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Post by Karnak on Oct 9, 2014 9:06:24 GMT -6
So how do YOU do it? Driver in the seat or not? What about shocks… connected or not?
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Post by mark18mwm on Oct 9, 2014 19:34:44 GMT -6
I used to weigh the first time with me in the car to get my percentages and total weight. It took two guys because I used grain scales. I then got out and re weighed and used those numbers from then out to scale it by myself with out having to be in the car. Shocks disconnected.
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bradl81
Steering Wheel Holder
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Post by bradl81 on Oct 9, 2014 20:40:15 GMT -6
I think the more important part of that equation comes when setting ride height. There you need the driver's weight in the car to get it right. So driver in, shocks hooked up and proper fuel level in the tank, etc. for ride height setting.
For scaling, once you get the baseline, then it doesn't matter which way you do it. Some manufacturers want a certain percentage of cross weight with the driver in the car. Since all drivers weigh a different amount and generally have a different seat setback, then you need to measure that with the driver in the car. Again, once that is done, all you have to do is get the driver out numbers and continue.
I scale with the shocks on the car. I let the car settle after changes on some setup blocks that match the scales. I roll the car on and off the blocks and reset the zero on the scales as the session goes on. This stops the front end from pushing the scales sideways and loading them in the horizontal axis when using a jack.
In my mind the most important part is scaling, setting up and measuring using the same spot, method, scales, etc. every time. Consistency is the hallmark of good chassis setup. I tape T's to the floor to mark the spots where I setup cars. Each car has its own color of tape.
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Post by racer96m on Oct 10, 2014 0:36:22 GMT -6
I scale with driver in and shocks unhooked, I also remove the LR axle as it will load the rear and throw off the numbers. I run a 4/4 A Mod and our shock package is very aggressive. Alot of people will leave the shocks hooked up and let the car settle, but my LR gas pressure is 200lbs and will throw my numbers off. The key is whatever way you do it, keep doing it that way, then you will have an understanding of how the car will react to changes. No right or wrong way as long as you have that understanding.
Dave
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bradl81
Steering Wheel Holder
Posts: 4
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Post by bradl81 on Oct 12, 2014 9:21:02 GMT -6
I have played with removing the axles or not removing them too. I didn't see any difference in my numbers so I didn't continue with it. I also have one rear end that has live oil to the wheel bearings. So I would have to drain the rear end each time I scaled. That is why I compared. It is a good thing if you can do it with little effort. I need to check it on my newer car to see if it does affect the scale numbers.
I do have a very aggressive shock for the left rear that I don't typically have on the car when I scale. So I opt to remove the shock all together when I scale. Kind of that consistency thing. I scale for a feature setup scenario and make adjustments from there to arrive at a heat race/tacky track setup. I don't run that aggressive shock on dry slick tracks.
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Post by sanguinary on Oct 12, 2014 17:22:23 GMT -6
I usually scale with driver in and shocks hooked up. Driver in is mostly personal preference. I always take my weight and write it down as well because more data never hurt anyone. Shocks I don't really have a reason other than I like to shoot for the car being ready to race off the scales. Every part and piece is as it will be when it takes the track.
This is QA1's take:
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Post by Karnak on Oct 12, 2014 23:49:02 GMT -6
Thanks for that QA1 info...
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Post by oldegreezer on Oct 13, 2014 1:19:08 GMT -6
I'm retired and have lots of time as racing is my only hobby. I scale with driver in, shocks hooked up, L.R. axle out, 3 gallons fuel. I give car plenty of time to settle each time it goes on and off the scales. When I get the numbers I'm looking for, I then repeat all steps again and see if I can duplicate numbers. I then start over without driver and repeat all steps so I have those numbers also. I set ride heights with driver in and also record with driver out. I do all this on a level 10'x20' steel plate that is 5" thick. I try to set my car up for the last laps of the feature. I might be wrong but it's the way I do it. L.O.L.
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Post by Karnak on Oct 13, 2014 4:04:29 GMT -6
Sounds good to me...
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Post by MWM 04 on Oct 15, 2014 22:26:45 GMT -6
I take out the RR axle since that's the larger tire and the oil will run away from the hub. Stagger can cause a bind in the rear which will hike the car up and really **** with your mind when trying to set percentages. It's also easier to roll on and off after adjustments.
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Post by sanguinary on Oct 16, 2014 22:01:17 GMT -6
Has anybody scaled with axle in vs out and shown a noticeable difference, other than the weight of the axle?
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richard
Steering Wheel Holder
Posts: 3
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Post by richard on Oct 17, 2014 9:49:56 GMT -6
Has anybody scaled with axle in vs out and shown a noticeable difference, other than the weight of the axle?
HUGE DIFFERENCE! Here's my story:
I was unable to get consistency between scalings. I'd set it all up, roll off and on and it would be different. Finally figured out I hadn't pulled the axle and the bind from stagger was hiking the LR up which kept changing my split aka wedge. Only need to pull the splines out of the hub, not the whole axle. I do the RR so the oil doesn't run out.
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Post by Karnak on Oct 18, 2014 20:45:41 GMT -6
Has anybody scaled with axle in vs out and shown a noticeable difference, other than the weight of the axle? HUGE DIFFERENCE! Here's my story: I was unable to get consistency between scalings. I'd set it all up, roll off and on and it would be different. Finally figured out I hadn't pulled the axle and the bind from stagger was hiking the LR up which kept changing my split aka wedge. Only need to pull the splines out of the hub, not the whole axle. I do the RR so the oil doesn't run out. Good first post… thanks! |
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csuzik
Steering Wheel Holder
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Post by csuzik on Oct 25, 2014 7:53:11 GMT -6
When it comes to determining driver in/driver out and shocks on/ shocks off, should go by the chassis builders guidelines to start, then once you are more acquainted with the car and how everything works then if you feel adventurous you can try different things on your own. You always have the builders guidelines to fall back on. As for pulling one axle or not, we tried both. What we found by not pulling an axle, when you roll the car on and off the scale pads with both axles in, the car had a tendency to bind up especially rolling backwards causing the car to tweak a little throwing the numbers off and creating inconsistent numbers each time you roll on and off the pads. If you can't keep getting consistent numbers, you will have a hard time getting your numbers correct. |
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Post by confused on Oct 25, 2014 12:11:29 GMT -6
I scale the first time, with any car, with the driver in. I make notes about scales numbers and ride heights. Then take notes without the driver. This gives me a good reference point to start with. Since I do most adjustments and chassis work by myself, this is the way that works.
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Post by Karnak on Oct 26, 2014 0:30:33 GMT -6
I was looking at CJ Rayburn's site a while back and he recommends something interesting… add the weight of the driver to the seat BUT do not put the driver in the car. I wonder why?
I have a lot of respect for his opinions… he's really the father of the modern LM race car.
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Post by confused on Nov 16, 2014 9:57:48 GMT -6
For the first time with a new car, I have the driver in the car. I can set everything where I want it that way. I will take notes after the driver gets out. This way I have a base to go back to when I have to adjust the car by myself.
As far as having shocks hooked up. I will disconnect twin tubes or shocks with a high rebound. I leave the stiff compression LR hooked up. Disconnecting that one will have a big effect on the wheel weights. I was told by Wayne Brooks and Kevin Shaw to disconnect all twin tubes, and leave gas shocks hooked up. Their thoughts were because of the amount of time it takes for the twin tubes to settle and lack of consistency.
That's what works for me. The main thing I've learned over the years is, once you find something that works well for you, keep doing it. As long as the crew does the same thing week in and week out, they will be fine. Scale number are base line indicators and nothing more.
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