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  • Soft brakes and spongy feel... diagnosis?

    Hello Fellow SmartCar Enthusiasts!

    I'm having a little problem with my brakes and thought I'd seek your expert advice.

    Background Information on the Car:
    I've got a low-mileage (25,000 miles) 2002 SmartCar Pulse 600cc (450). The car is standard, with the exception of fitting Yokohama tyres (high grip, low mileage) rather than the Continentals (low grip, high mileage) recommended by Smart of Glasgow. I figured that as annual mileage is quite low, I was replacing tyres due to punctures long before they wore out and I'd rather have the extra grip than resilient tread life.

    The car has been family-owned from new and has a complete Smart/Mercedes-Benz service history. After a few months of storing the car off-road, I inadvertently set all the electrical system on fire when I had a somewhat embarrassing adventure involving the battery over Christmas 2006. This was rectified by Smart of Glasgow in early 2007. Concurrently, new brake pads were also installed and the car has been used almost daily without fault since then.
    Describing the Problem:
    In the last couple of weeks, a gradual deterioration of pedal feel seems to have occurred. The way this is manifested is that firmer pressure than previously required must now be initially applied to stop the car, although very firm pressure will still apply the brakes harshly enough to activate the ABS. The initial bite point of the brakes feels a little more imprecise than previously.

    If I apply the brakes, release, and then immediately reapply braking, the second application of the brakes results in a more precise bite point and a firmer feel to the pedal (with a little less travel in it). The brakes feel good on the second application - certainly more of a 'normal' feel to them. If the brakes a left for a little while without touching them (just continuing down the road) then the next initial application feels soft again. Firm feeling to the brake pedal can be restored by repeating the brake-release-brake procedure.
    Hypothesising:
    In visually inspecting the brakes (i.e. just looking at the front discs and pads, not confident enough to dismantle the rear drums and inspect) I can see that there is still pad left and I don't suspect the condition of the pads/discs to be the root of the problem. I am aware of problems that can develop with the rear drums:
    Evilution - Brake Fluid Level
    However, as it seems a problem with initial feel and not overall stopping power, I donít think itíll be a problem with them. I attempted to inspect the level of brake fluid in the reservoir:
    Evilution - Rear Drum Brake Cleanout
    Unfortunately, this was difficult to spot at night with a flashlight, so Iíll have another go during the daytime over this weekend. I read in other threads that air bubbles in the brake lines can cause the pedal to sink to the floor.
    drumshade (08-12-08, 09:11 PM) - brakes
    However, the symptoms in this case are not nearly so severe and, unlike my case, a change of discs/pads/fluid seemed to have been complicit in the development of the aforementioned bubbles. As the loss of feel in my brake pedal is a recent development, are brake line bubbles something that can develop slowly over time or is it usually only incurred by work carried out on the brake system?
    Thanks very much in advance for your assistance, and I hope someone out there has some kind words of wisdom to impart. :thanx:

    All the best,
    Andrew.

  • #2
    Re: Soft brakes and spongy feel... diagnosis?

    When I read your thread, the first thought was air the system and maybe some water too. I would have the brake fluid replaced, only my initial opinion, but one of the others well be a long to say ya, or nah!!

    Comment


    • #3
      Re: Soft brakes and spongy feel... diagnosis?

      Pffff, how are we supposed to work with that? You should give more detail of the problem - wouldn't hurt to investigate online yourself a little first either.

      But seriously, I'm no use at all, but interested in this thread as the brake pedal in my smart also feels as though it has too much travel in it, 'double tapping' also brings back the sharpness.

      Comment


      • #4
        Re: Soft brakes and spongy feel... diagnosis?

