Koni struts - raised spindles: How to and a few question

[jpnovak]

I have been trying to optimize the front suspension on my car. The car handles great but has a bit of understeer. Part of the corrective solution is to lower the spindles. I measured that I can raise the spindles on my Koni struts about 16-17mm before the strut tube flare gets in the way. The second step will be lowering of the steering ackerman arm 935 style. This will give me quicker steering and also help with the bump steer by bringing the tie-rod and a-arm angle closer to parallel. More suspension travel is a bonus!

Today I jigged my spare Koni struts into the Mill and began the process of raising the spindles. The struts are setup with a rosette weld along the spindle assembly. It is located opposite the spindle.

I setup the strut so that the strut tube was level with the mill bed and the spindle was resting on the deck. I then clamped the setup in the vise mounted to the mill bed.

I set the minimum depth on the outside of the strut tube. Then positioned the cutter.



I used a 1/2" mill bit to plunge cut the center of the weld.




I then positioned the cutter as I milled out to the outside edges of the weld. I cut approximately 2mm outside the opening to account for weld penetration. On the outside of the holes you must rotate the strut to each side to account for the radius of curvature of the struts.

When you are finished there is a huge hole in the strut. don't worry it will be welded up later.



So now my questions start. I have no part line between the spindle assembly and the strut tube. Do I need to mill deeper or farther out in the perimeter? I am hesitant to go much deeper as the strut tube is very thin and I don't want to penetrate.

Currently the strut will not move even when heated with an oxy/acetylene torch. I did not put it in the hydraulic press since I did not have the right sized pipe to make a collar.

[kucharskimb]

That's black voodoo s**t there, Jamie...

Tangerine Racing seems to do the reduce top length/increase bottom length by cutting, removing/adding tubing, then rewelding. It looks like the Koni has a different bulge location than the Boge has. If you break the spindle free, is that where you have the 17mm to slide it upward? I had actually suggested maybe removing the spindle, then partially boring out the inner surface to accept the bulge up to a certain depth. the idea was that if you welded the entire upper and lower circumference, plus the old rosette weld hole, you would have enough strength. One side of the collar on the upper side is pretty thin already, and I'm not sure I could take out another mm out of that side. Couldn't seem to find anyone on the board to buy off on that one, so I still have this extra set of struts sitting here on the shelf. I think I'll do the Tangerine method when I get my welder setup.

Is it possible that you take another 10 thou out of the hole, or are you confident that you are deep enough? On my rosette weld, I can actually see the tubing in the center. If you're deep enough, then I would think a clam shell and a press would be your friend. I would put the wedge pin in place, just in case things try to deform on you.

[feelyx]

I just did this to my Koni's, You will need to press them, (tapping the sides with a hammer helped) just wait for the loud "POP". I was able to get them to move 19mm, I think I could of stretched another 2mm out of it. Make sure the paint on the tube is completely off, so there is no binding. I didn't lower the tie rod on these. I figure I would use those tie rod relocators. I didn't weld any extra supports either. I have a set of bilsteins next.
Tim

[feelyx]

...And as for the pipe, I used 2" square tubing 3/8" wall. It fit snug around the tube and was stabler than a piece of round pipe on the press.
Tim

[jpnovak]

Matt, I don't think this is voodoo. Just a simple garage project. I have seen how Tangerine Racing sections the tubes. I guess that would ultimately be simple if you had a jig to cut the tubes square.

Thanks Tim for the vote of confidence.

I went out to the garage tonight and did a bit of exploring with the dremel. I found that the lateral penetration of the weld was more than I expected. I just have to open the hole up a bit.

Now I just need to find a section of square tubing.

I have also considered removing the spindles and cutting down and tapering the top edge. this would allow it to slide up the taper a bit more. However, I think that 19mm should be enough.

I am out of town the rest of the week. Updates will need to wait until then.

[dshepp806]

I couldn't live more vicariously through another's experience...you guys' blow me away....good reads,..good "learning"....(man, I've much homework to do...)



..and thanks for sharing...

Best,

Doyle

[feelyx]

Installed my Konis, The spindles could be raised another 3mm/4mm with 16" wheels before measurements become critical. Stick on wheel weights would become a problem after the 23mm raised spindle.

If you plan to bend the steering arm, the distance between my tie rod and steering arm is 1-1/2" down. I also have the 1/4" spacers on the steering rack, so that would come into play there also.
Tim

[911st]

If my info is correct doing this might add up to about 1/2 deg of neg camber in a turn on a mild sport suspension set up. On something stiff like 400 lb front coil over it would be more like .25 deg more neg camber.

Also makes for an opportunity to de-camber the front at the same time and gets back some of the suspension travel lost from lowering.

Way cool project. Wish I had the skills and equipment to go there.

[jpnovak]

I found a bit of time at lunch to move the spindles on my struts. I used the hydraulic press in the shop at work.

