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      01-31-2014, 11:42 AM   #1
ChromeBlown
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Bump Stops

Hey bros aware me on the E36 bump stops... are they shorter than the stock E92 bump stops? On my 370Z we cut the bump stops down about .5" to 1" or so and that worked well and was recommended by Swift when installing their springs. Can we not do this on the E92 bump stops? I know it sounds a bit ghetto but what are your thoughts.
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      01-31-2014, 12:07 PM   #2
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You can indeed cut the stock bump stops or just purchase a set of e36. I was told mixed information about them. I was told you can run them and some told you can just run stock. So it is up to you
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      01-31-2014, 12:19 PM   #3
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E36 bump stops are shorter and Dinan claims that they add more travel to the suspension. The OEM bump stops are taller but they are designed to compress and are part of the suspension travel IMO. I had Eibach springs and didn't change the bump stops without adverse effects on the street (never used them on the track). I haven't experimented with any other springs, or bump stop scenarios so I can't say whether it is a good or bad move to change the stops.
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      01-31-2014, 07:13 PM   #4
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They're cheap so it doesn't hurt to put them on and keep a bit of travel
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      01-31-2014, 07:43 PM   #5
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I had them put on with my eibaach springs. Im happy.

the eibachs lowered the front .8" and the e36 bump stops are about a half inch shorter. Its a good compromise and better than keeping the oem bump stops IMO. Either way seems to work fine though.
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      02-05-2014, 11:11 AM   #6
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im running Swift spring and stock bump stop.. no issues so far and it has been 2 years. almost. if you drive hard i suggest to get the e36 bump stop but just regular normal driving your ok with OEM....
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      02-06-2014, 08:41 AM   #7
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I've yet to see any confirmation that the E36 bump stops behave in the same way as the E92. Thus I'd be wary about using them as the E92 suspension has been engineered to work as a complete unit, including the bump stops.

If the E36 bump stops do behave in a similar manner and are in effect a short copy of the E92, then they would be a good way to increase suspension travel without impacting the overall behaviour BMW engineers spent a long time developing.
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      02-06-2014, 08:50 AM   #8
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Quote:
Originally Posted by Ant Man View Post
I've yet to see any confirmation that the E36 bump stops behave in the same way as the E92. Thus I'd be wary about using them as the E92 suspension has been engineered to work as a complete unit, including the bump stops.

If the E36 bump stops do behave in a similar manner and are in effect a short copy of the E92, then they would be a good way to increase suspension travel without impacting the overall behaviour BMW engineers spent a long time developing.
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      06-03-2014, 05:22 PM   #9
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Is there any benefit to running the e36 bump stops with a KW Sleeve kit?
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      06-03-2014, 05:26 PM   #10
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Alot of odd info here, but a bump stop is a bump stop. It's a piece of foam. The e36 are indeed a little shorter and that's how Dinan claims travel is increased as it lets the strut travel futher prior to hitting the stops. It's just a clean installs and convienent that the e36 works, but you're fine cutting down the e9x one as well.
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      06-03-2014, 05:39 PM   #11
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Quote:
Originally Posted by s85e90 View Post
Alot of odd info here, but a bump stop is a bump stop. It's a piece of foam. The e36 are indeed a little shorter and that's how Dinan claims travel is increased as it lets the strut travel futher prior to hitting the stops. It's just a clean installs and convienent that the e36 works, but you're fine cutting down the e9x one as well.
Are you aware that the factory E9x M3 bump stops are designed to make contact on a regular basis and progressively get stiffer with travel? Cutting the narrow end of the E9x bump stop will probably cause an abrupt jolt upon impact. Cutting the wide end may not provide enough protection for the strut.
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      06-03-2014, 05:57 PM   #12
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Quote:
Originally Posted by FNG View Post
Are you aware that the factory E9x M3 bump stops are designed to make contact on a regular basis and progressively get stiffer with travel? Cutting the narrow end of the E9x bump stop will probably cause an abrupt jolt upon impact. Cutting the wide end may not provide enough protection for the strut.
Yes, all bump stops are designed to do this, not just the e9x. This isn't the wheel reinvented.
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      06-03-2014, 07:49 PM   #13
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Quote:
Originally Posted by s85e90 View Post
Yes, all bump stops are designed to do this, not just the e9x. This isn't the wheel reinvented.
OK i guess i should rephrase. E9x suspension is designed to ride the bump stops with regular driving, not only on large bumps. I don't know of many cars that do this. Hence the reason it might not he a good idea to cut the bump stops.
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      06-04-2014, 08:46 AM   #14
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I too would like to know the curve of the e36 stops and e9x stops before I changed. I imagine Dinan has at least checked to make sure they don't allow bottoming.

