aknovaman

iTrader: (7)

Here is what i built for him.

I can build as many as you guys you want.

https://ls1tech.com/forums/tools-fab...-capacity.html

Forcefed86

iTrader: (4)

With a little work you can build a jack pad and get all 4 corners with one scale. I was going to use a harbor frieght car dolly to build a jack pad that will go under the tire.

Aknovaman on this forum built it. He is using his "china sources" So I don't have the Pn's listed.

Would be easiest to just make 4 rigs like this. Would be $240 worth of parts if you did it yourself. You'll have to contact Aknovaman to see what he would charge to do it.

DW SD

Thank you. I posted on Anthony's other thread.
Do you know the approximate diameter of the button head on the load cell and the overall OD of the cell?

Doug

aknovaman

iTrader: (7)

Cell is 2.5 inches dia; button is approx. 0.5 inches. The load must be on the button.


I ordered another load cell in the S-type configuration. It essentially has a bolt hole on the top and bottom of the "S" which makes it easier to mount to the top of a floor jack and a platform or any size button on top of it. The scale auto zero's at power up to account for the weight of a platform. I do not believe you need more than one of these scales as you can mount it on a floor jack and just weigh each corner of the suspension. If you build a platform for it, you can weigh the corners under each tire too. I could adjust the code to make it read within one pound but I wanted to get it to Forced quickly.

DW SD

So to build simple individual weighing pads: I could bore a 2 1/2" recess in in a 8"x8" x 1 1/2" piece of wood and then bore shallow a 1/2" recess in a hockey puck and set wheels down on those? (or perhaps use a thick piece of aluminum instead of a hockey puck)?
I realize the four pads would need to be level.

Doug

aknovaman

iTrader: (7)

Leveling is overkill and overrated. I suggested a platform of 1/2 inch steel with a small stack of washers welded to the middle of it to center the button. As long as the stack is not too tall and the load is placed directly on the button. The S-type cell would be easier. I don't suggest wood as it compresses and could lead to not all of the load on the button.

DW SD

Hi Anthony,
I guess nominally off level doesn't change much if you calculate out the vector geometry.

Buying some square steel coupons (6"x6" maybe) with washers welded to center the pad about the cell is a simple and cheap. I had the same idea with the hockey puck and a partial bore down the middle (shallower than the button is tall). compressible shouldn't matter as long as the full load is supported by the button.

I'm going to PM you directly.

Thanks a bunch!

Doug

aknovaman

iTrader: (7)

Sounds good. S type cell is easier

DW SD

Something like this:
http://www.ebay.com/itm/1000kg-22CWT-S-TYPE-Beam-Load-Cell-Scale-Sensor-Weighting-Sensor-Qty-1/171905777298?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D34875%26meid%3Df0a036b1a8a941e492af16d4e68d464d%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D281265642259

aknovaman

iTrader: (7)

Yes. That will work.

cruisin'73

iTrader: (8)

Cool cheap scale!

But lifting one end that high is probably transferring weight and giving false readings. Maybe when you are weigh the front; put jackstands in the rear so the car is close to “ride t height”. Be worth a shot, see if you get different numbers from the current method.

Forcefed86

iTrader: (4)

Good point, I'll give it a shot and see if it changes. I'll throw a level on the rocker panel and get another reading.

aknovaman

iTrader: (7)

I bet you a soda it will be insignificant to any adjustments he is wanting to make unless the angular deviation is huge. In that case it would not be safe to jack up a car at such an extreme angle. Looking for my calculator now to computer the deviation based up a huge angular deviation.

Forcefed86

iTrader: (4)

I was thinking that and the fact that the car won't be level at the launch anyway. Both wheels a little off the ground is about how my car launches. I'm using garage door springs as limit straps to help keep the nose down. Currently only have 70lb springs installed. I think I just need to move up to a higher poundage. Going to try 200lb springs next year. I don't want to limit my power at the line, and I'm stuck with OEM suspension up front for now, no no adjustable after market shocks available.

aknovaman

iTrader: (7)

How about ultrasonicaly measuring lift then retard timing and/or reduce boost proportionately till the front end settles. There is a commercial version out there for as little as $1500. Possible for less than $15 using some engineering stink.

Pro Stock John

iTrader: (34)

What is the r/weight of your RX7 forcefed?

Forcefed86

iTrader: (4)

I saw those setups they seem pretty cool. I'm willing to try anything as well, but reducing the power is the last thing I want. I want to add power. I think limiting the front end rise rate would allow me to put more power to the aft tires netting a quicker 60'. No reason I shouldn't be in the 1.2x 60' range with these huge tires/tiny car. Best it's ever done is a high 1.3X in perfect conditions. Usually a 1.4x 1.5x range.

According to the new scale 1307 with a full tank and 100lbs of ballast. 1500 up front. Haven't weighed it with me in the car.

aknovaman

iTrader: (7)

My buddy runs 4.20 in the 1/8 mile. His car lifts at about the 200 foot mark. Works like a champ and is cool to watch on the datalog. Much different than tracking front and rear wheel speeds for traction control.

Ultrasonic sensors are $1 each, arduino is $5, assorted parts to condition input signal for microsquirt is about an additional $10. Finally, add $1 for the plastic soap dish.

Forcefed86

iTrader: (4)

Mine lifts to the point of unloading right on the line when I release the trans brake. It has the factory struts/springs up front. Need to slow it down for sure. Not that something like your suggesting wouldn't help after I get the initial rise sorted.

PCella

iTrader: (2)

Well I just burned three hours reading every post and watching every video in this thread.
Great build and great documentation.
Thanks for recording all of this for the rest of us.