To setup the struts I bought a 6" coupler section of 2" galvanized pipe from Lowe's. It was $7. For those who are not familiar, galvanized pipe dimensions refer to the ID. For reference the Koni strut lower section is 1.95" OD. Fits like a glove.

So I place the pipe section over the lower portion of the strut, inverted it and placed it on the hydraulic press. WOW I was at nearly 13 tons of pressure before it moved. Average was 12 tons to keep moving the spindle assembly down. The maximum movement on these struts is 25.1 mm before they bottom out on the taper. Unfortunately I have to lower them back down since I can only clear the a-arm at 18mm with 15" wheels. It should be fun to figure out how to move them in the opposite direction. Of course, I might just have to make the ball joint section of the a-arms a bit more narrow for clearance.

Here are a few crappy cell phone pictures. I should have taken the camera to work.

Next step, welding it up and bending the arms.

The degree of camber change will depend on the position of the a-arms when loaded and how the outside (ball joint) swings along the arc with a tangent length of the height of spindle movement.

[jpnovak]

Sorry hit wrong button. here are the pictures.

All jigged up...



Starting to move. Notice the change in the milled section as it passes the "window".



Finally reached our destination. I will get some better pictures once I restore the correct height.

[BAllen]

When i started reading the threads I never thought i could be surprised by the effort we put into our toys. I have 67S that i keep street legal and vintage race. I kept the interior complete, but all the sound proofing is out. The sound from a 2 liter 911's air horns at 4200 rpm's and up is Zen. I will now get to my reply. I use a koni double ajustable shock from a late model ford mustang in the rear. I don't use a rear anti sway bar. I run it this way at Sears Point with no ill effects. I use a shorter Koni shock up front with the strut shortened at the top and rethreaded. I have to find the pieces that were cut off, but i thnk it was about 2 inches. I didn't get all the travel back with a shorter shock. I did get some and i didn't have to get to deep in the engineering.

[CBRacerX]

Great info!

[jpnovak]

BAllen, I have been searching for a similar solution. While I was able to find the right shock body length I have not found the correct end mountings to make it work.

Do you have part numbers for the rear shock and front strut insert?

btw, I have a few ideas on how to fit the double adjustable inserts to stock 911 struts. It requires some cutting and a few drilled holes.

[kucharskimb]

Talked with Koni today. I'm currently using 8641-1039 sport inserts. I asked about shortening the strut length and using a shorter insert. He said to look at the 8610 Race series

http://www.koni-na.com/pdf/KONI_Motorsports_2008.pdf

page 13.

If anyone has an insert out for measurements now, I'd appreciate it. This might be an easier way for me to get back some of my travel. It would be like the Tangerine method, except I would only have to cut the top of the strut tube.

[911pcars]

Jamie,
Do you think this procedure will work with Boge struts as well?

Sherwood

[jpnovak]

Matt, Thanks for the info. I will take a look at the catalog tonight.

Sherwood,

There are some early 3" brake boge struts that might work. I don't think there is a taper to the upper section of the strut tube.



however, most of the later 3.5" Boge struts have a taper that is already located at the upper edge of the spindle assembly. This means that you can not actually move the spindle upwards unless you remove the spindle assembly and turn it down on a lathe such that it will slide up. This is probably not worth the effort.

[Tyson Schmidt]

Originally Posted by kucharskimb

Talked with Koni today. I'm currently using 8641-1039 sport inserts. I asked about shortening the strut length and using a shorter insert. He said to look at the 8610 Race series

http://www.koni-na.com/pdf/KONI_Motorsports_2008.pdf

page 13.

If anyone has an insert out for measurements now, I'd appreciate it. This might be an easier way for me to get back some of my travel. It would be like the Tangerine method, except I would only have to cut the top of the strut tube.

The 8610 series will not work with an '89 and older style strut. The compression dampening adjuster is at the bottom, which is completely blocked by the ball joint attachment on the strut housing.

[911pcars]

Jamie,
Thanks for your response.

I'm wondering if there's anything magical with the strut tube that it can't be replaced to conform to the potentially sliding spindle. I assume even the top and bottom ends can be spliced onto a more friendly tube.

Here's a thought: Per your suggestion, increase the ID of the spindle to remove the taper and to accept an internally threaded insert. With the spindle removed, the steering arm can be recurved and reinforced as needed. The modified spindle then threads onto an externally threaded strut tube. After the spindle height is accurately adjusted, it's fixed in place with lock rings and a locating pin. The external threads can also double as adjustable spring perches for a coil-over setup.

...or maybe this has been done already?

Sherwood

[JerryL]

JP very intresting stuff there, a new project :-) and to think I was thinking about offing a spare set.
Thanks for the food for thought. I will stay tuned.

Regards

[Elombard]

JP do you think a determined individual with a drill and a die grinder could remove the weld or would it take forever without the mill?