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Necessary To Cut Bump Stop Trimming? Koni FSD's & Eibach Pro Kit

15K views 20 replies 9 participants last post by  MrBen 
#1 ·
Hello,

This upcoming week I'll be installing Koni FSD's on my car, I searched the entire thread and did not find many cases in which people have installed FSD's with their Eibach Pro Kit, I mainly found the RB Springs and FSD's Combo.

My question is, will it be necessary to cut the bump stop trimming on the dampers? as per this link:

Bump Stop Trimming - TEIN USA Blog

Or is this only necessary when very "low" lowering springs are installed such as H&R's and TEIN'S?

Thanks for you input as always!
 
#2 ·
I have the FSDs with the Pro Kit.

If I recall correctly, the Eibachs come with the new bump stops. It's been a while though. But I don't think there should be any trimming needed on your part. Somebody else chime in if you remember differently
 
#6 · (Edited)
My European / German Eibach Springs Part# E10-55-016-01-22, they provide a drop of 1.18" front and back (Linear)

Eibach US Part# 5557.140, provides a drop 1.0"F & 1.3"R. (Progressive)

http://eibach.com/us/files/pdf/mazda3_2014_prokit.pdf

*As per the above link, they come with New Eibach bump-stop for the front and use OE bump-stop on the back.

When comparing both, my springs provide more drop in the front but less in the back, while the US springs provide more drop on the back and less on the front.

Putting these measurements into contest, is it still necessary to cut? Also do the FSD's make the car higher or lower?
 
#7 ·
My European / German Eibach Springs Part# E10-55-016-01-22, they provide a drop of 1.18" front and back (Linear)

Eibach US Part# 5557.140, provides a drop 1.0"F & 1.3"R.

When comparing both, my springs provide more drop in the front but less in the back, while the US springs provide more drop on the back and less on the front.

Putting these measurements into contest, is it still necessary to cut? Also do the FSD's make the car higher or lower?
The purpose of cutting is to retain same amount of suspension travel before hitting bump stops. Your FSDs will thank you for it. I would still cut even if it's fine not to. The springs here control ride height, not the struts/shocks.
 
#8 ·
Well I decided NOT to cut the bump stops, after some research and reading I don't think is necessary.

I received today my FSD's from the Tire Rack!



Now this is interesting, I would expect better quality control from KONI as in one of the shocks the coating is peeling, small finishing details that bug me. Perhaps since they were brought from the USA to Israel that area was being under constant "stress" with the box, who knows, but I don't care how they look, I care how they'll perform :)

 
#11 ·
Well I decided NOT to cut the bump stops, after some research and reading I don't think is necessary.
If you drive on roads that are pretty rough, you'll want to cut them about the same amount as the spring drop to restore suspension travel, otherwise you'll be hitting the stops a lot more often. Believe it or not 1/2" or so can make a big difference.

Now this is interesting, I would expect better quality control from KONI as in one of the shocks the coating is peeling, small finishing details that bug me.
Paint doesn't stick to rubber bushings. I'm surprised that much stayed on this long. The rest will go away very quickly once installed.
Make sure the installer uses never seize on all the nuts and bolts. If you don't the lower one could be a bear to get out next time.
 
#10 ·
I'm having these babies installed tomorrow, will do an alignment as well after the installation (approx. 265$ for everything).

I'll post my experiences on Eibach's with Koni FSD's later tomorrow since I haven't read a single review about these combo here yet.
 
#13 · (Edited)
Update!

Well my mechanic decided to cut the front OE Bump Stops, so much for my stance of "NOT cutting" them lol.

Thank you everyone that recommended me to cut the front one's despite the fact that I did not want to, this is why this forum rocks!. The bump stops were trimmed approx. 30mm or 1.18inches. as per the drop of my Eibach's lol, rear bump stops remain untouched and uncut!

A picture of the trimmed part for your viewing pleasure:



A picture of these beauties:

 
#14 ·
Update #2

Installation is done!

I need to drive more before I can give a better assessment about these dampers. But for anyone thinking that this will made your already "lowered" car ride like a comfortable "luxury" sedan or a stock, forget about that! When you lower your car you will always have a harsher ride no matter what dampers you put on!

Do they feel similar a Stock (Stock Springs, Stock Dampers)? ---> Yes
Better than Stock? ---> Not sure yet
Better than the Combo of Eibachs with Stock Dampers ---> Definitely Yes

For now The car definitely feels more planted at high speeds, more linear at taking corners, hard roads feel pretty much the same, but little imperfections feel softer a lot softer. I'll let these dampers more and report back here once I have more miles with them.
 
#19 ·
Well to be honest, never specifically noticed if the drop is linear, but I think that the car sits lower on the front and a bit more higher on the back. When comparing both the US and EU part numbers , my EU Eibach springs provide more drop in the front but less in the back, while the US springs provide more drop on the back and less on the front.

Overall the US Eibach provide +3mm difference on the back & -4.6mm in the front. I think that if you want a more linear look the US part number might give you that look.

If I had to do it again, I think I would love a tad bit of a drop on the rear, just a tiny bit :grin2: but overall I'm happy on how the car feel and handles.
 

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#20 ·
Sorry to necro but i found this thread interesting. I have thought my rear end sits just slightly higher than the front. Maybe this is the reason the rear spring lowers more than the front. At least it helps me justify buying these springs
 
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