mid-engine buggy rear kick

standfast

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So why is it that folks say a mid engine buggy tends to kick. I don't have any problems in whoops/rough stuff but a jump that rolls over (no lip to take off of) the rear tends to come up a bit.

I don't want the car to just be setup for jumping but I would like to not worry about it nosing down so much.

I was thinking... increase rebound damping until it starts to pack up in the whoops and try to hit the same jumps that have created problems to see if there is a improvement. Thats all I can think of to counteract it without sacrificing other aspects of the handling.

Any design criteria suggestions? Trailing arm pivots raised up higher is one thing I have heard. Longer/shorter trailing arms?
 

joe1369

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So why is it that folks say a mid engine buggy tends to kick. I don't have any problems in whoops/rough stuff but a jump that rolls over (no lip to take off of) the rear tends to come up a bit.

I don't want the car to just be setup for jumping but I would like to not worry about it nosing down so much.

I was thinking... increase rebound damping until it starts to pack up in the whoops and try to hit the same jumps that have created problems to see if there is a improvement. Thats all I can think of to counteract it without sacrificing other aspects of the handling.

Any design criteria suggestions? Trailing arm pivots raised up higher is one thing I have heard. Longer/shorter trailing arms?

Less spring, bigger bypasses with more valving, or just try the rebound valving as you stated. Let us know what works!!!!
 

Sparky

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Hmm, same thing happens on my dirt bike. The solution was to accelerate up the face of the jump and try to carry the front instead of letting it roll over the top.
 

redmist

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I agree with Joe in regards to the spring rates and bypasses. However increasing the rebound won't do much, just stop the wheels from returning over the smaller stuff. Unfortunately with the very low polar moments generated with mid engined cars it's very hard to get them to fly with a badly formed ("rolls over") jump.

Think of a car like a see saw. Weight on the middle of the see saw, middy, is very quick and easy to pivot. Shift the weight outwards, like a rear engined car and it's harder to pivot. This is true in two of the three axis. IE, a middy will not only pivot in jump (when a force is applied to it) quicker than a rear engine car, but will also turn corners quicker.

I don't believe that this inherant issue with jump can't be corrected but it'll take some time to get right. I've got the benefit of having 600hp to play with so on every jump I power into it, pulling the nose high. If the jump is poorly formed though... I'm FUBAR. Bigger bypasses will certainly help my issues and I'll be adding a fifth to my 9100's once this season is over. In your case you may also want to look at the front end. You may be able to apply an upward force to the front end (to counter the rear coming up) by increasing the spring rates and decreasing rebound.

Middy's are fantastic. I wouldnt run a rear engine class 1 in the courses we have here in New Zealand. Still it's a matter of huge amounts of testing time with a video camera and someone who knows a reasonable amount about shocks. Video camera is essential, you really don't have a clue as to what's going on with the car while you are in the seat.
 

westtexasbaja

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So why is it that folks say a mid engine buggy tends to kick. I don't have any problems in whoops/rough stuff but a jump that rolls over (no lip to take off of) the rear tends to come up a bit.

I don't want the car to just be setup for jumping but I would like to not worry about it nosing down so much.

I was thinking... increase rebound damping until it starts to pack up in the whoops and try to hit the same jumps that have created problems to see if there is a improvement. Thats all I can think of to counteract it without sacrificing other aspects of the handling.

Any design criteria suggestions? Trailing arm pivots raised up higher is one thing I have heard. Longer/shorter trailing arms?

It's not all suspension. Driving style effects flying as well.

I saw you race in ABQ. Car looked good. I remember thinking the rear looked a little too soft and low. Just an observation. Good luck.
 
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