Shark rack & pinion

[Bullitt]

I need some help, advice, ideas and information from anyone whom has thought of performing this swap or with in-depth knowledge of steering components. Okay, it's getting near decision time for me on whether I should attempt this conversion or not. Granted, I've only been thinking about this for a few weeks, but I'm at the point of wondering if updating to newer technology is worth it. I spent some time searching the net and read about systems for every other car. :eyerole There seems to be some worry about the strengh of the Steeroids systems for Camaros. It's a front steer vs. a rear steer design issue. By having the r&p up front, it's not required that the rack to be terribly strong or stiff. The theory is that brake loads on a rear steer system (behind the spindle) like Steeroids do require a strong and robust rack or failure will occur. Is this a moot point on Corvettes because of the stock configuration? The types of rack also came up, with some wondering where SpeedDirect gets their stuff. Another site I found, had a design for a system that required the r&p body to move, instead of the ends like a conventional design. Links were placed from the center of the r&p unit (Saab style) that relayed out to the connecting tie rod ends. It used bracketry (that would have to be fabricated), that would bolt up to the former locations of the steering box and idler arm. The problem seemed to be aligning the column with the rack. The guy who performed this conversion had to collapse the sterring column to get it to work right without binding the steering. The advantage of his system is the fact that most parts were sourced through the junkyard or parts cars. That means CHEAP! I'll look for the site and try to post a link, later. I would like to lessen the weight of the car and tighten up the steering at the same time. My alignment was a out of shape and the steering wheel had some play before I put my '71 on jackstands, so I'd like to fix that. Help!!!--Bullitt

 

[Bullitt]

Here's the link...

Shark Rack & Pinion

 

[69MyWay]

Steeroids has been developing the kit. It will set you back a little over a grand when all complete. I wish it was available when I decided to purchase all my parts. For a few hundred more I could have been racked.

It appears you have already explored the possibilities.

Take this for what it is worth, but I have heard that you can reverse the spindles (left to right, right to left), which puts the steering knuckle in front of the axle. At this point, you have a variety of rack options including a C4 rack. Building the linkage is not as big of a concern, as street rodders have been building custom linkage for years, and the materials are out there.

 

[Hib Halverson]

I looked at that image (http://www.corvetteforum.net/c3/zwede/71corvette/rackandpinion/rackand.htm) of the rack installed on a C3. Interestingly, the rack looks very much like the rack that was on an 88 Chevy Beretta I once owned. It appears similar to the racks used on millions of GM front-drive, compact vehicles

Anyway, simply stated, I wouldn't drive a car fitted with a rack-and-pinion set-up like that to the grocery store.

Keyrist--look at the huge difference in tie rod length to control arm length. Imagine the arcs in which those components move. Now imagine what happens to the knuckle as it responds to the differences in the arcs. Ohmahgawd is that ****** going to have a ton of toe steer. In fact, looking it it has me thinking the car is going to have a lot of roll oversteer. Wow! That'll be an e-ticket ride when the car is run hard.

Also, the opinion expressed that a steering rack doesn't have to be robust or mounted stiffly in a front-steer application (if you could even convert a c2/3 to ft.steer) is complete myth. Any steering system mounting on any car needs to be a stiff as possible for best performance and handling. Also, the rack itself needs to be strong enough to handle the cornering loads imparted by the vehicle, ie: you may not be able to safely use a rack designed for a car weighing 2800lbs on a car with big tires and weighing 3400 lbs.

Building rack-and-pinion into a C2/3 requires a lot more than simply shopping a wrecking yard and bolting on something that looks as if it will fit.

Why do you think companies like this Steeriods have taken so long to develop such a conversion.

Lastly, the comment was made that such and such a collection of junkyard parts would give a C3 R&P and, above all, doing it that way would be CHEAP.

What--are you guys nuts?

If you are going to make a major, safetly-related, change in chassis construction, you want it to, first, be safe, reliable and durable, that means a rack robust enough for Corvette use, mounted stiffly and with steering geometry appropriate for a performance sports car.

 

[Bullitt]

What I meant by cheap...

...is that the rack could be trial fitted without an outlay of money going to a part that wouldn't fit. I would use newer parts when the final fit was decided. I'd hate to put forth $600 when it doesn't eventually work. I still need to know where SpeedDirect sources their rack from. Surely, they didn't design a specific rack that would be cost prohibitive. I'm thinking of using something that is naturally strong such as on a C4 or an F-body rack with their weight similarites. Hib, what do you think of the bracketry that would have to be fabricated? I think the brackets at the posted link are too frail and need to have two additional mounting points. Perhaps made out of stronger, forged steel and an intergrated mount? So, is the stock set-up a front or rear type? How about a switching of the front spindles? I need to know more before I go on. --Bullitt

 

[69MyWay]

Bullitt,

Messing around with the front suspension is kind of scary. I can tell you that being out by 1/4" or less from one side to the other can cause bump steer. Bump steer is just that. You are riding down the highway at 70mph when you hit a small bump. The geometry goes whacky and the car shifts lanes and you never moved the steering wheel.

