Bilstein Mods

David W · 10-24-2002, 01:02 PM

I am building a RSR replica. I wasnt to mod my Bilstein stuts: raise the sipindle (35 mm) and add more neg camber. Any info/sites on this?

Thanks, David
84 Targa
72S Targa
73T/RSR

TimT · 10-24-2002, 02:52 PM

if you can weld and measure accurately you can raise the spindles yourself. If not a number of places come to mind that could do the mod for you, Smart Racing,Kelly Moss, to name two. Im sure if Pelican had machine and welding services they could do it as well.

Zeke · 03:48 PM

Do a search for Tangerine Racing. When I find the link, I'll edit it in.

Here ya go:
http://www.tangerineracing.com/Products_Services.htm
If he can do a 914 strut, he can do yours if he wants to.

beamonk · 10-24-2002, 04:35 PM

David, my buddy, Bill Webster in Meridian raised my spindles. It is not hard to do, but 35mm may be way too high unless you are using 17 or 18" wheels. We did mine @16mm, I have heard you do not need to go much further with standard wheels. I don't think it did too much for the camber though. 35mm might very well. However, it is not hard to do, just drilling out the weld in the back is not sufficent. We had to drill that weld out, cut a vertical line on the collar to get it to move. after the first one, it was a piece of cake.

ChrisBennet · ChrisBennet's Garage

When you raise the spindles I believe you are supposed to bend the control arm (in a jig) as well.
-Chris

TimT · 10-24-2002, 06:17 PM

No bending of control arms when raising the spindle . The changes in geometry from raising the spindle are negligable (none). The triangle formed from the ball joint to the the upper strut mount and a-arm pivot basically remains constant. The spindle remains in the same plane anywhere it is placed.

The spindle was raised so the car could be lowered and still maintain shock travel without bottoming out the shock.

ChrisBennet · ChrisBennet's Garage

"When the spindle is raised, the steering arms must be reshaped to correct the inherent bump steer. This must be done very carefully in a jig made for this purpose."
Rennsport Systems

beamonk · 10-24-2002, 06:24 PM

I think I spoke to Steve W. about that at some point, although bending the arms is most likely the best way, spacers can be used also.
John

TimT · 06:53 PM

I guess this is where experts, observers and, and those who throw there 2 cents in come together...

I have been party to and have helped with raising ( the already raised RSR struts) spindles, on more than one car... draw a triangle and imagine the upper suspension mount the ball joint and the pivot...... you can place the spindle anywhere and the geometry doesnt change...

I respect Steve W. Is the bending he mentions for making non RSR spindles RSR spindles? If you raise the spindle to high you run into probs with the bottom of the strut/ball joint interfering with the wheel.

ChrisBennet · ChrisBennet's Garage

Tim,
I'm not disagreeing with you. What you said (geometry doesn't change) makes sense to me. After all, I thought part of the reason the spindles were raised in the first place was to keep the geometry the same (keeping the tie rods level) at a lower ride height.
-Chris

Oldporsche · 10-25-2002, 03:41 AM

Bending the control arm portion of the spindle to get it down to the correct position keeps the tie rods parallel with the steering rack. It would not be a portion of the triangle you are describing.

Repositioning of the control arm however would adversely affect the bump steer of the car. My choice would be to use some sort of reinforced spacer such as Steve W. suggested.

Good luck,
David Duffield

David W · 10-25-2002, 05:09 AM

Thanks everyone. I have experiance in the past with true RSR struts thta have already been raised. It is very important to heat and reshape the contol arms after the car is lowered. THat is why the rack spacer kits are sold, even for stock cars that have been lowered. My street 911, somwhat lowerd has lowed (heated/bent) contol arm and no bump steer. It is actually worse when you raise the spindle. There are also special tie rod ends with built in spacers, it only cost $$$.

The best way to envision this is to inagine looking at the car from the front view. Draw a line through the center of the steering rack. To minimize bump steer, the contol arm tie rod ends must be on the same plane when at rest. Perf Products has a good illustration of this with their "rack spacer" kit in their cat. That said , I dont like the rack spacer kit as it tends to bind the rack.

So I do know about the "bump steer issue of the struts". What I need (and don't know about) still is how to mod the stock Bilstein stuts to raise the spindle height. I am not using coil overs so I see no need to pay for real RSR struts. have also heard of heating the spindle area to add more initial neg camber which I would like to do also.

john Brasfield mentioned: We had to drill that weld out, cut a vertical line on the collar to get it to move. after the first one, it was a piece of cake.

What did you mean by "cut a vertical line on the collar "?

Thanks guys!
David