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Author Topic:   scaling car and lost help ?? long sorry
brownstone
Dirt Freak

Total posts: 284
posted August 21, 2004 12:03 AM  
I am attempting to scale my car but starting to feel clueless about the whole thing.

I am leaning towards the scale themselves being the problem but really dont know anymore.

I can set ride heights no problem. Then when I put the car on the scales. The numbers are way off which by itself is no big deal.

For example if the scales show too much LR, I will take turns out of LR and then put the exact same number off turns in the RR. So as not to screw up the ride height.

After trying this a number of times, it seems no matter what I do when I try setting the weights the ride heights get screwed up horrribly.

I have the base springs in the car that are reccomended from the builder. I have tried different spring rates, but still have the same problem.

The scales that I m using are the ones from the dirt forum tool box where you build a frame and use a bathroom scales and multiply times 4.
Has anyone else out there had this issue ?
I was told that the scales all have to be at equal height is this true ?

Any help is appreciated.
Thanks

mod70
unregistered Total posts: 284
posted August 21, 2004 12:19 AM           send a private message to brownstone   Edit/Delete Message   Reply w/QuoteBBBBBB
Best way to scale without messing with the ride heights is to take equal turns, for example, out of the LR and RF, and put same # of turns into the LF and RR. You only have to do half as many turns. This should cure your problem.

2nd2none
Dirt Forum Champ
Total posts: 755
posted August 21, 2004 04:37 AM  
technically said that removing turns off lets say the LR and adding the same turns into the RR will keep the ride heights the same is a loose term. If you are having to adjust 5 or 6 or more rounds out of one side and putting that many into the other side it will effect the ride height. If this is what is happening work all four corners because you wont be putting so many turns on one wheel but splitting it up between two (LR-RF)x(RR-LF)

Also, I've seen that if the rearend isnt centered in the car where it is supposed to be(off by a few inches)it will effect the scaling especially if the springs are on sliders.....one slider is more vertical than the other creating more dynamic wedge on that side.

brownstone
Dirt Freak

Total posts: 284
posted August 21, 2004 05:14 PM  
Uncle... I have leveled scales and made sure they are all at the same height. Still the same problem.

When I make adjustments the ride height gets all screwed up.

The car is a two link with the following springs

700 RF
700 LF
200 LR
150 RR


The shocks are disconnected and the pull rod is backed off.

Any help is appreciated.

mod70
unregistered Total posts: 284
posted August 21, 2004 07:02 PM           send a private message to brownstone   Edit/Delete Message   Reply w/QuoteBBBBBB
Just a thought for you or anybody else...
Could this be an indication of a bent frame?

cd2
Dirt Maniac

Total posts: 161
posted August 21, 2004 07:12 PM  
brownstone,how much is the ride height changing? If you turn down on L.R. 4 turns & back off R.R.4 turns ,check the before & after results.Let us know. cd2

cd2
Dirt Maniac

Total posts: 161
posted August 21, 2004 07:14 PM  
brownstone,also what is each wheel weight before & after? cd2

brownstone
Dirt Freak

Total posts: 284
posted August 21, 2004 08:06 PM  
The ride heights change dramatically, to the point that the car is really low to the ground.

I will try it again and post numbers. I will have to reset the ride heights and try again.

Anyway the last time around, the car was heavy on he LR. So I attempted to adjust it out. I had 100 lbs LR bite. The setup sheet from the builder says to start with 30lbs LR bite.

here are the numbers I started with:

LF 536 RF 520

LR 680 RR 580

So I took 3 turns out of the LR and put 3 into the RR. Bounced the car and saw that it changed some but not enough. So repeated the same steps. As the weights finally started to get close, you can look at the car and see that now the LR is sitting WAY low and the RR is now way too high.

Here are the numbers after making these changes

LF 580 RF 460

LR 648 RR 620


Again though the issue is that the ride heights are way out of the ball park. Took car of the scales and LR way too low.

Thanks for the responses keep them coming ,

2nd2none
Dirt Forum Champ
Total posts: 755
posted August 21, 2004 11:18 PM  
dude, are you reading the post? What your saying is you are having to put 6 turns in the RR and 6 turns out of the LR to get the LR weight you want?

