I'm in the process of putting a Mustang rack & pinion on my 28 chevy. Mounting it on the axle (yeh, I know!). All was going very well until I turned the wheel today. Seems since I mounted the rack BEHIND the axle, so now I have to turn right to GO left. ****!! Am working on putting the steering arms out the front and putting the rack in front of the axle. 2 questions Will this distroy the ackerman AND I just noticed the 2 steering arms are shaped completely different. The pictures in my books show them as the same shape. Anyone know for sure? Damn frustrating day. Jim
to answer your original questions, yes, putting the rack up front will drastically change the ackerman geometry...if you understand how the geometry works, you'll see that the outer tie rod ends need to be further out than the king pins for front steer. and usually the driver side steering arm has that long piece that sticks out to connect to the drag link, so it looks different from the p*** side. At least that's how it is on 30s and newer solid axle chevys.
Just went through this with another guy. I mounted a Capri R&P on the axle of my '32 Ford. Worked fine. I made a gear box to reverse the rotation of the stearing shaft. I mounted mine on the frame where the shaft was giong to be located anyway. I used gears that were available to me, but not to you unless your overhauling CF-6 engines. You could hit up the Boston Gear catologe. Use two oil pump gears, hit the junk yard and grab two same Rack and Pinion pinions. Or what ever. I wasn't the first and you won't be the last.
Having studied gear design, in the case of a road car, you will want to insure the gearbox can handle peak and fatigue loads. Peak is easy to test, fatigue takes a little more care, and any pinning or "setscrew" arrangements need to be right. I. use quality shafting and gears, fit and key the gears in a manner that securely mounts them. 2. provide lube, and gear tooth overlap...i.e. a "mesh" that loads (look up contact ratio) more than one tooth. Since the rack ***y. was designed to handle certain loads, this box should be slightly stronger.
I'll have a post on a steering reverser (is that a word?) ready to go on Sunday. We're almost done with it. Rich Fox gently pointed out the problem to us, and pointed us to a solution. Ours uses gears that are readily available from Martin Mfg,that are bored for a 3/4 in shaft, and is relatively easy to construct.
That was my thought in recomending two pinion gears from like R&P units. They were made to be used for steering, The shaft is already attached or maybe it's a one piece forging that fits "D" or other factory steering shafts. Unless you have access to CF-6 parts, seems like a good idea. Never tried it so I really don't know.
Get a different rack. I think late model GM fwd **** boxes are rear steer. IIRC,Heidt's made a rear steer front suspension for the Alloway ch***is,using a Citation rack.
OK That's what I thought but if I could put the steering arms foreward in the correct position, could that work? j
earlier Saab's were rear steer rack and pinion. Used one along with a Corvair front suspension back in the dark ages of "street rodding". rode and steered just fine. In fact the last time I checked, the car is still on the road with the same setup. Frank
a rack from a chevy cavalier would give the right rear steer you looking for. I know many folks who use them in thier shoeboxes for the conversion.
Just about any front drive car rack would work. I used one from a Dodge Omni. It works great! If you were to mount the rack in front it would look a bit goofy, I have seen the axle swaped but just swap spindles that works too. I would mount it to the frame either way. I originally was going to mount mine to the axle but didnt like the idea of having a slip joint bind up on me. As the axle moves so will the rack in your case. That means your seering shaft is going to need to move with it. Keep that slip joint lubed well.
You can mount the rack in front and not screw up the Ackermann. The important part in this is the angle between the steering arm and the tie rod must be less than 90 degrees, which will usually result in the tie rod angling forward as it goes out to the steering arm. There is a good explanation in Woodward steering's catalog, which I think is online in a .pdf. www.woodwardsteering.com. My vote is for a different rack, or a reverser, just for looks. As mentioned before, both Citation and Omni racks are rear steer.
How the heck do you put appropriate joints in the steering to compensate for movement? Won't you feel every bump? With a frame mounted rack, you have the steering ratio to help overcome feedback generated by tie rod movement. Mounting the rack on the axle means you receive suspension feedback at 1:1 ratio through a single U-joint. Not good even with slip couplers. And we haven't even touched on the unsprung weight issue. Hope you've got nice shocks mounted vertically. It's OK to not be an engineer. But at least be smart enough to pay attention to how they usually do things. Then cut everything you've done off and start over, there's no point in trying to find a half-*** remedy to something that's already half-*** fundamentally. IT'S YOUR STEERING and it needs to be right. In the grand scheme of things, trying to use parts that aren't right usually ends up costing more than walking away now and buying the right parts. Good luck. You'll get there eventually.
Solid axle and a frame mounted rack won't work due to bumpsteering issues with the short tierod sections. Axle mounted rack will work better for bumpsteer but would have all the issues you mention...and might not p*** a roadside check anyway. WAIT! I just had a brain storm!!! MAYBE he could use a STEERING BOX!?!? Hey 28 Chevy...what ya got against a good old steering box?
I have a rack and pinion on my truck mounted on teh frame and it works just fine. Even wiith biasply tires. I have taken it down the ****iest roads I knwo to test it, and I mean old farm roads. Bump steer happens no matter what at some level. Even with A arm setups. I have seen some pretty high end vehicles with straight axles and rack and pinions. Maybe it's wrong but it works well for me. This has been argued TONS of times. If anyone was to perform a search they'd see that.
The late model front drive Malibu has a manual rear steer rack, the power steering is in the column. My son is going to use one one his shoebox Ford.
Bumpsteer happens no matter what at some level? Not unless compromises were made for looks or style. It's just geometry. I won't comment on your luck with a frame mounted rack because I've never seen your setup. I can comment on a guy who had it done and asked me what he should do to correct it, so that he could drive his Hot Rod. He had to pull some leaves from his front spring so that it had some give in the front and he wouldn't have to wear a kidney belt...but once he did that the resulting bumpsteer from the frame mounted rack & pinion made the thing almost impossible to drive! The lack of movement in the front end had made the thing drivable by limiting the m***ive bumpsteer that was just waiting to rear its ugly head. Thats why I don't like the idea. Wondering...your not using a Unisteer rack by any chance? The geometry with those is the same as a cross steer setup. I'll tell you one thing...I firmly believe there's a way around anything and who knows...maybe you found it with your frame/rack setup!!! I won't deny you having your opinion. Your driving it so you know how it feels on the road! But...I just can't see why it needs to be done... Boxes are traditional and look at home on a Hot Rod, work well, don't limit steering radius like some swapped in racks. You can adjust a box as it wears, easily set your toe-in and center the wheel... What makes a rack so desirable? It's those damn rubber boots isn't it...tell the truth!!!
Like this (see photo). The key is the last section of steering shaft needs to telescope, or the suspension is in a bind. In this case, we used a section of double-D shafting from Borgeson, with a Borgeson double-D to spline U-joint on the rack. Woodward makes a splined telescoping section, but it is about twice the money of the Borgeson stuff. This rack is a front steer unit out of a '92 T-Bird. They work well for a race car because they're a quicker ratio than some of the other OEM racks.
Why do some people want to use a rack? Because they are quite simple to hook up. Even mor simple than a steering box.
OK. I still think this is an acceptable idea but since I got in the car and had my setback I guess I'll go to a steering box and cross steer it. I like that idea for bump steer. This ****s but it is awesome because of all the "on the project" training I am getting. This is my 1st street rod. I've done 2 resto's. Thanks to all for your imput. I took it all to heart. My dad says "Get all the info you can from anybody you can and then make up your own mind." thanks again Jim
That's cool, you need to do what is right for you. My next rod will have a steering box as well. For no other reason than it is a T roadster and would not look right with a rack and pinion.
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