DoubleDeuce1973 Posted July 27, 2011 Share Posted July 27, 2011 Hi all, I am currently considering my options around lowering the car a little and decided to see what the current gap between wheel and arch was to get some idea of my options. On measuring everything, I have discovered that my car is a little lop sided with the passenger side sitting around 5mm higher than the driver side. I have made sure the car is level and taken several measurements but there is a clear difference. I assume this is not usual and have had a bit of a knock on the rear driver side when going over speed bumps since I bought the car. Is this likely to be just the springs sagging more on the driver side so would be resolved by changing the springs all around or am I looking at a bigger issue? Quote Link to comment Share on other sites More sharing options...
Zugara Posted July 27, 2011 Share Posted July 27, 2011 Lower the air pressure in the side thats higher, that will sort it... Knock could be your drop links. Quote Link to comment Share on other sites More sharing options...
leonk Posted July 27, 2011 Share Posted July 27, 2011 Could it be a broken spring? Quote Link to comment Share on other sites More sharing options...
Keyser Posted July 27, 2011 Share Posted July 27, 2011 If it was my motor it would be down to the hammering I give the drives side springs being a fat git and all! On a more seriuos note - Could be a worn bush if you have a knock? (but thats a lot of diffence for a bush) Could be bad adjustment you would need it on a proper alingment system to check that. That would also show if any of the adjusters got pushed out of alignment. Just of of intrest was the handbrake on or was it in gear when you stopped and took measurements? It is possible for the car to hold its own suspension from fully returning on the handbrake or against the diff - nice level piece of road and coast to a halt then re check. Just some thoughts with the usual disclaimer - I could be talking complete B****x Quote Link to comment Share on other sites More sharing options...
DoubleDeuce1973 Posted July 27, 2011 Author Share Posted July 27, 2011 Could it be a broken spring? Wouldn't there need to be 2 broken springs as both front and rear is lower by the same amount to the opposite side. Quote Link to comment Share on other sites More sharing options...
DoubleDeuce1973 Posted July 27, 2011 Author Share Posted July 27, 2011 Just of of intrest was the handbrake on or was it in gear when you stopped and took measurements? It is possible for the car to hold its own suspension from fully returning on the handbrake or against the diff - nice level piece of road and coast to a halt then re check. Just some thoughts with the usual disclaimer - I could be talking complete B****x Handbrake was on so will try measuring again in the way you have suggested to see if I get any different figures. The car has done 60k and I expect that springs have never been changed. I know you was joking but it did cross my mind that the majority of time the car will have the weight of the driver only on it. Over time could that affect the sag of the springs? Quote Link to comment Share on other sites More sharing options...
Keyser Posted July 27, 2011 Share Posted July 27, 2011 Just of of intrest was the handbrake on or was it in gear when you stopped and took measurements? It is possible for the car to hold its own suspension from fully returning on the handbrake or against the diff - nice level piece of road and coast to a halt then re check. Just some thoughts with the usual disclaimer - I could be talking complete B****x Handbrake was on so will try measuring again in the way you have suggested to see if I get any different figures. The car has done 60k and I expect that springs have never been changed. I know you was joking but it did cross my mind that the majority of time the car will have the weight of the driver only on it. Over time could that affect the sag of the springs? I suppose that logically you put more weight on that side but I'd have to say no unless your made of lead??? More likley a broken spring as leonk said than "uneven" spring wear - Id be looking for mechnical problems when you think how many posts with busted alloys from pot hole etc its not impossible to hit something hard enough to mis-align sometning on the suspension or maybe move an ARB - lot of things going on down there Just a quick thought those that know is the fuel tank of center on the drivers side??? I know it is on my truck and a full tank will make that sink a bit? What did you mean by its off the same amount on the opposite side at the front? Quote Link to comment Share on other sites More sharing options...
DoubleDeuce1973 Posted July 27, 2011 Author Share Posted July 27, 2011 Looks like I am back under the car again then. Have no idea what everything is called so will look for differences and post pics of any dodgy looking pieces for some guidance. Quote Link to comment Share on other sites More sharing options...
