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View Full Version : Introduction - Sachs Kit - Bump Stops



tomd365
07-04-2007, 09:10 PM
Hello. I want to do a quick intro and make a couple of comments on cutting bump stops. I live in Michigan and got my first BMW in October, a Alpine White 535iM in great shape. I have been lurking here and posting occasionally as I work my way through restoring stuff on my car. I have spent the past 30 years as an automotive engineer and every time I take something apart on the car I am just amazed. So much attention to detail and over-engineering. These cars are a far cry form the domestic cars I've been engineering throughout my career. BMWs are made to come apart and go back together without busted plastic bits laying all over the floor when you are done. What a treat to work in these cars!

I am currently installing the Sachs suspension kit and want to hear opinions on cutting the front bump stops down. It seems that the only correct way to cut them down would be to take some out of the middle and glue the two ends back together. The bottom of the stop (cone-shaped) is designed to carry the dust boot and can not be cut off or the boot will just slide down the strut housing without protecting the strut shaft. The top end of the stop has a smaller inside diameter which keeps the stop / boot assembly in the correct position at the top of the shaft for the stop to work and to hold the boot up covering the shaft. I decided not to cut them down and we'll see if they bottom out too often. Has anybody cut these down and how did you actually do it?

Anyway, great forum and a great bunch of very helpful BMW enthusiasts. You have all helped me out with lots of little project on the car...

ThoreauHD
07-04-2007, 10:19 PM
If you have OE tires, you don't need to cut them. If they look worn, you can replace them, but they are fine as is. If you have larger wheels than the 15", then yea, you need to change out the bumpstops with shorter ones. Can get them from bavauto.com or the like.

Macv
07-04-2007, 10:29 PM
I believe Whit has a picture of his front modified bumpstops.....

http://bmw4life.com/upGradesImages/suspensionLowellImages/suspensionLowellPic2.jpg

You can see how much he cut. Also you can see his full Sachs install instructions. www.bmw4life.com

632 Regal
07-04-2007, 11:01 PM
heh...welcome aboard friend!

the search function is fubared so I cant find my writeup so the only thing I have on it is this link, look for bumpchops...sorry the write up is gone forever...unless you want to search amoung my posts, should have been around a couple years ago or so.

http://www.bimmer.info/~regal632/

Jehu
07-04-2007, 11:42 PM
I may be mistaken as most of the original bump stops on mine were destroyed and we just pulled out the pieces but they seemd to have at one time been full sized from what i've seen of new ones in pictures online and of course my 540 came with the factory lowered suspension. Should i bother chopping my new stops or with the sachs(OE) replacements shouldn't i be able to use new(full sized) bumpies without cutting thus i'd assume diminishing their lifespan?