Since my B13's brake drums were on the outs I decided to pony up for a disc conversion. I ended up getting NX2000 rear spindle assemblies, rebuilt NX2000 rear calipers, rebuilt NX2000 MC, new SE-R Ebrake cables, SS lines and some blank rotors. I already have AD22VFs on the front so I pretty much have full NX2000 brakes. But now, the pedal is VERY spongy. There is little pressure until I get near the bottom where the brakes will grab rather abruptly. It's kind of alarming to the point where I will not let anyone else drive my car for safety concerns. The Ebrake also feels "soft". I'm not getting confidence inspiring resistance when I pull the handle up. I can pull it all the way to the top without effort, whereas I remember not being able to do this before. The brakes DO work. The car stops without fade and the Ebrakes lock up the rear calipers. But the pedal just doesn't bite where one would expect it to.

Anybody have any experience with this? I'm dead certain I got the NX2000 MC as it has a larger fluid reservoir than my stock one. Did I forget something in my parts list for the conversion? Does it have something to do with an ABS system not being present?
:confused:

The size of the reservoir doesn't mean anything, it's the size of the piston inside. I wonder if you got a Altima or other MC instead. I would doubel check that and try rebleeding the system before you drive more. Having brakes like that is dangerous.

You need to adjust your ebrake properly (inside the car by the handle and in the back)

You need to bleed the brakes, thoroughly.

You will want the proper MC with the larger piston inside, there are writeups on this all over.

Brent

x2
The rear pistons are moving too far before the pads contact the rotors. Needs adjustment.

The rear disks are self adjusting so that should not be an issue. The size of the master cylinder should be on the outside of the casting, that could be an issue if it is too small but should be fine if it is at least 7/8. The SER/NX2000 us 7/8 and the Altima is 15/16.

My advise, do a very good bleed of the brake lines starting with bleeding the master cylinder itself. The pedal should be nice and high and pretty firm with this setup. Also you should not have a lot of clearance between the brake pads and calipers either on the front or the back, check all this out and post back here with the results.

Thanks for the replies. I was so sure I specified an NX2000 MC but I'll have to double check it now. Someone mentioned to me a reverse bleeder system instead of pumping the pedal so I'll give that a try as well.

Id say its a brake bleed too, but try to do this ASAP like Eric said

Hi, i assume you have a sentra w/1.6L these cars have a very small brake booster and I would suggest also upgrading to a nx booster. The size difference is HUGE. This should help a lot but like others have stated start off my trying a bleed again.

Hi, i assume you have a sentra w/1.6L these cars have a very small brake booster and I would suggest also upgrading to a nx booster. The size difference is HUGE. This should help a lot but like others have stated start off my trying a bleed again.

Since my B13's brake drums were on the outs I decided to pony up for a disc conversion. I ended up getting NX2000 rear spindle assemblies, rebuilt NX2000 rear calipers, rebuilt NX2000 MC, new SE-R Ebrake cables, SS lines and some blank rotors. I already have AD22VFs on the front so I pretty much have full NX2000 brakes. But now, the pedal is VERY spongy. :


he has READ THE WHOLE POST BEFORE YOU POSTING

I have a question pertaining to the OP. I have a 1.6 with a 11/16" bore MC. Will upgrading the MC to the 7/8" SE-R MC along with the tandem booster and rear disc brakes be enough for a stock feeling (or better) pedal feel? The only difference I see it the cut-in pressure is higher with the proportioning valves in the 1.6 MC (569 psi) than the SE-R MC (427 psi). Will that pose a problem?

I didn't swap brake boosters. I had been told that it wasn't necessary. Wouldn't a bigger brake booster be needed if I was having the opposite problem, i.e. stiff pedal?

I should clarify that the pedal will not bottom and I've no issues being stopped on a steep hill, but based on above recommendations I'll be busing to work until this is solved.

Booster does just that, it boosts pressure. It would be needed if the pedal is too "soft".

I know on the B14's the brake booster is different, i used the SER booster with no issues. I would upgrade the booster and double check the MC to make sure it is clean.

Bleeding the brakes again didn't change the pedal feel. There's still lots of pedal travel. More and more I get the feeling that I got the wrong MC. I'm going to try an Altima MC but I've found two part #s 46010-2B100 and 46010-2B101. Both are U13 non-ABS units but 2B100 is for the XE, GXE, GLE and 2B101 is for the SE. I don't know what the difference is between the two except that I can get 2B101 for a lot cheaper.

edit: I dug through my receipts and found the part number for the MC I got. It's a Fenco unit m52584 4-wheel ABS. I think maybe the non ABS unit was the one to get instead?

Did you check the diameter on the master cylinder? It is cast on the outside.

The other thing is maybe it is just a bad master cylinder.

Just replaced the Fenco 4-wheel ABS NX2000 unit with a non-ABS U13 unit. The pedal feels better, more like how I remember a brake pedal should feel. It still feels like I have a touch too much pedal travel but the braking is solid now and more progressive instead of no resistance and then suddenly grabbing.

Just saw this. Some of the GA16 have the S205 or C205 brake booster which is single diaphragm. The sr20de has the M195T which is dual diaphragm.
If you compare them side by side you'll notice the rod that engages the master cylinder is slightly shorter on the 205 than on the 195, what this means is that even when the brake pedal is full depressed, the upgraded master cylinder is not fully engaged, so its like you are barely touching the brakes.
I found this out the hard way when I installed the thinner 205 brake booster to make more room under the hood. I have NX2000 fronts, maxima rears and an altima master cylinder. As soon as I swapped brake boosters my SE-R would barely stop, it was just plain dangerous.
One trip around the block and I switched back, that's when I compared rod lengths and discovered the difference.
A lot of the GA16 have the M165T brake booster and I think those are usable but I've never compared them.

Also did you bench bleed the MC prior to installation?

Also did you bench bleed the MC prior to installation?

I'm not sure since I had to leave the car with my mechanic but I was assured that the lines were bled properly. I'm not likely to solve this one but I'm going to return the car to stock to sell it now so it's a mute point. Personally I think it had something to do with the stock booster. The brakes were working, just too much pedal travel.

The problem is the brake proportioning valve! Fit a disc brake rear end BPV, which is on the firewall ;)