I experienced this first hand in my V8 Fiero. I was messing around with the rear suspension and almost ended up wrapped around a guard post.

Any company (like steeroids) building such a product assumes a HUGE liability risk. Not only for you, but any car, property, or pedestrian within striking distance of the car if something goes wrong.

I too love the idea of the rack. However, the standard system with good new parts works great. They were raced for years and years with no problems.

However, I admire anybody that looks for new and better ways to improve these old cars.

I hope you figure it out. I also agree, a proto type should be built with inexpensive parts, because there is a great chance the whole thing will fail.

 

[Tom Bryant]

I feel a need to express my opinion.

That picture of that rack scares me to death. I wonder what that rack came on. More than likely a McPherson strut suspension on a very non high performance car. You can bet that the only reason the tie rods connect where they do is because of space and design limitations. Can you imagine a nose heavy big block at speed in 4th gear in the middle of a high g force curve when it hits a dip in the road? Watch for the "CHECK ROLL CAGE" light to come on.

Take some time to study the stock system. Notice that the center link is specific to your car. Also notice that the tie rods are the same length as the lower control arm. As Hib said the tie rods and the suspension must travel in the same arch. A shorter/longer tie rod will push/pull on the spindle steering arm when the suspension travels up or down. This will steer one side or both in a way you won't like with absolutely no steering wheel input. The above pictured example would also be impossible to align. Any weight added to the car would compress the suspension effectively changing the toe angle. Even that 6 pack you just stopped to get.

Have you ever wondered why American auto makers resisted R&P systems for so many years. They were considered too flimsy for heavy American cars. Corvette never saw them until the big block was gone. They were great for light European cars and race cars where weight and packaging were important. A rack would have to be carefully selected for this car. Of course they have developed heavier racks for the bigger cars now but you can bet that they have millions in R&D.

Before you get into this project too heavily get the newest issue of the Chevy Power Guide and read the "Vehicle Dynamics" section. It's great reading and will give you a good understanding of steering and suspension design and how they work together. If you decide to go with a purchased system from an aftermatket supplier get references and find out how they like the change. You could end up spending a lot of $ and time just to end up with less than you started with. In other words it is probably best to let someone else tear their hair out perfecting the system. You also need to realistically look at what the intended use of your car will be. Are you spending wisely or looking for something to show to the car show guys?

Having owned a big block car I know that there is a lot to do in the handling improvement department before looking at the steering box. MIght be a good idea to attend NCCC autocrosses or other Corvette speed events and see what the hot dogs are running.

Tom

 

[Hib Halverson]

Besides the issue of toe steer and design-strength of the rack, you also have "ackerman" angle. I mention that in response to the post that suggested one can convert a rear steer car to front steer by simply swapping the knuckles from side-to-side.

Buzzzzzit.
You can't.

If you did, the ackerman angle would be off--way off. A car without ackerman won't track right in turns and will wear tires incredibly fast.

Lastly, the point was made that braking loads were the key factor in how a rack's inherant strength and the strength of its mounting should be designed. I'm not sure I agree with that. I think braking loads are only one issue to consider but cornering loads and steering effort are equally, if not more, important.

 

[Bullitt]

My intentions...

Are you spending wisely or looking for something to show to the car show guys?

I was never one to park her on the lawn and "show off", so to speak. I do want a performance edge to my '71, though. I appreciate everyone's input as I ponder any future mods. I'll sit on this for awhile and read up on the subject more, before I let loose with my ratchets and wrenches and make a big mistake. I don't want to have to deal with weekly or dangerous problems. I'll post a link to the Camaro discussion, so that everyone can exaimine the issues and questions, brought up there. I'm going to talk to a few mechanics and racers in the area to get their opinion on a R&P set-up. Perhaps I should just rebuild the steering box and update to spherical rod ends? --Bullitt

 

[Bullitt]

Camaro R&P link

Camaro Steeroids

 

[Hib Halverson]

The biggest problems with the C2/3 steering are:
1) the steering box.
Few people know how to properly adjust them. Still fewer know how to properly overhaul them. Even if you do know how to overhaul, there are certain key parts inside that are no longer available but also are normal wear items, ie: the ones in wrecking yards are often no better than what you take out unless you get pieces out of a low mileage vehicle.
2) the design of the power steering control valve.
It is such that even when new and properly adjusted, it has horrible on center feel.

Both of these problems would be solved by a rack-and-pinion conversion but only if the conversion is properly designed and installed.

One of the curses Duntov gave us with the C2/3 is that awful power steering system. It is a shame that GM did not spend the money to tool-up a Saginaw 800-series power box with the long pitman shaft needed by C2/3.

 

[redmist]

Relief

Ok I'm convinced this is one project I can pass on. Thank God.
Hib scared the **** out of me.

 

[Bullitt]

Lets' go farther...

...and examine what we agree on.

