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I have a 1997 2litre Nissan Primera. When I push the brake pedal really hard (with the engine running) I can feel the pedal come to a mechanical stop before it is anywhere near the floor. The brakes don't feel really up to the mark under an emergency stop either. I have checked the pedal to floor dimension and it agrees with the manual. There is no obstruction under the dash that could account for this. Any ideas?
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First thing I would do is get the brakes bled.
When was the fluid last changed - if ever? Might be worth having it changed while you're having the brakes bled.
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Steve:
My ideas:
If I am correct this car will be fitted with ABS, if it's a facelifted 1997 it certainly has ABS. Can you brake hard enough on a dry, grippy surface to activate the ABS?
If No then you have a brake problem, if Yes, then you probably have no problem, but if the brake fluid had not been changed within the last 2 years, it would be a sensible precaution to do so.
hth
Andy
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Have you checked the brake pads? this was the "problem" with my 96 2l primera i had then past on to my non mechanical son. The brake fluid was always changed ever two years, as for the ABS i found it too sensitive in icy conditions.
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I had a mondeo and then a Granada, if with the engine running you kept your foot on the brake pedal for aperiod of 30 seconds or so the pedal would gradually go right down to the floor, had the brakes checked on both and thay were ok. Than had a VW Passat, that didn't do it, nor does my Saab 9-3. still not worked out why, suggest you get the brakes checked by a good garage, if ok then it could be a characteristic of the car.
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Your 1997 Primera will be a P11 chassis with ABS. On a quiet lane (with no cars behind!) do an emergency stop. The brakes should not lock and you will feel the ABS pulsing under the pedal. If it does that it is probably OK.
Primera brakes should be very good - not over sensitive nor too 'dull'. Change fluid every two years (using a MityVac, if you can get one) and obviously check the pad condition as per service schedule.
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Thanks for the thoughts. All very good as always in this forum. This morning I did a further test. With an assistant opening a bleed screw I pushed on the pedal. The pedal slowly dropped as fluid was expelled until the pedal was only about half way through its travel. Then I couldn't move the pedal any further. I had the bleed screw closed to prevent air ingress before releasing my foot. As a check I rang the Nissan main dealer and asked if the brake pedal should travel to the floor when bleeding. They assure me the pedal should be able to hit the mat!
As a possible aside, the brake pedal was low compared to the dimension in the Haynes manual so I lengthened the master cylinder push rod a while ago. Apart from raising the pedal it made no difference.
I will investigate the servo/master cylinder next. It feels that as though there is a nut (or something) stopping the master cylinder spool from reaching the end of the bore, or is the spool not returning fully, which could account for the previously low pedal?
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Now, not that I am an expert but...
>>I lengthened the master cylinder push rod
Depending on how much you lengthened it, that could be stopping your foot getting to the floor.
I suggest you return it to how it was and then try your various steps again.
The pedal being lower could have been indicative of a problem elsewhere, or simply worn pads/shoes.
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Reset the pedal pushrod to its correct dimension - you may be inhibiting the opening of the inlet orifice to the master cylinder.
Your 'test' was not really valid. Like virtually all cars the Primera has dual circuit brakes and the master cylinder is actually 2-in-1. By cracking open the bleed nipple you were allowing one master cylinder to 'bottom out' but not the other - hence it stopped half way down. You would need to open both circuits to make your test valid.
As I said earlier, I think you have air in one of the circuit. Bleed it through with a MityVac and new DOT4 fluid.
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Thanks again. I think "Aprilia" is right. With 2 assistants operating front and rear offside bleed screws simultaneously, the pedal virtually reached the floor (adjusting the push rod could allow the pedal to hit the deck?). However, the original problem persists i.e. the pedal moving half way before feeling "mechanically" locked. Perhaps air in the system is bringing the pressure-regulating valve into operation, which can be felt, through the pedal.
As everybody says, careful bleeding is in order (and putting the push rod back to where it was). I need to order a suitable cap for my pressure bleeding kit. I will report back.
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Could you get access to another Primera to do a comparison?
Also, don't overlook the possibility of a servo fault and make sure you do your test with the servo exhausted (i.e. pump brakes on-off about 10 times to exhaust the vacuum).
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My wife's 1995 2-litre is similar - very light pedal with little or no effect, then the pedal comes to a dead stop halfway down - there's not a lot of braking feel.
I have no confidence in its brakes but it's passed two MoTs like that and does actually stop pretty well.
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I wonder if someone could answer this question for me...
I too find the ABS a pain in icy conditions but otherwise the brakes on my 95 Primera are superb.
I had one scary moment last winter when a car in front braked sharply on an icy road, fortunately I had left a big enough gap but it was a close one, and the ABS went crazy without any actual braking!!
During icy conditions is it possible to disconnect the ABS by removing the fuse or something??
Cheers
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On really poor surfaces like ice and packed snow you are (usually) travelling slower and will hear and feel the ABS working (especially in fresh snow which muffles sound).
Because the retardation is so poor it doesn't feel like you are actually stopping - what is almost certain is that you will stop sooner than without ABS.
ABS and brakes must have worked cos you didn't hit the car!
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Its not about stopping quicker, its about stopping AND steering at the same time. The ONLY times ABS is not a significant safety advance is gravel, and loose snow. Under both of these locking wheels causes a ridge to build up in front of the tyres and slows you faster - you still CANT STEER tho.
Disconnecting your ABS would be foolish, possibly invalidating your insurance policy.
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Should you really be mucking about with your brakes when you obviously don't have much of a clue? Mines a blue car please leave lots of space!!!!
