[Alvin Mpower]

I'm generally curious about how lowered suspension go over potholes vs stock ones. Before the car is lowered it can take small potholes pretty well, relatively smoothly, but when you go over a big one it makes pretty bad sound. When the car is lowered and I hit any pothole the car makes a loud banging sound, like something bad happened. Can someone explain to me why and what that sound is? Is it worst for a lowered car to go over potholes? Does it damage suspension component more when going over a pothole vs stock suspension?

[Wires]

I'd suspect you bottom out the suspension so it's banging against the bump-stops.

And yes, lowered suspension will be a lot worse since you have less suspension travel (think of the difference between a monster truck and your BMW for example).

As for bad, not sure. I doubt it's doing to damage anything more than the OEM other than your nerves and sanity from the banging.

[HarryTee]

Yes, there is a cost involved in lowered suspensions: the ride discomfort, potential damage over potholes, etc. Otherwise, manufacturers would just have all their suspensions lowered to improve handling.

[Fliplegend]

The quality of the suspension also has a lot to do with how it handles pot holes.

[erickonphoenix]

I've gotten pretty good at driving around them. Occasionally one will catch me off guard but in general I can spot a problem area and drive around it or slow down. However, I am particularly hypervigilant about my driving. I don't relax behind the wheel.

[Runner340]

When I had my e90 I had lowered the the car about 3/4"" with Eibach springs to maintain some drive comfort. At the time Eibach did not have an xDrive spring set for the car so I went with the 2WD springs which had a soft spring rate. I use to cringe on potholes and highway pavement transitions waiting for that dreaded bang. One rainy night on a back road I hit a sunken patched hole from some road maintenance that caused the suspension to compress/hit hard enough to ruin the right front runflat PS2 tire and broke the xenon adaptive headlight mechanism on the right headlight from the sudden jolt of the hit.

[myownreality]

IME the worst part of having a lowered suspension isn't the potholes, those are easy enough to dip and dodge and doing so becomes kinda like a video game, nah the real problem with being so close to the ground is drive ways scraping your bumpers and those fucking speed hump things, not the bump the hump. You can do you best to tac over that shit but inevitably you're just a scrippin' and a scrapin'. These aren't inexpensive cars, if you're gonna drop it it would make way more sense to find an air suspension then you can just raise and lower as needed, plus the ride tends to be pretty breazy. They eliminate most of that acoustical road feedback.
-mor

[Alvin Mpower]

Thanks to all the replies, I am riding on H&R sport springs so the drop is not as aggressive, but every time I hit a pothole my heart goes ouch. I'm trying as hard as I can to avoid the potholes but New England road just sucks, on highway or local, I'm doing the best I can.

[alohasurftoad]

Originally Posted by horrizenashisland

I am riding on H&R sport springs so the drop is not as aggressive, but every time I hit a pothole my heart goes ouch.

sounds like your OEM dampers are on their "last legs". how long have you had the springs? lowering springs often cause stock dampers to wear quicker and shorten their lifespan(basically because they're not designed for it), especially when doing a lot of "work" in poor road conditions.

consider swapping your OEM dampers to KONI Sport Yellow(at most comfortable setting) along with F80 bumpstops. Eibach Pro-Kit springs are also the most comfortable although they don't go as low as others

also what size, brand and model of tires are you using? this also plays a large part and is often overlooked
.

[Billfitz]

If you live in pothole country lowered suspensions and large rims with super low profile tires are just asking for trouble. If you've got both you're begging for trouble.

[Samuaw]

Asking a side question, because I am also keen to lower my car as I already bought my springs. Would changing to shorter bump stops make a difference ?

I assume because of the shorter spring travel on lowered springs, a shorter bump stop compared to stock will allow just a little more travel before it maxes out.

[im_an_alien]

Originally Posted by Samuaw

Asking a side question, because I am also keen to lower my car as I already bought my springs. Would changing to shorter bump stops make a difference ?

I assume because of the shorter spring travel on lowered springs, a shorter bump stop compared to stock will allow just a little more travel before it maxes out.

Correct

[HighlandPete]

Originally Posted by Samuaw

Asking a side question, because I am also keen to lower my car as I already bought my springs. Would changing to shorter bump stops make a difference ?

I assume because of the shorter spring travel on lowered springs, a shorter bump stop compared to stock will allow just a little more travel before it maxes out.

