Rack and pinion conversion

[frederick]

I'm thinking of converting my car to R/P.
Main problem with the current system is the umber of balljoints; more than 10!
So if there is only a tiny bit of wear in each of them the steering becomes woefully vague.
The other problem is the pitman arm; original ones are known to snap and uprated ones are $700.

Since there is no system available it will have to be a custom rack.
I was thinking about a Unisteer rack, but the comments on them aren't always positive, to say the least.
Same with Flaming River.
Recently I came across Woodward steering, does anybody have experiences or comments on them?

Or do you have another firm which can build custom racks.

Thanks,

Frederick

[Mike DC]

 
Not sure how a R/P is gonna cut down on the # of balljoints . . . 

The balljoints usually aren't really the problem though.  Plenty of modern cars & trucks have just as many joints between the steering wheel and the tires, and they do it without the slop we deal with on these cars. 



I'd get a rebuilt regular steering box, fix any other obvious stuff like balljoints & pot coupler joints, etc, and get some more caster in the front end with A-arm changes.  I doubt you'll want more after you do this stuff, and the end result will probably be better all around.  A lone R/P conversion could help but it really only fixes one out of several potential steering issues under there.  (The A-arm caster thing makes a real difference, it gives the front end more centering action instead of the really "floaty" feeling these cars were built with.)

Even the steering box mount on the K-frame allows some flex and benefits from some gusseting work.

   

[frederick]

Thanks for the reply Mike,

Not sure how a R/P is gonna cut down on the # of balljoints . . . 

With a R/P you will have just 4 joints, one on either side of the steering arms.
Currently there are 14 joints in the system. (after the steering box)
Replacing them rapidly adds up to much more than a R/P conversion.

It's not really the steering box that is the problem, that has been rebuild.

I'll look into getting more caster, thanks.

Cheers,

Frederick

[Rolling_Thunder]

Your best bet would just be going with an alter K tion kit if you're looking for R&P...   bolts in with minor work and are very well engineered...   plus it wont break the bank.

[frederick]

Thanks Rolling Thunder,

The AlterKtion system doesn indeed look very well designed, price doesn't seem that bad either.
Only I'd have to do some mayor chopping about to fit it.
Which is really a step to far, I'd like to be able to return it to original spec if need be.

Frederick

[Mike DC]

      
Yeah, the AlterKtion kit is a lot of good parts for the money.  It seems to have earned its popularity honestly.  

(BTW, you shouldn't need to cut the car with that deal from everything I've read and been told.  The coilovers bolt onto brackets on the replacement K-frame itself and the upper A-arms still use the stock mounting points in the shock towers.)

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I just personally think people are too quick to toss the stock system these days.  

IMHO the aftermarket setups generally rely too much on wringing all the play out of everything.  It's very easy to make a car feel tighter that way, but not all that "give" in the factory setup was bad to have.  

[HPP]

The Alter K is a bolt in deal, no cutting required.

Where are there 14 ball joints after the steering box? I only count 6 in the steering linkage, plus 4 in the rest of the suspension system. I also have to question the weakness of the stock pitman arm. It is as strong or stronger than any rack extensions. Heck, in my oval track days I bounced cars off the walls and off other cars and never broke a pitman arm. I've sheared steering shafts, but you usually have to hit a wall pretty hard to do something that extreme.

The issue I've heard of with R&P systems is that racks typically do not have the amount of travel that recirculating ball boxes have. So you end up with reduced turn radius, unless you continue the exercise further and develop and install custom steering arm links to change the steering ratio at the wheel. Then you in to more custom parts, more $$, and the possibility of breakage.

So if your biggest problem is the number of joints, perhaps you can reduce that number some, but not eliminate all of them. If the issue is vaugness in the steering response, then additional postive caster is the first step. This could be achieved as easily as changing the upper control arm bushings. After that, a replacement box from Firm Feel, not necessarily just a rebuilt box, to change the actual assist needed and provide more road feel will net a huge increase.

[frederick]

Sorry, should have made it clear from the beginning, I wasn't talking about a mopar.

[Blown70]

Sorry, should have made it clear from the beginning, I wasn't talking about a mopar.

  your on a dodge charger web site.....hahaha  what do you think we chat about around here?

[Mike DC]

  

The issue I've heard of with R&P systems is that racks typically do not have the amount of travel that recirculating ball boxes have. So you end up with reduced turn radius, unless you continue the exercise further and develop and install custom steering arm links to change the steering ratio at the wheel.

That's because I think the majority of the R/P's out there are designed with a different kind of suspension in mind.  They're designed for front-steer suspensions whose spindles also have very short arms for the steering linkage to attach to.  

Then we come along and try to retrofit them behind the front axle and re-use the long factory spindle arms.  But a R/P has no pitman & idler arms so the length of the spindle arms is critical for determining the steering ratio.  


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In theory the modern front-steer setup is really the better way to go.  It gets the steering outta the way of the oil pan.  And it also fixes things so that any bushing play affecting the steering will cause it to err on the side of under-steering rather than over-steering the front wheels.  

