Bump Stop cut on 545i Spring Install DIY
10-31-2008, 08:43 PM
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Originally Posted by salaki' post='708986' date='Oct 31 2008, 04:46 PM
I remember H&R tech saying that the bump stop is a part of the suspension assembly??? It you cut than it might lower it further more???? I don't think cutting bump stop would lower it more.
How do you measure the bump stop clearance? Load the suspension (wheels/tires resting on ground) w/o jack then peek inside the rubber boot and measure the distance b/ lowest end of bumpstop to the strut body?
How do you measure the bump stop clearance? Load the suspension (wheels/tires resting on ground) w/o jack then peek inside the rubber boot and measure the distance b/ lowest end of bumpstop to the strut body?
As for measuring the clearance, you can do as you say by loading the suspension with all 4 wheels on the ground, but that only works if you have enough room to actually sneak a peak. Most lowered cars do not have that luxury, obviously. The other way to do it is to load the front (or rear) with the wheel off, using a jack under the control arm....while leaving a jack stand in place just in case. This will load the suspension the same way, but at least you can get a good look at the distance between the top of the strut and the bottom of the bump stop.
My old 530xi had its bump stops cut in half in the front, and I still barely had a half inch of travel. My rears were cut by a bit over an inch (about 1/3rd), and I still had plenty of room. It was the fronts that were the problem. Oh...they were H&R sport springs. Had I cut the entire bump stop off the fronts, I still would have had at most 1.25" of travel.
It's a topic many folks don't know about, and many will tell you that if the springs didn't come with instructions to cut the stops, then don't cut them. Mine came with no such instructions, and even with some initial trimming up front and none in the rear, I was totally sitting on them on both ends. I think I had about 1" of foam left on the fronts by the time I actually was OFF them. And it was only after that (and after trimming the rears by 1.25") that my car actually dropped another 1/2" or so, front and back.
The whole process was a real PITA, and it's one reason I won't drop my cars again...aside from the harsh H&R ride. Most folks have no issues, but you definitely want to check the strut travel after any drop, just to be sure.
10-31-2008, 08:44 PM
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The bump stop cutting master has spoken! All rise! 
Originally Posted by DrLev99' post='709318' date='Nov 1 2008, 12:43 AM
Cutting bump stops won't lower anything more, unless your car is sitting ON the bump stops. They are just the last measure to absorb the "big blow" that could damage the strut without them. And, yes, they are part of the suspension in the sense that bmw's utilize their bump stops more than you'd realize in every day driving. My M5 had slightly over 1" of travel in the front, stock.....so you have to assume the stops are being contacted during those potholes or any big dips in the road.
As for measuring the clearance, you can do as you say by loading the suspension with all 4 wheels on the ground, but that only works if you have enough room to actually sneak a peak. Most lowered cars do not have that luxury, obviously. The other way to do it is to load the front (or rear) with the wheel off, using a jack under the control arm....while leaving a jack stand in place just in case. This will load the suspension the same way, but at least you can get a good look at the distance between the top of the strut and the bottom of the bump stop.
My old 530xi had its bump stops cut in half in the front, and I still barely had a half inch of travel. My rears were but by a bit over an inch (about 1/3rd) and I still have plenty of room. It was the fronts that were the problem. Oh...they were H&R sport springs. Had I cut the entire bump stop off the fronts, I still would have had at most 1.25" of travel.
It's a topic many folks don't know about, and many will tell you that if the springs didn't come with instructions to cut the stops, then don't cut them. Mine came with no such instructions, and even with some initial trimming up front and none in the rear, I was totally sitting on them on both ends. I think I had about 1" of foam left on the fronts by the time I actually was OFF them. And it was only after that (and after trimming the rears by 1.25") that my car actually dropped another 1/2" or so, front and back.
The whole process was a real PITA, and it's one reason I won't drop my cars again. Most folks have no issues, but you definitely want to check the strut travel after any drop, just to be sure.