You get slightly more spring travel... but the shorter bump stop has to absorb more energy in less distance, when it is required. In a worst case situation the load/shock can be harder.

[HighlandPete]

Originally Posted by Billfitz

If you live in pothole country lowered suspensions and large rims with super low profile tires are just asking for trouble. If you've got both you're begging for trouble.

Which is of course is the usual combination.

Would make much more sense, if lowering, to reduce the rim diameter to get more sidewall on the tires. Use the tire to absorb some of the shock loadings.

[Billfitz]

We take good care of our roads in New Hampshire, so potholes are seldom a problem, although frost heaves can launch you like a ski jumper. Boston and New York are a different story, and since I regularly go to both I made it a point to get 17s with 225/55 rubber as a self defense measure.

[Alvin Mpower]

I'm on 225/40/19 and 255/35/19, this is the OEM set up for the bigger M sport brakes, I don't think I can go smaller. I have switched out the OEM run flats with extreme contact dws06 and it definitely rides better, but still gets eaten by potholes. Because of the plow trucks and slow asf road construction the road is a disaster around my town and my neighbor, I'm trying my best to avoid them holes.

[Billfitz]

Originally Posted by horrizenashisland

I'm on 225/40/19 and 255/35/19

That's fine on the pristine Autobahn, or a well maintained track. Marginal on urban US roads in summer, bad news in pothole season.

[im_an_alien]

Originally Posted by horrizenashisland

I'm on 225/40/19 and 255/35/19, this is the OEM set up for the bigger M sport brakes, I don't think I can go smaller. I have switched out the OEM run flats with extreme contact dws06 and it definitely rides better, but still gets eaten by potholes. Because of the plow trucks and slow asf road construction the road is a disaster around my town and my neighbor, I'm trying my best to avoid them holes.

18s will fit over your big brakes...

[rjd_F30]

FWIW my bilstein B14 coilovers ride great over bumps. A little harsher than stock but just barely. It has more to do with the quality of your suspension then how low it is. Also, a lot of that initial bang over potholes has to do with tires. The stock runflats have no sidewall give and are thus way harsher over bumps. Switch to some quality non-runflats and you'll notice a massive difference.

[Runner340]

Originally Posted by horrizenashisland

I'm on 225/40/19 and 255/35/19, this is the OEM set up for the bigger M sport brakes, I don't think I can go smaller. I have switched out the OEM run flats with extreme contact dws06 and it definitely rides better, but still gets eaten by potholes. Because of the plow trucks and slow asf road construction the road is a disaster around my town and my neighbor, I'm trying my best to avoid them holes.

I live in MA and the roads are pretty bad. I have KONI actives with Eibach Pro Kit springs on my 340i xDrive. I roll on non run flat 18's with Blue M Sport 4 & 2 pot brakes and they do fit the 400M wheels as well as my 18" Apex summer wheels. I still have to be careful but do have some peace of mind with that setup. 19's in the winter in our area are an accident waiting to happen.

https://www.getbmwparts.com/oem-part...kgUGFnZQ%3D%3D

[Alvin Mpower]

Originally Posted by Runner340

I live in MA and the roads are pretty bad. I have KONI actives with Eibach Pro Kit springs on my 340i xDrive. I roll on non run flat 18's with Blue M Sport 4 & 2 pot brakes and they do fit the 400M wheels as well as my 18" Apex summer wheels. I still have to be careful but do have some peace of mind with that setup. 19's in the winter in our area are an accident waiting to happen.

https://www.getbmwparts.com/oem-part...kgUGFnZQ%3D%3D

That sounds like a really good set up, but I'm thinking about selling my car soon while the market is high so I'm just going to leave the car as it is.

[cfm56d7b]

OEM shocks with lowering springs is the least optimum combination.

Because the lowering spring is shorter, the OEM shock's starting position is now 1"-2" below the neutral position. The shock will simply bottom our sooner.

Lowering springs + shock absorber designed for lowering springs is a better combination but doesn't solve the basic problem of needing more suspension travel to absorb unwanted road imperfections.

Encounters with potholes can be quite expensive. Lowered suspensions and potholes do not coexist well.

When I lived on the East Coast, I gave up cars for SUVs with upgraded aftermarket suspension and tires with more sidewall. Did not not replace any suspension component or wheels even once.