Narrow Power Steering Rack

[Coburn_Performance]

I'm in need of some assistance finding a narrow power rack. I bought a Flatout Engineering C4 Corvette IFS that is narrowed to 57" hub to hub. The C4 rack is a high mount rack and it interferes with my engine. I can't really raise the engine, so I need to drop the rack. I've strung up the pivots and determined that 20.75" between the pivots is what I need to prevent bump steer. I'm going to have to drop the tie rod...but one problem at a time.

The rack that I bought from Flatout is made by Unisteer. I've contacted them and was told that they can't shorten it and didn't seem at all interested in helping me out. Flaming River were about the same. The current rack is 21.5" between the pivots...you'd think it could loose 3/4" without having to break the laws of physics.

I've looked up some of the custom racing units and they are all narrower...I'm out of ideas. Anyone got some advice?

[ravege]

Probably not much help, but I did run across this posting on maliburacing.com:

TRZ, is there some reason why there cannot be a power rack and pinion setup for our cars? Why is a power rack apparently so different?

Yes there is. In order to get the bump steer correct on the G-body, we have to use a narrowed version of a Pinto Rack. Not narrowed from the outside ends, but narrowed from the middle of the rack so that the tie rod pivot points are in line with the lower control arm pivot points. And nobody makes a power rack in this narrowed version. We've asked Flaming River if they could do it, and they said it'd be impossible in a power version to be narrowed like this. So we can't do it because of this, and we won't sell a rack thats incorrect because the bump steer is bad enough that an accident will eventually happen.

[sccacuda]

This should help you figure out what you need. http://www.streetrodgarage.com/c4vettesuspension.aspx

Lower the rack and tie rod attachments on the spindle.

[astroracer]

Be careful moving stuff around. Check out this article from Longacre.
http://www.longacreracing.com/articles/art.asp?ARTID=13
The diagram at the end is self-explanatory... Getting the pivots right is critical to the operation of the rack. Also be aware of clearance to the wheel and and stab bar when working this up.
Mark

[Coburn_Performance]

Be careful moving stuff around. Check out this article from Longacre.
http://www.longacreracing.com/articles/art.asp?ARTID=13
The diagram at the end is self-explanatory... Getting the pivots right is critical to the operation of the rack. Also be aware of clearance to the wheel and and stab bar when working this up.
Mark


Here's what I've got Mark. I've "strung-up" the suspension and checked that the current rack is giving the correct center to center measurement (21.5") for the inner pivots. Then I've computed the new center line for what I need to clear the oil pan (the ruler bottom edge is on the center line) this gives me 20.75". So to keep the arc in the same plane, I need a shorter rack (pivots move in). The tie rod would ideally have to drop and go out a little. I was thinking that a bump steer corrector with shims should get the job done. It's only 1.5" from the original location. I could buy the steering arm relocation kit, but I'm a little sketchy about a welded steering arm.

I'm trying to figure out if Coleman Racing or someone else can fab me up a rack or if I should just move the darn engine up (messing up the CG location but making life much easier and a pile cheaper).

Craig

https://static1.pt-content.com/images/noimg.gif

[sccacuda]

I'm with you about a welded steering arm. I built this for a customer several years ago. The rack was lowered, requiring lowering the tie rod point. I wasn't comfortable with a long pin from the existing tie rod hole. I think it has way too much mechanical advantage on the spindle. This is a C4 spindle. I machined a pin that has the correct taper to seat in the tie rod hole. I machined the remaining pin straight to fit the hiems and spacers. The bracket I built is only a support for the pin, with a DOM sleeve that is an interference fit. I know it added some weight, but I chose this route so that all the parts were still common readily available stuff. The pin and bracket are not a concern for wear or replacement.
https://static1.pt-content.com/images/pt/2013/01/file11-1.jpg

[Coburn_Performance]

I'm with you about a welded steering arm. I built this for a customer several years ago. The rack was lowered, requiring lowering the tie rod point. I wasn't comfortable with a long pin from the existing tie rod hole. I think it has way too much mechanical advantage on the spindle. This is a C4 spindle. I machined a pin that has the correct taper to seat in the tie rod hole. I machined the remaining pin straight to fit the hiems and spacers. The bracket I built is only a support for the pin, with a DOM sleeve that is an interference fit. I know it added some weight, but I chose this route so that all the parts were still common readily available stuff. The pin and bracket are not a concern for wear or replacement.
https://static1.pt-content.com/images/pt/2013/01/file11-1.jpg


That's a really good idea, Craig, I try to stay away from the hot rod stuff as much as possible (sorry if that offends) as much of it is quite literally for show and an occasional cruise. If a steering arm broke on a track...that's my a$$ in the grass and I'm too old for that sort of thing to be remotely funny anymore.

Has anyone used a racing steering rack on the street? If so what are the pros/cons?

Craig

[Bryce]

Craig,

Call up Woodward Steering, Tony can help you out with everything. They make custom racks, manuals are pretty reasonable.

[Coburn_Performance]

Craig,

Call up Woodward Steering, Tony can help you out with everything. They make custom racks, manuals are pretty reasonable.

My sense of things (sorry for the ignorance) is that the racing racks are all pretty interchangeable. I'll call them tomorrow as I've had variable response from some of the other vendors. Looks like they all have a three bolt bracket and height adjusters. I'm really looking forward to getting the engine LOW and not having to raise the CG of the car to make this suspension fit.

Craig

[Bryce]

Woodward makes racks for some of the street super cars. They make many different models.

[bret]

Woodward = great quality, great tech advice, especially for those who arm themselves with the info that Woodward already has published on their website, and the willingness and ability to accommodate a wide range of dimensions.
Don't expect it to be cheap.

[Coburn_Performance]

Woodward = great quality, great tech advice, especially for those who arm themselves with the info that Woodward already has published on their website, and the willingness and ability to accommodate a wide range of dimensions.
Don't expect it to be cheap.

Thanks Bret - the rack is in production and on it's way to me. Had a great chat with Tony - he sure knows his stuff and was finishing all my sentences. Brilliant stuff...now if your email system could answer my question about coil overs, I'd be set :). I'm trying to figure out the IRS suspension when I'm not bashing my head against the C4 wall:cheers:

[Bryce]

woodward for the win

[wellis77]

Love my Woodward and Tony has been awesome!