Would appreciate some advice on ride-height measurements on my high-mileage M3, which despite stock suspension has always looked to me as if it rides lower than standard -- almost too low for comfort.
Official ride-height specs are supposed to be done with 345 pounds of "passengers and luggage aboard" but I measured mine unladen. I also have 18-inch rims. From the bottom of the wheel rim I got 584 mm front, 572 mm rear.
Stock spec is F/R is 585/540 mm on 17s, so I'm figuring it should be 600/555 on 18s, laden.
So if I'm getting 584/572 Unladen, I figure my car is definitely riding low at the front and maybe also at the back (I don't have 345 lbs of deadweight -- not even family members -- available to do the ballast.
Is my reasoning sound? And what's more likely to cause the loss of ride height -- springs, spring pads, a combination of both?
Thanks!
Last edited by daytonabitch; 08-13-2020 at 03:07 PM.
Half an inch is 12.7mm. Not that it's that meaningful, but...
Springs sag over time. Pads compress. The rear control arms arms bend in the spring perch. You can get some play in the bushings that impacts ride height. You might not have stock springs either.
2011 M3 Sedan
2006 GMC Sierra 2500HD LBZ
1999 323i GTS2
1995 M3 - S50B32/S6S420G/3.91
1990 325is
1989 M3 - S54B32/GS6-37BZ
Hers: 1996 Porsche 911 Turbo
Hers: 1989 325iX
The front ride height in Bentley is 560mm for the sport suspension, which I believe was standard on the M3. So I think the correct stock values are 560F/540R on 17 inch wheels.
Your wheels/tires are going to throw off the measurement. The Bentley values are for 17 inch wheels with stock tires. Your wheels will add an extra half inch (12-13mm) all around when compared to 17's. Then tires may adjust that further, depending on the aspect ratio.
If you're at 584/572 empty that doesn't really seem low. With two people in the car and a full gas tank that probably gets you pretty close to the Bentley values, compensating for your wheels. The rear may even be a little high. Do you have the spare tire in the trunk?
Also, what do you mean when you say it seems uncomfortably low? Is that in terms of how close your car is to the ground, or how close the tire is to the fender? With 18 inch wheels and a stock suspension I'd certainly believe that fender clearance could be quite a bit tighter. I have a fully adjustable suspension and with my 17x9 wheels and meaty tires I can't actually lower my car that much beyond stock without clearance issues under high suspension load and/or steering lock. I'm down about half an inch in front and maybe slightly more than that in the rear.
Last edited by TostitoBandito; 08-13-2020 at 03:59 PM.
1999 M3/2/5 - Titanium Silver - Track/Weekend Toy
Thanks! FYI I added 15 mm for the 18-inch wheels because that's the difference between 15, 16 and 17-inch wheels in the Bentley manual. I'm pretty sure the springs are stock as I know the history -- I bought the car from my brother, who owned it from new.
My concern is that I need new shocks and might as well upgrade the whole suspension at the same time, but don't want a ride height that's even lower than what I have now.
Thanks for the prompt reply TostitoBandito. I don't have any issues with wheel/tire clearance with 225/40R18 tires. I just worry how close the underside is to the ground.I have a mid-rise hydraulic lift in my garage and I can't drive the M3 over it unless I lay down 12 x 2 planks either side to drive up onto.
Bentley gives two different ride heights for the M3 itself -- regular and Sport. My car doesn't have the Sport suspension. I guess where I'm going with all this is that I'm considering a suspension upgrade but don't want to go any lower than the car is now. Hence my need to know whether the present ride height is correct or abnormal. I guess I'll have to wait until some family members are around to be ballast so I can measure it again by the book!
Last edited by daytonabitch; 08-13-2020 at 04:30 PM.
2011 M3 Sedan
2006 GMC Sierra 2500HD LBZ
1999 323i GTS2
1995 M3 - S50B32/S6S420G/3.91
1990 325is
1989 M3 - S54B32/GS6-37BZ
Hers: 1996 Porsche 911 Turbo
Hers: 1989 325iX
Yeah, if you're gonna refresh the suspension either keep your stock springs or throw on fresh new OEM spec springs. Then you should have no issues with ride height. Or, if you wanna spend $2K or thereabouts you can find a full adjustable suspension kit which has height adjusters so you can set it wherever you like regardless of what springs are used.
1999 M3/2/5 - Titanium Silver - Track/Weekend Toy
2011 M3 Sedan
2006 GMC Sierra 2500HD LBZ
1999 323i GTS2
1995 M3 - S50B32/S6S420G/3.91
1990 325is
1989 M3 - S54B32/GS6-37BZ
Hers: 1996 Porsche 911 Turbo
Hers: 1989 325iX
Yeah I'm pretty sure my GC setup is capable of adjusting to stock height, or at least very close to it. I'm not lowered that much, and at a glance it seems like I have sufficient threads on my adjusters to get there (front might be close, rear has plenty of room). But yeah, the different makes/kits may vary in this respect.
Last edited by TostitoBandito; 08-13-2020 at 09:17 PM.
1999 M3/2/5 - Titanium Silver - Track/Weekend Toy
Thanks for all replies. While I have your attention, is there any consensus on the best brand for springs/shocks upgrades? My usage is mostly fun driving on the street and some lapping days -- for the fun of it, not to win any trophies. And TBH I think the stock chassis set-up is such a good ride/handling compromise that I wonder if any spring/shock mods can meaningfully improve handling without wrecking the ride. (Yes, I know there are other things like chassis bracing, stabilizer bars etc that can help handling without affecting ride). I'm running 225/40R18 Michelin Pilot Sport A/S 3+ rubber.
Thoughts?
2011 M3 Sedan
2006 GMC Sierra 2500HD LBZ
1999 323i GTS2
1995 M3 - S50B32/S6S420G/3.91
1990 325is
1989 M3 - S54B32/GS6-37BZ
Hers: 1996 Porsche 911 Turbo
Hers: 1989 325iX
Koni cut-n-gut w/Dinan springs.
Very light drop (to eliminate the ‘Jeep’ look), very similar to OE ride quality.
Sent from my iPhone using Tapatalk
Official Koni strut insert video...
https://www.youtube.com/watch?v=PXSnNZt3NiI
Estoril/Modena '97 M3...sold for the second time.
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