Eibach's take on Bumpstops

[TLud]

Originally Posted by MrHarris

So Eibach springs +e36 bumpstops is a win? Where do we purchase e36 bumpstops?

Originally Posted by CT-Bimmer

Curious as well.. received my Eibach's a couple weeks ago along with my MS Spacers and MS filter! Too bad the weather in CT sucks! In the meantime.. I guess I will order the bumpstops. Anyone know the price on these?

I'm very happy with that setup on my car, but I haven't compared it back to back with the stock bumpstops. It is very possible, likely even, that Eibach intended for these springs to rest on the stock bumpstops and factored that into the spring rate of the Pro kit. I have some ideas regarding the practical implications, but I don't pretend to be an expert on this, so I'll keep them to myself rather than starting more internet rumor and conjecture.

For purchasing info, check out this very helpful thread from rldzhao. The part number for the E36 M3 bumpstop is 31 33 2 225 377 and they retail for under $20 each. You can get them from Tischer (getbmwparts.com) for $15.74 plus shipping.

[Sleeper519]

Originally Posted by quality_sound

Trimming the bumpstops will make them less linear.

No. I think what you meant to say is that trimming the OEM bumpstops will make them more linear (less progressive).

Just as the springs are progressive over a compression cycle, so are the rubber bumpstops. When you cut them down, the graph of compression force vs. travel distance will be less parabolic, and more linear; a more abrupt stop.

[disruptv]

Originally Posted by Sleeper519

No. I think what you meant to say is that trimming the OEM bumpstops will make them more linear (less progressive).

Just as the springs are progressive over a compression cycle, so are the rubber bumpstops. When you cut them down, the graph of compression force vs. travel distance will be less parabolic, and more linear; a more abrupt stop.

So by trimming the oem buimpstops, i made the ride worse vs stock bumpstops w/ the eibachs? BTW, is it true that by trimming the oem bumpstops, the front will be dropped a little bit more vs leaving the stock one in unaltered?

thanks

[quality_sound]

Originally Posted by Sleeper519

No. I think what you meant to say is that trimming the OEM bumpstops will make them more linear (less progressive).

Just as the springs are progressive over a compression cycle, so are the rubber bumpstops. When you cut them down, the graph of compression force vs. travel distance will be less parabolic, and more linear; a more abrupt stop.

I meant the bumpstops will be more, abrupt, I guess is the word, because you'd be cutting off the lower rate part of the bumpstop. I meant what you said, you just said it better. My apologies.

[hammbone50]

Originally Posted by quality_sound

I meant the bumpstops will be more, abrupt, I guess is the word, because you'd be cutting off the lower rate part of the bumpstop. I meant what you said, you just said it better. My apologies.

I hate to dig this post up but I am searching for a simple yes no answer to is it better to leave the stock bumpstops for the Eibach springs or should I replace them with e36 ones?

[quality_sound]

I would leave them since Eibach designed the springs and their rate around keeping the OEM bumpstops in the car and their engineers are smarter than I am.

[Dieselino]

I bought E36 bumpstops and also shaved my guide supports. Car rides awesome.

[quality_sound]

Because the spring rate is now lower than Eibach intended.

[kmac1980]

The one issue the posts of this thread fail to address is the potential risk of installing shorter bumpstops.

I have recently installed an eiback pro-kit on my e93, (slightly more drop than e90/e92) and chose NOT to modify or install aftermarket bumpstops.

My reasoning for this, is the OE shocks are designed to ride at a certain height, and have a certain amount of travel, much like the overall suspension is. Without consulting the design specs of the OE shocks, I wouldnt be able to rule out the potential that lowering the car, and modifying the bumpstops to effectively retain travel will not damage the valving on the OE shocks from over-travel.

I'm sure lowering the car in the first place adds strain to the OE shocks (the shocks are now riding at a compressed level), but inducing over-travel seems like a recipe to wear out the OE shocks fairly quickly. Again, I dont know anything about the specific design specs, perhaps they were engineered for additional travel?

As a whole, I think the idea of "lowering springs" is a cost effective way to 1) provide a nicer stance to the M3 and/or 2) stiffen the ride up slightly. If your setup burns through your OE shocks in a couple years, that seems to defeat the cost effectiveness of the whole solution and you might as well pony up for a truly upgraded suspension system from day 1 (i.e. MOTON, KW etc.)

Just my 2 cents, and for what its worth, the ride in an E93 with eibachs and factory bumpstops is quite liveable in an area with less than desirable road conditions.

[hammbone50]

Originally Posted by kmac1980

The one issue the posts of this thread fail to address is the potential risk of installing shorter bumpstops.

I have recently installed an eiback pro-kit on my e93, (slightly more drop than e90/e92) and chose NOT to modify or install aftermarket bumpstops.

My reasoning for this, is the OE shocks are designed to ride at a certain height, and have a certain amount of travel, much like the overall suspension is. Without consulting the design specs of the OE shocks, I wouldnt be able to rule out the potential that lowering the car, and modifying the bumpstops to effectively retain travel will not damage the valving on the OE shocks from over-travel.

I'm sure lowering the car in the first place adds strain to the OE shocks (the shocks are now riding at a compressed level), but inducing over-travel seems like a recipe to wear out the OE shocks fairly quickly. Again, I dont know anything about the specific design specs, perhaps they were engineered for additional travel?

As a whole, I think the idea of "lowering springs" is a cost effective way to 1) provide a nicer stance to the M3 and/or 2) stiffen the ride up slightly. If your setup burns through your OE shocks in a couple years, that seems to defeat the cost effectiveness of the whole solution and you might as well pony up for a truly upgraded suspension system from day 1 (i.e. MOTON, KW etc.)

Just my 2 cents, and for what its worth, the ride in an E93 with eibachs and factory bumpstops is quite liveable in an area with less than desirable road conditions.

Thank you!!! That was very well put and written!