Hoppin Car?

[Wabash99]

Hey Gang

So I finally got my 135i and have been getting used to it. Despite everything I love about the car, there is one thing I particularly do not care for: the tendency for the car to hop around a bit (especially through corners). If I hit any uneveness in pavement, it's like the car feels like I may lose control. It seems at times to be the front end wheels hopping (not progressively breaking loose, and often the rear end doing the same). My car is a 135i w m sport.

My old 335i acted a bit liked this as well, and replacing the runflats helped substantially, but the 135i issue seems to be worse. I've read up on M3 bushings, suspension mods, etc -- but I can't quite put my finger on what would curtail this the best

Thanks for any insights!

[Wabash99]

Ok, minor edit... I should be more specific. I've read some great info from Dackel, but it's not clear to me the difference that M3 Rear Subframe bushings vs Axle Bushings will make. This may be a total n00b question...

[cvc 22349a]

Shorter wheelbase=more hop.
I'm guessing you're still riding on runflat tires and the underdamped oe shocks. Those are the primary culprits.

Adding: that hop in a turn when you hit a bump can't be totally eliminated but it can be reduced. It's an unfortunate effect of the MacPherson strut design.

[Black Gold]

if you are happy with the stock ride height, i suggest the following

-better shocks / struts (koni sport or bilstein hd)
-rear subframe bushings
- m3 front control arm kit (optional, but will help get back the precise and heavy steering lost when replacing the stiff sidewall'd rft's)

Personally, i will soon have ohlins R&T coilovers combined with m3 front control arm kit and subframe bushings. This is overkill for most, but i want the car to feel as planted and solid as possible because i plan to keep the car until the new m3 comes out in a few years and i track my car a handful of times per year. I also drive on bad roads lol

[cvc 22349a]

^Wow. Ohlins R&T That sounds like a great damper. I guess you're not so happy with the BMWPS

[Black Gold]

Originally Posted by cvc 22349a

^Wow. Ohlins R&T That sounds like a great damper. I guess you're not so happy with the BMWPS

yea, thats a good way to put it.

the shocks and struts dont seem to be up to the task to handle the relatively high spring rates of the bmw ps. in addition, i think the rear rates are too high to use with stock m3 subframe bushings.

the ohlins dampers are the difference in their coilover kit, and should be able to adequately control the motion of the car, especially combined with the subframe bushings.

i want to keep this car for a while, so i might as well improve teh only thing i really dont love about the car : the handling

[mike the snake]

The rear spring placement in the suspension itself causes the rear wheel rates to be off compared to most other cars, so even though the spring rates seem high, the actual rear wheel rates are slower.

I asked some knowledgeable people and researched, and with the Ohlins R&T shocks, I went with the kit supplied fronts, and 700lb rear springs, and also added the M3 rear subframe bushings, and Apex wheels and PSS tires and the handling and especially the hopping/shuddering went away. I'm very happy with how my car feels and handles after these changes. Harold at HPA or Beau at PSI can definitely help you out.

[Black Gold]

How's the ride quality?

I decided after speaking with Harold to stay with the supplies springs since I do mainly street drivig on bad roads

Glad you are happy with the kit! Love to hear your feedback so far, specifically about ride comfort and track performance. (pm of you want to keep this thread on topic)

Thx

[cvc 22349a]

Originally Posted by KennyPowers

yea, thats a good way to put it.

the shocks and struts dont seem to be up to the task to handle the relatively high spring rates of the bmw ps. in addition, i think the rear rates are too high to use with stock m3 subframe bushings.

the ohlins dampers are the difference in their coilover kit, and should be able to adequately control the motion of the car, especially combined with the subframe bushings.

i want to keep this car for a while, so i might as well improve teh only thing i really dont love about the car : the handling

That's why I pieced the PS kit together w/o the dampers BMW supplies w/it. Other than EDC maybe, the dampers BMW provides suck..
If you don't mind a kind of firm ride, Koni sport dampers work really well w/the PS springs. There's also a couple E8x drivers using Koni FSD's w/PS springs and are happy w/that set up. I didn't like the FSD's.