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Can someone explain to me why bumpstops need to be cut?

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    Can someone explain to me why bumpstops need to be cut?

    Ok, now this is where im confused...

    Now IF YOU KNOW whether or not im right, please post. This is not me making another quiz, this is actually information that i've believed that I was right, but now im questioning and I may be wrong, because im being told different things and i've been told im wrong in a few cases, so i'd like to clear it up.

    1.
    Ideally when you lower your car, you NEED struts that have a shorter rod, shortened with a distance equal to the amount the vehicle is being lowered. You also need struts with dampening abilities that equal the new lowering spring rate. (up to this point i know im right)

    Now the part that i'm unsure of is: Do you have the SAME amount of suspension travel than you did before?

    2.
    Say freddy buys lowering springs for his protege, and he buys some struts with the dampening ability needed. The springs lower the car 1 inch, however the new struts do not have a shorter rod.

    Even though his new struts are going to be continually compressed by 1 inch,
    he is told to cut his bumpstop in half, and the bottom half stays installed, and the top half gets discarded.

    Now this is where I would come in and say "the bumpstop also theoretically has a 'spring rate' in the sense that it compresses a small amount, but as it compresses it becomes progressively stiffer... at a fast rate. if you decide to cut off the top half of it, you're cutting off the portion that 'eases you in' to the stiffer section of the bumpstop. when you do this, sure you get increase suspension travel by the amount that you cut off, however in the event that you DO hit the bumpstop (or whats left of it) you are no longer "eased into" it, and it is much more rigid than it would be originally, because the top section is removed. so you go from having 200lb spring rate to WHAM 600lb spring rate. This sudden increase would lead to unpredictable handling and a more harsh impact, and would therefore be a poor idea. Now in every instance where i've ever lowered a car i'd trim a portion of the bumpstop off (less than half... probably close to a quarter) OR i'd just go look for aftermarket bumpstops that are shorter to begin with. And i've never once had a problem. Now, i've been told that you MUST cut the bumpstop in half (the instructions in the lowering spring even tell you to).

    But can someone EXPLAIN to me why?
    *note that i said explain, and not insult/flame me

    Again, ideally a shorter strut should be used, however in the situations where a shorter strut isnt made for the car, or the person just doesent want to buy one.... removing that much of your bumpstop to ME seems like a risk. I know doing it the way I usually do it decreases suspension travel overall, but it still remains reasonably progressive.

    Ok, now discuss... and please enlighten me on why i am wrong. I've been told im wrong by a few people, but nobody explains WHY... so i remain confused

    so thats what im looking for here.... jesse's and edwins input would also be beneficial

    #2
    it's cut to make up for the travel lost by using lowering springs. it doesn't HAVE to be cut in half. usually only cut enough off the bump stop so that the strut rod/piston will not bottom out. and yes that why they make aftermarket bump stops, to prevent the harshness/stiffness cause by cutting a bump stop.
    Almost there

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    Still trying for a bp swap..:
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    Comment


      #3
      Bumpstops are there to protect the shock in the case of a very hard "bump". Cutting it in half is to make up for travel, as 95pro said. This is a bigger deal when you have cars with limited suspension travel, like the front of a protege, or the front of an early Sentra SE-R. Both run into problems when you lower them without using a shortened strut.

      Of note, the issue is not using a strut with a shorter rod, but using one with a shorter BODY. Rod length doesn't really matter.

      Only a few cars really use the bumpstops as a "spring". The miata is the biggest example.
      "Never run out of real estate, traction & ideas at the same time"
      -93 MR2, 129 ES
      ClubProtege.com Tech Articles

      Originally posted by WTF
      Remember low compression makes more space for AIR, HEEELLOOOO!

      Comment


        #4
        Originally posted by JesseSays
        Bumpstops are there to protect the shock in the case of a very hard "bump". Cutting it in half is to make up for travel, as 95pro said. This is a bigger deal when you have cars with limited suspension travel, like the front of a protege, or the front of an early Sentra SE-R. Both run into problems when you lower them without using a shortened strut.

        Of note, the issue is not using a strut with a shorter rod, but using one with a shorter BODY. Rod length doesn't really matter.

        Only a few cars really use the bumpstops as a "spring". The miata is the biggest example.
        but by cutting the bumpstop to make up for the lost suspension travel, arent we encouraging unpredictable handling? and shortening the life of the strut by removing some of its cushioning?

        Comment


          #5
          ok thanks
          that pretty much answers it for me

          as for my car, last summer when i put in the GR2's, i noticed that all my boots on the stock struts were torn... and the GR2's didnt come with any, so I bought replacement boot kits and it came with new bump stops... and they were bout 1/2 an inch shorter... so i put them in and havent noticed any problems yet

          didnt know the mp3's were shorter... i'll keep that in mind
          thnx everyone

          Comment


            #6
            Originally posted by pigeon
            but by cutting the bumpstop to make up for the lost suspension travel, arent we encouraging unpredictable handling? and shortening the life of the strut by removing some of its cushioning?

            Unpredictable handling will happen when the suspension hits the bumpstops. So shortening them will make that happen LESS. By the way, "unpredictable" basically means push.

            There's still enough bumpstop to hopefully protect the strut in the case of hitting a large pothole. Hopefully the stiffer springs will also help to keep the struts from bottoming out. This is why it's quite bad to lower the car a lot without stiffening it quite a bit.
            "Never run out of real estate, traction & ideas at the same time"
            -93 MR2, 129 ES
            ClubProtege.com Tech Articles

            Originally posted by WTF
            Remember low compression makes more space for AIR, HEEELLOOOO!

            Comment


              #7
              how do you know if your hitting the bumpstop?? i havne't noticed anything out of the ordinary and i stuck MX3 springs w/ ZX2 struts underneath i replace the bumpstops with some from tire rack for the ZX2 if memeory serves correct.
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              1992- project FE3..... 313 WHP @ 9.3psi




              I pet my dash when I get into the car..."good car"
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              Comment


                #8
                put a zip tie around the shaft of the strut. drive around. come back and see where the zip tie is. if its shoved up into the bottom of the bumpstop, umm, then obviously its hitting it.
                "Never run out of real estate, traction & ideas at the same time"
                -93 MR2, 129 ES
                ClubProtege.com Tech Articles

                Originally posted by WTF
                Remember low compression makes more space for AIR, HEEELLOOOO!

                Comment


                  #9
                  Originally posted by JesseSays
                  put a zip tie around the shaft of the strut. drive around. come back and see where the zip tie is. if its shoved up into the bottom of the bumpstop, umm, then obviously its hitting it.
                  im gonna do that, thats an awesome idea

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