Watshot Posted July 27, 2011 Share Posted July 27, 2011 You don't measure ride height from the bodywork. The wings could easily be 5 mm out through alignment of the panel gaps. Ride height is measured from components in the suspension. I don't know what specifically on a Z, but usually a set point on the hub and a wishbone, i.e. something that would close or open up subject to changes in the geometry. May have been from a level surface up, really can't remember now, but measuring say from a wing edge to the centre of a wheel is never going to line up. Obviously a 'general' reading of space above the tyre to see if it can be lowered is a separate thing, but won't tell you if your springs are sagging. Quote Link to comment Share on other sites More sharing options...
Iwantone Posted July 28, 2011 Share Posted July 28, 2011 This is a problem for all car builders. I've been involved with vehicle suspension spring manufacture for much of my working life and so I should know what I'm talking about. A well made coil spring will have gone through a process called pre-setting (scragging to the trade) and this sets the final free height of the spring and and hence the height at any given load. It also adds durability to the spring and prevents it settling (permanetly losing height) in service. This is a brutal and not totally accurate process and does not deliver springs whos' height is sufficiently accurate to meet the vehicle designers' needs. The way around this is to accurately load the springs to the static load that they will see in service and then accurately measure the loaded height. The springs are then split into bands and given a colour code to identify which band they are in. So long as two springs with the same colour are fitted to the front or rear of the car, it should sit level. If springs that are more accurate than the above are needed, then they must be machined to height, but I don't know of any volume car company that can afford to fit springs like these. Another variable in the springs is something called rate. Its the ratio between load and height. A simple coil spring will obey "Hook's Law" and a plotted graph of load/deflection will be a straight line. Its stated as something like 16kg/mm meaning that the spring will shorten by 1mm for every 16kg of load placed upon it. Every spring varies about this nominal value and a car designer will normally accept +/- 5%. So even two springs that are exactly equal in length when free may vary quite a bit by the time they are loaded. This is another reason why the load band colour code is established at the vehicles' static load. I've just covered the coil springs above. Throw in all the other mass produced suspension components and considerable tolerance "stack ups" will occur. I hope that this explains a bit about why a mass produced car may have a side to side variation in height when parked on level ground. Steve Quote Link to comment Share on other sites More sharing options...
Cragus Posted July 28, 2011 Share Posted July 28, 2011 One side lower than the other It's perfectly natural mate - don't worry I'll let the helpful people continue now Quote Link to comment Share on other sites More sharing options...
DoubleDeuce1973 Posted July 28, 2011 Author Share Posted July 28, 2011 One side lower than the other It's perfectly natural mate - don't worry Don't get me started!! Quote Link to comment Share on other sites More sharing options...
neo Posted July 29, 2011 Share Posted July 29, 2011 This is a problem for all car builders. I've been involved with vehicle suspension spring manufacture for much of my working life and so I should know what I'm talking about. A well made coil spring will have gone through a process called pre-setting (scragging to the trade) and this sets the final free height of the spring and and hence the height at any given load. It also adds durability to the spring and prevents it settling (permanetly losing height) in service. This is a brutal and not totally accurate process and does not deliver springs whos' height is sufficiently accurate to meet the vehicle designers' needs. The way around this is to accurately load the springs to the static load that they will see in service and then accurately measure the loaded height. The springs are then split into bands and given a colour code to identify which band they are in. So long as two springs with the same colour are fitted to the front or rear of the car, it should sit level. If springs that are more accurate than the above are needed, then they must be machined to height, but I don't know of any volume car company that can afford to fit springs like these. Another variable in the springs is something called rate. Its the ratio between load and height. A simple coil spring will obey "Hook's Law" and a plotted graph of load/deflection will be a straight line. Its stated as something like 16kg/mm meaning that the spring will shorten by 1mm for every 16kg of load placed upon it. Every spring varies about this nominal value and a car designer will normally accept +/- 5%. So even two springs that are exactly equal in length when free may vary quite a bit by the time they are loaded. This is another reason why the load band colour code is established at the vehicles' static load. I've just covered the coil springs above. Throw in all the other mass produced suspension components and considerable tolerance "stack ups" will occur. I hope that this explains a bit about why a mass produced car may have a side to side variation in height when parked on level ground. Steve great post, very informative Quote Link to comment Share on other sites More sharing options...
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