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bullet proof timing chain system

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  • bullet proof timing chain system

    Hello all- I have an 88 M5 (that recently blew up) and an 88 S14. Seems like both these engines have some thing to be desired in the timing chain end of things. I was wondering if there would be any comments on this post found on another board regarding the S38. I am specifically wondering if anyone has rethought the timing chain guide rails...



    I am dreaming of a bullet proof timing chain system. Seems like Fahey has got the hub settled, but there are a couple of other things that need to be addressed. There is a lot of talk about S14 tensioner failure and an upgrade from a later engine (sorry I can't remember what). Is there something similar for the S38? Also (and here is the dream part) the guiderails for these cars are plastic and can fail due to age. Does anyone else think it is crazy to have these things made out of plastic? I know I am talking about a large amount of money for a limited sales possibility, but couldn't these be made out of something more hardy and then be coated with some antifriction material at the interface with the chain? Or have the main body of the thing be of metal and then have a plastic skid pad, so that instead of breaking and jumping teeth you would get some metal on metal noise indicating it is time to change the rails?

  • #2
    Hello,

    I cant give you any advice on the s38 setup,
    however the S14 really doesnt have a timing
    chain issue. when its time to change it, you
    will hear it. the original S14 timing chain tensioner
    was improved by BMW twice, but its still not as good
    as the e36 M3 3.2L tensioner. usually startup noise
    (from lack of oil buildup on start) subsides with the e36 m3
    tensioner installed. if it doesnt, e.g. your chain
    assembly is really worn, its time to redo all the
    guides. if you do hear timing chain noise, dont
    rev the engine and if it doesnt go away,
    redo it all. FWIW, the assembly lasts quite a long
    time (200k KM and more) usually.

    I have all new assembly in my new engine, have no intention
    of designing something else.

    John

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    • #3
      To add to what John said, the plastic guide simply does a very good job as is. It's not under any stress anyway as its only there to keep the chain settled along this long stretch between gears. I've never heard of them breaking and if I did, I'd suspect something else caused it. In other words, you've got a bigger problem if you're breaking chain guides.

      HTH,
      Jake Larsen

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      • #4
        The problem with the M88 is the single row chain. The E30 M3 has a double row, that's the reason some M88's have a chain break failure.

        All this is only valid if you have an E28 M5 as the E34 has a double chain...

        Adwo

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        • #5
          more of a problem of the S38, I guess

          Timing chain guide failure has taken a few s38s lately, not a terrible lot but enough to make me wonder. I guess this is more of a problem on the S38 than the s14. Just thought I'd check with the S14 crowd, because there are so many more of them that if it was a problem there would be a fix.

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          • #6
            Why not upgrade the S38 to the double row chain? All the parts should bolt right in.

            Do not click
            At least it's German

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            • #7
              s38 failures

              The american s38 from the e28 M5 does have a duplex chain. Euro versions have the simplex which can be retro fitted but it takes some milling work of the top covers.
              What has happened on a few S38s is that the chain guide rail breaks from age or fatigue. In a few cases, the bits of disintegrated rail lodge between the chain and cog, causing the chain to jump some teeth and with catastrophic results. See here for some images of the horror...

              http://scottiesharpe.com/bmw/m5/

              whether other things are causing the rails to fail is up to speculation, however the end result is the same. 5-10k in a rebuild.

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              • #8
                well, I cant see his other photos.
                where is the proof that is was in fact the timing
                chain guide that was the culprit?

                if all the valves are bent, I think his pistons wont be
                looking very good either...

                he is going to have to check his rods too. also the
                bearings.

                instead of buying new cams he may be interested in
                some kind of after market uprated cams,
                or there are/were 304/292 BMW motorsport cams available
                for the S38. Just in case he wants to make something
                a little wilder while he is "in there".

                John

                Comment


                • #9
                  Is that an M5 (US) or an M535is (Euro)? The US E28 M5's all had hand sewn dash and center consoles?

                  Tony

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