As for measuring the clearance, you can do as you say by loading the suspension with all 4 wheels on the ground, but that only works if you have enough room to actually sneak a peak. Most lowered cars do not have that luxury, obviously. The other way to do it is to load the front (or rear) with the wheel off, using a jack under the control arm....while leaving a jack stand in place just in case. This will load the suspension the same way, but at least you can get a good look at the distance between the top of the strut and the bottom of the bump stop.
My old 530xi had its bump stops cut in half in the front, and I still barely had a half inch of travel. My rears were but by a bit over an inch (about 1/3rd) and I still have plenty of room. It was the fronts that were the problem. Oh...they were H&R sport springs. Had I cut the entire bump stop off the fronts, I still would have had at most 1.25" of travel.
It's a topic many folks don't know about, and many will tell you that if the springs didn't come with instructions to cut the stops, then don't cut them. Mine came with no such instructions, and even with some initial trimming up front and none in the rear, I was totally sitting on them on both ends. I think I had about 1" of foam left on the fronts by the time I actually was OFF them. And it was only after that (and after trimming the rears by 1.25") that my car actually dropped another 1/2" or so, front and back.
The whole process was a real PITA, and it's one reason I won't drop my cars again. Most folks have no issues, but you definitely want to check the strut travel after any drop, just to be sure.
10-31-2008, 09:41 PM
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Originally Posted by salaki' post='632598' date='Jul 25 2008, 12:37 PM
Severed my retracting tendon....had to have surgery to mend the tendon back together, followed by 10 weeks wearing a wrist cast, then 6 months of physical therapy. Totally sucked....and I still don't have full mobility of it and it's been about 3 years.
Morel of the story..........put stuff in a vise when cutting with a blade
10-31-2008, 09:48 PM
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Ewe nasty....looks like the central slip tendon got cut. I learned the hard way with an electric trimmer for the hedges. I still have only partial feeling in my finger, and that happened 25 years ago.
10-31-2008, 10:00 PM
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Originally Posted by DrLev99' post='709360' date='Nov 1 2008, 12:48 AM
Ewe nasty....looks like the central slip tendon got cut. I learned the hard way with an electric trimmer for the hedges. I still have only partial feeling in my finger, and that happened 25 years ago.
That trimmer accident sounds horrid!
11-02-2008, 11:30 PM
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Originally Posted by DrLev99' post='709318' date='Nov 1 2008, 04:43 AM
Cutting bump stops won't lower anything more, unless your car is actually sitting ON the bump stops, with the springs wanting to go lower. The stops are just the last measure to absorb the "big blow" that could damage the strut. And, yes, they are part of the suspension in the sense that bmw's utilize their bump stops more than you'd realize in every day driving. My M5 had slightly over 1" of travel in the front, stock.....so you have to assume the stops were being contacted during those potholes or any big dips in the road.
As for measuring the clearance, you can do as you say by loading the suspension with all 4 wheels on the ground, but that only works if you have enough room to actually sneak a peak. Most lowered cars do not have that luxury, obviously. The other way to do it is to load the front (or rear) with the wheel off, using a jack under the control arm....while leaving a jack stand in place just in case. This will load the suspension the same way, but at least you can get a good look at the distance between the top of the strut and the bottom of the bump stop.
My old 530xi had its bump stops cut in half in the front, and I still barely had a half inch of travel. My rears were cut by a bit over an inch (about 1/3rd), and I still had plenty of room. It was the fronts that were the problem. Oh...they were H&R sport springs. Had I cut the entire bump stop off the fronts, I still would have had at most 1.25" of travel.
It's a topic many folks don't know about, and many will tell you that if the springs didn't come with instructions to cut the stops, then don't cut them. Mine came with no such instructions, and even with some initial trimming up front and none in the rear, I was totally sitting on them on both ends. I think I had about 1" of foam left on the fronts by the time I actually was OFF them. And it was only after that (and after trimming the rears by 1.25") that my car actually dropped another 1/2" or so, front and back.
The whole process was a real PITA, and it's one reason I won't drop my cars again...aside from the harsh H&R ride. Most folks have no issues, but you definitely want to check the strut travel after any drop, just to be sure.
