Scottie-GNZ Posted August 1, 2001 Share Posted August 1, 2001 Forgot to mention that I put my car on a scale before I pulled it apart. Since I intend to change the Vette spring, I needed to know what the rear weight was in order to get the correct spring rate. Total Weight - 2,620 lbs Front - 1,380 lbs, 52.7% Rear - 1,240 lbs, 47.3% Not sure how to factor in my 220lbs, but since it is just forward of the rear axle it should be mostly on the rear. If I put it all on the rear it is 48.6% & 51.4%. Not sure how that compares to a stock Z, but any car that has better than 50-50 with the driver is great IMO. Should be interesting when I get the Vette IRS in. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 1, 2001 Share Posted August 1, 2001 Maybe short pants worn commando style and sandles would help the distribution a bit ... Regards, Lone Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 1, 2001 Share Posted August 1, 2001 Very similar to mine too. Mine started out 1140/1110 for a 50.6/49.4 F/R distribution (without driver in race trim). But add the same size and heavier street tires (front and rear) and wheels, a front lip, headlights, fans, wiring, and body mods to make it bolt on probably get it to more like 1210/1130 for a 51.7/48.3 F/R. Quote Link to comment Share on other sites More sharing options...
stony Posted August 4, 2001 Share Posted August 4, 2001 AHHHHHH!!!! How do you weigh a Z???? i Have access to a set of scales at work that they weigh pallets with. Would i just drive the car up on it with the fronts take a weight then with the rear and take that weight. Then add up for total weight? Help me out here ;> thanks stony oh yea check this forum out http://www.automotiveforums.com Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 5, 2001 Author Share Posted August 5, 2001 I use a big drive-on scale at a junkyard. Sounds like the scale you are referring to should work. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 5, 2001 Share Posted August 5, 2001 One more note, for an acurate weight, the height of the scale (the surface that the tires rest on) must also be added under the tires to the other side of the car so that the car is essentially level when you take your readings. Terry Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 5, 2001 Author Share Posted August 5, 2001 Excellent point. That is why the drive-on scales are better. Most junkyards that crush cars or sell metal have scales, but the trucking and moving companies are your best bet. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted August 6, 2001 Share Posted August 6, 2001 I went to a place that sells landscape materials such as bulk rock, mulch, and fertilizer. When I pulled up in the 74 260Z (2610lbs w/o me.) I asked to have my car weighed and the lady just laughed and said sure - no charge. The scale by law is very accurate (<10lbs in 1,000lbs) because of the commercial business so here is another place to get your car weighed. Also, most drag strips have scales but they generally cost. Danno74Z Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 6, 2001 Share Posted August 6, 2001 A little while back I weighed my 5.0L ford powered 260Z at the drag strip. With 16 gallons of fuel, fifty pounds of tools in the passenger floor, and my daughters baby seat, the car weighed 2675 w/o me. I have since put the car on a little diet. The front bumber and mounts were removed, etc... So, curious about weight distribution, I did the following to get a rough estimate of weight distribution. 1. I measured the length of the springs with the car on level ground and the suspenion settled from a short drive. Front springs 8.5 in compressed Rear springs 6.5 in compressed 2. I subtracted the compressed height from the free length of the springs. Front Free Length = 12 in (200 lb/in) Rear Free Length = 10 in (175 lb/in) therefore each of the springs was compressed 3.5 in. Knowing the spring rate of the springs, I then calculated the force being applied along the spring axis. Rear 3.5 in * 200 lb/in = 700 lb Front 3.5 in * 175 lb/in = 612.5 lb Then using the angle of the struts and some trig, I calculated the force perpendicular to the road surface. 700 lb / cos(13.5) = 680.7 lbs /rear wheel 612.5 / cos(13.5) = 595.6 lbs / front tire As a reality check, I summed the four tires 2* 680.7 + 2* 595.6 = 2552 lbs This is what I would have expected because the car had only 12 gallons of gas and no tools, baby seat, or front bumper. This yields the following weight distribution. 46.67 % on front 53.33 % on rear I view these results with some skepticism because of inaccuracies in spring rate, etc..., but I find them encouraging. Dan McGrath Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 6, 2001 Share Posted August 6, 2001 Doh, I just realized that this only accounts for the sprung weight of the car. The overall balance should remain the same, but the weight of the car will increase by about 80 lbs. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 7, 2001 Author Share Posted August 7, 2001 Dan, not to be a doubter, but I doubt a V-8 Z could have that good a F-R weight distribution. Aluminum heads and battery in the trunk would go a long to helping though. Where you been. Have not seen you and the car in a while. I am planning on going down to Moroso this Sunday for a big import meet. You up for it? Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 7, 2001 Share Posted August 7, 2001 Yeah Scottie, I doubt the results too. I need access to some wheel scales to get accurate numbers. I've been autocrossing the car rather than drag racing lately. I've been concentrating on handling and braking. I'm going to the Lockheed Martin plant this weekend to compete in the Martin Sports Car Club event. Moroso sounds enticing. Hopefully you will invite me next time you go. Your project has taken an interesting turn. A corvette IRS . Hope to see you soon, Dan McGrath Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 7, 2001 Share Posted August 7, 2001 Dan, the friction in the strut cartridges are going to play havok with this method. Plus it's difficult to measure the actual lever arms that the springs work at, and hence the wheel rate vs the spring rate. Some blown out struts could help MEASURE the wheel rate, I'd think. Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 8, 2001 Share Posted August 8, 2001 It seems to me that another way you could make a rough calculation of the weight at each corner is to multiply the area of the contact patch of the tire by its air pressure. You could estimate the contact patch using 4 pieces of cardboard placed on the ground around the tire, pushed up tight to the tire, to form a rectangle. Then just measure the length and width of the rectangle to get the contact area. I don't know how acurate it would be, but it would be pretty fast and easy to try. Nigel Quote Link to comment Share on other sites More sharing options...
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