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Thread: Strange noises

  1. #1
    Join Date
    Jan 2016
    Location
    North Somerset
    Posts
    12

    Strange noises

    After a weekend away, the Smart is making a strange noise.

    My wife said there was a nasty sound from the front - a bit like the noise the seats make when not locked into position - clanking - just much louder and metal like. Now it also make a slight hissing noise from the front when going over slight bumps and imperfections in the road. It's not that loud but is consistent and on the off side.

    This afternoon I jacked the car up to check the front spring. There is no obvious break, but at the top where it goes into the housing is some rough metal - perhaps a break as it looks like newly exposed metal. It's where the spring looks to go into the top housing so I can't tell if it is snapped.

    Do the springs break that high up? Also is the hissing likely to be the shock?

    Many thanks

    Hugh

  2. #2
    Join Date
    Dec 2015
    Location
    Auckland, New Zealand
    Posts
    32
    Greetings, no mention as to what flavour Smart you have but it's not uncommon for the suspension springs to crack, more likely on the front than the back but it happens due to the nice stuff you guys but on the road. Normally they crack and break away at the top, did you hear a shot clatter, as the piece that fell of exited the suspension?? The reason the springs crack is because the paint finish applied by the manufacturer is not up to the standard required and allows surface corrosion to occur. As time moves on the corrosion gets deeper into the steel (which is high tensile) causing cracks to appear - no you can't see them unless you take the spring out and have it cracked checked. Eventually, what's left of the steel is not enough to support the car and it breaks. You may fine that one side of the car is lower than the other if you're parked on a flat surface. If both sides seem to be low, maybe both springs have broken???
    You need a special bit of kit to remove the front strut, as well as knowing what you're doing, rather than those that think they know and you're paying them to learn!!!!!
    Have look at evilution.co.uk and/or fq101.co.uk - both have the process of how to go about it - there is also on this site, a thread of which spring makers to go after.
    As to the hissing, that may well be from either front shock or back shock, all of them or just one. When you drive over the bump, does the car seem to keep bouncing once over it?
    Have a look at the shocks to see if there's any liquid around where the chrome shaft enters the body of the shock - it should be clean and dry, if it's not, probably the shock is dead as well.
    Might pay to buy a, new, complete shock/spring assembly but whatever you do to one front or rear corner, you need to do the same for the other front or rear corner, otherwise your car will become unbalanced and hence unsafe to drive.
    Big performance, may chime in here when he reads the thread.
    The same problem has happened here but not as regularly as in Blighty - being this is the 'sunny south pacific'.
    Cheers, Ian
    Cheers, Ian.

  3. #3
    Join Date
    Jan 2016
    Location
    North Somerset
    Posts
    12
    Many thanks for your reply. Certainly sounds like the spring has broken - the noise my wife described and the jagged top end to the spring.

    I have a Smart specialist a few miles up the road. Shall get it checked. The Shocks looked fairly clean when I looked yesterday.

    It's a '59 Cdi.

    Cheers

    Hugh

  4. #4
    Join Date
    Nov 2007
    Location
    BANCHORY
    Posts
    2,983
    I have examined dozens of broken unSmart springs having myself enjoyed at least 15 spring fractures on my current 450. The bar spring material is mainly loaded in torsion and cause for break is always brittle fracture just like if you take a crayon and twist it until it snaps in two. Brittle fracture is contrary to what the AA is saying who indicates the cause is material fatigue. In that case evidence of fatigue cracking should be visible on the fracture surface. On all springs I have examined the fracture surfaces showed no fatigue crack only brittle fracture on the plane of maximum shear at 45 degrees to the round bar principal axis.

    The hissing noise is most likely high frequency creaking in suspension bushes. The bushes will twist more when a spring is broken causing unusual noise.
    Drives a Smart Cdi - 65 to 85 MPG

  5. #5
    Join Date
    Nov 2007
    Location
    BANCHORY
    Posts
    2,983
    Your 451 front strut from lower spring support and up will look identical to the 450 strut:

    Above photo taken 3 January 2013 shows a cheap Anschler China spring acquired from Carparts4less for just under 8 each, postage included. These springs looked fine when fitted but not so fine about 12 months later:


    All paint is gone and spring looks pitted and rather miserable.

    Four years later these two Anschler springs have not yet broken and are in fact the longest lasting front springs my Smart has ever had. I conclude these China springs are made out of material that has better impact toughness properties than OEM springs hence less susceptible to brittle fracture.
    Drives a Smart Cdi - 65 to 85 MPG

  6. #6
    Join Date
    Jan 2016
    Location
    North Somerset
    Posts
    12
    Many thanks for that. Looking at my springs I think it has broken near the top. I have suggested my wife and son don't drive it until sorted!

  7. #7
    Join Date
    Nov 2007
    Location
    BANCHORY
    Posts
    2,983
    Drive sensibly and not too fast. There is always a chance a broken spring may puncture side of tyre so if you do drive keep that in mind. This applies mainly to those that have fitted extra wide tyres. Mine has 135/70-R15 on the front with plenty of clearance between tyre and spring so nearly physically impossible to puncture a side wall.
    Drives a Smart Cdi - 65 to 85 MPG

  8. #8
    Join Date
    Jan 2016
    Location
    North Somerset
    Posts
    12
    Does anyone know what the going rate is () for having the front springs replaced?

  9. #9
    Join Date
    Oct 2009
    Location
    Bury Lancs
    Posts
    69
    Quote Originally Posted by Avantime View Post
    Does anyone know what the going rate is () for having the front springs replaced?
    No idea of cost but it only took me a couple of hours to do both my Roadster's front springs & that was the first time I'd ever done them. I reckon an experienced garage could do them both in an hour. My OE springs were about 70 IIRC though there seems to be loads of pattern for much less.

  10. #10
    Join Date
    Jan 2017
    Location
    Suffolk
    Posts
    24
    I think we recently paid around 200 to have both springs replaced inc the springs (genuine) through clickmechanic.

    I'll post up pics of the old ones in a bit with my thoughts..

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