        Given the age of the car I'd whip the rear drums off (Easy Job) and have a looky at my rear cylinders, the rubber seals can and do perish causing fluid loss, you may even see a leak / damp patch at the base of the drum from under the car, water / moisture is also likely, air less so.
        Fudge!
        fudge@fudgesmart.co.uk

        Engine Rebuilding - sw-exclusive Remaps - TAN Codes - Key Fob Coding - Servicing

        All Services Available Mobile, Key Coding Available 24/7

        www.fudgesmart.co.uk
        www.sw-x.co.uk


        Comment


        • #5
          Re: Soft brakes and spongy feel... diagnosis?

          See, told you some one with more knowledge would arrive!

          Comment


          • #6
            Re: Soft brakes and spongy feel... diagnosis?

            Originally posted by trebor-g View Post
            See, told you some one with more knowledge would arrive!
            I'm flattered that you think that! (j/k)

            Comment


            • #7
              Re: Soft brakes and spongy feel... diagnosis?

              Get the whole system bled , yes the fluid can deteriorate (mostly at the calipers/cylinders) over time.
              When the fluid gets hot (from braking) it starts to boil (again at the calipers/rear cylinders.)
              this results in a spongy pedal and complete loss of braking effect at speed.
              Also try checking the travel of the pedal after pulling up on the handbrake a couple of notches and see if the pedal travel comes up. this would indicate poorly self adjusted rears.

              Comment


              • #8
                Re: Soft brakes and spongy feel... diagnosis?

                and when you do want to brake when the fluids stale and boiled/boiling it'll be one of the scariest thing you've ever felt, so it's recommended you change the fluid every 2 to 3 years (max imo) depending on how you drive and what miles you cover.

                Comment


                • #9
                  Re: Soft brakes and spongy feel... diagnosis?

                  If as you indicate live in Glasgow, why not arrange to let Sam at McSmarts check it out ?
                  The brake pads can look ok on a quick visual check,but will wear in a wedge shape. The portion easily visible is the thickest portion of the wedge.
                  Fudge has covered the rest.

                  Comment


                  • #10
                    Re: Soft brakes and spongy feel... diagnosis?

                    Originally posted by trebor-g View Post
                    When I read your thread, the first thought was air the system and maybe some water too. I would have the brake fluid replaced, only my initial opinion, but one of the others well be a long to say ya, or nah!!
                    Thank you for your advice. I'm hoping it'll be an easy fix like a fluid change.

                    Originally posted by ForTwo View Post
                    Pffff, how are we supposed to work with that? You should give more detail of the problem - wouldn't hurt to investigate online yourself a little first either.
                    :redface: Sorry, I'll try harder next time.

                    Originally posted by Fudge View Post
                    Given the age of the car I'd whip the rear drums off (Easy Job) and have a looky at my rear cylinders, the rubber seals can and do perish causing fluid loss, you may even see a leak / damp patch at the base of the drum from under the car, water / moisture is also likely, air less so.
                    Thank you very much, that's very helpful. However, I feel there is perhaps some additional information you need to know about me personally... erm... I must admit that I don't have a great record when it comes to DIY:
                    While I was doing my undergraduate degree (I'm a PhD student now) I needed to save money, so I had the SmartCar declared off-road for some time and thus it had not been driven for a few months. Occasionally when I'd remember I'd go out to start it every couple of weeks just to keep the engine ticking over. I had actually forgotten about it for some time and when my girlfriend passed her driving test just before Christmas, I wanted to get it back on the road for her to use.

                    So we arranged insurance and road tax to start in the New Year, and I started doing a few things to get it going again like checking the oil level, filling with windscreen washer tank, having a look at the tyres etc... however it became pretty obvious that the battery was flat. In order to get a new one fitted, it would have been about £80 to buy a new one and have it fitted by a professional mechanic (including either him coming to me, or towing the car to him on a flat-bed truck), etc... which I thought was too pricey for something that looked so simple.

