Rebuilding the ABS pump
 

Hello everyone.

So after my brake refresh project, I peaked over at my ABS pump and saw a small amount of leakage at the base of one of the solenoids. This would be my second ABS pump so go bad unfortunately. I realize there is currently no rebuild kit and it seems few attempts have been made at the rebuild itself. Seeing as I had a spare ABS pump, I decided to tear it down to investigate the seal that leaked on both of my pumps.
https://cimg4.ibsrv.net/gimg/www.rx7...d5a462a6e.jpeg

(The o ring is removed in the above picture)


https://cimg5.ibsrv.net/gimg/www.rx7...eb26453f0.jpeg

At the base of the solenoid is a strange o ring. It's kind of square cut yet has a mated inner O ring.


https://cimg2.ibsrv.net/gimg/www.rx7...92cd525f7.jpeg

In this picture, the factory seal is pictured on the right and my sizing replacement on the left. The packing shown here is a fluorocarbon 116 packing which makes it a 3/4" ID 15/16" OD 3/32" CS packing.


https://cimg1.ibsrv.net/gimg/www.rx7...ae67cd380.jpeg

I test fitted the packing and the ID/OD seem about right, however the cross section (height if you will) is a bit too thick. I think a 1/16" CS packing might fit better. I'm also in the process of trying to source a standard square cut packing in a 116 (3/32" cross section) size or a 019 (1/16" cross section) size. Once I figure out all my sizing requirements, I'll work then on what material construction they should be as well as a durability test. I've dropped my current fluorocarbon seal in a cap of brake fluid and I'll see how it looks after a bit of soaking :)


https://cimg2.ibsrv.net/gimg/www.rx7...4e413ce88.jpeg

I'll keep this thread updated with my results as I go. The vision for this thread is to provide effective o ring part numbers with appropriate materials to re pack a leaking ABS pump.

Matt

Good luck Matt. Check McMaster Carr for square sided o-rings. Always great to see contributions like this to the forums.

Nice! Would be good to be able to take apart an ABS pump, clean/paint/new seals, and reinstall.

Dale

Smokey,

I've already checked McMaster however the only offer square cut in fluoroelastomer (Viton), Buna-N, or Silicone. The unfortunate issue with that is my research show they all fair poorly with brake fluid. I'm looking into EPDM (ethylene propylene) or IIR (Butyl) rings. The EPDM ones are more common but not so much square cut. I'm considering buying a pack of the McMaster ones as test fitters in the event I need to custom order the set in EPDM. This way I don't spend the dough on custom o rings that don't fit :) I'm gonna grab a micrometer this weekend as well and I'll begin sizing the rest of the o rings.

Dale,

Being that this is my second pump to spring a leak and that all our pumps are 23 years old, I figured it's about time someone tackles this for real :)

Matt

serious question:

why go through all this trouble to fix it when deleting it is a very real and simple option? what reasons are there to keep it outside of the rare occasions that its actually used?

The ABS pump is a factory safety feature. I view it like a gun: I'd rather have it and not need it, than need it and not have it. Yes, it is an older system being a three channel. However, it does serve a purpose. The aim for my personal RX7 is to remain mostly OEM. I like the occasional track day, however it's still my daily driver. This venture also is going to cost me less than a delete kit :) being that O rings are about a whopping $0.04 a pop. I imagine once I nail down all the sizing, a good repack should be under $20 (assuming minimum quantity purchases and shipping included).

Matt

McMaster Carr is a very good jack of all trades, but if you need something special, you need to go to a specialist.

Give these guys a call for both size and material

https://www.sealingdevices.com/

You may also want to shoot that pig with some degreaser before you get any contaminants inside

Gotta love the initiative. I'd just keep adding fluid if it were me. :lol:

Thanks for the source Tom! Once I figure out my sizing I'll hit them up.

So I grabbed an 019 and a 020 packing today. The 019 is a 15/16" OD 1/16" CS packing and I was considering using it for the lower solenoid portion. However the cross section is too small to seal.


https://cimg2.ibsrv.net/gimg/www.rx7...315cb70ed1.jpg

Looking at the upper portion of the pump, there are retainers, a big square ring and a small square ring. I think the smaller packing will be a 008 in square cut.


https://cimg3.ibsrv.net/gimg/www.rx7...2d9a743d79.jpg

I like the fit of the 020 packing under the retainer and I think I need to grab the appropriate square ring for it. There are transfer rods that connect the upper and lower portions of the assembly as well.


https://cimg9.ibsrv.net/gimg/www.rx7...2f9641a72b.jpg

My guess is these are standard o rings in a 009 size.

So today's findings are: the 019 packing at the bottom of the solenoid is a bad fit. The 020 at the top however is a good fit!

