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Old 10-20-2009, 12:37 PM
  #1  
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Default Droop-question

Simple question: How is droop measured?

I have learned to measure it between the chassis-level and the bottom of the A-Arm (suspension arm) ... but someone told me it has to be measured between the chassislevel and the bottom of the axle.

I guess both measurements can work as long as one always uses the same ... but what is the most used method. This is important to know when one has to know how to understand a setup-sheet correctly.
(I am the owner of a Schumacher Mi4)

thx for all advice
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Old 10-20-2009, 02:14 PM
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The easiest way is to use a ride height guage for checking the droop and ride height. Settle the suspension on the table and check the ride height.Say it's 3mm, then lift the car and check the fully extended height. Let's say 5mm. Subtract the ride height from the total extened number and that is your droop. 5mm - 3mm = 2mm droop.
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Old 10-20-2009, 02:32 PM
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or jjust keep doing what u doin.. its much easier... doing droop over ride height is kinda hard if your not use to it.. cuase you have to lift the car up and make sure u dont lift it too much that tire will leave the board..

most setup sheet on tc5 gives you droop on the a arm measurement.... or check youtube and search jilles video from redrc....
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Old 10-20-2009, 02:38 PM
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Actually the most common way of measuring droop is with droop blocks. These measure the maximum amount of downtravel of the a-arms at the outer hingepin measured against the bottom of the chassis. This system however doesn't take into account the rest of the suspension parts which vary in design from car to car making comparing these numbers almost useless. You can however make changes on your own chassis and compare the results. It is very simple a quick to do and can even be done holding you chassis in the air with the right type of droop guage.

I personally prefer the system of measuring droop over ride height as this is what droop actually is. I do this by calculating my current ride height setting against my current droop setting using setup wheels. When I factor in the height of my droop blocks (19mm in my case) I can work out droop correctly and compare to my brothers completely different chassis setup in the same fashion.
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Old 10-20-2009, 02:52 PM
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IMO the "best" method for measuring "droop" is to measure axle height.
It's the only way which you can transfer between different brands of cars or the same cars with different wishbone heights.

To do this effectively. Place the car with no wheels on a flat set up board.
Get a set of verniers and measure to the top of axle then subtract half the width of the axle itself.

hth
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Old 10-20-2009, 03:24 PM
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Hey luke, How are you doing?
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Old 10-20-2009, 03:48 PM
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hey dennis

I'm ok thanks mate, not really touched any TC stuff since I came home, no enthusiasm for it, I think I've raced twice in total lol and that was off road.

How you been fella?
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Old 10-20-2009, 04:21 PM
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Be VERY warry of what guys with silent Hs in their names have to say!

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Old 10-20-2009, 04:58 PM
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that's very true Mr Weiss (in distinct german accent lol)

Yours sincerely, Mr (H)'obson
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Old 10-20-2009, 10:52 PM
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Originally Posted by rced1
The easiest way is to use a ride height guage for checking the droop and ride height. Settle the suspension on the table and check the ride height.Say it's 3mm, then lift the car and check the fully extended height. Let's say 5mm. Subtract the ride height from the total extened number and that is your droop. 5mm - 3mm = 2mm droop.
ok dude, I have no problem there ... but my question was actually: WHERE do you measure, till what part of the car.
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Old 10-21-2009, 07:34 AM
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Originally Posted by Low_E
Simple question: How is droop measured?

I have learned to measure it between the chassis-level and the bottom of the A-Arm (suspension arm) ... but someone told me it has to be measured between the chassislevel and the bottom of the axle.

I guess both measurements can work as long as one always uses the same ... but what is the most used method. This is important to know when one has to know how to understand a setup-sheet correctly.
(I am the owner of a Schumacher Mi4)

thx for all advice
I suggest using the method used on the setup sheets in the kit, that way you can compare apples to apples when looking at other's setup sheets.
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Old 10-21-2009, 07:50 AM
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Originally Posted by Low_E
Simple question: How is droop measured?

I have learned to measure it between the chassis-level and the bottom of the A-Arm (suspension arm) ... but someone told me it has to be measured between the chassislevel and the bottom of the axle.

I guess both measurements can work as long as one always uses the same ... but what is the most used method. This is important to know when one has to know how to understand a setup-sheet correctly.
(I am the owner of a Schumacher Mi4)

thx for all advice
the lower surface of the arm (on electric TC) or upright (gas 1/8) is the most common, but there have been others. i looked at a mi4 setup and it just stated 5mm with no reference. funny it defines ride height as 'chassis to floor' (thanks for clearing that up!) but droop is not defined. seems a good question for a mi4 specific thread.

a quick search in the mi4 thread had 'marcos' indicate the bottom of hub to surface. (it was his setup sheet i saw on the schumacher website)
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Old 10-21-2009, 08:05 AM
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Originally Posted by rced1
The easiest way is to use a ride height guage for checking the droop and ride height. Settle the suspension on the table and check the ride height.Say it's 3mm, then lift the car and check the fully extended height. Let's say 5mm. Subtract the ride height from the total extened number and that is your droop. 5mm - 3mm = 2mm droop.
I m also using the above method, its the easiest I think. Just remember the droop value will change if you change your ride height without resetting the downstop adjustment.
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Old 10-21-2009, 12:29 PM
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I perform the following to measure droop.

Tools required:

Flat board and Vernier calipers


Taking the measurements:

1) Measure ride height with all electronics and shocks installed.
2) Remove wheels, shocks, and stabilizer bar and place chassis on flat setup board.
3) Measure from the top of the wheel axle to the setup board.
4) Measure the diameter of the tire your planning to use.


Calculating droop:

[((Td/2) + 2) - Ha] - Rh = Droop (in mm)


Legend:

Td = Tire diameter; Ha = height to top of axle, Rh = Ride height


Reference:

Link
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Old 10-21-2009, 09:20 PM
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Remember that while most of the above methods are correct there are variables such as tire diameter (which in real life is not identical between tires to the precision some people claim they achieve when measuring droop) there is suspension slop, air gap and so on.

I think the most accurate way of measuring is to lift the car up (as if using a floor jack) and measuring how far you lift before tires leave the ground. This is of course easier said than done so usually I try to compromise somehow until the car looks right.

The easiest is to measure axle height (to eliminate the extra variable introduced by measuring under some part of the suspension arm which relies too much for my liking on arms being moulded perfectly identical) with the chassis on blocks but as I said, once the tires are on, there can be differences, so I check quickly if they lift at the same time off the ground and if they don't, I readjust.

Using setup wheels again introduces another horde of variables because you don't know if the wheels are exactly the same diameter as your tires, plus your tires compress (so ground clearance will be different) and then when unloaded, they spring back, another unknown quantity (depending on insert, air gap and manufacturing tolerance). You've really got to find where enough is enough for you and try to keep consistent.
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