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currently, we are finishing up assembly of our rolling chassis. Everything is on the chassis before we drop the body back on. So, we decided for kicks how much it weighed without the body on and where all the weight is being distributed per tire/wheel. We have verified our scales are accurate down to the lb.
we noticed looking at the numbers that there is over 100lbs favoring the right rear tire. Which left us scratching our heads and brainstorming..... How?
the only "assumption" we could make is the engine/transmission being offset, however, looking at the cars centerline front to back I dont see how that much weight is being put over the right rear tire. I was sure the numbers would somewhat favor the left rear as when I installed the sump into the fuel tank it was put 1/4"-1/2" towards the driverside for reasons. the entire cars suspension is vansteel's independent coilover setup.
My question(s) is:
Are our assumption or idea of the engine/transmission offset the cause for the big weight difference side to side? If not, where is the 100lbs coming from?
Thanks!
Last edited by 61grandsport; Jul 10, 2019 at 08:54 AM.
It would help if you used the terms Driver front/rear....Passenger front/rear.
If you take the total weight of the engine/transmission and the amou t of offset and any components/alternator, steering box, etc. .......I could easi.y see a 100 pound difference.
The problem would be.....why does only one wheel show 100 pou ds more. Maybe the front opposte coil spring is not seated exactly as the other spring, or the spring is slightly taller, or stiffer......causing the chassis to push down more on the "heavier" rear wheel.
Is the batery installed? That is additional weight.
Maybe the scale misread. Maybe the floor is 1/4" unlevel where the wheels rest compounding the weight difference?
Let us know what you discover.
Last edited by doorgunner; Jul 10, 2019 at 09:54 AM.
It would help if you used the terms Driver front/rear....Passenger front/rear.
If you take the total weight of the engine/transmission and the amou t of offset and any components/alternator, steering box, etc. .......I could easi.y see a 100 pound difference.
The problem would be.....why does only one wheel show 100 pou ds more. Maybe the front opposte coil spring is not seated exactly as the other spring, or the spring is slightly taller, or stiffer......causing the chassis to push down more on the "heavier" rear wheel.
Is the batery installed? That is additional weight.
Maybe the scale misread. Maybe the floor is 1/4" unlevel where the wheels rest compounding the weight difference?
Let us know what you discover.
will do, I look the suspension over and check the dampening/stiffness on the coilovers and other variables. the scales are good and accurate, we zero'd them out and used a known good weight that was spot on. Even went to the extent of moving the scale per tire to different locations, To which the weight stayed with each tire location and did not move with the individual scale.
the tank does have 5 gals of E85(6.59lbs/gal), which the math comes out to be a extra 32.95lbs in the tank over the rear.
The weight difference over the driver side front compared to the passenger side front makes some sense with the steering gear box installed.the battery is out and not a factor at this time. 100lbs difference between the driver side and passenger side rear is what I have in question.... However, did over look the fact the numbers show more weight over the passenger side rear vs the passenger side front with the engine and transmission a factor.
To get a more accurate reading, I'll go back over each coilover again to inspect, and ensure I adjusted all 4 to the exact same settings.
Last edited by 61grandsport; Jul 10, 2019 at 10:36 AM.
Reason: add more info for clarity.
Your frame is only 26 lbs heavier on the right side.
What you have is weight jacked diagonally to the left front (like a Nascar car) and right rear. and you need to adjust the springs. The LF & RR springs are handling 226lbs more than the other diagonal, like a 3 legged chair.
To adjust the springs: Like a race car:Since you have coilovers it should be easy
Disconnect all sway bars
Reweigh
Adjust ride height DOWN on any one heavy corner to lose weight on that corner, and put more weight on other springs
Adjust ride height UP on any one light corner to gain weight on that corner, put less weight on other springs
For ideal handling you would like the extra 26 lb right side bias to be all the the RR spring and the fronts exactly equal
If you can get within 20 lbs of that you'll be great. right now your LF is 100lbs heavy.
Now set ride-height by moving both Fronts up or down equally, same with rear, wheel weights should not change
Re-attach sway bars and make sure wheel weights do not change
If they do, use an adjustable link on one end of the sway bar until you can hook it up/off with no weight change
If you still have coils in front, you can do it all in the rear. It's just hardrer to adjust ride height in the front.
If you want all 4 exactly equal Right -Left you need to move 26 lbs to the left by moving something heavy, like battery, gas tank or engine, or ballast weight.
Last edited by leigh1322; Jul 16, 2019 at 10:45 AM.
If you want all 4 exactly equal Right -Left you need to move 26 lbs to the left by moving something heavy, like battery, gas tank or engine, or ballast weight.
Thanks for that write -up. However, when he adds the battery, steering column, master/booster and the driver's body, he will biased to the left by a few hundred pounds.
Ideally all the spring balancing should be done with body on, all fluids, full tank, driver, etc. "As-raced"
But he's pretty far off right now with a 100lb heavier corner. Not that it is going to take much adjustment on a coil over to fix it, just a part of a turn probably.
c3 weight distribution Q?(Chassis)