What FNG is saying is true and it's a valid concern. All foam is not created equal and a 3600lb car compresses foam differently than a 3200lb car, not to mention a car that is capable of much higher speeds will see bigger impacts and more wheel travel as a result. Handling that is just fine at sane speeds can get hairy at high speeds if the spring package (which includes the bumpstop, just another friction spring) is too stiff too fast. The properties of a bump stop can be changed drastically depending on application and it's not as simple as just shortening. Ideally you increase the rate on a stop when you shorten it to get the same fully compressed height as the softer stop.

Probably close enough not to matter though. I wouldn't want to run the E36 stops on an E93 but my car is only a couple passengers heavier than the E36.
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      06-04-2014, 11:09 AM   #15
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I have Eibach springs on the car and didn't swap bump stops and they were fine. When I put in camber plates, I took the opportunity to swap bump stops to E36 and found the first track day that I heavily rubbed the wheel arches (Apex ARC-8, 18x10, 275 Hankook RS-3). I swapped the OEM bump stops back in next chance I got.
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      06-04-2014, 12:26 PM   #16
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My understanding is the E92 has very little travel to begin with. BMW uses relatively soft springrates to create the compliant ride but when driven hard you are on the bumpstops most the time thus effectively raising your springrate.

My question is then this; is this a progressive or linear setup from the factory? They are linear springs with progressive bump stops. So in the case of lowering the car with say Swift springs for example would you rely on the higher than factory springrates with short bumpstops or keep the OEM E92 ones to create an effectively even higher springrate. I would think the E36 bumpstop would be better.

I recall a thread by Malek using E36 bumpstops and trimming strut guides to regain travel and have a controlled suspension while lowering. I would trust his judgement being one of the most accredited suspensions Guru on here.
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      06-04-2014, 12:46 PM   #17
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If I did the e36 bumpstop I would jack up the front nitrogen pressure in the dampers but most people don't have that option.
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      06-04-2014, 01:21 PM   #18
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Could anyone help me with these bump stops? http://www.m3post.com/forums/showthread.php?t=989399 is it better or safer to put the bump stop inside the sleeve or on top.
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      06-04-2014, 03:38 PM   #19
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Quote:
Originally Posted by dereksM3 View Post
My understanding is the E92 has very little travel to begin with. BMW uses relatively soft springrates to create the compliant ride but when driven hard you are on the bumpstops most the time thus effectively raising your springrate.

My question is then this; is this a progressive or linear setup from the factory? They are linear springs with progressive bump stops. So in the case of lowering the car with say Swift springs for example would you rely on the higher than factory springrates with short bumpstops or keep the OEM E92 ones to create an effectively even higher springrate. I would think the E36 bumpstop would be better.

I recall a thread by Malek using E36 bumpstops and trimming strut guides to regain travel and have a controlled suspension while lowering. I would trust his judgement being one of the most accredited suspensions Guru on here.

FYI that is what Dinan does and anyone can do the same. Just shaving the tophat
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      06-04-2014, 07:15 PM   #20
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Yes, but I was more referring to his usage of the E36 bump stops as well. Seems to be a common question on whether to use them and most accredited vendors do.

My questions were hoping to gather a more technical response as to why this is and if there's any concrete data of whether one or the other is better. The engineers at Swift who arguably probably have the best springs for the E90-92 chassis opted to use OEM bump stop to design around. So there is some conflicting options on what is better.
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      06-30-2014, 11:52 AM   #21
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Quote:
Originally Posted by LiM3y View Post
I have Eibach springs on the car and didn't swap bump stops and they were fine. When I put in camber plates, I took the opportunity to swap bump stops to E36 and found the first track day that I heavily rubbed the wheel arches (Apex ARC-8, 18x10, 275 Hankook RS-3). I swapped the OEM bump stops back in next chance I got.
Is your car edc or non-edc. Which eibach springs are you running. Thanks in advance.
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      07-01-2014, 12:50 AM   #22
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Quote:
Originally Posted by LiM3y View Post
I have Eibach springs on the car and didn't swap bump stops and they were fine. When I put in camber plates, I took the opportunity to swap bump stops to E36 and found the first track day that I heavily rubbed the wheel arches (Apex ARC-8, 18x10, 275 Hankook RS-3). I swapped the OEM bump stops back in next chance I got.
Did you notice this because of the extra travel the e36 bumpstops provide? How was it with the OEM ones?
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