Arguments Against Lowering the Car

[HarryPotter]

Lowering an E30 has its cons but has its was of being fixed.
Rear camber is a con. Can be fixed with adjustable RTAB or modified subframe.
If you get camber plates the front doesn't have to many issues. If you go lower than 2 inches you get way to much bump steer. Then you have to space the tie rods
The oil pan is kinda a given.
But then I guess you have to make a choice. Do you want your car to look cool or function? My car is lower and functions but most here dont think it looks cool. Though was built professionally.
Oh as for ride quality. Well higher rate spring require higher dampening. So buy high end shock and the ride wont suffer to much. I daily drive 750 springs everyday.

Care to explain how spacing the tie rods fixes bump steer? I just don't see how that effects anything. Maybe I am not imagining it correctly. Do you put a spacer between where the tie rod connects to the strut assembly?

[MarshallM]

Very true, GC sells for more cars than just E30's. If you really wanna lower the car right and still keep your rear alignment in check you have adjustable rear suspension. For that there are two potions, eccentric bushings and weld in eccentric tabs. That right there will cost over 200.00, maybe less if you know the right guy.

even a kit from GC is still gunna fuck the geometry up. Just look at the angle of the control arms.

[Roysneon]

Buy some good quality springs and struts, replace your mounts if needed, rock out wit cock out.



No homo.

[BMC227]

Buy some good quality springs and struts, replace your mounts if needed, rock out wit cock out.



No homo.

love it lol

[Wh33lhop]

Care to explain how spacing the tie rods fixes bump steer? I just don't see how that effects anything. Maybe I am not imagining it correctly. Do you put a spacer between where the tie rod connects to the strut assembly?

Yes. Tie rod relocation is a good start at bump steer reduction, but sometimes it just causes even more strange behavior, and really what needs to be done to truly eliminate bump steer is a full ball joint and tie rod relocation to revert their respective angles back to what they would be at stock ride height.

I am lowered about 2" and I don't notice much if any bump steer, so if you can keep it to a reasonable height you don't have to worry about it.

[simplyclean325i]

only thing for me is the oil pan is 3 finger clearance from the floor. running a skid plate and the exhaust scrapes on speed bumps. life of the low.

[z31maniac]

Yes. Tie rod relocation is a good start at bump steer reduction, but sometimes it just causes even more strange behavior, and really what needs to be done to truly eliminate bump steer is a full ball joint and tie rod relocation to revert their respective angles back to what they would be at stock ride height.

I am lowered about 2" and I don't notice much if any bump steer, so if you can keep it to a reasonable height you don't have to worry about it.

I'd love someone to come up with a tubular front subframe, that addresses the suspension issue.

I also wonder if you could design it in a way to allow the use of stock oil pans on S54/LSx swaps.

[Sagaris]

Disadvantage of lowering your car: The lower you go, the stiffer your springs need to be to counteract body roll due to the roll center changing faster than the center of gravity changes. It is a leverage/moment type thing. The greater the distance between the two, the easier it is for weight to transfer side to side.

I have H&R sports and 15mm drop hats. My control arms are parallel to the ground which surprises me, I figured that this setup would still leave me with a little control arm travel before they are parallel but it is completely parallel. Unfortunately my roll center has dropped a bit more than my center of gravity has. I have only felt bump-steer once when hitting an expansion joint on a freeway interchange but haven't noticed any besides that.

Sport Compact Car had a great tech article about roll centers (I miss those) which should still be available through Modified Magazine online.

[quickervicar]

does any body know what season/episode this is?

Season 16, Episode 4

[nando]

you aren't going to get bump steer by lowering an E30 an inch an a half

there's a difference between "lowered" and "slammed"

[shiboujin]

I'd love someone to come up with a tubular front subframe, that addresses the suspension issue.

I also wonder if you could design it in a way to allow the use of stock oil pans on S54/LSx swaps.

A tubular front subframe wouldn't solve any bump steer problems, there isn't any space to raise the front subframe so there isn't anywhere to go. I want people to make RCA kits and bump steer kits for our cars :(

you aren't going to get bump steer by lowering an E30 an inch an a half

there's a difference between "lowered" and "slammed"

You mean a noticeable amount of bump steer :). You might if you autox heavily and have cut springs or something. Bump steer really manifests on harsh transitions or high suspension movements. 95% of the people on these boards wouldn't notice it if it happened or don't track their car. In which case, bump steer will almost never be an issue.

[FunfGan]

Honestly(in relation to the topgear episode), the amount of roll they seemed to have was crazy, so it would appear to be chopped stockies, or heated springs as somebody said earlier. My skidplate is 2 inches off the ground, and I can still truck over speed bumps w/ out scraping. Plus, handles like hell now.

[RickSloan]

i am fairly slammed and have no bump steer issues, even on the track I don't notice anything significant.

That said i do have issues with what feels like swaybar links binding cause of the angles, but this will soon be fixed with e36 M3 sway barlinks.

isn't it true that for proper handling your control arms should be parallel to the ground? With my car all the way down parallel is what i have and i am about 2 to 3 inches clearance with my skidplate

[shiboujin]

suspension components (even your trailing arms) are designed to be parallel to the ground when the car is on level ground and with the full weight of the car on the wheels.

So yes, your control arms, trailing arms, and tie rods shouldn't angle up or down. The same physics that creates bump steer applies to control arms.

[LJ851]

suspension components (even your trailing arms) are designed to be parallel to the ground when the car is on level ground and with the full weight of the car on the wheels.

So yes, your control arms, trailing arms, and tie rods shouldn't angle up or down. The same physics that creates bump steer applies to control arms.

Not true. A trailing arm that is flat will have substantial squat issues under power. A lower control arm that is flat will start losing camber as soon as the suspension starts to compress which is no good for handling. There are very good reasons BMW designed the suspension with front and rear arms angled down. And dont give me the "just put on stiffer springs" argument, that does not correct the poor geometry.