ADJUST ALL 4 CORNERS AND YOUR RIDE HEIGHTS WONT CHANGE AS DRASTIC AS CHANGING 12 TURNS ON ONE END.

[This message has been edited by 2nd2none (edited August 21, 2004).]

brownstone
Dirt Freak

Total posts: 284
posted August 22, 2004 07:35 AM  
Okay, I will give it a go.

With corner weights below, where should I start ? The front is not that far off. I assume I would take of the LR and RF and then put in the LF and RR ?

LF 536 RF 520

LR 680 RR 580


by doing this wont it then screw up the weights in the front. Thanks again.

mod70
unregistered Total posts: 284
posted August 22, 2004 10:30 AM           send a private message to brownstone   Edit/Delete Message   Reply w/QuoteBBBBBB
Yes, take 2 turns out of the LR & RF, and put 2 in LF & RR and check it. If it's still a little off, do another turn on each.

cd2
Dirt Maniac

Total posts: 161
posted August 22, 2004 02:16 PM  
brownstone check your pm. cd2

brownstone
Dirt Freak

Total posts: 284
posted August 22, 2004 06:14 PM  
will do.

cd2
Dirt Maniac

Total posts: 161
posted August 23, 2004 11:49 AM  
brownstone,check your pm. cd2

brownstone
Dirt Freak

Total posts: 284
posted August 23, 2004 12:57 PM  
As directed I have adjusted at all 4 corners taking out at the LR and RF and putting in at the LF and RR.

This took the 70 pounds out of the LR that I wanted. However now the LF is almost 200 pounds heavier than the RF.
Thanks

[This message has been edited by brownstone (edited August 23, 2004).]

2nd2none
Dirt Forum Champ
Total posts: 755
posted August 23, 2004 03:25 PM  
When ever you take weight off the LR/RF it adds weight to the RR/LF. If you want a closer split on the frontend 1) increase your LR weight or 2) decrease left side percent.

BrianW
Dirt Freak

Total posts: 385
posted August 23, 2004 04:07 PM  
Have you thought about adding lead?? I can't remember how it was explained, but I was told if the car was built right then after setting the proper suspension angles and ride heights, etc. the weights will be close to the right %. When initially scaling the cars you should end up with numbers that are close - if not add lead to get it close then adjust the weight jack bolts to move a little weight around.

You said that you set up per the chassis maker - why not give them a call - that's what sets the good chassis makers apart from the poor ones...

JT54
Dirt Maniac

Total posts: 170
posted August 24, 2004 10:37 AM  
2nd is right ,you need to move or add lead to get good percentages......I have seen and driven more cars that perform better a little on the heavy side with great percentages and kicked but on the guys that are obsessed with staying super light and not quite having good percentages.....with these guys it is taboo to add lead .....I guess they rely on seacret voodo magic to get hooked up.

S_motors1
Dirt Newbie

Total posts: 4
posted August 24, 2004 04:41 PM  
what kind of numbers you looking for? Next what kind of chassis do you have? Im guess ing your looking for about 70#s of bite on the left rear,and about 60% of rear. Try this get your lr bite you want and your rear percentage,and make sure your ride heights are close.Then look at the numbers and percentages if the car is still way off in other areas you probably have samething bent like a ball joint, lower control arm, etc. Try that and post your new numbers.

tlkdlw
Dirt Full Roller

Total posts: 42
posted August 27, 2004 10:37 PM  
Screw jacks only adjust cross% Always set ride hight and make 4 corner adjustments. LF/RR
in or out RF/LR opposite.
Left % and Rear % are only changed with balast
(lead)

brownstone
Dirt Freak

Total posts: 284
posted August 28, 2004 08:44 AM  
To all thanks for your help. I found the trouble. Really had two things going which were both key and I feel pretty dumb about the whole thing.

It turns out that two of the scales were off considerably for one thing.

The second thing is the lack of RF weight is how the builder designed these cars, so my numbers across the front were close all along. The car is from a small builder that does excellent work but his setup sheet leaves alot to be desired.

I took car to fellow racers shop and used his digital scales and after setting ride height it too 4 turns and WHAM ! I was on the numbers.

I have ordered new scales, needless to say. Thanks again to all for your help.

I ran the car last night and it handled pretty good, so all is well.

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