challenge rack modification

My mechanic will be installing my Challenge rack in a few weeks and we talked about the overassist of the rack. We decided to put in a adjustable valve in line and mount it in the trunk so you can adjust the "road feel" by turning a valve. He has done this on a number of Viper race cars so the steering is not so sensitive. We will need to make all new hydraulic lines but should work out well. The steering is too sensitve to me on a high speed track like Road America. Same could be done with the stock rack. Will take pictures as we progress and post them.

 

Very interesting, Bob. Assuming this works out, I'd be very curious to learn the details. Please keep us posted. Thanks.

 

Keep us posted on the innovations!

 

+1. This might be a great, less expensive solution.

 

Bob,

Does the 355 have a servo on it like this? Does the 355 have a steering ECU? like other ferraris like the 550 which also uses the 5.2 motronic and talks via CAN?
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No I don't think it has an ECU or servo. The Challenge looks just like a stock rack from the outside.

 

http://ferrarichat.com/forum/showthread.php?t=343759

One of my many future projects is to play with your exact issue. Anyway do a search on ZF racks and there are many explainations of how the power rack works...and therefore can be modified.

If I had a 355 I would serious consider putting a 348 manual rack in there. You would save many pounds on track and even parking the 348 is a breeze. I never understood why the 355 had a power rack especially when the weight up front did not increase vs. the 348.

One of the things I did on my Vette racecar which has a stock power rack also overassisted is to use a smaller diameter removeable steering wheel. Now I like the steering. In a steetrcar you loose the airbag unless you start getting untested and custom.

 

Problem with a smaller wheel, I've done in on the 355 is that it blocks the speedo and tach.
I'm sure this will work since there are valves made specifically for the purpose of adjusting the steering rack pressure. New lines will need to be made but it should be pretty straight foward. You could put a mark on the valve knob that is a street setting and another mark on the knob where you want your track setting for less assist. I think the gear in the rack has different spacing on the teeth to make it faster? The Challenge rack looks from the outside just like the stock one, same size, hose fitting same place etc.

 

I saw your post for the 550 and the F355 does not have a steering ECU. It is just different internals that changes the steering response. Like I mentioned, my mechanic did this on many Viper race cars for the same reason. He had a steering rack valve at his shop when I left the car theer today for winter storage but I didn't have time to look at it. I had a Viper Coupe and it was over assisted steering even with 285 front tires and felt like the F355 at speed.