When talking steering ratios, I usually hear how many turns lock to lock. On my 70 Duster going from a stock OE suspension and 215/65/15 tires to 245/45/17 tires with some "trick" suspension parts it was so so hard turning at lower speeds, I seriously considered going to a Borgeson power steering setup. Fast forward to my new wheel/ tire setup 255/40/18, the manual steering has loosened up so much that parking lot and low speed turning is manageable compared to what it once was. Steering at speed is not quite 2013 Challenger caliber, but way better than my 72 and 74 power steering A body cars, which need my undivided attention a when driving. At this point I'm considering leaving it as is. What is the upside going to 20:1 ratio which brings me back to perhaps my 17" tire era.
Manual steering ratios
- Thread starter Mojoe9955
- Start date
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cudamark
Well-Known Member
It would help to know which ratio you have now if you want a comparison. Basically, 16:1 boxes need less turns lock to lock, but, it takes a lot more effort. They give great road feel and quicker steering. 24:1 is easier to turn, but, less road feel and way more understeer. 20:1 is somewhere in the middle.
70SwingerGuy
Long Haired Freaky Person
Stupid question, but is there a way to tell which one a person has?
The stock 24:1 ratio means the steering wheel should turn about 5 1/2 turns lock to lock, the fast ratio boxes at 16:1 are close to 3 1/2. The aftermarket 20:1 boxes should be about 4 1/2 turns lock to lock.
You need the wheels in the air to check it, you don't want to be dry steering it through a full lock to lock cycle.
What else did you change when you went from 245/45/17's to 255/40/18's? Because between those two tire sizes there really shouldn't be much of a change in steering effort, all things being equal.
You need the wheels in the air to check it, you don't want to be dry steering it through a full lock to lock cycle.
What else did you change when you went from 245/45/17's to 255/40/18's? Because between those two tire sizes there really shouldn't be much of a change in steering effort, all things being equal.
Unless I'm mistaken, the stock power boxes are close to or right on 16:1, right?
Vaanth
Well-Known Member
Practically 16:1 ratio, right.
The specified ratio for the Chrysler power steering gear from 1962-1989 (-1993 for B-series vans) as installed is 15.7:1, or 3.5 turns lock to lock. The Trans Am cars equipped with the fast ratio pitman arm, and some later E-bodies equipped the same, are effectively 12:1 ratio, or 2.75 turns lock to lock. The "TA" steering gear itself's internal turn ratio is the same as the standard steering gear. Adding the fast ratio pitman arm changes its effective ratio.
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"Understeer" has nothing to do with the steering box ratio.
It has everything to do with how the car maintains a line in a turn.
Yes, but if you do it that way there’s pretty much nothing for headers you can run unless you’ve got a 440 with Schumacher tri-Y’s, and even the down pipe for manifolds isn’t easy if I recall correctly. Oil pans can be an issue too.
And unless you’re putting them on a 16:1 box you end up with a steering ratio you could just accomplish with the steering box itself. And for the price of the fast ratio pitman and idler you can pretty much buy a reproduction manual steering box.
Could it be a change in scrub radius?
He didn't say anything about wheel width and back space.
For instance 18x8 with 5.5 B.S.
VS.
17x7 with 4.0 B.S.
I suppose? If it was a significant change that certainly could make a difference. At least theoretically anyway. I would think it would have to be a pretty darn big change though for it to make a noticeable difference in effort.
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