                    So I went to Halfords (an auto store, for those of you outside Britain) and bought a battery charger for about £26. Unfortunately, the two ends on the charger with the +ve and -ve signs were pre-fitted the wrong way round. There was a fuse on the charger that was supposed to blow in the event that you hook it up to a battery the wrong way round, but there was too little energy left in the battery to blow a tiny little 3 amp fuse. Therefore, the charger actually charged the battery with reversed polarity.

                    So, the 23rd of December... In attempting to re-connect the battery in the passenger foot-well, I was electrocuted - burning my fingertips and leaving my arms feeling funny for a few minutes. Foolishly undeterred, I went back inside for some marigold gloves so that I could continue with the battery installation. Battery connected, exactly as the manual showed. Unfortunately, as the polarity was reversed inside the battery, this had the effect of connecting the battery the wrong way round. I heard a bubbling noise, and bent down to the battery to ascertain where the noise was coming from. I then smelled the smoke. The bubbling noise was all the electrical cabling in the car setting alight around me. I ran back into the house and made the following admission...
                    Me: "I think we need to call someone."

                    Girlfriend: "Why?"

                    Me: "The car is a little bit on fire."
                    So we phoned the fire brigade who attended to help put the car out. The end result was £1800 worth of damage to the car's electrical systems, burning out such items as the alternator, the engine control units, the electric windows... etc. The maximum liability for Halfords was £26.00. This was the cost of the charger. As the car was not insured at the time (insurance was set to activate only days later), I could not file a claim under and "fire" part of the policy. After some pretty pathetic pleading on my part to the head of the service department at the Mercedes-Benz/Smart dealer, they offered us a few goodwill fixes on a few items like the new alternator and a few cheap replacement parts were sourced from collision-totalled cars. Fortunately, everything I'd damaged was put right again (after about 3 months) and the girlfriend is now thoroughly enjoying her SmartCar.

                    Since then, I've decided I'm not so much a DIY Amature as a DIY Disaster (usually when electricity is involved) and become absolutely terrified of undertaking any form of electrical DIY work... each of my previous disasters set me back many thousands of pounds each (ok, I guess I should admit there's been more than just this one incident). Bearing that in mind, we decided it would be safer - and cheaper - for me to leave jobs in the hands of a professional from the start, rather than pay extra for them to repair my damage as well as do the job. About the most I'll undertake now is simple things like trying to stop interior trim rattles. I can't possibly set anything on fire trying to secure those... can I?

                    Still... at least I can say I got my girlfriend a truck-load of firemen for Christmas.

                    I have looked at the Evilution page on dismantling the rear drums and, in theory, it does look fairly simple. However, I've neither been shown or acquired general practical skills when it comes to automotive DIY and would really need some fool-proof practical advice for how to do things like jack the car up, and not drop it on my own foot, etc... so I've had another look at the Evilution pages for some advice:
                    Evilution - Jacking Up A Smart
                    I really am a complete and total novice (not to mention inept) when it comes to mechanical work. So do you have further advice to add to this guide (i.e. should I buy a supplementary jack, a jack stand - and where to place it? - or will the roadside kit included with the car suffice, do I need additional tools to take the wheels/drums off, etc...) Otherwise, I fear I may acquire yet another interesting tale to tell involving cars and catastrophe.

                    All the best,
                    Andrew.

                    PS:
                    Apologies if others have been busy posting things I've not acknowledge here - it's taken some time for me to type it since Fudge's post. :redface: I'll get to reading any subsequent whilst you're reading this.

                    Comment


                    • #11
                      Re: Soft brakes and spongy feel... diagnosis?

                      ROTFPMSL.........

                      Sorry.....

                      No I Am, those than know me know that I'd never type what I would not say face to face, in a pub I'd have just spat beer at you!

                      Phone Sam..... Mc Smarts..... First Thing!

                      Please, for everyone's sake....

