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Old 03-06-2005, 08:45 PM   #1
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Default Better Droop Measurement

Hey everyone,

I have been measuring droop differently from the stock method and I was wondering if anyone else does it this way.

1. measure ride height

2. Pick up one end of the car and slowly lower it until the tires just barely touch the ground. Measure this "max ride height"

3. Subtract the ride height from the max ride height and that is the number that I call droop.

This method has a couple of advantages. You don't have to figure out where to measure from using the droop gadge, arm or c-hub or set screw. This number doesn't change with different size tires. That is, if you lower the ride height you will then set the "max ride height" to be the same amount larger than ride height as it was before. Thus the difference will be the same. With foam tires and a standard droop gadge this can be a pain because your number will change as the tires get smaller and I don't know the correlation between droop gadge number and ride height if the tires are always getting smaller.

Your opinions are appreciated.

matt
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Old 03-06-2005, 08:52 PM   #2
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Default My method

The way I measure mine is set the desired ride height (5mm front & 5.5 mm rear) On a flat surface I use hudy drop blocks and set the drop screws until the tyres touches the board. I normally repeat the steps every run as we run foams. so I guess that give me 5mm front and 4.5mm rear droop.
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Old 03-06-2005, 11:19 PM   #3
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Default hmmmmmmmmmm

"hudy drop blocks and set the drop screws until the tyres touches the board."

Thats clear as mud.
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Old 03-06-2005, 11:33 PM   #4
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imjonah:
Basically the droop changes each time the wheel size does, which isnt a very cleaver way of setting your droop.

danjoy25:
The droop should be set to a value you want it to be, the wheelsize isnt important, and plays no part in alterations to the droop.
Once you've got the droop set, throw the wheels back on, check your ride height and then if its too high/low adjust the shock collar so that its correct.

The droop is a set value, it has an effect on the cars handling, if your tyres are getting smaller, then the only effect that has is making the chassis a little lower down, so raise it, certainly dont go setting important values by a decreasing sized foam tyre!


Kufman:
I dont do it that way, but i can see what your suggesting, however you could also fall into the trap of your wheels diameter changing resulting in a false setting.
The only real way of measuring the drop is to have the car off a flat surface, remove the shocks from the arm to allow them to sit comfortably (a good time to check there moving freely), and then measure the height change from the bottom of the chassis to a fixed point on the end of the arm.

If your car is lifted 5mm up, and the end of the arm is 8m up, then you have +3mm
Your better using either the hudy blocks and tool or i think RPM make one (as others probably do too) which has the chassis block and the measurement steps all on 1 unit, and you can see what setting it is at clearly from this.

Using a wheel which could slowly change in size as a fixed value to judge your droop will only cause trouble later on. You'll never get a true value
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Old 03-06-2005, 11:38 PM   #5
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But that is exactly what he is saying. If you set droop with a gauge that doesnt take into account the changing diameter of your tire, once the tire gets smaller and you raise the ride height to compensate, you have just lessened your droop value.
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Old 03-06-2005, 11:49 PM   #6
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Your droop is a fixed value, that can only be changed by adjusting a screw.
The droop is the change from the bottom of the chassis against the end of the wishbone. It has absolutely no relation or impact on ride-height, they are seperate values you sort out irrelevently to the ride height.

If you want 3mm droop, then set that on the car, that is a fixed value, nothing else but the screw changes that value.
When you put the wheels back onto the car, if the ride height is in-correct, then the correct way to fix this is by altering your shock collar on the ends needing it.

The Droop screw plays a completely different roll in the setup, and shouldnt be changed just because the ride-height is too high/low.

