I have read a lot here about lowering the front end, with lowering springs. Some think it will ruin the handling, ruin the comfort, that it will look slammed, look raked, etc.
I am a former suspension design engineer from a well known suspension manufacturer, the worlds leading actually (not mentioning any names here). I did some investigations to see what kind of suspension system that's fitted on the M5, since I have one and I wasn't too happy about the gap between the front wheel and fender and the under-steer in some situations, on an otherwise near perfect car.
I scanned the net for after market spring kits and found the German designed Lowtec springs, bought a set of front springs (25 mm lowering, about 1 inch), installed them and did a 4 wheel chassis adjustment. The actual difference in ride height was 23 mm and it will probably be around 25 mm, when the springs are run in.
The springs are not much shorter than stock, but have a more progressive spring rate, giving more sag. When the car is lifted up, the spring still have pre-load left and is not sitting loose.
I can say that so far I am happy with the results. The wheel-to-fender-gap is equal all around the car now, it does NOT look neither raked nor slammed. The handling is not ruined nor the comfort. It handles with a tad bit less under-steer, but hardly detectable. The HID lights adjusted them self. Thanks to the EDC-system the results from just installing lowering springs are far better than on a passive damping system. Just changing springs is a shortcut, that sometimes won't give the results you want. Coil overs can be an option for people that are not happy with the chassis stock performance, but you will loose the ability to use the EDC-control and I am sure that the engineers at BMW did their homework setting up this car.
Some cautions:
I would not recommend lowering more than this, with stock shocks, due to an increased pressure in the shocks and loss of wheel travel.
Protect the fenders before removing the suspension.
And don't forget to make a 4-wheel chassis adjustment after installing the springs! Don't skip this, it may become a costly mistake.
I have posted some before/after pictures
I am a former suspension design engineer from a well known suspension manufacturer, the worlds leading actually (not mentioning any names here). I did some investigations to see what kind of suspension system that's fitted on the M5, since I have one and I wasn't too happy about the gap between the front wheel and fender and the under-steer in some situations, on an otherwise near perfect car.
I scanned the net for after market spring kits and found the German designed Lowtec springs, bought a set of front springs (25 mm lowering, about 1 inch), installed them and did a 4 wheel chassis adjustment. The actual difference in ride height was 23 mm and it will probably be around 25 mm, when the springs are run in.
The springs are not much shorter than stock, but have a more progressive spring rate, giving more sag. When the car is lifted up, the spring still have pre-load left and is not sitting loose.
I can say that so far I am happy with the results. The wheel-to-fender-gap is equal all around the car now, it does NOT look neither raked nor slammed. The handling is not ruined nor the comfort. It handles with a tad bit less under-steer, but hardly detectable. The HID lights adjusted them self. Thanks to the EDC-system the results from just installing lowering springs are far better than on a passive damping system. Just changing springs is a shortcut, that sometimes won't give the results you want. Coil overs can be an option for people that are not happy with the chassis stock performance, but you will loose the ability to use the EDC-control and I am sure that the engineers at BMW did their homework setting up this car.
Some cautions:
I would not recommend lowering more than this, with stock shocks, due to an increased pressure in the shocks and loss of wheel travel.
Protect the fenders before removing the suspension.
And don't forget to make a 4-wheel chassis adjustment after installing the springs! Don't skip this, it may become a costly mistake.
I have posted some before/after pictures