                      And have some rep, that story is worth paying for.
                      Fudge!
                      fudge@fudgesmart.co.uk

                      Engine Rebuilding - sw-exclusive Remaps - TAN Codes - Key Fob Coding - Servicing

                      All Services Available Mobile, Key Coding Available 24/7

                      www.fudgesmart.co.uk
                      www.sw-x.co.uk


                      Comment


                      • #12
                        Re: Soft brakes and spongy feel... diagnosis?

                        Originally posted by trebor-g View Post
                        See, told you some one with more knowledge would arrive!
                        Originally posted by ForTwo View Post
                        I'm flattered that you think that! (j/k)
                        Hehehe
                        Originally posted by Trouble View Post
                        Get the whole system bled , yes the fluid can deteriorate (mostly at the calipers/cylinders) over time.
                        When the fluid gets hot (from braking) it starts to boil (again at the calipers/rear cylinders.)
                        this results in a spongy pedal and complete loss of braking effect at speed.
                        Also try checking the travel of the pedal after pulling up on the handbrake a couple of notches and see if the pedal travel comes up. this would indicate poorly self adjusted rears.
                        Thank you, I'll check pedal travel with the handbrake applied when I'm inspecting the brake fluid levels tomorrow.

                        Originally posted by Trouble View Post
                        and when you do want to brake when the fluids stale and boiled/boiling it'll be one of the scariest thing you've ever felt, so it's recommended you change the fluid every 2 to 3 years (max imo) depending on how you drive and what miles you cover.
                        Is the brake fluid condition actually changed during the official Smart/Mercedes-Benz inspections? Or do they just peer at the level measures to see that the volume is acceptable?

                        Originally posted by Bertie Basset View Post
                        If as you indicate live in Glasgow, why not arrange to let Sam at McSmarts check it out ?
                        The brake pads can look ok on a quick visual check,but will wear in a wedge shape. The portion easily visible is the thickest portion of the wedge.
                        Fudge has covered the rest.
                        Aha! Sam sounds like a professional... who are McSmarts, where are they (actually in Glasgow?), and how do I get in touch with them?

                        Ooh, not realised that. Should I also look from the bottom-up at brake pads for judging wear rather than just top-down?

                        All the best,
                        Andrew.

                        Comment


                        • #13
                          Re: Soft brakes and spongy feel... diagnosis?

                          PM SAM on here, tell him to call you about your brakes.... he's somewhere in Scotland..... I know its a big place, but there aren't that many houses are there? there can't be that many poeple that like the cold and wet and all that darkness....
                          Fudge!
                          fudge@fudgesmart.co.uk

                          Engine Rebuilding - sw-exclusive Remaps - TAN Codes - Key Fob Coding - Servicing

                          All Services Available Mobile, Key Coding Available 24/7

                          www.fudgesmart.co.uk
                          www.sw-x.co.uk


                          Comment


                          • #14
                            Re: Soft brakes and spongy feel... diagnosis?

                            The car is a little bit on fire.
                            Sorry but




                            you will now know if you ever get in that situation again , get that battery terminal off the battery at all costs,there and then FAST !
                            car batterys are *really* dangerous if abused..they can supply hundreds of amps resulting in what you saw

                            Comment


                            • #15
                              Re: Soft brakes and spongy feel... diagnosis?

                              Originally posted by Trouble View Post
                              Sorry but




                              you will now know if you ever get in that situation again , get that battery terminal off the battery at all costs,there and then FAST !
                              car batterys are *really* dangerous if abused.
                              And can cause side spliting amusement when someone gets it wrong, like when Zorroreturns welded one of Shawns ratchet spanners to the belly of a fortwo with the spenner glowing red...... i don't know how I didn't wee

                              In all seriousness, batteries are hugely danderous and very under estimated
                              Fudge!
                              fudge@fudgesmart.co.uk

                              Engine Rebuilding - sw-exclusive Remaps - TAN Codes - Key Fob Coding - Servicing

                              All Services Available Mobile, Key Coding Available 24/7

                              www.fudgesmart.co.uk
                              www.sw-x.co.uk


                              Comment

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