As you say, the tyre diameter changes reasonably quickly on foams, making the car lower to the ground, but thats the ride-height which is no longer correct, the droop is still at the desired height (or should be, it still needs checking now and then), if the ride height has changed, adjust the collars and remove some of the sink/play in the shocks till its at the correct height.
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Old 03-06-2005, 11:57 PM   #7
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If you set the car at 5mm ride height and 2mm up travel on 59mm foams and you wear the foam down to 58mm, your ride height is now 4.5mm. Then you raise the ride height .5 mm back up to 5mm, you now have 1.5mm up travel with the same droop setting based on your gauge.
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Old 03-07-2005, 12:11 AM   #8
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Default

Quote:
Originally posted by PaulC2K
Your droop is a fixed value, that can only be changed by adjusting a screw.
The droop is the change from the bottom of the chassis against the end of the wishbone. It has absolutely no relation or impact on ride-height, they are seperate values you sort out irrelevently to the ride height.

If you want 3mm droop, then set that on the car, that is a fixed value, nothing else but the screw changes that value.
When you put the wheels back onto the car, if the ride height is in-correct, then the correct way to fix this is by altering your shock collar on the ends needing it.

The Droop screw plays a completely different roll in the setup, and shouldnt be changed just because the ride-height is too high/low.

As you say, the tyre diameter changes reasonably quickly on foams, making the car lower to the ground, but thats the ride-height which is no longer correct, the droop is still at the desired height (or should be, it still needs checking now and then), if the ride height has changed, adjust the collars and remove some of the sink/play in the shocks till its at the correct height.
Obviously you don't race with foam tires. Because if you have you would understand that your droop settings and ride height are inversely proportional sorta speak. As your ride heigt decreases because of foam tire wear, you need to adjust the collars to get back to original ride height. AND you need to adjust your droop settings proportionaly.

For example. (basically what Jack said) If your tire wears from 58 to 57 mm, you need to adjust your droop settings by 1 mm. Otherwise your chassis uptravel will not be the same.

Personally, I don't use droop blocks like the Hudy ones. Too much of a hassle. Instead, as someone posted earlier, I measure how droop by lifting chassis and take measurements right before the wheel comes off the setup board. That way I will always have 2mm of chassis uptravel or 1mm, or 3 mm....etc. Hope this makes sense...its late so my apologies for any typos.
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Old 03-07-2005, 12:22 AM   #9
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http://www.treadztires.com/Graphics/tire5.gif
For the record, i always run foam, barely ever run rubber and im having my first shot at outdoor racing this summer. Helps being sponsored to run foam tyres that you actually do

[edit]
OK, i see what your suggesting, but its still not a true value is it.

You'd have the problem of not having a true value per wheel if the wear is wrong on one of the wheels, surely getting the true value of each would be the correct way to measure it, i run without any additive on and the diameter barely changes over 2-4 meetings, i think one set lasted me 5 meetings before chunking a rear tyre, going down only 2mm during that time (5x 5min per round) so say its .5m per meeting, .1m per 5min thats not really going to be noticable to a point where your needing to adjust it between races, so the proper droop value should be used i would have thought regardless of what the tyre diameter was at.

Last edited by PaulC2K; 03-07-2005 at 12:32 AM.
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Old 03-07-2005, 12:48 AM   #10
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Default Running foams

Well in our track, foams wear 1mm every heat (5 mins) so I need to raise the ride height every heat and also adjust the droop screws the sametime to get the same droop level I started with.
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Old 03-07-2005, 12:59 PM   #11
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Default

Quote:
Originally posted by PaulC2K
http://www.treadztires.com/Graphics/tire5.gif
For the record, i always run foam, barely ever run rubber and im having my first shot at outdoor racing this summer. Helps being sponsored to run foam tyres that you actually do

[edit]
OK, i see what your suggesting, but its still not a true value is it.

You'd have the problem of not having a true value per wheel if the wear is wrong on one of the wheels, surely getting the true value of each would be the correct way to measure it, i run without any additive on and the diameter barely changes over 2-4 meetings, i think one set lasted me 5 meetings before chunking a rear tyre, going down only 2mm during that time (5x 5min per round) so say its .5m per meeting, .1m per 5min thats not really going to be noticable to a point where your needing to adjust it between races, so the proper droop value should be used i would have thought regardless of what the tyre diameter was at.
PaulC2K,

The method that you are supporting is based on a predetermined ride height, i.e. Hudy Droop blocks etc, so therefore you are measuring droop off of the amount those blocks lift the chassis of the ground and not the actual amount that your car will see during actual race conditions…that is unless your tires are the same size as the Hudy droop gauges..

