Why 4cyls cars are higher than 6cyls in the rear? Even with aftermarket suspension...

[nuvola rossa]

I have this doubt from long time...
Why 318is are higher than 325-328-M3s in the rear?

I don't know.. the weight in the rear axle is near the same, not enought to justify all that gap...

I need to say that rear KONI are identycal and interchangeable between 316->328s...


KONI SA and H&R Sport
Take for example Koni SA with H&R sport, a great combo used by a lot of people... on 6cyls people some people need to add another spring plate to raise the rear, that otherwise will be low... on 4cyls with same koni SA rear (they are identical, even in code number), and H&R sport, there is gap between the wheel and arch...

318is:

328:

M3:
http://img2.putfile.com/main/6/15209280016.jpg
http://forums.***************************************?att achmentid=28457&stc=1&d=1049848023
http://forums.***************************************?att achmentid=28506&stc=1&d=1049860979

Koni SA and Eibach sportline
Here you can see the difference... look at the rear wheel of the 318is... there is a little gap:( and then look the 328


318is with 18":
http://i3.photobucket.com/albums/y75/nuvolarossa/firmanew.jpg

328 +5mm rear spring pad, 17" wheels:
http://www.we-todd-did-racing.com/wetoddimage.wtdr/wODYzNTc4NnM0MTNkZmQzMXk1NDE%3D.jpg

H&R Race

318is:

328:

M3 with 19":
http://img.photobucket.com/albums/v37/maaeco6969/047.jpg


You see that on six cyls the rear wheel is always wheel covered by arch, but on mine and a lot of other 4cyls the real lowering isn't the lowering that the seller declare...

I'll add other pics that aren't on.

If you don't know the answer, but you have pics that lack, please post them...

[orthm]

Don't know if it's the same with the E36 bodies, but with the E30, there was about 80 pounds of ballast placed in the trunk of the 325 bodies to off set the weight distribution change with the heavier 325 motor. It also helped a bit in getting better traction on the rear wheels. The stuff looked like sound insulation on the floor of the trunk.

Throw 100 pounds in the trunk and see if that reduces the gap....

[nuvola rossa]

Don't know if it's the same with the E36 bodies, but with the E30, there was about 80 pounds of ballast placed in the trunk of the 325 bodies to off set the weight distribution change with the heavier 325 motor. It also helped a bit in getting better traction on the rear wheels. The stuff looked like sound insulation on the floor of the trunk.

Throw 100 pounds in the trunk and see if that reduces the gap....

Yes, but I can't find anything like that on my ETK...
but calculating bigger halfshafts, bigger diff, big exhaust and co. the "overweight" will be around 70 pounds, accordly to my parts catalogue...

maybe you're right.. but two passengers at rear make a significative difference in height, but they aren't 70-80 pounds...:confused

I'll continue my research...
I hope only that aftermarket springs for 6cyls are not shorter than 318is...
on my bentley manual, the ride height at rear is the same from 318 to 328, only the m3 is different... so it's only a aftermarket thing?

[TC535i]

Just get coilovers and set whatever heights you want?

[Daved]

Just get coilovers and set whatever heights you want?
That's the ultimate solution but not cheap.

I got custom springs made at the height I wanted so I didn't need to spend in coilovers.

[nuvola rossa]

318is with 18":
http://i3.photobucket.com/albums/y75/nuvolarossa/firmanew.jpg

that is mine:D
it has koni SA and they have 5000 miles, so like new...
springs are eibach sportline.

it's because koni are like new that I can't put coilovers.. and I love my konis:eyebrows;)

but damn... this thread have a question that nobody can answer:shifty

the point now is: aftermarket springs for 6cyls are shorter than 4cyls?

[ublemaschine]

I know that the front springs are definately different to compensate for engine weight. I would think that reputable aftermarked spring companies would have different springs in the rear to compensate for the weight difference due to the diff/axle difference. I guess the best way to get to the bottom of this would be to try to get ahold of an aftermarket manufacturer that specifies different springs sets between 4cyl and 6cyl and find out if only the fronts are different or if all four are different.

[nuvola rossa]

I know that the front springs are definately different to compensate for engine weight. I would think that reputable aftermarked spring companies would have different springs in the rear to compensate for the weight difference due to the diff/axle difference. I guess the best way to get to the bottom of this would be to try to get ahold of an aftermarket manufacturer that specifies different springs sets between 4cyl and 6cyl and find out if only the fronts are different or if all four are different.

Look how much is low your car in the rear... and it has bilstein and hr race...:banghead:
and then look this 318is with h&r race:
http://img.photobucket.com/albums/v224/008311/shoot6.jpg
It's a beautiful car, but why is so higher than your 328's rear???

damn, mine with sportline+koni on the charts should lower like your... but in reality it's another story:rolleyes

[TC535i]

My car was actually pretty slammed on Sportline springs & shocks, but even with the Eibach swaybars, it STILL had too much body roll :rofl

http://b5.ac-images.myspacecdn.com/01168/53/95/1168195935_l.jpg

[bmw728ivik]

can i just say that the m3 is already lower than the lower series of e36 say so if you stick diff dampers and springs that are shorter say then the stock that would make some difference? anyway you guys probably know that tho ;)

[earthwormjim]

Having more weight in the rear all the time (due to axles and the diff), probably makes the springs in the rear settle even more over time than you think.

It's not quite like throwing that extra weight in your trunk to test the difference.

[ublemaschine]

Having more weight in the rear all the time (due to axles and the diff), probably makes the springs in the rear settle even more over time than you think.

It's not quite like throwing that extra weight in your trunk to test the difference.


Very true. Maybe if you drive around a month or so with an extra 60 lbs it will settle some? I honestly, after seeing that 318 with HR race springs, would have to say it looks like the rear springs for both spring sets must be the same. Which would set the 318 higher due to it having less weight.

BTW I have no spring pads in my car which lowers it slighly a bit more but not nearly as much as the difference between mine and that green 318. Actually, the front fender gap on that looks slightly less than mine.