Rack & Pinion question

[Zandoz]

I know many think rack & pinion steering is a bad idea with a solid axle, but I'm planning on giving it a try anyway. I have an Omni R&P that cost me nothing, so it won't be a costly experiment.

My question is, given a 4-bar suspension configuration with the R&P tie rods passing between the bars, how much clearance is necessary between the bottom of the upper bars and the tops of the tie rods?

 

[2old2fast]

Depends on how much caster you run, the steering arms raise & lower when they turn in relation to the bars.
dave

 

[Zandoz]

I was planning on about 7 degrees positive caster built in...but loosing around 2 degrees of that with the "rubber rake" effect of larger rear tires.

 

[old round fart]

Remember the rods move up and down with the bars so you just need enough to clear when you turn from lock to lock.

 

[stroker]

Tried that 40 years ago. Didn't work! Toe change was unreal!!! How about mounting the r/p to the axle and using an early Pinto flex steering shaft?????

 

[donsrods]

I know some people on here have them and love them, but everything I have seen leads me to believe otherwise. I drove a buddys T home from a show one time and it was the scariest ride I have ever taken........white knuckle time the whole trip. The car just had a mind of it's own and the slightest bump would send it off in every direction.

I realize you are going to try it, but I just had to interject that.

Don

 

[Ma_n_Pa T]

I like mine but we are using the Chevy Metro R&P, I would be happy to give you any info you need, PM me your emil and we can do some talking, it needs to be set up right just like anything else you do, I have never had bump steer, it is a little fast in ratio but very nice to drive. I just installed one in our new build, used longer steering arms to slow the ratio down, its not on the road, so no info on it yet.

Jerry

 

[Zandoz]

I know some people on here have them and love them, but everything I have seen leads me to believe otherwise. I drove a buddys T home from a show one time and it was the scariest ride I have ever taken........white knuckle time the whole trip. The car just had a mind of it's own and the slightest bump would send it off in every direction.

I realize you are going to try it, but I just had to interject that.

Don

What I'm planning on is to try and set this up so that if there is a problem, I can easily convert it to a home-grown version of Unisteer's cross-steer set up.

 

[Zandoz]

I like mine but we are using the Chevy Metro R&P, I would be happy to give you any info you need, PM me your emil and we can do some talking, it needs to be set up right just like anything else you do, I have never had bump steer, it is a little fast in ratio but very nice to drive. I just installed one in our new build, used longer steering arms to slow the ratio down, its not on the road, so no info on it yet.

Jerry

Thanks. I appreciate the offer. I already got some great info from you a few months back, when I first started considering using a R&P set up. I'm sure I'll be pestering you when it comes time to do the actual building.

 

[Zandoz]

Now I have a request of anyone out there who has an Omni/Horizon R&P. My unit is in storage 200+ miles away, and I need a couple simple measurements. I need the diameter of the cross tube, and the distance from the bottom of the mounting flange to the bottom of the cross tube.

 

[Gerry]

you could always do it this way. Get R & P benefits and no problems (negligible) with suspension movement.

 

[grazza]

Here in Australia, between 1982 and '89 Holden made a car called a Camira ( http://www.google.com.au/search?q=h...&ei=Gqo0UOXrBoWimQWC_YDgDQ&sqi=2&ved=0CFQQsAQ ). It was a front wheel drive thing and not all that good at that. The one redeeming part about the car was it had a rack operating the steering. The rack had the Tie rods mounted to the centre of the rack, instead of the ends. http://www.google.com.au/search?q=H...v&sa=X&ei=Sqs0UJK0LvGSiAfaooDYAw&ved=0CFsQsAQ. These racks have found their way under a heap of Aussie Rods, along with the original beam axles. They steer really great with next to no bump steer or other nasty surprises. Dead easy to fit to an early chassis. I am fitting one to my '27 and although not installed yet would be happy to post a pic or two once it is. I don't know if GM produced anything similar in the US, but could be worth a look around your local parts yard for something similar.

 

[fordsbyjay]

Was it the Dodge Omni rack looked like that? I know Wurthit designs has a unit like that in their 56 Ford R&P unit.

 

[RocknT]

I thought I had picture of ToolMans T ,, He used a R&P mounted like or pretty close to the way a Corvair box is mounted

 

[PotvinGuy]

I just stumbled onto this thread. I run an R&P with tube axle and 4-bars:

You can see there is maybe 5" between the bars. I've been using this setup for 20 years without problems.
Bump steer is only noticeable on bad roads. Around town is fine. I have more pics; just lemme know.

 

[Zandoz]

I've admired your R&P set up for some time. Unfortunately it's worked out that with as low as my frame will be, it will be a LOT simpler to run the R&P tie rods above the 4-bars, instead of between. To run between, the centerline of the R&P would be only about a 1/4" above the top edge of the frame rails...requiring the rails be notched to almost half their height and some how reinforced. By running above the 4-bars and using steering arms mounted in the upper position on the spindles, everything clears the frame, spring perch, and 4-bars nicely.

The problem I did run into was getting the pinion to clear the radiator...it turned out to be a lot closer to the centerline of the rack than I anticipated. At this point it's looking like I'm going to have to extend the wheelbase about 4" in front of the radiator, to get the steering shaft routed around the radiator.

 

[Hot Rod Todd]

Down here, the vast majority of buckets have the same setup as Gerry has in the UK. From memory my bucket has a Austin Mini R&P with one end attached to a rod that steers the car and the other end is cut short and just living inside a boot.

Back in around 1973, our New Zealand Hot Rod Magazine built "Project T" that way & it worked & everyone just copied it.

I had a previous bucket with that setup, and it had wicked bumpsteer. A couple of owners later took it to a speedway (dirttrack) guy for some help, and the speedway guy took about half the leaves out of the front spring & the new owner reckons it rides like its on rails now.

So that may be worth looking at by those with bad bumpsteer. Or Ted can drop in and tell us the right way to eliminate the problem.

 

[sstock]

Wow, that is one of the cleanest R&P setups I've seen, great work on the frame and finish. Just goes to show, you can form an opinion about something and someone can put it together nicely to change your mind.