• There is an appreciacble fault with the design of the Shark steering system.
• Finding a rebuilding specialist would probably be a better idea for a steering box. What is the stock ratio, anyways?
• The ideas provided by '71 Shark Rack&Pinion link are not thought out and do not take into account several steering angle issues.
• A rack&pinion could solve these problems, but proper and safe mounting along with performance use are the main concerns.
• A longer pitman shaft would help, on a stock C3 system, but again it comes down to proper mounting. What are the main concerns of this swap?

Finally, can anone provide a diagram of the C4, C5 or even a F-body r&p steering system and mounting? I know that some of these models used steering boxes into the'90s. So pics on these systems would also be appeciated. Right now, I' m going to wait and see what is possible and what is unpractical. I have other things to do on my Shark, so I can wait. I just wanted to make sure that I spend my time and resources, wisely. Thanks guys. --Bullitt

 

[Hib Halverson]

(snip)
Has anyone ever converted a power steering gear to a shark?

I'm not sure about that. There was a guy out west who was converting Saginaw 605 boxes for use in 55-57 Chevrolets. The 55-57s used a long-pitman box that was similar to a C2/3's. I heard this worked on a Vette but have never seen it. I'd be skeptical, though, because the Saginaw 605s aren't near as strong as the 800s that were used on full-sized Chevys, Chevelles and Camaros.

In the north east dirt modifieds, there are guys who take a GM power steering gear box and make the pittman shaft longer. i mean a lot longer. I once saw the process, they are well made and take the stress of dirt racing.

I'd be interested in the specifics of that.

I quess one of these guys could take a GM Saginaw 800-series power box and make the pittman shaft longer to fit a shark. Then you bolt it on and remove the power assist crap.

I think a properly built Saginaw 800 would be a better choice for a C2/3 that trying to add a rack-and-pinion.

 

[Bullitt]

Saginaw

So I guess this idea of converting the power steering Saginaw box seems to make more sense. Is the box found on '80s Grand Nationals and/or Monte SS the quickest ratio available? I found a Haynes manual of Firebirds in my garage. Finally, something useful in all that junk. :L Anyways, it has an undercar pic of the front suspension mounting of the relay rod and tie-rods. It does seem to be an easier mounting system since it uses the same points as a Shark. I guess had I paid attention to my '74 Camaro's set-up, I'd know more. I'll try to post a pic of the system. --Bullitt

 

[Tom Bryant]

The Trans Am with the WS6 suspension used to be considered the best high performance GM box out there because of it's feel and ratio. It was first available in the late '70s. I can't get any more exact than that as I don't have any Pontiac books.

Tom

 

[Bullitt]

Surfing the Web

I spent some time trying to find out some more information on the Saginaw and other things. I hit Borgeson and came up with sizes and diameters. The link is at the bottom. I thought it was interesting that the Ford box had the same diameters as the Vette. I found out that F-body (Camaro&Firebirds) got a performance ratio of 12.7:1 and B-bodies got a 14.4:1 in '70, which other GM cars got by '73. What gives a box it's stiffness and tight feel has to do with the torsion bar in the spool valve. The GM range is 22-32in lbs. Third-gen F-bodies received a 28in lb. spool with 15" tires resulting in a 2.5 lock to lock turn. The 16" option tire got a 32in lb. valve resulting in a 2.25 lock to lock turn. The high performance boxes found their way in 1985 Z28, IROC, and GTAs and continued on through the years. The Grand National and Monte Carlo SS from'84-'87 recieved the boxes in 30in lb. variety. These easily bolt up to Chevelles, Buick Skylarks and Oldsmobile Cutlass with little changes and no significant modifcations to the box or car. I haven't found any sites mentioning a Saginaw conversion into a Shark, but I'll keep on looking. --Bullitt http://www.borgeson.com/boxesandracks.htm

 

[Bullitt]

No treasure, yet

I haven't found anything of converting a Saginaw power box to a Vette. I did find someone selling brackets to mount a box on '55-'57 Chevys, but I still don't know if it's a 605 or 800 style that's used. I now know more about Camaro, Firebird and G-body steering systems than I think I wanted to, but at least it's useful information. All types of RPO codes, identifying a quick ratio box and even a site to decipher a VIN on a 'Bird. Some guy was talking about Lee's Manufacturing in Sun Valley, California on Pendelton Drive? I'll try to find out a phone#, but the discussion was that they know quite a deal about steering boxes. I went to the AGR website (located in Fort Worth), but didn't find anything that was of use to a Corvette. There's BRT-Racing that deals with r&p for race cars, as well as Woodward. I was thinking that a Saginaw bolted to my Vette might interfere with the mounting of my sidepipes. Would using it on a dropped down bracket to get it out of the way, be a good idea? It might not require converting to a longer piman shaft. I'm working it in my head right now, so I'll give you guys some detail tomorrow. Here's the links:Woodward and http://www.brt-racing.com/power.htm I'll keep on looking, but it's getting thin. --Bullitt