are a couple ways to reproduce rubber components. Draft something up in CAD (I do frequently) and sending it off to a factory to create, or sending the part off to a factory to have them replicate it. From what I can tell, the seals can be reproduced using a simple two-part mold.

There are 3 different size V-style seals, 5 in total, plus an o-ring. Two seals on the lower stem, one midway, below the o-ring, and another two on the secondary piston.

The valves come apart by removing the nut at the top. You'll have to hold the stem in a vice to prevent it from rotating, there's a portion on the lower part of the stem for this.

What you could try to do first is disassemble the valves, clean them, lube, and put them back together and see if that works. I have some spare 2mmx6mm o-rings if you'd like. After a cleaning, and if these valves are bad, you'll most likely notice fluid transfer to/from the ABS reservoir and the master cylinder reservoir.


I'd like to buy a spare set of valves just for the rubber seals. Chances are you won't be getting them back. I need to slice the seal to verify profile shape and tolerance from what I draft up in CAD.

I have a cost in mind that I'm willing to spend. If it goes beyond that, then more research will need to be done to see if these same seals can fit in other Honda modulators. Molds cost anywhere from $500-$3000 each depending on complexity, tolerance, and size. If it's at the low end I'll eat the cost. If it's at the upper end, then maybe crowd sourcing is the only option to offset the cost. It depends if there are enough enthusiasts that want their vehicles to remain 100% stock.

There's another catch to rubber components, it has a shelf life. So it's not like we can run an initial batch of a gagillion and expect them to stay fresh. Most likely we would have to do smaller batches. That increases costs. The molds we can pretty much keep forever though.
 
I am 100% out of o-ring kits for the 91-92 Modulator tear down and rebuild as of 12-Jan-2016

If you want a kit. Please reply on this thread with your name and once I have 10 or more people needing o-rings to rebuild their modulator, I will then order more o-rings. They are sold in bulk and there are 5 different sizes. It takes a bit of effort to put these kits together, so please add your name by replying on this thread.
 
On my '95 if I don't drive it for a few days the ABS pump cycles once for like 5-10s the first time I step on the brakes after moving. Sounds like this may be a similar condition to the 91-92? With the car down for the winter now would be a perfect time to pull the assembly and rebuild.

As Warren suggested, the 94-up modulators aren't prone to the same issue. If you don't drive your car for a few days (how many days do you mean?) and it only cycles for 5-10seconds once at the beginning of your drive, that sounds like a normal operation to me. It is just building pressure in the system.
 
I need at least 10 people on this list to build more 91-92 modulator rebuild kits:
please copy and paste the list below and add your handle/name.

thanks.

1. RJD1022
2.
3.
4.
5.
6.
7.
8.
9.
10.
 
1. RJD1022
2. miles_away
3. asylum
4.bsansx
5.
6.
7.
8.
9.
10.
 
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