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Steering ratios

When changing to a faster ratio, you have to think about turning the tires with a loss of assist.

I think the first things are a good frame brace by the steering box, a well-adjusted box and swapping out the rag joint for the U-joints. You also need a real tight front spring bushing bolt on the DS to reduce slop. Then maybe look into changing the ratio.
 
Blue85 said:
When changing to a faster ratio, you have to think about turning the tires with a loss of assist.
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My understanding of power steering is pretty limited, but it doesn't seem like the amount of power assist should have to be tied to the amount of mechanical advantage provided by the gearing. Are you sure that's the case?
 
The gear ratio is set by the thread pitch of the worm and also the tooth counts on the piston and pitman shaft. I believe the "variable" part is in the teeth. They are also cut to be slightly "tighter" on center. The power assist is acting on the piston, so it still passes through the teeth, so changing that ratio affects the leverage the power assist has. The "amount" of assist is most directly tied to the torsion bar, setting the amount of oil flow vs. driver input torque, but is also affected by line pressure.

So from an assist standpoint, you can probably make up for the quick ratio with just the pump output fitting mod. But when the assist goes away, it's just your arms and the gear ratio that puts force on the drag link. The quicker the ratio, the harder it will be to turn the wheels. Will having your tire against a rock make you run into that tree because you can't turn fast enough after stalling? I have no idea. I just wanted to mention that changing the ratio will have an effect.
 
A longer pitman arm or a shorter steering arm would also make the steering quicker. If you're going crossover, you could probably get a custom steering arm done for almost no additional cost. I don't know how short you could go without creating clearance or other problems, but I imagine it's been discussed here somewhere. If you had 2 holes 1.5" apart on a steering arm (let's say it's 8" from the kingpin), that would be like going from 17:1 to 14:1, so having multiple holes wouldn't allow much fine tuning - you'd need to know the right length upfront.

My guess is that somebody has tried this and hated it, or else it would catch on.
 
Good point about the impact of steering geometry. ORD had to make some design decisions when they designed the steering arms, so presumably they picked what felt best, to them at least. Then again, they may have specifically tried to make it mimic the original steering in terms of turns lock to lock.

It seems like I'm out on my own here a bit, and most people just keep the factory ratio. I don't need to be different, though I did drive a 12:1 truck and it felt pretty good.
 
Warning about reman boxes is that they generally are pretty sloppy. Unless yours is leaking or worn in some specific way, I'd keep it since the reman box probably won't be any better.
 
bp71k5 said:
Warning about reman boxes is that they generally are pretty sloppy. Unless yours is leaking or worn in some specific way, I'd keep it since the reman box probably won't be any better.
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I'll need a 2WD box for crossover. It seems worn to me, both from driving and it sure seems like I can turn the input a lot before the draglink moves. Benchworks seems like a good place to get a factory style box rebuilt properly - just based on their fast response and how knowledgeable the guy seems.
 
Mastiff said:
it sure seems like I can turn the input a lot before the draglink moves.
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The reman units from parts stores tend to have the same problem. I went through 3 of them and gave up. Maybe benchworks is better at it than the corporate shops...
 
bp71k5 said:
The reman units from parts stores tend to have the same problem. I went through 3 of them and gave up. Maybe benchworks is better at it than the corporate shops...
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That is why I suggested Benchworks. They were recommended to me by by a friend that used them when he lived in AZ. He had been to their shop and installed their parts when he worked as a tech for Freightliner. The one on my '70 works great. Plus Mastiff could go right to their door! Surely he has a reason to go to Phoenix?
 
I searched on PSC and AGR sites and indeed, 12:1 isn't available in our years (2WD or 4WD). Benchworks seems to know what they're talking about. I'll probably give them a shot. They aren't really much more expensive than an off the shelf box anyway.
 
I called Benchworks to order a steering box and the guy told me they could indeed put other ratios into these boxes. I'm a little confused by the mixed messages, but I went ahead and ordered a 14:1 instead of the factory ratio, which he called 18:1. I'm not totally confident, since the other guy said they were variable and maxed out at 17:1... I guess I'll wait and see what shows up.
 
AFAIK, if the box physically looks like our steering boxes, the parts are interchangeable. Which means that most RWD cars up until at least the 90's are potential donors. And since they had ratios such as 12:1, there is no reason that shouldn't be possible with the proper parts.

I've already played around with pump pressure and that alone won't fix the issue. I tend to believe the torsion bar is going to make a large difference. Just got a 2WD truck box to play with on the bench, I suspect I can get my hands on a "fast ratio" camaro box pretty easily.

I'd tend to agree with starting with the XJ shaft swap (assuming all other steering components are in good shape) and the steering box brace since those both eliminate known problems, but you are a bit beyond that already. I'm not sure if all non-braced trucks are like this, but on one of the trucks I deal with, if you look at the steering box while someone turns the wheel as the vehicle idles, you can clearly see the deflection in the frame from the forces working against it, and that is with ~33" tires, no lift.
 
This guy claimed they couldn't go all the way to 12:1. Something about large bore vs. small bore or something. 14:1 sounded like a good middle ground anyway.

I'm doing the whole deal. I already have the ORD brace, but I'm going with a Borgeson shaft and installing crossover. The D60 was just rebuilt, so everything will be fresh. Fingers crossed.
 
What about one of the steering doublers they have for dirt track guys? I don't know exactly how they work but I've seen them in speedway magazines, supposed to be 2x faster. like making a 12:1 box into a 6:1 box.
 
sweetk30 said:
why big $$$ borgeson shaft ?

just go jeep shaft . a LOT cheeper .
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Depends how much you value your time. Off ebay you'll pay $100 to 150 or so for a Jeep shaft. That's a lot of money for an unknown quality item that has to be melted and modded to fit, or whatever. Or I could go to the pick-n-pull and try to find the right year and pry it out in 110 degree heat, and hope it's not worn out.

To each his own. I figure I'm spending $750 or something on crossover and a rebuilt steering box, why cheap out for $80 on the shaft.
 
Sometimes I wish I'd done more research for future reference when I worked in the Saginaw Steering Gear plant. What I remember is that the gears ending in "0" were the smaller bore (700, 800) and the ones ending in "8" were large bore (708, 808). The quick ratios were mostly in the small bores and truck ratios in the large bores. Possibly, there was some crossover, but I have no idea what the applications were.

EDIT: Let me add some more information as I remember:
There is an "old" 600 gear (605?) from like the 1960s which looks a lot different than the 700s and 800s we're used to seeing. It does not have the 4-bolt sector shaft cover, for example:

steer08.jpg


Then there is a "new" 600 gear being used in trucks from like 2000+, sometimes called "Nascar". It has a separate housing piece on the input shaft that bolts to the main housing, so it's easy to spot:

product-large_image-3098.jpg


Mostly, the truck gears use the 4 mounting pads and the car gears use 3 mounting pads, but going way, way back, all of them had 4 pads (like 1960's maybe). Later on the castings just started deleting the 4th pad on car gears since they weren't being used. So for most of the stuff we will find in the junkyard, just use the familiar looking gear, make sure it has 4 mounting pads, compare the size of the end cover so you get the larger 80mm bore, check the input splines and make sure it rotates in the correct direction. You really don't want backwards steering, but a few applications did take them.

It might be worth researching the ratios offered in 708s and see if those guts could be swapped into an 808 housing to get the 4-bolt pattern.
 
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