Modify Boge spindles or go Bilstein
 

Any opinions on modifying the spindle height on a Boge strut vs doing so on a Bilstein strut?

I am gearing up to do a complete suspension overhaul on my '88. Will continue running euro ride height; i bought Bilstein HD inserts to rebuild my Boge struts and while i was at it was going to send them to Elephant to raise the spindle height. I see that the limit one can raise the spindle is 19mm with the Boge struts.

Any thoughts on just getting new Bilstein struts that offer greater flexibility or is it not worthwhile at euro ride height? Price difference between a strut insert for the Boge and a new Bilstein strut is nearly $500 each, but that can be offset a bit by selling my complete Boge struts.

I am using rubber bushings from Elephant on everything, large torsion bars and will have Elephant also revalve the struts and shocks. Car is all street right now but if and when i ever sell my track car the 911 may see a few events a year so i can get my fix. I plan to keep running 16" Fuch's but eventually may gravitate towards a 17" wheel... but still want to keep the ability to run the 16"s so i wouldn't exceed +30mm on the spindle height.

I switched from Boge to Bilstein struts, went with revalved inserts matched to 21mm bars, stock ball joint and camber plate, rubber bushings, dropped my arch height to under 25", installed a 12mm rack spacer, and maxed out negative camber with only a strut brace. I have no noticeable bump steer with my Prototipo.

What is your reason for wanting to raise the spindles?

You can not raise the spindles on a Boge. The strut body flares in diameter right above the spindle assembly preventing any movement. Bilstein struts are the same diameter from top to bottom.

Koni struts also flare but high enough above the spindle to allow for raising.

Make sure to only raise the struts by the amount dictated by the diameter wheel you are using.

Yes, this is a very worthwhile modification.

It depends on what Boge strut you have. This is true that the older Boges have a flair. Even so the older Boge spindles can be raised if you can find someone willing to do the job.

Post a pick of your struts and measure the diameter of the bottom of the strut and above the spindle to see if has a flair.

You can raise the spindle 24mm and still use 16 x 7 inch Fuchs on the front.

However, in your case a 19mm raise would work well, since you aren't going to drastically lower the car.

Keep in mind that you will have to use a bump steer kit, not just the rack spacers, AND adjust your bump steer after you raise your spindles. Otherwise you WILL have a darty car.

The other side effect of raising the spindle is the front roll stiffness will increase, it will feel like you put on a larger swaybar.

I have raised Boge struts before... mill out the weld, put a plit down the spindle collar and raise up and reweld. Not the optimum perhaps but works fine.

Appreciate the input. Leaning towards just getting a pair of Bilstein struts and sending those to ER for revalve and modifying the spindle height. Will sell the complete Boges to recoup some cost. And it will simplify things somewhat just swapping the complete Bilstein strut in rather than having to swap the inserts on the Boges. Ill get in touch with ER before ordering anything to get the final opinion though and see what they suggest for how much to raise the spindle.

I figure while i am at it i will go with the racing bump steer kit and have the double shear brackets welded on the strut at the same time. I have the bump steer kit on my 951 track car and it works great.

And increased roll stiffness? I would love to get a picture of my three wheeling it through a turn :).

Raise spindles + a bump steer kit (steering rack spacers)?

Why? For fine tuning or ....?

Sherwood

I found that after I raised my spindles I had those two unexpected side effects.

For a street driven car the stiffer front roll is not an issue. A larger rear sway will balance out the handling for those who have a problem with understeer.

My car's steering and stability felt very unstable, with the car hunting and darting about, for example on the freeway. I had to adjust the spacers on my bumpsteer kit to minimize my front suspension's bumpsteer. It is a tedious but necessary procedure measuring and minimizing the toe change with respect to the suspension movement. It is not as simple as just making sure the tierods are level.

Yes. Raised spindles and rack repositioning will get you closer. Race car prep for minimal toe changes requires a bump steer measurement setup and a lot more work to achieve that goal - maybe the difference between an ok car and a very good car.

Sherwood