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Trailering question

Discussion in 'E85 Z4 (2002-2008)' started by mjmyers, Sep 6, 2010.

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    mjmyers

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    Going a ways to my next HPDE and the wife's encouraging me to flat bed the car there and back. Can borrow an enclosed trailer, so can't really object.

    Question is, car will be secured with straps, should it also be left in gear, or is that just avoidable wear on the drive train?

    I'm not planning on using the parking brake, especially at the end of the last day, but I certainly could after the brakes cool overnight.

    Thanks!
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    • Staff

    steven s

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    If the car is flatbedded, how is that wearing the drive train?
    Never use the e-brake after coming off the track PERIOD.
    Brakes don't need overnight to cool. :)
    They will be cool to the touch in an hour or less.
    I can swap my pads 30 minutes after my last session using gloves.
    • Member

    MGarrison

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    I have read (via the internet, so consider the source, ymmv) that there is potential for transmission damage if a car is left in gear while trailering. I could see this being possible if the car isn't secured otherwise by not tightening straps down well enough initially, or straps loosening during transit (which happens), and no parking brake on, or a parking brake that doesn't hold well. Couldn't be good for a transmission gear to be taking the forward/backward motions while in transit.

    Steven is correct, applying the parking brake while the brakes are hot right after a track session is just asking for the parking brake shoes to glue themselves to the inside of the rear rotors. Just how cool is cool enough to use the parking brake is a matter of judgment and guessing. I haven't had a problem once the wheels have cooled to be mildly warm to the touch (ie: I could keep my hands on the wheel indefinitely with no discomfort). Depending on ambient temps and how hot the rear brakes got, that's typically at least 1/2 hr. to around the hour mark that Steven mentions.

    I usually load the car onto the trailer and get it properly positioned (so there's enough tongue weight), and if on a hill, pull up the upside straps enough to hold the car in position, release the parking brake, and affix the opposite straps, and begin to tighten them so the straps are pulling only against themselves, and making sure the car isn't being pulled out of position as the straps are tightened. Once the straps are tightened down securely, I put on the parking brake, but I leave the transmission in neutral. Obviously, the rear brakes have to be cooled enough for applying the parking brake.

    Trailering has its own set of caveats - check the age of the trailer tires before you go. Make sure you have at least one spare trailer tire, and all are properly inflated. Make sure you have a breaker bar and socket the correct size for the lug nuts. Trailer tires should be inflated to their max pressure indicated on the sidewall, cold. Trailer tires are made to operate @ 65mph and should be inflated more if you expect to run much over 65, but you also increase the risk of a tire failure. Trailer tires older than 4 yrs. are going to be more prone to suffer a failure.

    Read these:
    http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=11&
    http://www.tirerack.com/images/tires/goodyear/Marathon_Special_Trailer_Applications.pdf
    http://www.discounttire.com/dtcs/infoTrailerTireFacts.dos
    http://www.easternmarine.com/em_store/tech_info/trailertires_tech_info.html
    http://www.sherline.com/lmbook.htm

    Consider one of these if the trailer isn't already stocked with one:
    http://tweetys.com/trailer-aid.aspx

    The trailer likely has electric or surge brakes - familiarize yourself with how each works. Electric brakes need a brake controller (properly adjusted) in the tow vehicle.

    Might be a good idea to check the lugbolt torque on the trailer wheels before you head out. There may be a sticker on the wheels indicating torque range. Mine are 90-120 ft-lbs.

    Weight distribution in the trailer is important for safe hauling - tongue weight should be 1: Within the weight limit of the hitch & 2: 10% of the weight of the fully loaded trailer. If everything's loaded well, both the trailer and tow vehicle should sit relatively level. You may know already, but too little tongue weight can lead to the trailer swaying, which is dangerous, to say the least. More trailering details in the above Sherline link.
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    CRKrieger

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    Just to be contrary, I'd like to know if either of my friends here has ever seen a problem arising out of using a BMW parking brake right after a track session. I never have, and I seriously doubt that anything bad will happen if you do so. The center of the disk isn't where most of the heat is and the parking brake shoes, if anything, would help the disk to cool by conducting a little of the heat away from it.

    I suspect this advice came mostly from the Audi folks whose parking brakes clamp the pads directly onto the disk. That's just asking for trouble in two ways. One is that these two hot surfaces can literally warp the disk and the pads will cook at the same time. The other is that, as they cool and parts contract, the brake loosens and the car can roll if not left in gear.
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    MGarrison

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    Interesting - I don't think I have, and I've had a few students pull on the parking brake after a session out of force of habit. By the same token, these were all 1-2 school novices who weren't pushing things to the nth degree and it's not like the rear brakes were sizzling at that moment. Plus, I had them move the car a bit just to make sure. Having been duly warned countless times, I never took the risk of trying it at the end of a session. True though, the rotor hat on the rears acts as more of a heat sink and the rotor surface contacted by the pad would be the hot part. One of those things where I never tried to push my luck! :)
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    CRKrieger

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    I think I may have set it a few times, but I'm not much of an example either. I'm (relatively) very easy on brakes.

    'Cause yer a wimp. How's that cash register cleaning up for ya? :D
    • Member

    MGarrison

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    Ha! :p Well, y'see, I always preferred to drive home at the end of the weekend vs. the envisioned time-consuming rear-parking-brake disassembly-before-departure debacle.

    Cash register cleaned up fine, (thanks much again for that!) but polishing it up would be an entirely different matter. I don't know if they originally were all sparkly-shiny or not, that'll have to wait until it could move up in the priority list... which will be awhile!

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