Do your own test with 60mm tires with a ride height of 4 mm and then check your droop. Next mount 56 mm tires with a ride height of 4 mm and then re-check your droop and you will see an obvious difference.

Basically, droop is a relative measurement.

How many times do you see the pros breaking out the droop gauges??? I can tell you that they measure droop with the tires on the car and lift the chassis to check how far the chassis comes up prior to the wheels coming off of the ground.
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Last edited by Michal101; 03-07-2005 at 01:22 PM.
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Old 03-07-2005, 01:18 PM   #12
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Quote:
Originally posted by Proteus
Obviously you don't race with foam tires. Because if you have you would understand that your droop settings and ride height are inversely proportional sorta speak. As your ride heigt decreases because of foam tire wear, you need to adjust the collars to get back to original ride height. AND you need to adjust your droop settings proportionaly.

For example. (basically what Jack said) If your tire wears from 58 to 57 mm, you need to adjust your droop settings by 1 mm. Otherwise your chassis uptravel will not be the same.

Personally, I don't use droop blocks like the Hudy ones. Too much of a hassle. Instead, as someone posted earlier, I measure how droop by lifting chassis and take measurements right before the wheel comes off the setup board. That way I will always have 2mm of chassis uptravel or 1mm, or 3 mm....etc. Hope this makes sense...its late so my apologies for any typos.
I do believe I read that Kinwald measures droop like you do,may be wrong.
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Old 03-07-2005, 03:27 PM   #13
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Default droop

actually to compensate for 1 mm tire wear (60 to 59mm) you would need to adjust your ride height back .5mm and adjust droop screws to change "actual" droop by .5mm . When you lose 1mm tire wear (diameter) you are affecting ride height by .5mm (radius) and when you readjust ride height with spring colars to compensate that .5mm you now have" taken up" .5mm between the droop screw and chassis so now you need to backoff the droop screw to make actual droop equal to where it was before tire wear. I use droop guages to get to a basic starting point then use "actual droop" to tune the car. "actual droop" is difference between ride height and extended suspension travel with the tires touching setup board. If your real smart you can figure out how far to turn droop screws to equal certain amount of change.... example 1/4 turn may equal 1mm droop change 1/8 turn may equal .5mm droop change.(measuring still most accurate) That would be dependant upon the threads per inch of the screw. What do you think ??? Ryan
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Old 03-07-2005, 03:59 PM   #14
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Default Re: droop

Quote:
Originally posted by ssscamaro
actually to compensate for 1 mm tire wear (60 to 59mm) you would need to adjust your ride height back .5mm and adjust droop screws to change "actual" droop by .5mm . When you lose 1mm tire wear (diameter) you are affecting ride height by .5mm (radius) and when you readjust ride height with spring colars to compensate that .5mm you now have" taken up" .5mm between the droop screw and chassis so now you need to backoff the droop screw to make actual droop equal to where it was before tire wear. I use droop guages to get to a basic starting point then use "actual droop" to tune the car. "actual droop" is difference between ride height and extended suspension travel with the tires touching setup board. If your real smart you can figure out how far to turn droop screws to equal certain amount of change.... example 1/4 turn may equal 1mm droop change 1/8 turn may equal .5mm droop change.(measuring still most accurate) That would be dependant upon the threads per inch of the screw. What do you think ??? Ryan
Oopps...yeah your right. Forgot about the radius. But hopefully they get what I meant.
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Old 03-07-2005, 04:35 PM   #15
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I think this is why its better to call it up travel then droop.

Basicly if you have to raise your ride hight up 1mm you will have 1mm less of up travel now so you need to loosen the droop screw to get back the same amount of up travel as before.

I can understand that after you set that up taking it and putting it on blocks to make sure left and right arms are at the same level at max travel so the car has no tweek to it.
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