Raised Strut Spindle vs ERP Bump Steer Kit, same cost which is more useful? Options

[kdfoust]

So I'm already hemoraging money all over the suspension bits of my car. Why stop the bleeding so soon when there are so many parts to buy... (IMG:style_emoticons/default/happy11.gif)

When the car goes back together I'm lowering it as far as practical for an AX/street ride (my driveway may be the ultimate constraint). I've already experienced the near complete elimination of bump steer by installing washers under the steering rack so I never want to put up with bump steer again. So I'm looking at my options and see two. The first is to install a ERP bump steer kit (hit page down a couple of times to find it) so I can dial out the bump steer no matter where the ride height is set. The second option is to go to the Tangerine racing raised strut spindleswhich appear, looking at the digipic, to have the control arm bent to a corrected position to eliminate bump steer while resetting the ride height via the relocated spindle. I suppose the raised spindle also has the advantage of not using any of your suspension travel to achieve the lower chassis height.

Whata ya think? The price is a wash. Anybody done both or one or the other to provide and comparison/comments? Oh this all assumes that the dreaded bump steer will show up with a vengance as I crank the car lower...

Thanks,
Kevin

[campbellcj]

I think these two things serve different purposes -- the bump steer kit allows fine-tuning to negate bump steer effects on the front end geometry, whereas the raised strut spindles allow you to get back some suspension/shock travel when lowering the front end significantly (I think 17-21mm is a typical range of travel recovered).

I will most likely be doing both mods this summer and of course will take pics and report any findings (good or bad).

[ChrisFoley]

Without raising the spindles there are two limitations other than bump steer to how low you can go. Both affect cornering limits. The first is bottoming the shock, which will cause a sudden increase in spring rate and potential loss of control, and could damage the shock if bump rubbers aren't installed. The second is that the camber change is altered when the a-arm is angled upward. This adversely affects the tire contact patch.
Raising the spindles improves both of these conditions.

Yes, when I raise the spindles I also re-curve the steering arm so the tie rod end is in the same relationship to the steering rack as before. This has the added benefit of slightly increasing the steering rate, due to the effective length of the steering arm being shortened.

[Brad Roberts]

The raised strut is the hot ticket... BUT..BUT.. if your thinking about 5 lug later I wouldnt do it. Hold off until you convert the car (I dont recall if your car is already 5 lug or not).

The ERP/Smart bumpsteer kit awesome. It really lets you fine tune the bump for your car.

B

[kdfoust]

I'm a 4 lug guy. I don't have any plans to go 5 with this car.

I think what I'm gonna do is put 'er back together and set the ride height were it's going to be, check the bump steer and talk to Chris about the raised spindle position (It'd be pretty cool if he does custom spindle positions). I really like the idea of having full strut travel AND lower ride height.

Thanks!
Kevin

[Brad Roberts]

He can do it (as well as others) Its a lot of work to raise a 4 lug strut.

B

[Gint]

How is the 4 lug strut different than a 5 lug for the purpose of raising the spindle?

Or, why is it more difficult?

[Brad Roberts]

You cant raise the spindle on a 4cyl strut or a early 5 lug strut. The strut is tapered.

SC/Carrera/Bilstein/Koni/Boge are not tapered and the spindle can be raised without "major" hassle like the 914 strut.

You have to cut the strut in two places... instead of just moving the spindle up.

B

[Brad Roberts]

Whatever he adds to the bottom (raise spindle) has to be removed from the top yet still retain your threaded collar "threads".


B

[Brad Roberts]

Nice Berber carpet Chris...LOL


B

[Gint]

Got it. Now that I've asked the question I vaguely recall a similar thread not too long ago.

[ChrisFoley]

Nice Berber carpet Chris...LOL


B

That's the left over from doing my sister in law's condo. It covers the stained carpet in my basement office until we install new stuff here.

I can set the spindle height wherever you want it. It's really important to check the clearance between your ball joint collar and the wheel so they will fit after modifying. I use a piece of DOM roll cage tubing for the insert piece at the bottom, instead of re-using the cut out piece from the top. The result is better that way.

[914werke]

You cant raise the spindle on a 4cyl strut or a early 5 lug strut. The strut is tapered.

SC/Carrera/Bilstein/Koni/Boge are not tapered and the spindle can be raised without "major" hassle like the 914 strut.

You have to cut the strut in two places... instead of just moving the spindle up.

So Brad, if Ive got this straight on the SC/Carrera struts you just break the welds from the spindle casting to the strut housing and slide it up then re-weld?

Couldnt you the get a little more creative after cutting those welds and machine threads in the Strut housing and on the ID of the spindle casting use a couple of lock and jam nuts and have a Adj. assmbely?

[Brad Roberts]

Rich,

I could do that.. but its way cheaper to build a little ledge above the spindle and set a threaded aluminum collar down on it for a cheapy coil over conversion. The threaded collars and aluminum setup runs about 100$

Koni Converted:

B

[914werke]

Ok so this is getting a liittle OT, but please excuse the dumb Q?

What is the purpose of front coil-overs? if you have a gas preasureized strut insert * and torsion bar * and anti-sway bar that provide compression/rebound forces working in concert to keep the tires on the pavement, isnt the addition of a sprint overlapping one or many of those elements?
And adding weight?
(IMG:style_emoticons/default/sad.gif)

[Gint]

I would think the torsion bars that would be removed would weigh pretty close to the weight of the additional springs.

[Brad Roberts]

Yes to everything... but.. The largest torsion bar I can possibly fit in a 914 or 911 control arm is 26mm. What if I need something bigger ?? I have to go to coil overs.

B

[Brad Roberts]

Oh.. Rich.

We remove the torsion bars.. NOBODY runs a torsion bar AND coil overs (at least not on purpose)

B

[TMorr]

I believe the factory ran Torsion bars and coil springs together in the 911 RSR, early 70's.
It was a homologation stunt to circumvent having to keep the original spring medium as homologated, not sure of the specifics, but it has been done.

Raising the spindles also has a positive effect on restoring some height to the front roll center which is adversely effected by lowering the car, also exacerbated by larger Ø wheels & or tires, which fortunately allow additional space inside the rim to raise the spindle to recover....

Hayden PTBT

[914werke]

Ok makes sense. but what holds the A arms in place w/o the T-bars? never mind.... Im not likley to be running coilovers, my thought of threading the bodies was simply to address the lowering of the car w/o the cutting and rewelding of the strut tubes.
Seemed simpler to me.