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Thought I'd give an update as promised. I bought a Mityvac (through Ebay) and tried it today but without taking the wheels off or jacking the car up! I found a lot of bubbles showed in the pipe as fluid was extracted, but I think that may be due to air entering the bleed screw threads (Mityvac advise sealing bleed screw threads with tape).
I will have another go with the wheels off and seal the bleed screws before I start.
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Should you really be mucking about with your brakes when you obviously don't have much of a clue? Mines a blue car please leave lots of space!!!!
Ditto. One of mine is silver, the other is red.
Tyres and Brakes - remember, these are the two most crucial safety items on your car.
Steve: I think Mark(RLBS) was probably on the right track.
(P.S. I take it steve42 and steve52 are different people.)
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Final and successful (?) attempt at bleeding the brakes using my new Mityvac. I found it necessary to apply both brake grease and thread tape to the bleed nipple threads to avoid misleading air bubbles.
Unfortunately the result on the road seems the same. The pedal is like "Sheepy-by-the-Sea's" description, in that the pedal seems to stop about half way down, when presumably the rear antilock valve (?) comes into action. The result is a brake pedal that feels fine under normal running (and passes MOT's ok) but seems to have nothing in reserve under emergency braking. (The ABS works in slippy conditions ok and isn't a factor in this problem, in my opinion!).
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With regards to using the MityVac - don't open the bleed nipple too much (just a fraction of a turn) and take your time. Just use a gentle vacuum (a few strokes at a time) - the brake fluid will come out slowly, but you'll do a good job.
I am still puzzled as to the exact nature of your brake problem. I would expect the brake pedal to 'stop' about half way down - this is when the pads are fully extended and the system is 'solid'. A 'spongy' pedal or one that goes to floor would indicate a fault.
I don't understand your comment about the pedal having 'nothing in reserve under emergency braking'. If you still have doubts then get in down to an MoT station and ask the tester to put it on the rolling road. Its likely he'll have a good idea of how the pedal should feel and will be able to assess efficiency on all four wheels.
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Thanks for the advice re using Mityvac. I can see it will be very useful when carrying out regular brake fluid changes.
When operating the brake pedal with the car stationary (with the servo exhausted or not) you can feel the pedal come to what feels like a physical stop about half way through its available travel. Considerable effort is required to reach this stage, but it's definitely there. When bleeding the brakes with 2 nipples open (both halves of the split circuit) the pedal hits the floor ok, so there is no obstruction in the master cylinder or pedal travel.
When an emergency stop is called for I think the pedal reaches this "physical stop" which seems that however harder you press, nothing extra is available.
My thought is that the rear brake antilock valve comes into play? The pedal feels physically obstructed because the rear pipe work, flexible hose and pads fitted to the rear axle are then effectively isolated by the antilock valve, just the front pads and hoses are felt at the pedal. But why pressing the pedal even harder in that situation doesn't appear to increase the grip of the front pads on their discs I don't understand.
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I should add that Mrs Sheep feels quite safe in the car; it spoils an otherwise good car for me, but I suppose it's a matter of taste. I had a 1994 Mazda 626 which had similarly 'feel-less' brakes - but they always worked well.
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Well I must confess to being puzzled by Steve52 and Sheepy's comments. I have driven a few Primeras (P10, P11 and - briefly - the new P12) - the brakes have always been very good.
The Primera brake system is entirely conventional; it uses the Lucas 'Colette' type caliper and a version of Bosch ABS2E.
There is no 'physical stop' on the master cylinder (as you've proved by opening two bleed valves) and with the car stationary there is no possibility of a 'rear anti-lock valve' operating and isolating the rear part of the system. That will only happen when lock is detected; its a four-channel system so the rear wheels will be controlled individually anyway.
There IS a pressure regulating valve for the rear brakes, but it is unlikely that would be at fault.
One final thought - since your basic problem seems to be one of friction between the front pads and discs have you considered the possibility that the front pads/discs are glazed or contaminated in some other way? If the pads are being forced hard against the discs but there is insufficient stopping power then this must be considered a possibility. Maybe a change of discs and pads would be in order?
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The pedal feel on my 96 primera did change over the three years i had it ,but the brakes always stopped the car, shortly after i gave it to my son he complained to his repair garage who changed the pads, afterwards he was happy. I did at the time think he had been taken advantage of because the pad thickness was well within min spec.
My present A4 brake feel has also changed over three years, most noticable after the garage had changed the brake fluid, however the wife said the brakes felt as normal when i mentioned it and as with the primera the car stopps ok. Try new pads as mentioned.
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Again, thanks to all whom have taken the trouble to log on and provide comment/advice. I should have pointed out that the pads and discs were replaced a few months back as an attempt to solve the problem.
I was able to try another Primera yesterday. Although I couldn't get the pedal to feel "physically stopped" like mine, I felt the braking performance was similar to mine (i.e. nothing in reserve under emergency breaking). The ABS could be felt to operate momentarily on both cars on the dry road used to test.
I then removed the ABS fuse and road tested my car a short distance. Applying emergency braking resulted in wheels locking and clouds of tyre smoke! I replaced the fuse!!!
My conclusion is that the action of the ABS gives the impression of inadequate braking. When the fuse was removed there is nothing preventing the full effort on the pedal acting on the wheels, leaving black marks on the road and giving the impression of good brakes. With ABS enabled, the car probably stops in as short a distance (with no drama) but heaving on the brake pedal beyond a force necessary to get the ABS to cycle produces no reduction in stopping distance.
I'm sure everybody reading this realises that’s how ABS is supposed to work, but I haven't read it described in such a manner!
Rest assured the ABS will remain enabled.
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