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Droop
Dec 17, 2009 9:32:06 GMT
Post by martinchallis on Dec 17, 2009 9:32:06 GMT
I have just lowered my roll centres back to the deck of my cyclone TC. It then dawned on me that I had to reset my droop. This has been done at 4.8 & 5 mm But I don’t understand what effect more / less droop has on a chassis. Can anyone offer an explanation, as this is something I would like to stat playing with. also am i correct in thinking you measure from the end of the wishbone.. Thanks in advance guys…
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Droop
Dec 17, 2009 10:17:04 GMT
Post by Reuben on Dec 17, 2009 10:17:04 GMT
Droop has a massive effect on how your car handles, and effects the car at everypoint on the track. Btw when i talk about droop, more droop is a lower number on the gauge (so more uplift movement), Less droop is a higher number (less uplift movement). You can use droop to account for bumps in the track, as more droop will allow the wheels to stay in contact with the track when the car hits a bump and lifts (making the car smoother down the straight. Less droop and as the car hits a bump and lifts it cannot lift any further so the wheel looses contact with the track and the car starts to hop and becomes difficult at speed. Droop also effects acceleration and braking. As when you accelerate the front of the car lifts, now more droop is going to allow the car to lift further and absorb some of the aggression of the acceleration (which may make the car feel heavy or slower to respond on acceleration), less droop and the car wont lift as much which i found makes the car seem more responsive when accelerating (but also makes the car twitchy front end), however the more the front end can lift the more weight it transfers to the rear wheels giving more rear grip. Braking has a similar effect as when you hit the brakes the rear of the car lifts, and if it cant lift enough and you have a tight corner or bump then the back end is more likely to step out. more droop absorbs that lift and keeps the rear in contact with the road. with Cornering droop can control the amount of weight shifted left to right, less droop will transfer less weight and corner flatter but in certain grip levels will cause the car to spin or understeer depending on front-rear droop. More droop will transfer more weight and the car will feel like it rolls more into the corner making it more predictable, but direction changes will be slower (as the car will rotate arround its roll centre more before biting into the track). My advice would be to keep the front and rear droop similar (max 1mm more on the rear than the front), eg 3/2, 4/3, 5/4. Try all the settings for yourself one day to see how the handling is effected, when you found somewhere that is best for you, then tweak each end to see how it effects the car. Now this is from what ive learnt and found over the last year or so. So a more experienced driver may be able to sum it up better and in fewer words, or even have a different feel on droop .
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Droop
Dec 17, 2009 11:54:02 GMT
Post by martinchallis on Dec 17, 2009 11:54:02 GMT
thanks a bunch for that explanation mate... i understand much better now. i shall fiddle with it on sunday.
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Droop
Dec 18, 2009 0:15:07 GMT
Post by yellowshark on Dec 18, 2009 0:15:07 GMT
Hi Martin, I wouldn’t disagree with most of what Reuben says but I would add a slightly different perspective on measurement. One thing to remember is that if you change your ride height, that will change your droop, so you will need to change your downstops to compensate. It is not that relevant to rubber tyres, more to foam. But it is relevant on foreign tracks because you may well be playing around with ride height, and if you do not compensate with your downstop setting ,you will have introduced two variable that have changed – was it your change to ride height or change to droop that improved/worsened your setup? I maintain the setup of our cars by measuring uplift. Yes you have to set your downstops but as final step I measure the uplift and ensure it is what it should be. This also has the advantage that at the same time you will discover tweak. IE if the two wheels do not leave the floor at the same time then you are tweaked. Downstop settings not the same on both sides; shock settings not the same on both sides; chassis is tweaked. Yes I think most will measure downstop settings on the end of the A- arm. The important point is that YOU measure it in the same place every time. The precise location only really matters if you are copying somebody else’s setup sheet – even then you need to know where they made their measurement! This is important on an XRAY because on the underneath of the outside edge of the A-arm there is a protrusion which holds a grub screw and measuring there introduces a measurement difference compared to placing the downstop gauge to the left or right of the protrusion. To measure uplift, say at the rear, looking at the rear of the car, slide your ride height gauge under the centre line of the chassis and push it in towards the front until the wheels just leave the surface- the measurement on your ride height gauge minus your rear ride height measurement , is your uplift measurement.
HTH
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