As for measuring the clearance, you can do as you say by loading the suspension with all 4 wheels on the ground, but that only works if you have enough room to actually sneak a peak. Most lowered cars do not have that luxury, obviously. The other way to do it is to load the front (or rear) with the wheel off, using a jack under the control arm....while leaving a jack stand in place just in case. This will load the suspension the same way, but at least you can get a good look at the distance between the top of the strut and the bottom of the bump stop.
My old 530xi had its bump stops cut in half in the front, and I still barely had a half inch of travel. My rears were cut by a bit over an inch (about 1/3rd), and I still had plenty of room. It was the fronts that were the problem. Oh...they were H&R sport springs. Had I cut the entire bump stop off the fronts, I still would have had at most 1.25" of travel.
It's a topic many folks don't know about, and many will tell you that if the springs didn't come with instructions to cut the stops, then don't cut them. Mine came with no such instructions, and even with some initial trimming up front and none in the rear, I was totally sitting on them on both ends. I think I had about 1" of foam left on the fronts by the time I actually was OFF them. And it was only after that (and after trimming the rears by 1.25") that my car actually dropped another 1/2" or so, front and back.
The whole process was a real PITA, and it's one reason I won't drop my cars again...aside from the harsh H&R ride. Most folks have no issues, but you definitely want to check the strut travel after any drop, just to be sure.
Sorry if this is a thread hijac, but some very usefull info.
11-02-2008, 11:40 PM
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Originally Posted by salaki' post='708986' date='Oct 31 2008, 08:46 PM
I don't think there's any different in bumpstop model b/ model or maybe there's?
Might be due to weight of 545's V8 engine vs 530d engine? I'm still new to bimmer and I don't really have extensive knowledge about BMW suspension.
I remember H&R tech saying that the bump stop is a part of the suspension assembly??? It you cut than it might lower it further more???? I was confused.. I know on MB cars, there's a rubber "spacer" to drop the car but on BMW??? I don't think cutting bump stop would lower it more.
How do you measure the bump stop clearance? Load the suspension (wheels/tires resting on ground) w/o jack then peek inside the rubber boot and measure the distance b/ lowest end of bumpstop to the strut body?
Unfortunately, I sold my Koni Sport Struts last time because I thought I didn't feel the need of upgrading because my drop was only .7 (fairly conservative) and the HR Sport wasn't that significantly stiffer (not a threat to bust to Sport OE suspension). Well I admit, there's another reason
. It is because of Koni's Sport limited rear adjustability.
I was upset to learn the hard way that you need to adjust the rear before you install.
http://www.koni-na.com/comp.cfm
And once it's installed, you can't adjust w/o removing the whole assembly out of the car = re-allignment, reworking, etc.
The rear design defeated the purpose of having "adjustable" suspension that you can't even adjust externally.
Currrently, I'm running on Sport OE Strut & H&R Sport temporarily and I know I will have the itch to upgrade in the future
So far so good, but I still feel it's too soft for me. Not enough dampening somehow. I want it to be a little stiffer.
Tell you the truth that I wanted to opt for H&R Race but I would hate the drop. If only H&R made a spring in between H&R Sport and Race
Right now, I'm researching on Bilstein Sport (Not HD) as a replacement maybe sometime next year.
I read around that H&R Sport is about 30% stiffer than HD.
The idea is just go w/ Bilstein Sport (Like your Koni FSD) and be done w/ it w/o caring about adjusting it at all.
When I work on the Bilstein, I will for sure cut the bump stop about .3 as you recomended or maybe even cut about .7 just to be sure. I will measure it when I get a chance.
Which side of the bump stop did you cut? Top part or the bottom part?
Top part seems to be composed of "harder" rubber than bottom part. If you the bottom, did you just "force" the rubber boot mount ring into the bump stop or maybe did a little of trimming of the ring to slide it in easier?
Might be due to weight of 545's V8 engine vs 530d engine? I'm still new to bimmer and I don't really have extensive knowledge about BMW suspension.
I remember H&R tech saying that the bump stop is a part of the suspension assembly??? It you cut than it might lower it further more???? I was confused.. I know on MB cars, there's a rubber "spacer" to drop the car but on BMW??? I don't think cutting bump stop would lower it more.
