[reyoasian]

What's the full part no. for the F8x rear bump stops?
The light is too bright on the photo

[Tommi_Mav]

Originally Posted by reyoasian

What's the full part no. for the F8x rear bump stops?
The light is too bright on the photo

See post #7.

[johnung]

Originally Posted by reyoasian

What's the full part no. for the F8x rear bump stops?
The light is too bright on the photo

F8x Bump Stops
Front 31336859768
Rear 31337847662

[JBF30]

Long time reader, recent new member, first time caller.

I'm about to install an Eibach pro kit on my 330i RWD. I can't decide on which bump stops to order. The car is 100% a daily driver and it may see a mountain road or two a year.

As it seems, the choice of bump stop is subjective. However, would I be better off with the "Dinan" kit or F80 bumps.

I appreciate any and all responses.

[Solid67]

i just ordered the dinan lowering springs and bump stop kit for my 2019 m240i xdrive. Can I also use the F80 rear bump stops and would it be worth it with the dinan springs?

[JBF30]

Originally Posted by JBF30

Long time reader, recent new member, first time caller.

I'm about to install an Eibach pro kit on my 330i RWD. I can't decide on which bump stops to order. The car is 100% a daily driver and it may see a mountain road or two a year.

As it seems, the choice of bump stop is subjective. However, would I be better off with the "Dinan" kit or F80 bumps.

I appreciate any and all responses.

I went ahead and bought the F80 stops. Hopefully they'll be the better option for me.

[Cristian3010]

Hi everyone, new to the group. I read the topic, just need some help. Want to buy H&R Sport springs for my F30 320i and after I read this topic, it made me think to change also the bump stops. Should I get the F8x bump stops?
Thanks

[Emerson335]

Originally Posted by Cristian3010

Hi everyone, new to the group. I read the topic, just need some help. Want to buy H&R Sport springs for my F30 320i and after I read this topic, it made me think to change also the bump stops. Should I get the F8x bump stops?
Thanks

I would. Two weeks ago I installed Eibach 05-22 springs with Koni Yellows, and I replaced the bump stops with new F8x ones and I'm very happy with the ride.

[BimmerBoy21]

Can anyone guide me to the OEM part number for the E39 bump stops (Or the ones that are compatible with Dinan handling kit/springs for 340i RWD?) I want to make sure to get oem quality when installing some new springs soon

- Thanks

[xingqianli]

wow found this useful thread while browsing. I saw you did so for the F8X bump stops in your youtube video.

which are progressively 129~329 lbs/in front and 138~239 lbs/in in the rear.

Do you happen to have measured the rates of the other two bump stops?

[damack]

I know, dragging up an older thread…

If there's any question on bumpstops, this is after 1 year with the stock ones on Eibach Pro springs. Swapped in the rear F80 ones today. Oddly the passenger side was quite damaged, drivers side is looking a bit ragged but not this bad.

[pauli18c]

Has anyone used the Eibach bumpstops?

https://eibach.com/us/i-182-eibach-bump-stop.html

[johnung]

Originally Posted by damack

I know, dragging up an older thread…

If there's any question on bumpstops, this is after 1 year with the stock ones on Eibach Pro springs. Swapped in the rear F80 ones today. Oddly the passenger side was quite damaged, drivers side is looking a bit ragged but not this bad.

It's interesting that the deterioration happened at the middle of your stop bump stop. How did it look at the very bottom which is covered by the dust shield in the photo?

I'm speculating that the bottom of the bump stop should show the most abuse of it has been bottoming out excessively because the bottom is the smallest diameter so it should be the weakest area. Thanks

[damack]

Originally Posted by johnung

How did it look at the very bottom

Not bad actually. I wonder if it was resting on the bumpstops or very close to it.

[MEN54]

Hi All,

I have 2017 BMW 330xi , about to upgrade my suspension to Koni Special Active with Eibach Pro springs, so question is, do I have to install F80 bump stops only in front or should I used F80 bump stops front and rear as well?

Thanks

[tpoddar]

Hey guys,
I'm installing a set of Bilstein B8s with Eibach Pro Kit Springs (Bilstein B12s) on my F30 RWD next week. Rear drop is estimated to be an inch. Should I switch to m3 bump stops on the rear or stick to OE? Most people changing bump stops seem to be xDrive hence wanted a bit of clarity if it's recommended. Bilstein B8s are shorter dampers compared to the B6s and I don't know if that affects my decision regarding bump stops.

[FaRKle!]

