thumping under brakes

i brought this issue up early in 2011 with no real answer, the problem went away for quite a while , but has now come back.
i have an 06 d40 auto and when braking under normal conditions, at the point where the car is almost stopped, i get 3 distinct thumps thru the car/brake pedal as i'm releasing the pedal. if i brake hard and hold the pedal down hard, it might only thump twice, and then when i release the pedal to move off, it thumps again?
if i coast to a stop in neutral, or if in reverse, it won't do it.
can't be loose/worn suspension, as it comes in a distinct 3 evenly spaced thumps.
any ideas anyone

sounds like the ABS to me, maybe??

nathand22 said:

sounds like the ABS to me, maybe??

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i thought that too, but it won't do it unless it's in drive

so, if you were going down a hill in neutral and stomped on the brakes it wouldnt do it, BUT would if you had it in drive?

Maybe it has something to with the stall converter/torque converter???

This is a weird one.

The ABS would normally be felt as a high-frequency vibration back through the pedal. If there was a bit of debris in the ABS sensor - like one of the teeth was filled in, every time that tooth went past the sensor it would make the ABS unit think the wheel had stopped turning and with the other wheels still turning, it would then assume wheel lockup and it would activate. The next opening comes past, the ABS unit thinks rotation has commenced again and deactivates.

To determine if this is right, you'd need to test whether or not the thumping matches the rotation of the wheel.

There's a good chance that at higher speeds, the ABS unit doesn't have time to activate.

It could be something else, too. I'm not sure what "thumping" means because we all interpret and explain things differently. Is it a thump like an acetylene bottle is in the back and has rolled forward, or is it a twitch in the brake pedal with a light thud?

I wonder if it's a damaged ABS wire, perhaps?

What about the engine/gearbox mounts? Do they look healthy? Have a look at the gearbox crossmember too, someone reported a crack in theirs.

I don't think it's going to be drive shafts but it could be CVs, or shocks if it only happens as the nose dives deeply.

I guess we can only wait and get some feedback, and maybe some more clarity on the noise.

that's right, only in drive and only when the cars barely moving. not as obvious when i have a big load on but still does it.
i do have the shuddering torque converter problem, but it has always done it from 50k, it now has 130k. i don't understand why it would have dissappeared for 12 months
the only 2 problems i have with the car are the long running t/c shudder and a lightly leaking pinion seal

when your approach a full stop with your foot firmly on the brake, you can time the thumps by slowly lifting your foot off. let it off a bit and thump, alittle more and thump again. by keeping the pedal down after the first to thumps with the car at a standstill you can hold the last thump till you let the pedal off completelyto accelerate off
it sort of feels like someone bumping into the back of the car, it's not sharp say like driveline backlash
it's 12month absense has me baffled

This is probably way off, BUT when i owned a falcon ute it would make a soft nock,nock, noise that could be herd when i was in traffic and going from a stand still to a slow walking pace and would continue while i was idling along.
It turned out to be the Steering rack...... i know its sounds odd, but once they changed it the noise was gone.

My point is, sometimes we can be looking in the most obvious place but in fact its quite the opposite

mine is doing the exact same thing, it sounds like something is rolling around in the back of the truck, and only heard as a thump and felt as a general shudder through the vehicle

mine does it just as or just after the car comes to a stop, mine is also doing it occasionally as i accelerate and shift to second and rarely to third (its a manual)

at first i thought is was a misadjusted brake load compensator valve, but now i am starting to think that

a) either the spring bushes are worn out, or
b) the diff is rocking on its mount as the vehicle weight shifts

the only consistency i can think of is that it happens as the vehicle mass shifts against the suspension

Connaught said:

mine is doing the exact same thing, it sounds like something is rolling around in the back of the truck, and only heard as a thump and felt as a general shudder through the vehicle

mine does it just as or just after the car comes to a stop, mine is also doing it occasionally as i accelerate and shift to second and rarely to third (its a manual)

at first i thought is was a misadjusted brake load compensator valve, but now i am starting to think that

a) either the spring bushes are worn out, or
b) the diff is rocking on its mount as the vehicle weight shifts

the only consistency i can think of is that it happens as the vehicle mass shifts against the suspension

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other than the t/c shudder, mine is completely smooth in all driving conditions, other than coming to a complete stop. i too thought it might be bushes and a loose rear end, but then it would be present all the time

true that,

it would be noticed at all times,

the one consistent point in mine is the vehicle weight shifting against the suspension ie weight moving when the vehicle comes to a stop and again weight shifting when acceleration stops to shift gears


possibly worn out shockies??????

another possibilty,

could the brake shoes be shifting in the drum????

i had a honda civic do this after i changed the pads was a disk setup that did it and made a completely different noise though (honestly sounded like it did when frozen brakes let go )

i thought it might be the brakes also, but if i have braked to a stand still, with the typical shudder and then roll off without accelerating, then brake again it won't do it. seems it will only do it once you have driven off

I have a manual d40 and i get only one very faint thump noise when i brake gently. But its not always there...

how bout if the shoes are loading in the the opposite direction, and coming to a stop sets them into the position that they won't move until you move into reverse again (this is what my civic did popped once stopping in reverse, and then again first time going forward)

The thing about this noise is that it only does it when its in gear..... and doesnt do it at all in neutral
makes me think its in the driveline...... maybe?????

If it were in the driveline, what would it be?

Is the noise soft enough to be NOT noticed at higher speeds?

If it were drive-line-related it'd have to be related to torque converter too, which at that point should be well and truly slipping.

Does the engine RPM fall below 750 as you're coming to a stop? This might indicate the wrong oil has been used in the gearbox. Nissan are really, really adamant that ONLY their ATF is used, because their oil is the correct weight/shear strength etc for the torque converter and valving they designed.

I wonder if the TCM is erratically trying to activate the torque converter clutch (TCC)? It would have to be ignoring the speed sensor, but I know 100% that this is possible since my own TCM is locking the TCC at speeds as low as 60km/h when its minimum is supposed to be 75km/h. This could indicate a fault in the TCM software or the data stream used by the TCM, although if I had been the one writing the software in the TCM, I would have made that speed check mandatory and thrown an error if I didn't have it and the rotation sensor in the gearbox was showing activity.

The TCC is going to activate when it thinks you're cruising with light engine load (and braking = light engine load). It should NEVER do it in anything but overdrive ... ahh, we have a means of finding out if it's the TCC.

Put the car in drive (D) but turn overdrive OFF - press the button so that the "O/D OFF" light comes ON on the instrument panel. Try to repeat the motion that makes the noise.

If you get the noise, then it's NOT the TCC. If you don't, turn overdrive back on and repeat. If you THEN get the noise, it's possibly a TCM problem. The TCM is a computer that lives in the sump of the gearbox. It has external connections on the side of the gearbox and it is possible that some of these have had foreign matter (dirt/mud etc) that cause erratic or failed connectivity resulting in the problem you're experiencing, OR the TCM software in the gearbox is faulty. In this case, it'd be back to Nissan for an update OR if there's no warranty, you might consider replacing the module completely with one of the modules from that mob in Victoria.

mines a manual tho, there is no 'd'

mind you its almost due for the driveline fluids to be changed,

might pull this 160k service ahead and see what happens

Connaught said:

mines a manual tho, there is no 'd'

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Until you get in each others car and listen to the noise there is no way of telling that the two are actually the same...... Your definition of a thump can be quite different to someone else's.
i had a similar thing on here with a taping noise in the motor, i was talking injectors and it turns out the other bloke had the famous clutch line vibration.

So i think Tony and myself are going off the original question and statement that it only does it in "DRIVE"