How do you measure the bump stop clearance? Load the suspension (wheels/tires resting on ground) w/o jack then peek inside the rubber boot and measure the distance b/ lowest end of bumpstop to the strut body?
Unfortunately, I sold my Koni Sport Struts last time because I thought I didn't feel the need of upgrading because my drop was only .7 (fairly conservative) and the HR Sport wasn't that significantly stiffer (not a threat to bust to Sport OE suspension). Well I admit, there's another reason
. It is because of Koni's Sport limited rear adjustability.I was upset to learn the hard way that you need to adjust the rear before you install.
http://www.koni-na.com/comp.cfm
And once it's installed, you can't adjust w/o removing the whole assembly out of the car = re-allignment, reworking, etc.
The rear design defeated the purpose of having "adjustable" suspension that you can't even adjust externally.
Currrently, I'm running on Sport OE Strut & H&R Sport temporarily and I know I will have the itch to upgrade in the future
So far so good, but I still feel it's too soft for me. Not enough dampening somehow. I want it to be a little stiffer.
Tell you the truth that I wanted to opt for H&R Race but I would hate the drop. If only H&R made a spring in between H&R Sport and Race
Right now, I'm researching on Bilstein Sport (Not HD) as a replacement maybe sometime next year.
I read around that H&R Sport is about 30% stiffer than HD.
The idea is just go w/ Bilstein Sport (Like your Koni FSD) and be done w/ it w/o caring about adjusting it at all.
When I work on the Bilstein, I will for sure cut the bump stop about .3 as you recomended or maybe even cut about .7 just to be sure. I will measure it when I get a chance.
Which side of the bump stop did you cut? Top part or the bottom part?
Top part seems to be composed of "harder" rubber than bottom part. If you the bottom, did you just "force" the rubber boot mount ring into the bump stop or maybe did a little of trimming of the ring to slide it in easier?
Ive yet to measure the rears to see how much suspension travel there is.
11-03-2008, 09:27 AM
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Here is a relative article by Dinan
Suspension_Travel.pdf
Another possible solution is to buy the Msport bump stops, I think they are the shorter OEM available for the E60.
Parts 7905316 and 7905317 from set below ...fronts are not cheap though.
http://bmwfans.info/original/E60/Lim/530i-...33/ill-33_1339/
Suspension_Travel.pdf
Another possible solution is to buy the Msport bump stops, I think they are the shorter OEM available for the E60.
Parts 7905316 and 7905317 from set below ...fronts are not cheap though.
http://bmwfans.info/original/E60/Lim/530i-...33/ill-33_1339/
11-03-2008, 11:47 PM
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Originally Posted by nicke60gre' post='711000' date='Nov 3 2008, 06:27 PM
Here is a relative article by Dinan
Attachment 63629
Another possible solution is to buy the Msport bump stops, I think they are the shorter OEM available for the E60.
Parts 7905316 and 7905317 from set below ...fronts are not cheap though.
http://bmwfans.info/original/E60/Lim/530i-...33/ill-33_1339/
Attachment 63629
Another possible solution is to buy the Msport bump stops, I think they are the shorter OEM available for the E60.
Parts 7905316 and 7905317 from set below ...fronts are not cheap though.
http://bmwfans.info/original/E60/Lim/530i-...33/ill-33_1339/
11-04-2008, 06:53 AM
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dont know if im posting in the right place now but i guess its all related. Very strange that the m5 runs a higher stock ride ht than a sport package e60 yet the m5 has shorter bump stops !? meaning lots more suspension travel without using the b stops.
http://forums.e60.net/index.php?showtopic=...mp;#entry595751
I cant imagine the m5 ever sits on the bump stops with regular driving, so it does seem to me the sport package using bump stops for regular suspension movement is some sort of design compromise, unless its some sort of marketing thing to get us to buy the superior m5
http://forums.e60.net/index.php?showtopic=...mp;#entry595751
I cant imagine the m5 ever sits on the bump stops with regular driving, so it does seem to me the sport package using bump stops for regular suspension movement is some sort of design compromise, unless its some sort of marketing thing to get us to buy the superior m5