I'm thinking I should really buy one of those "o ring kits" that come with a large amount of packings. It might make this selection process a bit simpler :P

Matt

I received an order in the mail today. A handful of EPDM O rings.


https://cimg6.ibsrv.net/gimg/www.rx7...a1d4d003e6.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...3db8c0f452.jpg

Old packings on the left. Replacements on the right. The upper solenoid packing is a tight fit but it does well. I had ordered it in square cut but they were out of stock so shown is a standard o ring. The fit of the lower solenoid square ring is spot on. I think it will seal well. Where I am currently concerned is the upper solenoid packing below the retainer. It fits loosely in the groove, yet snug around the top of the solenoid. This weekend I will complete the rebuild of my spare pump and I'll need to work on a fixture to pressurize the pump to check for leaks.

Few more pics.


https://cimg4.ibsrv.net/gimg/www.rx7...1829db7dc9.jpg


https://cimg6.ibsrv.net/gimg/www.rx7...55f48359b5.jpg

Once I finalize everything with part numbers and proper sealing, I'll proceed with a full how to including part numbers.

Matt

I've had a bunch leak too, mostly on customer's cars that sat for a long time. I'm interested as well.

Nice work :icon_tup:

I have aluminium flakes in my brake fluid.
Based on my assumption that the pistons and calipers are steel?

Have you guys seen that before? My abs pump doesn't leak and works fine, but I figure the flakes might be coming from this, but don't know how/which part?

I have one that I'm taking off my FC I'll sell the ABS pump an control module for $150 shipped. My paypal is mrynef1982@yahoo.com

Nice. Subbed

Six months later, any update on how it's holding up?

I rebuilt one a few years back, will see if I can still find the part numbers for all the seals...

Are you going to pimp it up while you're in there? You can make them look pretty cool.

https://c8.staticflickr.com/8/7322/9...ddbfd641_z.jpgIMG-20130915-01006 by Tom Kinsman, on Flickr
https://c6.staticflickr.com/8/7388/9...ddd77a54_z.jpgIMG-20130915-01008 by Tom Kinsman, on Flickr

Added to FAQ. Looking forward to seeing how this turns out.

Update:

I figured out most of the o ring sizes. I ran into two issues that put this on the back burner though. One was that I didn't have a way to pressure test the system with the new o rings unless I installed it in my car and pumper the brakes. The other issue was I need to see how the solenoids in the ABS pump actuated. If the tops of them actuate in an external motion, I think it will require different pickings for the top. This project also took a backseat because my other pump quit leaking. I think what I thought was a leak was just residual.

Matt

Probably clutch material, they share the same fluid via the one brake resevior.
I know it's been months since you asked the question but I'm just seeing it now.

Shoot me the part numbers and I'll give it a test.

Update

So my current ABS pump sprung a leak from where the motor mates to the hydraulic manifold.

https://cimg4.ibsrv.net/gimg/www.rx7...38694424d7.jpg


Here you can see where the motor mates to the manifold and there is a cutout section. A "weep hole" if you will. This is where mine is leaking.

https://cimg2.ibsrv.net/gimg/www.rx7...bbff293b15.jpg

On the side here is a set screw retainer for the valves that actuate via the motor.

https://cimg1.ibsrv.net/gimg/www.rx7...af6f77738d.jpg
So upon removing the set screw you can pull out the valve out and find that there are three packings on it.
https://cimg9.ibsrv.net/gimg/www.rx7...3af929771e.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...caeccb8815.jpg
From left to right, the large seal is either an 014 or an 015 packing (1/16" CS 9/16" ish ID. The 014 is a 1/2" ID.) I need to order them and see what fits better. The center seal is an 012 packing (1/16" CS 3/8" ID). The small piston seal is a special one. It's a quad ring and it's a 009 (1/16" CS 7/32" ID). I'm working on finding a source for an EPDM quad ring in this size and it's not proving easy. The others should be easy though.

Matt

so how many O-rings are we talking about total? Cause i bought a spare one that i want to strip down and nickel plate, :). But i like to change out all the o-rings while i have it open.

Should be like 19 total O rings. It including the crush seals for the banjo fittings in top. Those are available OEM still I believe.

Matt

So when you reassembled this pump.. you don't need to do any special bleeding just hook it up and bleed the brakes. I guess I have looked at how abs pumps work and I see an area where maybe once exposed to atmosphere it could create a air pocket. That area being in the accumulator area. But I could be completely wrong about this

I haven't actually completed a rebuild on a pump yet. I've been just disassembling my spare in my free time and sizing replacement o rings for it. Should just be a normal bleed procedure. Nothing special.

Matt