[selo]

I recently purchased a low mileage 2013 335i, non-sport package, manual. Because the car was a base model, the OEM wheels on the car were the kind of boring 17" rims. The dealer agreed to change out for a set of 18" rims from an '09 sport package car, which I like much better, and they put on a new set of Bridgestone Drive guard run flats, which from my research seem to be pretty good tires. As I'm getting to know the car, I'm finding the ride a bit jiggly or unsettled. The tires are at 36 psi all around, and it does not pull or have a shimmy upon braking. Any ideas? Is this the character of the vehicle? Will a set of lowering springs help settle the chassis?
I owned a 2007 335i manual convertible when they were released, but it had the sport package. I don't remember thinking the ride was jiggly at that time, but it was a long time ago and I might not have been quite as picky back then.
Thoughts please.

[bimmette]

I've never felt this "jiggliness" you are describing, both before or after I got my sport springs.

[Cory S]

Tires could have a crappy balance. Describe Jiggly/unsettled...

[BruceJ]

Originally Posted by selo

I owned a 2007 335i manual convertible when they were released, but it had the sport package. I don't remember thinking the ride was jiggly at that time, but it was a long time ago and I might not have been quite as picky back then.
Thoughts please.

Even a base BMW E93 should exhibit pretty good handling characteristics.
We all understand when a car feels like it does not handle as expected but you need to describe exactly what "Jiggly" means in your situation, i.e.:

Car doesn't track straight - pulls at an angle to the road direction at highway speeds (55+mph).
Car too easily changes direction at highway speeds.
Car is susceptible to trammeling (follows ruts) on rutted roads.
Car over or under steers at less extreme turn/speed conditions than expected.
Excessive body lean in turns.
Excessive bounce after bumps.
Car shifts direction when hitting a slight bump in a turn.
Car exhibits sudden shifts in direction unexpectedly.

If any or all (hopefully not all) of these conditions exist then its time to take it to a trusted alignment shop. When you go:
1. Tell them what the car is doing
2. Tell them you want BEFORE and AFTER Printouts of your car's alignment
3. You want a 4 wheel alignment

Hopefully just a toe adjustment

Good Luck
Bruce

[selo]

Originally Posted by BruceJ

Even a base BMW E93 should exhibit pretty good handling characteristics.
We all understand when a car feels like it does not handle as expected but you need to describe exactly what "Jiggly" means in your situation, i.e.:

Car doesn't track straight - pulls at an angle to the road direction at highway speeds (55+mph).
Car too easily changes direction at highway speeds.
Car is susceptible to trammeling (follows ruts) on rutted roads.
Car over or under steers at less extreme turn/speed conditions than expected.
Excessive body lean in turns.
Excessive bounce after bumps.
Car shifts direction when hitting a slight bump in a turn.
Car exhibits sudden shifts in direction unexpectedly.

If any or all (hopefully not all) of these conditions exist then its time to take it to a trusted alignment shop. When you go:
1. Tell them what the car is doing
2. Tell them you want BEFORE and AFTER Printouts of your car's alignment
3. You want a 4 wheel alignment

Hopefully just a toe adjustment

Good Luck
Bruce

Thanks Bruce. I'm thinking I'll go to a good alignment shop soon. I guess I'd say it feels a bit vague, as if there's some excess play in the steering. It's not quite s direct as I'm used to. And there's a slight, rhythmic vibration in the steering wheel. I guess the other things to consider is that these are run flats, and that our other cars now all have electronic steering, whereas this is hydraulic, I believe.

[tlow98]

Is reduce tire PSI to the 30-33 range. You're not doing high speed autobahn runs...

Run flats are extremely hard and mine came at 36-38 all around. I vastly prefer 30-33 range.

[gds52]

Get the shocks checks..:make sure they are all good.

[jt335i]

Because the 18 inch wheels are larger in diameter and the tires are lower profile, you can 'feel' the road more because the tires absorb more of the road surface bumps, cracks, potholes, etc. as opposed to the taller OEM 17s. In addition, because your car does not have the sport suspension, and the 18's are no longer the OEM set, this makes the ride quality feel different or ‘jiggly’ and 'unsettling', as you mentioned, because of the softer shocks and springs as opposed to the 2007 with the sport suspension which you used to own. Someone correct me if I’m wrong. You may also notice your acceleration and fuel economy may suffer because the 18 inch rims are larger and heavier.
Now on the upside, the handling will be improved.

[selo]

I do think the softer shocks and springs likely have something to do with it. The ride feels a bit bouncier than I remember. I'm hoping maybe a set of sport springs will help some. Also will lower the psi and get an alignment, and check balance. Thanks.

[csu87]

Originally Posted by jt335i

Because the 18 inch wheels are larger in diameter and the tires are lower profile, you can 'feel' the road more because the tires absorb more of the road surface bumps, cracks, potholes, etc. as opposed to the taller OEM 17s. In addition, because your car does not have the sport suspension, and the 18's are no longer the OEM set, this makes the ride quality feel different or ‘jiggly’ and 'unsettling', as you mentioned, because of the softer shocks and springs as opposed to the 2007 with the sport suspension which you used to own. Someone correct me if I’m wrong. You may also notice your acceleration and fuel economy may suffer because the 18 inch rims are larger and heavier.
Now on the upside, the handling will be improved.

what? no. These could also come with 18s stock.

Also, depending on which wheels he got, they could be lighter. My OEM 17s weigh about 5lbs each heavier than some 18" M Wheels I got.

The main thing OP you need to do is ditch the runflats. I had the OEM Bridgetone RFTs and had similar "feelings" as you. switched those out for some performance tires, and its gone. also you dont feel every little bump in the road like i did with the RFTs.

It is always a good idea to get the alignment checked and get an inspection on a used car, so that should be done as well, but I would start with good tires 1st.

[selo]

Originally Posted by csu87

what? no. These could also come with 18s stock.

Also, depending on which wheels he got, they could be lighter. My OEM 17s weigh about 5lbs each heavier than some 18" M Wheels I got.

The main thing OP you need to do is ditch the runflats. I had the OEM Bridgetone RFTs and had similar "feelings" as you. switched those out for some performance tires, and its gone. also you dont feel every little bump in the road like i did with the RFTs.

It is always a good idea to get the alignment checked and get an inspection on a used car, so that should be done as well, but I would start with good tires 1st.

Eesh. I hate to have to go down that road, although I understand your point. Did you have the sport suspension?

[csu87]

Originally Posted by selo

Eesh. I hate to have to go down that road, although I understand your point. Did you have the sport suspension?

no

[Mr. Tasty]

This is called "Scuttle" or "Cowl" shake that happens with an open roofed car such as a roadster/convertible.

[selo]

Originally Posted by Mr. Tasty

This is called "Scuttle" or "Cowl" shake that happens with an open roofed car such as a roadster/convertible.

Maybe. But I've had plenty of convertibles, and I think this is different. We actually owned an 07 335i convertible, but it had the sport suspension, and I don't remember this driving characteristic. The Genius at my local dealership says the base suspension cars are a little bit floaty like this, a little bit less precise. I believe that. But now what to do about it? I lowered the tire pressure today and I think it helped a little. But what about springs? Dinan and BMW don't make any performance springs, so who makes the best? I'd like to try that mod before I get rid of the run flats. Do I need coil overs? Strut tower braces? If anyone here has a car set up for road courses, but also enjoys it on the street, please let me know your thoughts.