[AcquaCow]

In my continuing mission to get my RS off and away from it's bumpstops, I have procured a set of D_rex koni bump extenders from TurninConcepts.
Available here: http://www.turninconcepts.com/product_info.php?products_id=458

These bump extenders allow the Koni inserts to sit lower in the strut housing, giving you 1" more wheel bump travel before you encounter the factory bumpstops. This is very useful, as most all lowering springs for the Impreza cause the car to sit on, or very near the bumpstops, giving you only 1" or less of bump travel before your spring rate goes infinite and your handling suffers due to too much weight being transfered to the front tires.

Most of you now know that I've been a huge advocate of the Koni + Gymkhana install, so I thought I'd take a moment and inspect how the setup is doing after ~10k miles of use between November 2007 and April 2008.

1) My old setup with cut stock bumpstop:


2) Wear on the gymkhana springs:



3) Condition of mounting bolt + lockwasher + washer.


4) Condition of damper top



Alright... time to get started.
Step 1) undo bottom bolt, and re-install bolt w/o washers and start it ~3-4 threads. Hit with hammer a few times and the damper will pop out of the tube.


Step 2) take note of how far the damper was sitting in the tube when installed initially.


Step 3) I found 7/8" to be a good amount of material to cut off.



Step 4) Making the old tiny hole...bigger...
Just to show that my work isn't always pretty...

 

[AcquaCow]

Step 5) But like everyone always says... "I clean up really well..."


This is what the bump extender looks like:


Step 6) Drop insert back in and use the bump extender + bolt to crank the insert in all the way.


Step 7) Stock, uncut bumpstops installed.


Step 8) Note, installed spring length is now 8" compared to the 9" without the bump extenders. Adding an inch more bump with this setup removes an inch of droop...Notice how close together the lower, progressive coils are...very difficult to get spring compressors in/out of there.


Step 9) Note, stock washer should not be used, as it touches your axle grease boot at full droop:


Step 10) Washer gone, but still very minimal clearance...I'll chance it.


Step 11) Go get a new alignment and enjoy.

Fin.

-- Dave

 

[SleepySubie]

you should just make a suspension book

 

[22wannabe]

Thanks again Dave for working all this out for me(us) before going about it on my own car.

+1 for the book. Or at least a manual of sorts. PDF style. (Not joking btw.)

 

[Racecomp Engineering]

Nice work.

- drew

 

[SIMER]

interesting

 

[spinninhye]

can't wait to do this

 

[2slo4u]

So when you tighten that bottom koni bolt does it bottom on the metal thread collar, so it won't back out? Nice writeups

 

[AcquaCow]

So when you tighten that bottom koni bolt does it bottom on the metal thread collar, so it won't back out? Nice writeups

No, it doesn't bottom out...

The lock washer keeps it from backing out...

I'm going to take the fronts apart one last time in a few weeks and see if I can grind out more material from the bottom of the strut, or the spacer to get that bolt a little more clearance at max droop...

At static ride height, there's a good 1/2in of space between the two, so it'll only affect me if the car goes airborn, which is not something I have planned for it anytime soon...

-- Dave

 

[poormansporsche]

You're a rockstar Cow.

I bought the last of these from D_Rex back in the day. Good right up.

cheers

poorman

 

[BRP_GM6]

At static ride height, there's a good 1/2in of space between the two, so it'll only affect me if the car goes airborn, which is not something I have planned for it anytime soon...

-- Dave

is the CV boot pushed out as far as it goes?
what about limiting straps like the offroad guys use?
Conversly, couldn't the drivetrain be lowered to flatten out the axles? That would have the added benifit of lowering your C/G.
Random thoughts..:lol:

 

[Hyper]

Dave, you can use smaller Lobro CV boots from VW/Audi
that's what I ended up doing as mine were touching the bottom of my coilovers

 

[AcquaCow]

is the CV boot pushed out as far as it goes?
what about limiting straps like the offroad guys use?
Conversly, couldn't the drivetrain be lowered to flatten out the axles? That would have the added benifit of lowering your C/G.
Random thoughts..:lol:

Not really needed.

If I grind the bottom of the strut 1/8in narrower, this will all be a non-issue.

I just didn't have any grinding bits left after grinding it out as much as I did =) I needed to buy something more abrasive.

I'll fix it in a week or so.

-- Dave

 

[Sparticus]

Thanks again Dave for working all this out for me(us) before going about it on my own car.

+1 for the book. Or at least a manual of sorts. PDF style. (Not joking btw.)

+1

 

[AcquaCow]

I can build a PDF in a few weeks...

This is my last week of classes for the semester, then I'll have some free time to do other writeups.

First one will be SOHC headgasket swap + maybe some port/gasket matching work =)

-- Dave

 

[22wannabe]

Nice!

Back on the suspension topic, how do you think the Koni's and extenders will feel with H&R's? I want to squat the car a little. I was thinking Koni, H&R, Grp N tops with hat shims in the back. I've got some camera equipment to buy as well and the Gymkhana's would nudge me over budget a smidge. Also, I don't think I can wait a month for them to arrive. uppy_dog

Any thoughts?

 

[AcquaCow]

Nice!

Back on the suspension topic, how do you think the Koni's and extenders will feel with H&R's? I want to squat the car a little. I was thinking Koni, H&R, Grp N tops with hat shims in the back. I've got some camera equipment to buy as well and the Gymkhana's would nudge me over budget a smidge. Also, I don't think I can wait a month for them to arrive. uppy_dog

Any thoughts?

What ride height would the H&Rs put you at?

If 14" or lower in the front, you may want to add in whiteline ball joint extenders too...could add to the price...

-- Dave

 

[2751]

Bringing it back...

What's your impression of the suspension on the street with the extenders now? Are you using uncut bump stops or cut with them?

Now I'm thinking of going with the tarmac springs, but still confused to the extenders and bump stop length combined???

Trying to figure all your modifications out...would'nt installing the extenders compress the spring an additional inch
(I believe you stated from 9" to 8" spring lentgh) making it less useful when being compressed on the vehicle under load and with street obsticles because the coils are now closer to each other? Perhaps I'm confused, help me out.

 

[AcquaCow]

Oh, I haven't answered this... dunno how I missed it.

I am using the factory un-trimmed bumpstops now (see pic above).

Yes, the compressed spring length is now 8in static instead of 9in, but that's not a big issue, as it's just part of the softest rate of the spring and doesn't even affect ride height. The car naturally compresses it to that length anyways once you put it on the ground.

What this does do is limit your droop travel by an inch, but subies already have soo much droop travel compared to bump, that you aren't really sacrificing anything. You are just shifting the amount of total travel towards bump vs droop. I think I measured an equal amount of bump/droop with the D_Rex extenders installed, but I'd have to read my threads to find that out...or you can just do the math based on my initial Koni thread below, accounting for an extra inch of bump travel.

I think it worked out to ~2in bump, ~2in droop from static ride height instead of 3in droop, 1in bump w/o the extenders...

That said, I've hit some pretty nasty bumps with this and have still not managed to coil bind it (main reason I went back to a factory length bump stop...)... I wouldn't worry. If you wanted to get real particular, you could measure the coil widths with a caliper, add them all up, then compare that # to the amount of total bump available, keeping in mind that the bumpstop compresses down to 1inch before it effectively becomes solid... I think that info is also in my Koni thread below...

-- Dave

 

[AWDALBERT]

good write up and good job aquacow, very informative