Tuning and Tweeking

These posts were posted on PKF Forum, I was very impressed by the knowledge and experience given, the disscussion was about testing two different used buggies, but this part was about tuning and tweeking the race buggy.

 

• Krohn1999 – Sure the buggy will work for anyone that can fit into it, BUT for it to work the way it should it needs to be fit in the length and width of the person using it. For example it was written above that he got lifted out of the Apexx, if an Apexx is the correct size the driver can decide if he wants to get lifted out or not. In My Apexx all I need to do is either push my legs apart and the buggy will be lifted with me. if I pull my knees together the buggy will drop off me.

  Another statement from above was about the sitting position, something about sitting on top of the rails. The Apexx is made so the driver can decide how deep he wants to sit in it. That is why you have the height adjustment on the rear axle. By using this in conjunction with lowering or raising the seat you can go low enough that the side rails are in your armpits.

  When Ruudje builds an Apexx for someone he wants to know a lot of different things about the persons riding style. For example if the person uses only race kites he will add a little length to the side rails so there is more pressure on the front wheel. Also the down tube length is made to fit the person’s height. On “off the rack buggies”, if you are short like me, you have a lot of down tube sticking into the seat. He makes them to the length that the person needs.

  With the MG Aero you have also the option of side bar width, and seat height.

  After you find the best sitting position for you, you then have to get the buggy ” back in balance”. This is mostly done with adding weight. Usually you need the extra weight up front to keep enough pressure on the front wheel so it does what you want it to.

  I am sure most people here have ridden in a buggy where they will turn the front wheel and the buggy keeps going straight for a bit before it starts to turn. The problem is that there is not enough weight on the front wheel. Or if you go into a drift and the backend swings to far around, then you need to add a little in back.

  If you start out with a buggy that already is set up for your size you can make these fine adjustments using very little weight. If the buggy is not set up for your size then you may need a lot of weight to make these corrections.

  I see a lot of people making adjustments to buggies by going with wider rear axles or with side bar extensions. Lots of times this will just create other problems.
  I myself am about 5’8″ and use a 135 cm rear on my Apexx and it works just fine.
  On the MG they all come with a 150cm axle and I have been thinking of cutting it down.
  Both buggies do not have extensions.

  I do need to add the extensions will help you get more weight on the front wheel but it is more effective to just use weights.

  So that’s enough for now.

  So that being said, yes anyone can get into any buggy and ride it. But at the same time, No it is not a good idea for someone to start testing buggies ( and writing things in forums) when they are custom sized buggies not made for them.

• Danger – Adding weights is only the very last option someone should go. Adjusting the seat position/point of pull right is one if not the most important thing you have to learn if you want to ride a race buggy to its full potential. first problem is that most people tend to set their seats up like deck chairs, while a nearly straight upright sitting positing is the way to go as it centers the mass of the upper body and gives much more control. this will not be the most comfortable way to ride, but there is a reason u have bucket seats in a sporty car and not wing chairs. with a spot on adjusted buggy leaning your upper body 1 inch in front or back gives u full control over rear or front breakouts (a point why you won’t see fix back rests on most competitive bugs). Easiest way to test that is driving overpowered enough that gusts drag you slightly to lee, if the buggy slides over all 3 wheels while you sit straight and don’t move its perfect.

  getting lifted out of a Apexx without wanting it really shows that the buggy does not fit. if the Apexx fits you are locked in it as you slide in, to get out you have to slide your bottom to the front or really push our knees together and let a force from above lift you. that’s one of the major advantages i see in the clamping the Apexx uses over other buggies. i have seen other bugs where u have to push your legs to the sides etc. to clamp, but that won’t help you at all with unforeseen lifts where you just won’t have the time to react.

• Krohn1999 – The most important thing in setting up a buggy is getting it balanced so when you go into a drift that it equally slides over all three wheels. Once you have that you can start to add your personal preference. I personally like a little more weight up front because I use kites that fly more towards the front of the window ( Vapor, GT, Z3, Spirit). This keeps enough pressure to keep the wheel going straight even when you are overpowered. When you go into a drift the rear might feel a little light but is normally possible to keep on track with a slight counter steer up front.

  The weight can be achieved by either moving your seat closer to the front, or adding weight. A lot of times you have several possibilities on where you mount your foot pegs. If you put them in the most forward position and then adjust your seat accordingly you will have the max pressure on the front wheel without adding weights.
  I really suggest to everyone that has such a buggy to try this, you will be surprised what a difference it will make. If you still want more add weight, but start small, 3 or 4 pounds. Mount the weight directly over or in front of the front axle for max effect.

  Another good thing is keeping your CG as low as possible. This keeps the buggy from tipping. Also in buggies like the Apexx if you are low enough your spreader bar will hook under the side rail which is cool because the pressure of the kite gets transferred directly to the buggy instead of over your hips. This is really nice in long distance races or in day long rides.

  What has not been discussed yet is tires and pressure. This is a very hard thing because every beach has a different type of sand. What I can say is the harder the ground, the more pressure you can use.
  Tire grooves, also very important. Up front I run 13 grooves. In back 7-9 is plenty. Make sure that the grooves have sharp edges and are wide enough so they don’t just get plugged up with sand.
  Which tire is the best? No Idea! I think it is a personal decision that everyone needs to make for themselves. I personally like Duros the best, but am still running CadKats on my Apexx, simply because the difference is so small that it is not worth buying a new set.

  Bearings? This is another hot topic. I personally use good but cheap bearings. The real el- cheapo ones can cause alot of damage when they freeze up at 60. The really expensive ones run nice but seem to have the same problem as the ones I use. Over time the bearing seal will be damaged by sand and small rocks. Once it has been damaged to grease will flow out and sand will enter. Then it is just a matter of time.
  The ones that I use cost around $5 each and I just change them out as soon as they start to make a grumbling noise.

  I think the biggest trick is finding a way of just keeping the sand and salt water away from the bearing. One easy way is just spread a thick layer of grease over the top of the bearing, quite messy but it works. I have been experimenting with capsuling the bearings so that nothing can get in to them. Some of the things I have tried have been successful but still to early to talk about.