325i Koni Short Sport + H&R (?!) + Bump stop Q.

[FaragMan]

Hello r3v,

I recently bought new adjustable Koni Short sport:

Front: 8641-1210 SPORT (Lmax 20mm shorter than regular sport)
Rear: 80-2522SP1 (Lmax 40mm shorter than regular sport)

Front pads: 3mm+9mm (genuine BMW sport pack)

I looking for H&R spring, for street drifting, little track..and fun.
This is not my daily drive, I like my bmw stiffy, and I expected for some 40mm+- lowering...

I really don't know if the Sport or Super sport or the Race is the best choice for me..
Because this Knoi's are really stiff, I think that maybe It's better for me some springs are little bit less stiffy (in the middle ..)


About the bump stop,
I bought new genuine, But I think they are too long,
How can I know what is the optimal length of bump-stop to use? And if it's ok to stay with this bump stop and shorten them, how much mm to cut?
Is it possible to use any universal plastic dust?

Sorry about the many Q, my E30 is new for me :) I had d2 drift coilovers on my eX e36.. everything was much simpler :)



Thanks !

[FaragMan]

Hey,
So today I went to the garage, after he finished to assemble the headers,

Unfortunately structure of headers is not good, and is very low !!
I could not get out of the garage without scrub,

The RACE SPRINGS probably be too low for me ..

So I'm debating between the H&R SPORT vs. H&R Super SPORT. (what is the spring rate of the super sport?)


Does anyone know how much mm lowering is the green Weitec kit I have now? (Attach photos) (I know there no bump stop and the spring pads are ripped. I bought all new..)

[Gkwan]

Did you ever figure out your bump stop issue?

I think there are two bump stops one for stock non sport suspension and one for sport suspension. Do you know which bump stop you have?

Sport suspension bump stop part number:31331133513
Stock suspension bump stop part number: 31331124449OE

Anyone else have this issue? I'm looking to get a new bump stop as well and don't want to order the wrong part!

[S.J.1981]

I am sorry to bring up this near 6 year old thread, but that is correct Gkwan.

E30s fitted with M-Suspention (sport suspention/lowered from factory) do indeed have a shorter bump stop.

Just measured mine since i am switching from B8s to B4s and the bumpstop is required (mine is with M-Tech suspension). The part is 31331133513 and has a total length of 73mm-74mm, sadly it can only be purchased from BMW, i could not find anyone selling them (Febi, Meyle, Bisltein etc).

The standard bump stop 313312449 is available from virtually every manufacturer, as part of a "kit" that includes either plastic solid covers or bellows and measure 85mm total length.

So, if you are keeping the M-Tech height with say B4s or any other brand equivilent dampers (KYB, Sachs etc) then you need the 513 part. Or if you do not have M-tech suspension and wish to lower slightly to M-Tech level, you need that shorter bump stop.

B6s and B8s do not require any bump stops, they are internal and integrated into the system.

The rear bump stop is required regardless of aftermarket (B4, B6, B8, Koni, Sachs etc) with or without M-tech suspension, another BMW only part 33521125078, some call it a "shock buffer" and others "rear bump stop".

Here in Germany, we do not have H&R OE, Sport, Super Sport or Race springs. We have the 29664-1 which H&R claim would keep the M-tech ride height more/less the same, so technically it is more of an OE and blue in colour (anything from 30-35mm lowering on NON M-Tech suspension). One can order some period correct "race springs" from H&R for the young timer racing series, but i have no idea on their specifications.

You guys in NA have several spring options from H&R, and they are vasty different compared to what we have here in Germany at least (there are E30 rally springs, Group A springs and Group G springs, but all are special requested directly from H&R and not available to public purchased from anyone else due to specific TÜV regulations and racing rules).

Hope this helps anyone in the future.

[Vincenze]

The rear bump stop is required regardless of aftermarket (B4, B6, B8, Koni, Sachs etc) with or without M-tech suspension, another BMW only part 33521125078, some call it a "shock buffer" and others "rear bump stop".
.

If I understand correctly, you can't install that rear bump stop into the rear Konis. They should have their own inside of the protection cover.

[S.J.1981]

If I understand correctly, you can't install that rear bump stop into the rear Konis. They should have their own inside of the protection cover.

Thank you for correcting me, i completely forgot about the rear Konis how they are delivered. I never used Konis on the E30 and thus completely missed it.

[mike.bmw]

Along the lines of what S.J.1981 posted, I'm wondering how much to trim my KYB SB105 bump stops (front) installed with H&R OE Sport springs (50404.55) and Bilstein Touring (B4) shocks. I recently realized I didn't have much front suspension travel due to the length of the KYB bump stops.