 

[frederick]

Well you seem to have the same problems with the steering I'm having and the basic setup is the same.
And since this is the best mopar site I've found, I thought you might be able to give some sound advice.

But you are right it might be better to keep it original.
Maybe try someone's car which has good original steering.

Frederick

[Blown70]

Well you seem to have the same problems with the steering I'm having and the basic setup is the same.
And since this is the best mopar site I've found, I thought you might be able to give some sound advice.

But you are right it might be better to keep it original.
Maybe try someone's car which has good original steering.

Frederick

Ok, tell us more of what you have blue oval?

[frederick]

 

The issue I've heard of with R&P systems is that racks typically do not have the amount of travel that recirculating ball boxes have. So you end up with reduced turn radius, unless you continue the exercise further and develop and install custom steering arm links to change the steering ratio at the wheel.

That's because I think the majority of the R/P's out there are designed with a different kind of suspension in mind.  They're designed for front-steer suspensions whose spindles also have very short arms for the steering linkage to attach to. 

Then we come along and try to retrofit them behind the front axle and re-use the long factory spindle arms.  But a R/P has no pitman & idler arms so the length of the spindle arms is critical for determining the steering ratio. 


-------------------------------


In theory the modern front-steer setup is really the better way to go.  It gets the steering outta the way of the oil pan.  And it also fixes things so that any bushing play affecting the steering will cause it to err on the side of under-steering rather than over-steering the front wheels. 

 

That's real interesting Mike, because my car has front steering.
Didn't know that on chargers arms are behind the front axle.
That make's a R/P more attractive.
So front steer should have shorter arms, I'll check tomorrow.

Here's a pic of the car.
facel vega

[John_Kunkel]

For rear mounting I like the Cavalier rack, it is a center steer rack which takes out a lot of the bump steer that is common with side steer racks that don't match the suspension's geometry. The '82 Cavalier power rack has a total of 6" of travel which allows the use of stock steering arms with a minimum of lost turning radius.

Below is a pic of a conversion I recently finished on my '50 Olds, the rack is only 2.5 turns lock-to-lock so I takes a little getting used to.

[Mike DC]

            

So front steer should have shorter arms, I'll check tomorrow.

Well, the front steer setups don't inherently demand shorter arms than rear-steer setups.  Not if they're both using the same kind of steering gearbox/rack.  If you look at an 2nd-gen Camaro from the 1970s, they have the steering box (old school recirculating-ball type) in front of the axle but the same sort of big spindle arms and pitman/idler arms that you would find on a rear-steer Charger from the era.



I think the factory went to shorter spindle arms along with the R/P setups because the front-steer deal didn't always put as much force on the linkage compared to the rear-steer deals.  (The outside wheel in a turn is being pulled by a front-steer setup as opposed to being pushed by a rear-steer.)  

Try to push the critical outside wheel the way a rear-steer setup does, and your steering linkage has to be pretty stiff to keep from bending instead of remaining straight enough and shoving the wheels.    But if the outside wheel is being pulled instead of pushed, then a linkage that will see its highest stress in tension rather than compression can be a bit less sturdy.  

And the longer the spindle/idler/pitman arms, the less severely that any bushing flex (at the control arms) is going to over-steer the front wheels.  But if you go front-steer and let the spindle/idler/pitman arms get shorter, the bushing-flex-steer will still happen, but it will be happening in an under-steering fashion which is less objectionable.

And when the spindle arms can be shorter, then the R/P itself doesn't need to move as far side-to-side just to pivot the front wheels a given distance from lock to lock.  Which means the R/P can be more compact.  Not to mention allowinwing the lighter/smaller linkage.  This is all stuff that the factories like these days.      

[John_Kunkel]

The main problem with trying to retrofit a front-mounted rack is the Ackerman, in order to keep the correct Ackerman angles the intersection of the steering arm and tie rod needs to be inside the tire.

[frederick]

Well, the front steer setups don't inherently demand shorter arms than rear-steer setups.

Seems that you are correct, the arms come right up to the rims, which are 15".
The arms swing sideways quite a bit when on full lock, which might be difficult to reach with a R/P while keeping the inner joints at the correct place.(no bumpsteer)

I tried putting the front suspension in Solid Works to see if a conversion is a good option, but I am having difficulty in measuring the suspension points accurately in three dimensions.
Have you got some tips for this?

I found some pics of the suspension, to give you an idea of the setup.

The main problem with trying to retrofit a front-mounted rack is the Ackerman, in order to keep the correct Ackerman angles the intersection of the steering arm and tie rod needs to be inside the tire.

I thought the advantage of front steer was the reverse Ackerman steering.
The outside tire then turns more than the inside tyre.
Greater stability/traction at high speed, but tyres scrub at low speed.

Frederick

[Rolling_Thunder]

OH GOD!!!   I was working on a Facel Vega at the old shop -  what a PITA!!!   

[frederick]

Took the words right out of my mouth.

Everything you do ends up taking 4 times as long as on another car.

Maybe I should just get a charger.