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Old 11-19-2008, 07:17 PM   #1
DriftIt
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Default Installing springs. Should I cut the bump stops?

I've seen install threads that say yes and others don't mention it. I know I don't need to cut the bump stops inside the rear struts but do I need to cut a section off of bump stops inside the front struts?

Any advice on this as soon as possible is much appreciated.

Thx
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Old 11-19-2008, 07:21 PM   #2
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mmmmm..no..those are there for a reason
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Old 11-19-2008, 07:27 PM   #3
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Depends on the springs, how low they're dropping you, and what struts you're using.
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Old 11-19-2008, 07:31 PM   #4
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i just installed prodrive springs in my 07 TR and i did cut a notch off each bump stop.
My .02 cents
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Old 11-19-2008, 07:51 PM   #5
DriftIt
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Sorry. Guess I was a little vague with my post. I'm installing Tanabe GF210 springs on my 05 WRX and will be keeping the stock struts on for now. (Hopefully can get some KYB's next summer.) Drop (I think) is around 1.5" front and 1" rear.
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Old 11-19-2008, 08:59 PM   #6
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NO.

Don't cut them, as they are there to help limit the travel of the strut without the rod bottoming out in it. The bumpstops are there so you don't blow those struts.

Also, it's recommended to buy new struts any time you pick up new springs, as they will work far better together for longer without wear issues. And once you install both (or either), get a good alignment so you aren't replacing tires again soon.
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Old 11-19-2008, 09:09 PM   #7
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no dont cut the bump stops, i installed prodrive blues and didnt cut them and am doing just fine.
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Old 11-19-2008, 09:12 PM   #8
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Why did this thread get moved?
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Old 11-19-2008, 11:49 PM   #9
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you should cut off the smallest nub. It's not like your struts will explode without it.
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Old 11-20-2008, 04:01 PM   #10
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I had prodrive blues on my 02 wagon w/ stock struts w/ ~35k miles and originally didn't cut any bump stops.

after half a year of driving around I still didn't like how it handled itself over bumps, uneven pavement so I figured maybe I needed more shock.

I then installed koni inserts+group n f/r strut tops hoping it would help, but it still handled like crap over bumpy roads.

a few months later I took everything apart and trimmed the one short softest nub off the the bump stops on the front and rear to gain more strut travel stroke.

after all was done banging in the front over bumps, bad roads was much much better but still not to my liking.

I then realized I wanted/needed more bumpstroke up front since the prodrives lowered too much in the front(although the asthetically the springs made the car look great), and got some 05 sti takeoff front springs and jdm v7 sti wagon springs in the rear(so I could keep my rear strut tops).

The firmer sti springs and ~1 inch raise in the front makes the car feel alot more stable going over bumps, rail road tracks, dips, uneven pavement, especially during mid-turn.

I now have some scooby921 koni spacers, shorter and firmer koni bumpstops, and paranoid fab. rear 1/4 spacers waiting to be installed. I want even more bump travel
just my experience.....
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Old 11-20-2008, 04:55 PM   #11
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I have prodrives. Cut the bump stops.
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Old 11-20-2008, 05:07 PM   #12
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Thanks for all the replies. I decided to leave the bump stops as is for now. May decide to take it apart later and cut 'em if I don't like it. Thanks again guys!

BTW, Tanabe GF210's ftmfw!!! Can't wait 'til I can afford some GOOD struts to put under them.
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Old 11-20-2008, 05:45 PM   #13
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don't cut the bump stop, they are there to prevent shock from bottoming out.
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Old 11-20-2008, 06:28 PM   #14
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I hate this issue. No one really knows, and anecdotal evidence isn't sufficient. One thing for sure is that this is dependent upon the rate of the spring, the travel of the strut used, the intended application, and the weight of the car. And people don't seem to be taking all these factors into consideration... probably because there's too much unknown.

The bumpstop needs to be short enough not to affect the suspension significantly in the application range.

The bumpstop needs to be long enough to prevent coil bind and bottoming out the strut.

IIRC
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Old 11-21-2008, 04:20 AM   #15
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FYI
14" fender to hub give you less than .5 inch of travel.

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Old 11-21-2008, 06:35 PM   #16
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when i put on my d-specs with gc sleeves i set the ride height to 14"f and 13.5"r and i cut 1 hump off of the rears but the fronts i cut off 1, installed and the strut was still bottomed out on the bump stop, so i cut the 2nd off and now its ok, ive got about 2"-3" between the strut and the bump stop now.
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Old 11-21-2008, 08:19 PM   #17
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Quote:
Originally Posted by jamal View Post
you should cut off the smallest nub. It's not like your struts will explode without it.
Worked for me. H&R springs with Koni inserts ans Group N top mounts.
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Old 11-22-2008, 01:02 PM   #18
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Quote:
Originally Posted by Kentrik View Post
NO.

