Home Forums Tech Talk And now for my next question? Axle hop!

This topic contains 14 replies, has 6 voices, and was last updated by  David McDowell 11 months ago.

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  • #12605

    Chris Beebe
    Participant

    Being new this summer to karting and not knowing many who are active in the sport I have to come here for my next question! I was out testing today and it seems like I was getting more axle hop and possibly a little rougher ride on the track today. This track is kind of rough in sections to begin with but is seems like in the past it has been a little better. I read on here at one point that if the bearings are to tight in the casette you can get axle hop.  I tried loosening the pressure on them but it did not really change anything.

    Would air temp play into this problem? Summer time temps are usually in the 90s give or take and today it was in the low 60s. Do all karts have axle hop to some degree? Or is this something that I should be able to fix? This is a 125cc shifter kart and I am sure this probably needs to be known. Also running YLC tires. 40mm axle.

    At this point its just kind of annoying but I can live with it if I have to.

    Any info would be great.

     

    #12606

    Matt Dixon
    Participant

    You have got yourself overstuck.

    you need to free the kart up.

     

    #12608

    Chris Beebe
    Participant

    How do I free the kart up?

     

    Edit!

    I found some good reading on a CRG site that talks a lot about setup and how to adjust a kart for different issues!

    This should keep me occupied for a while!

    #12651

    Walt Gifford
    Participant

    Allot of axle hop is new driver. They go into the turn fast and shallow then try to make the turn all at once in the middle. Your kart develops tremendous lateral G force and takes a bite then either bicycles up or releases and repeats. Slow down and go much deeper and wider before you turn.

    Gif

    #12667

    Chris Beebe
    Participant

    Good info Walt. I know for a fact that I come into every corner hot. I know this from practicing alone on the track and then running with the pack. They all seem to take the corners a lot slower than I typically do. I did move my rear hubs in a bit today and I still run my rear torsion bar. I was going to go out and test today but its raining now :(  We have a race tomorrow and its going to be nicer so we will find out in the morning. I figure if I still have hop I will remove the rear torsion and then just hammer down at race time and hope for the best!

     

    #12682

    Matt Dixon
    Participant

    Chris without knowing anything about your setup both things you mentioned (moving in hubs/rear bar in) will be adding more grip not free up the kart.

    #12685

    Chris Beebe
    Participant

    With a little more reading I see what you are talking about Matt. It is slowly sinking in…..At least I think it is. I might be best off just removing the rear torsion and see what that does.

    #12943

    Brian Degulis
    Participant

    First remove the rear bar. Still tight Try increasing the front width . If it’s still tight bring the rear width out to 55″. Still tight add caster. Still tight put everything back to neutral and weigh the kart.

    Brian

    #13088

    David McDowell
    Participant

    Chris,

    First off welcome to Karting and to Southern Oregon Karters. What corner were you hopping in? If it was when you turned up the hill and threw the S’s that is pretty typical for that part of the track, and is more a line and turning issue than kart set up. Since in that corner there is one sweet spot and if you are out of it a little you get hop.

    #13111

    Chris Beebe
    Participant

    David, the biggest place I notice it is the big 180 turn at the bottom of the hill before the s turns. The slower tighter turns I dont notice it so much.

    I think the crazy part is that at the beginning of the day I pulled the rear torsion off completely and the kart was getting real loose in the corners. I will say that the wheel hop was less than usual.  By the end of the day the temps warmed back up and I put the torsion back in and it was handling great for the final! Makes me wonder how much of it is me and not the kart at this point?

    #13115

    TJ Koyen
    Participant

    Most people throw their rear torsion bars in the garbage because they’re rarely useful. They lock the rear down too hard in almost every occasion, binding the kart up and not letting it release off the corners properly.

    Putting the bar in might have made the kart feel better because you were so bogged down it couldn’t release and it felt stable. Lots of times in lower horsepower classes the kart can feel really stable and predictable but it’s just off the pace. And that’s because it’s got too much grip in the chassis and it’s not letting the kart roll on corner exit. It won’t slide because it’s all bound up. So it feels better but it’s much slower. I know this isn’t a lower horsepower kart but it might apply here as well.

    Sliding and out of control loose isn’t fast, it’s equally slow as being tight and locked down. But you need the kart to lift, rotate, and release and be on the edge a bit to be quick.

    Given that you’re relatively new, it very well could just be your driving or line. How consistent are your lap times?

    #13116

    Chris Beebe
    Participant

    I have no idea how consistent my lap times are at this point. It would be nice to pick up something this winter so I can keep track of lap times and changes I make.

     

    #13155

    David McDowell
    Participant

    <span style=”background-color: #ffffff;”><span style=”color: #444444; font-family: Arial, Helvetica, serif;”><span style=”font-size: 11.818181991577148px; line-height: 20.99431800842285px;”>”the big 180 turn at the bottom of the hill before the s turns” are you referring to the left hand turn as you drive back towards the pits at the bottom of the roller coaster,  or the one at the end of the main straight?</span></span></span>

     

    <span style=”background-color: #ffffff;”><span style=”color: #444444; font-family: Arial, Helvetica, serif;”><span style=”font-size: 11.818181991577148px; line-height: 20.99431800842285px;”>I would start by taking out the rear bar to free up the kart. Also on our track the last few races it has been really slick with minimal rubber to start the day. So your kart will seem loose, but I would say don’t change a thing to add grip, since our track usually comes in fairly fast and by the heats your are sticking. Lastly the YLC’s on our track are about 2-3 seconds a lap slower than the MG yellows. Last year when one of the guys switched to the yellows he passed the whole field in a lap just due to the extra traction. . </span></span></span>

    #13168

    Chris Beebe
    Participant

    Interesting info there.

    As far as which straight, I was talking about the back straight/roller coaster into the left hand 180 turn.

     

    #13442

    David McDowell
    Participant

    Chris,

     

    I’m not an expert tuner but I would say hopping in the corner you mentioned is due to over driving/driver error and not the kart set up. I would also loose the rear bar if not all bars.

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