Today I trimmed the top section (about 1" off) of the bump stop and now I have about 1.5" of room between the bump stop and top mount, meaning the front springs/struts can compress 1.5" until the bump stops are engaged. Should I take more off? How much suspension travel / compression should there be before the bump stops are engaged?

[S.J.1981]

Along the lines of what S.J.1981 posted, I'm wondering how much to trim my KYB SB105 bump stops (front) installed with H&R OE Sport springs (50404.55) and Bilstein Touring (B4) shocks. I recently realized I didn't have much front suspension travel due to the length of the KYB bump stops.

Today I trimmed the top section (about 1" off) of the bump stop and now I have about 1.5" of room between the bump stop and top mount, meaning the front springs/struts can compress 1.5" until the bump stops are engaged. Should I take more off? How much suspension travel / compression should there be before the bump stops are engaged?

Mike, how do you tell if you need more travel? I am running a similar setup to yours here in Germany. B4s with H&Rs (the H&R springs we have here in EU are 29664-1 and H&R claim that they will not change the ride height for models with M-tech suspension), so i guess they are "Super sport" springs to you guys in America. But i have not noticed a difference from either bump stop, then again i have a shot steering shaft, so maybe that will change once i replace/repair it.

(I also have the M-Tech suspension, which includes the beefy 20mm front and 14.5mm rear sway bars and it is a stiff ride, but smoother than B6/B8s for sure).

[mike.bmw]

Mike, how do you tell if you need more travel? I am running a similar setup to yours here in Germany. B4s with H&Rs (the H&R springs we have here in EU are 29664-1 and H&R claim that they will not change the ride height for models with M-tech suspension), so i guess they are "Super sport" springs to you guys in America. But i have not noticed a difference from either bump stop, then again i have a shot steering shaft, so maybe that will change once i replace/repair it.

(I also have the M-Tech suspension, which includes the beefy 20mm front and 14.5mm rear sway bars and it is a stiff ride, but smoother than B6/B8s for sure).

With the car on the ground and the suspension loaded, I'm able to get my hands and fingers past the springs and pull the bump stops down as far as they will go, leaving a void between the top spring mount and the bump stop. This distance is how much travel the suspension has before engaging/contacting the bump stop. In my case this was about half of an inch, which wasn't enough travel. The bump stops do compress a bit, but not much.

The aftermarket KYB SB105 bump stops are a bit tall to begin with, and combined with the "H&R OE 50404.55" springs, there wasn't much travel before the bump stops were engaged. So I raised the car onto jack stands and trimmed off the top 1" section of the bump stops.

Trimmed KYB SB105 bump stops:

20210121_162630 by mike.bevels, on Flickr

The 1" section I trimmed off:

20210120_162631 by mike.bevels, on Flickr

I now have about 1.5" of travel before the bump stop is engaged. The length of the trimmed bump stop is about 2.5" (63.5mm). Even after trimming, the Bilstein B4s won't bottom out and there now appears to be enough travel in the front suspension over larger bumps/dips.

I hope this helps (and makes sense).

[S.J.1981]

It kind of makes sense, but i do not like cutting out things. Those M-Tech bump stops are a BMW only item and €15 each, pricey compared to non M-Tech bump stops.

I would be removing the struts again to replace some items, i might go back to M-Tech bump stops.

[mike.bmw]

It kind of makes sense, but i do not like cutting out things. Those M-Tech bump stops are a BMW only item and €15 each, pricey compared to non M-Tech bump stops.

I would be removing the struts again to replace some items, i might go back to M-Tech bump stops.

From what I've read, trimming bump stops seems to be a common practice and some are even designed for it. Cutting mine was certainly a quick (and easy solution) to allow for some more compression travel without having to take everything apart. If I have the suspension apart again at some point, I'll take a look at what (correct) bump stops are available that are compatible with the Bilstein B4s.

[S.J.1981]

From what I've read, trimming bump stops seems to be a common practice and some are even designed for it. Cutting mine was certainly a quick (and easy solution) to allow for some more compression travel without having to take everything apart. If I have the suspension apart again at some point, I'll take a look at what (correct) bump stops are available that are compatible with the Bilstein B4s.

There are, to my knowledge, two bump stop versions.

The standard one (85mm) in length, one could get from BMW, Febi, Meyle, Sachs, Bilstein, KYB etc Part Number: 31331124449

The M-Tech Suspension (75mm) in length, one could only get from BMW, part number: 31331133513

The M-tech one seems to be a bit softer as well, but with so many OE/OEM to compare the standard with M one, it is not fair to say that. But as i mentioned, i have both, measured both and the M-Tech one is shorter.