Don't cut them, as they are there to help limit the travel of the strut without the rod bottoming out in it. The bumpstops are there so you don't blow those struts.

Also, it's recommended to buy new struts any time you pick up new springs, as they will work far better together for longer without wear issues. And once you install both (or either), get a good alignment so you aren't replacing tires again soon.
Quote:
Originally Posted by seanvetter123 View Post
no dont cut the bump stops, i installed prodrive blues and didnt cut them and am doing just fine.
How long have you two been doing Subaru suspension tuning?

This is not your friends honda or your moms Nissan guys. To get the most out of your springs, you generally have to trim the bumpstops
Quote:
Originally Posted by chimchimm5 View Post
I hate this issue. No one really knows, and anecdotal evidence isn't sufficient. One thing for sure is that this is dependent upon the rate of the spring, the travel of the strut used, the intended application, and the weight of the car. And people don't seem to be taking all these factors into consideration... probably because there's too much unknown.

The bumpstop needs to be short enough not to affect the suspension significantly in the application range.

The bumpstop needs to be long enough to prevent coil bind and bottoming out the strut.

IIRC
This is one of those situations that was addressed and was worked out long ago. That is why you don't see it discussed much anymore.

1/2 to 3/4 of an inch of bumpstop removal does not equal blown shocks people. Stick with the manufacturers recommendations.
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Old 11-22-2008, 01:27 PM   #19
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Oh well, they're in now and I probably won't take them out til I either add Koni inserts or go with a new set of shocks. Either way, probably not til next summer. I am, however, enjoying the new found handling capabilities of my new springs and definitely enjoying it!
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Old 11-22-2008, 04:31 PM   #20
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Quote:
Originally Posted by 4wdrift View Post
This is one of those situations that was addressed and was worked out long ago. That is why you don't see it discussed much anymore.

1/2 to 3/4 of an inch of bumpstop removal does not equal blown shocks people. Stick with the manufacturers recommendations.
Ok, I must have missed that party then. Any links?

What is the "manufacturers recommendation" for USDM SPT wagon pink springs on a 06 wrx wagon (with D-spec struts)
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Old 11-22-2008, 06:13 PM   #21
4wdrift
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Quote:
Originally Posted by chimchimm5 View Post
...

What is the "manufacturers recommendation" for USDM SPT wagon pink springs on a 06 wrx wagon (with D-spec struts)
What does D-spec recommend?
...and does SPT recommend trimming the bumpstops?
Have you ever heard of any Subaru spec springs binding?

I can't think of one Impreza strut application that does not mimick the longtravel suspension that these cars are known for (Coilovers are a different story). Ever see a stock Subaru in a slolomn or in the cones? Every spring replacement guide that I have seen for our cars recommends trimming the bumpstops. That is not to say that I have seen them all but I have seen LOTS over the past ten years.

There are many things that are considered general guidelines and recommendations for tuning our cars that have been developed over the years: wheel offsets, fluid viscosities, antilift kits, grounding mods, blow-off valves , turbos that work well on our cars, etc... Read the UK boards, the Australian sites, the Japanese blogs and you get the same things. (Hmmm, i wonder why that is...?) You can accept it or question it, it really doesn't matter to me that much. As a matter of fact, since you are the one that can't accept it, why don't you go and do your own research, get the imperical data, then post it in a thread. That way you have all the facts for anyone else that has questions.

O/P, You have to do your homework and decide, but with the stock struts and aftermarket springs, I would recommend trimming them. You will figure it out as soon as you realize that you keep bouncing off of them under hard cornering on uneven surfaces.

Last edited by 4wdrift; 11-22-2008 at 06:21 PM.
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Old 11-22-2008, 06:34 PM   #22
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Old 11-22-2008, 08:10 PM   #23
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if you lower more than 10mm (that's basically ANY spring other than the oe STi ones) I'd recommend cutting the stop or purchasing shorter ones

the above posted pic (post 15) pretty much tells the story
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Old 11-22-2008, 08:23 PM   #24
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^^^exactly.

this link tells the same story...
http://www.rs25.com/forums/showthread.php?t=76419
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Old 11-23-2008, 03:07 AM   #25
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Quote:
Originally Posted by 4wdrift View Post
As a matter of fact, since you are the one that can't accept it...
I have no idea where you get this incorrect assumption.
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