Brake bleeding After Rotor, Pad & Braided Lines Upgrade

[Lmic]

Hi all,

 

1997 R33 GTST with ABS

Have a question regarding brake bleeding as this is the first time ive attempted it. Changed over my rotors, pads and to braided lines all in one hit and am at the stage of bleeding the brakes and have noticed that there is now a hiss sound coming from the brake pedal/engine bay area (as well as not firm) after the first bleeding process (1L of fluid added give or take, some may have recirculated into the bottle). Certinatly got air in the lines during the changeover process.

Seems like there are no bubbles coming from the bleeding nipples but definatly have a spongey feel to the pedal and definatly isnt drivable. When bleeding, it builds up plenty of pressure and as the nipple is release, with my foot down on the brake pedal, it continues a slight bit more before re pumping

In terms of the ABS system, is there something that should have been done prior to bleeding, like disconnecting it ? Is the hiss noise, that isnt something I noticed prior a damaged part or is that the air moving through the lines somewhere near the ABS ? Is this just a case of needing to do more bleeding ?

Brakes were working fine prior to this (other than being worn) and have checked everything ive touched in regards to being tight. Rolled the car back and fourth and the pads do grab (but with the foot all the way down on the brake)

Thanks

Edited December 29, 2023 by Lmic

[GTSBoy]

OK, so the number one danger of inexperienced bleeding is pushing the pedal all the way down, which (depending on the state of the master cylinder bore) can push the MC piston down into an area of the bore that it never normally goes, where crud is built up, which can tear up the piston seals, leading to a recirculating/failed MC. So, put a piece of wood on the floor under the pedal to stop it at about the max travel it normally sees.

Then the next peril, which can come from the same over-actuation, is damage to the booster. I wouldn't normally worry about it, but your report of a hissing noise suggests that you might have wrecked a seal in there too.

[joshuaho96]

Also worth mentioning that there is a way to activate the ABS pump and valves with Consult to help bleed things. But if you suspect a damaged master cylinder or booster I would start there.

[Lmic]

Thanks for the info. Defiantly sounds like a failed seal or something similar

just took a video of it now for reference 

[Duncan]

Just consider that an air leak at the booster (I've never had one, but that sure sounds like an air leak) will not affect the hydraulic system for the brakes, the booster just helps move the rod in the master cylinder.

I would start by simply bleeding more fluid through first. In about 20 years' of stuffing with these cars with multiple caliper/master replacements etc I've only once had an issue with air in the ABS, generally as you bleed it the new fluid and any air moves through the open ABS channels and nothing gets trapped in the closed chambers; it is is only when the ABS is activated that the various cylinders move around so if the car has been stationary it is unlikely to be that. On the 32 there are 2 bleed nipples on the ABS that you can try.

There are also a couple of more modern options for bleeding the system if you are having trouble, vacuum bleeding (which I think needs a compressor) to pull fluid out of the bleed nipple, or pressure bleeding where you seal the master under pressure and just open the bleeders to let fluid through. Maybe something is on sale if you want to try them.

[MBS206]

I'd pull the master/booster off.

 

That definitely sounds like something being pumped around. The check I'd be doing is looking for brake fluid between the booster and master.

 

When you pump it heaps with the spongey pedal still, and all bleed nipples shut, does the fluid level drop down slowly in the reservoir?

 

How high up is the fluid level in the reservoir? I have heard the same sound bleeding brakes before when still having air up high in the lines.

If you have let the fluid level drop too low on first bleed, you may have air in the lines closer to the master cylinder.

 

Which order did you bleed the rotors in?

[Lmic]

Sorry for the delayed response guys but we managed to get it sorted!

Turns out there was so much air in the lines it just took hours of bleeding to remove as much air as possible. Not sure if some air was stuck at the high point of the lines where the ABS system was or not

Ended up using a friend’s suction type bleeder at the nipple end. We kept the nipple closed, he pumped up the handheld suction bleeder while I pumped the pedal and we did quick releases of the nipple which managed to get the air out. Did this a few times on all 4 starting from the rear passenger’s side and got it working

Definitely took some time but got there in the end and now the feeling is super firm

Brakes have been bedded in and grab super well once warmed up. Lots of brake dust from the fronts, as expected, after a hills run

DBA T3 Rotors / Endless MX72 Plus Pads / GKTech Braided lines (Hard line delete) for anyone wondering

[Duncan]

Great to hear it is sorted....it is amazing how much bleeding through is required some times

[joshuaho96]

On 12/29/2023 at 2:16 PM, Duncan said:

Just consider that an air leak at the booster (I've never had one, but that sure sounds like an air leak) will not affect the hydraulic system for the brakes, the booster just helps move the rod in the master cylinder.

I would start by simply bleeding more fluid through first. In about 20 years' of stuffing with these cars with multiple caliper/master replacements etc I've only once had an issue with air in the ABS, generally as you bleed it the new fluid and any air moves through the open ABS channels and nothing gets trapped in the closed chambers; it is is only when the ABS is activated that the various cylinders move around so if the car has been stationary it is unlikely to be that. On the 32 there are 2 bleed nipples on the ABS that you can try.

There are also a couple of more modern options for bleeding the system if you are having trouble, vacuum bleeding (which I think needs a compressor) to pull fluid out of the bleed nipple, or pressure bleeding where you seal the master under pressure and just open the bleeders to let fluid through. Maybe something is on sale if you want to try them.

I highly recommend the Motive pressure bleeder. For R33/R34 I have confirmed the Motive 1107/1117 cap is a direct fit. Putting 20 psi at the master cylinder helps to make sure even if your bleeder threads are not airtight you will push fluid through. The vacuum bleeder setups don't work IMO. Preventing vacuum leaks on the geometry of the bleeder just isn't possible and it never seems to fully purge the system of air. 

The only method I haven't tried is using a syringe of brake fluid to force fluid back in from the bleeders which might help in some cases, supposedly it helps a lot with bleeding clutches.

[Kinkstaah]

I also briefly used mine the other day and I ranted and raved. One of the first things anyone should have for any car. 

However the cap I ordered is the 0117:

Though the adapter clearly has different names associated with it. But the options above (which I think is the same that josh above used) 100% is good for my BM57 BMC Reservoir.

[TurboTapin]

Does Motive have a cap for R32's? I ask as my motive bleeder has been in a cabinet collecting dust for the last 5-6 years as I couldn't find one back then. 

[Duncan]

The SP pressure bleeder just uses a regular nitto air fitting for the cap, if the motive pressure vessel is the same you can probably grab any brand cap

[Kinkstaah]

I think he's referring to the cap for the reservoir itself.

Motive are pretty decent, but if the cap size is the same across all Nissans then the answer would be yes. If it's different, measure and Motive will likely say "Ah yes our XYZ cap is blah diameter"

[Duncan]

Yeah sorry i wasn't clear, so was I.

Eg in this kit, the reservoir cap is attached to the pressure bleeder via a standard nitto air fitting, therefore the cap is interchangeable with any other brand pressure bleeder that also uses a nitto fitting (Or, without too much creativity, the fitting could be swapped for another style of air fitting)

[joshuaho96]

On 1/10/2024 at 7:23 AM, TurboTapin said:

Does Motive have a cap for R32's? I ask as my motive bleeder has been in a cabinet collecting dust for the last 5-6 years as I couldn't find one back then. 

You have to email them, they really should but I've never been able to figure it out as they don't show the full list of adapter caps available anymore. CTA also has the Nitto fitting which can be adapted to Motive bleeders but requires the Nitto to BSP adapter, then a BSP to NPT adapter which is pretty hard to come by.