The shorter B8 damper only limits droop compared to the B6. It doesn't have an effect on which bump stop to use. Go with the shorter bump stops.

[rated_m3]

Originally Posted by BimmerBoy21

Can anyone guide me to the OEM part number for the E39 bump stops (Or the ones that are compatible with Dinan handling kit/springs for 340i RWD?) I want to make sure to get oem quality when installing some new springs soon

- Thanks

I would like to know this as well and the part number for the e60 bump stops.

[FaRKle!]

Originally Posted by rated_m3

I would like to know this as well and the part number for the e60 bump stops.

E39 bump stop: 31331138814
E60 bump stop: 33536762722

Make sure to get genuine BMW ones as I've seen aftermarket ones have very different spring rates...

[vcx]

Originally Posted by pauli18c

Has anyone used the Eibach bumpstops?

https://eibach.com/us/i-182-eibach-bump-stop.html

I would also like to know.

It's strange though the bumpstops don't appear when you select the f30 340 car.

Are their bumpstop compatible with f30 cars ?

[z3cta]

Originally Posted by FaRKle!

Bump stops often come up as part of the discussion when people talk about lowering springs. From what I've seen here, most people only know that a set came with their car from the factory, and that Dinan offers a set to be used with lowering springs.

Bump stops can/are used for a couple of reasons. First is to do what they're called, stop/soften the bump when you hit a feature that would cause the damper/shock to bottom out. It does that by offering resistance by increasing the spring rate since it has a spring rate of its own. Some bump stops are linear in nature and others are progressive. Some manufacturers/tuners also use the spring rate increasing property to provide body roll resistance. Tuners typically do this with "packers" or shims that reduce the damper travel before engagement, and OEs do this by making long bump stops that engage after not too much damper travel.

Front Bump Stops


Here are a couple of front bump stops. On the left is my OE F3x bump stop, middle is F8x, and right is an E39 bump stop, the same one Dinan includes in their kit. The F3x bump stop is about 3.25" long and progressive (hence the tapered shape), the F8x one is about 2.5" long and also progressive. The E39 bump stop feels more linear and is much softer than the F3x and F8x stops. Both the F3x and F8x stops get really stiff pretty quickly.

Rear Bump Stops


Here are the rear bump stops from the same kits, F3x left, F8x middle, and "Dinan" (E60) rear. The F3x one is about 3.5" long, F8x 2.5" long and E60 2.25" long. Once again the F3x and F8x ones are progressive and much stiffer than the E60 one.

From this we can see that the F3x and F8x bump stops were designed to engage somewhat early on and add a significant amount of rate to the soft OE rates. I did a bump stop travel test on my rear dampers with Eibach lowering springs and found that at static ride height the damper was already engaging the OE bump stop. I try to aim for at least .75" of damper travel before engaging the bump stops so the suspension can absorb modest road features without adding additional spring rate/bounce.

When I had my OE adaptive dampers and Eibach springs I had the E39 front/E60 rear "Dinan" kit. They worked fine and I didn't have any complaints about them. With my existing damper setup I've run all three sets in the rear (the fronts have internal bump stops). Since the OE bump stops already engaged the dampers at resting ride height this caused more jolt when the rear hit bumps since the stop was so stiff and adding to the spring rate early on. The rear of the car felt like it danced/squirmed around with this. The next bump stop I went to was the E60/Dinan one. This smoothed the rear out and I was pretty content, but I was curious about the F8x rear bump stops and decided to throw that on there to see how they would feel. In normal driving I don't notice any difference, because they're weren't really being engaged or only being engaged lightly, however when cornering at the limit I could feel the stiffer rate and it felt like the rear of the car stopped rolling earlier than it normally would've. I was pleasantly surprised by this and decided to stick with the F8x rear stops.

So for folks looking to lower their cars, you might want to consider the F8x bump stops in addition to the E39/E60 "Dinan" ones.

Farkle, Great write-up.
I have an F31 that I am about to get Koni active with the Eibach E10-20-031-14-22 ProKit. What do you recommend for the front bump stop? The OE f31 or the F80? I am planning on using the F80 for the rears, just like you did

[FaRKle!]

Originally Posted by z3cta

Farkle, Great write-up.
I have an F31 that I am about to get Koni active with the Eibach E10-20-031-14-22 ProKit. What do you recommend for the front bump stop? The OE f31 or the F80? I am planning on using the F80 for the rears, just like you did

I'd go with the F80 bump stops.