TorAtle Posted July 12, 2003 Share Posted July 12, 2003 The question is - how do you corner weigh the car? Digital bathroom scale (goes up to 130kg). Garage floor pretty level. I have made up 3 pieces of wood to correct for the height of the scale, so the scale is moved from wheel to wheel while the 3 others are on those wooden pieces. All in all pretty level. I am not a large chap, so the only thing I can say is that the digital bathroom scale is beliveable when it comes to my weight, which is about 72kg. Small stuff, ie a wheel/tyre is also correct. How the scale is over 100kg is unknown, but one should think it is ok given the the above. The car is the bare minimum. Aeroscreen'd, Tilletts (non carbon), no capets, no crap in the boot, standard brakes, wet sump, no apollo (at the time), standard flywheel (at the time), stripped loom, light front and back lights, A032R/13" minator, no hand brake (ooo!), old type radiator. 1.8l on TBs. Plus a lot of mods that doesn't cost a lot of money, like a home made alu cam cover. The car has oil and water in it, and I guess somewhere between 5 and 12 litres of fuel. The reason why I'm asking how to corner weigh the car is this: Front left/right 123.8/105.6 Rear left/right 114.8/116.4 A total of 460.6kg.......... What have I done wrong? Do I need to disconnect the front anti-rollbar (none at the rear)? Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 12, 2003 Share Posted July 12, 2003 Your method is very likely to have errors, because the suspension settles considerably differently each time you move the car on its spring/dampers. It is a pain, but you could try repeating the method and seeing if you get the same numbers at each corner. If you had sufficient scales to measure each corner it would not be prone to the same errors. That said, a stripped out K-series can be pretty light. Mine is probably ~475kg with a full roll cage. Link to comment Share on other sites More sharing options...
TorAtle Posted July 13, 2003 Author Share Posted July 13, 2003 Will have another go tomorrow. I'll even turn the car around and measure a 3rd time. Btw, what numbers are we most interested in - is it the diagonals? With me in the car (calculated, not weighed), rear right+front left = 268,3kg and rear left+front right = 264,3. If these should ideally be the same then it seems like a brilliant idea to move the fuel tank to the front of the passengers feet (LHD car). Makes me wonder if adjustable platforms really is necessary in this case. Also, with me in the car, front/rear is 45.9%/54.1%. I must say everything looks very dandy, except for the front-left corner which is a fair bit heavier than the others - but one shouldn't look at one corner isolated perhaps Link to comment Share on other sites More sharing options...
Jason Plato Posted July 13, 2003 Share Posted July 13, 2003 Tor , I think you may have some errors in the method , the weight of the front corners of a K are normally around the 126 - 132 Kg range , depending upon tyres and wheels . I would try it again or go and buy another 3 cheap scales ? dave Link to comment Share on other sites More sharing options...
Graham Perry Posted July 13, 2003 Share Posted July 13, 2003 Look at the positioning of the scales. Bathroom scales tend to have a deliberate amount of sideways movement built into them, but this means that the cars suspension can force the top plate of the scales sideways and cause it to catch on the inner body of the scales and hence ruin the measurement, so you need to position them so that they don't catch Link to comment Share on other sites More sharing options...
stevefoster Posted July 13, 2003 Share Posted July 13, 2003 You need roller plates on at least one front wheel and equal thickness all round. I use 2 scales per wheel and bridge the load. This has proved very accurate. Speedy Steve's Workshop, Race reports, work done here Hants (North) and Berkshire Area club site here Link to comment Share on other sites More sharing options...
TorAtle Posted July 13, 2003 Author Share Posted July 13, 2003 Did it again with the same scale and got within 0,5% of the result from yesterday. Also tried a different digital bathroom scale and again got within 0,5%. I was suspisious of the different front wheel weights, but when I jack the car up the front left wheel takes a longer time to lift, so that makes sense. The garage is a mess so will have to clean it up before attempting to weight the car in the opposite direction. Do we have some data from other K cars to compare with? Graham, have been very careful about positioning. I know about the problem. Steve, why do I need roller plates? Link to comment Share on other sites More sharing options...
Joe 90 Posted July 14, 2003 Share Posted July 14, 2003 Looks like you don't have a lot to complain about as you have close to 50:50 front/rear weight distribution and 52:48 left to right. Of course that will all change when you get in it! The front left and right rear diagonal are taking more than their fair share, so you want to adjust the spring seats to get as to: Front left/right 118.8/110.6 Rear left/right 119.8/111.4 Which corner you adjust depends on which end or side is high or low. Good luck, and keep us posted. Crash team to the Upgradeitis ward, the withdrawal symptons are getting worse ❗ Link to comment Share on other sites More sharing options...
stevefoster Posted July 14, 2003 Share Posted July 14, 2003 It sounds a bit light but a fully loaded K weighs about 530 depending much on fuel load. It is possible to loose 80kgs of 'comfort pack crap'. I did, but that would include mag wheels and other nice bits. So you could be ball park The suspension on the front settles sideways a good inch or so. Scales do not like this as they operate vertically. It is easy to damage the scales so they read falsely esp at the higher end of their reading. You could check them in the range you are using by getting two of you to stand on them at once (best done with someone you would want to embrace 😬). Oh god, I feel another Kylie hijack coming along... That way you would know if they are accurate. If you don't have roller plates two sheets of acetate / plastic with a washing up liquid film between them will work but can get messy. Ask if you can wash Kylie with whats over..... 😳 Speedy Steve's Workshop here Hants (North) and Berkshire Area club site here Edited by - stevefoster on 14 Jul 2003 18:25:31 Link to comment Share on other sites More sharing options...
TorAtle Posted July 15, 2003 Author Share Posted July 15, 2003 Ah Steve, so that's why. Thanks. I think I have some pieces left of perspex(?) lying in the garage, will try those. Link to comment Share on other sites More sharing options...
scooby dooby doo Posted July 15, 2003 Share Posted July 15, 2003 Tor's car seems pretty similar to mine. so I'd suspect the 480-500 region. HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Ol Posted July 15, 2003 Share Posted July 15, 2003 Isn't there an additional and perhaps overriding error here to do with the relative support stiffness of a set of bathroom scales compared to a solid piece of wood. This being so I would suspect the less stiff scales to attract less load than the wood, with the consequent effect of under reading the weight of the car. Obviously to rectify this you need the same support, and hence scales under all four corners at the same time. Ol Link to comment Share on other sites More sharing options...
stevefoster Posted July 15, 2003 Share Posted July 15, 2003 Yes, I guess the scales settling on their springswould have an effect. I always use 8 scales, paired under all 4 wheels at the same time. One easy way around that is to do the same axle at a time. You need 2 scales them. I have proved to myself that the rake on the car does not affect the weight measurably by popping only the rear on the scales, measuring while level, and then jacking the front up as high as I could, settling everthing and then reading off again. No difference. Rake might affect weight tranfer on a moving vehicle but it did not on my static test. Speedy Steve's Workshop here Hants (North) and Berkshire Area club site here Link to comment Share on other sites More sharing options...
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