Just stating I got the first feel of a 500 box in s 56 wagon today. I run one one in my A-body the tri five felt the same very tight and percise very happy to verify!!!
Just stating I got the first feel of a 500 box in s 56 wagon today. I run one one in my A-body the tri five felt the same very tight and percise very happy to verify!!!
A "very tight box" is a good thing.
How many turns are those things lock to lock?
Last edited by chevynut; 03-31-2016 at 07:36 PM.
56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension
Other vehicles:
56 Chevy 2-door BelAir sedan
56 Chevy 210 4-door sedan
57 Chevy 210 4-door sedan
1962 327/340HP Corvette
1961 Willys CJ3B Jeep
2001 Porsche Boxster S
2003 Chevy Silverado 2500 HD Duramax
2019 GMC Sierra Denali Duramax
Just found it....14:1 ratio and 3 1/2 turns lock to lock.
My C4 rack is a 13:1 ratio and 1.96 turns lock to lock. It's the Z51 sport version, and the standard rack is 2.32 turns lock to lock, 15.7:1 ratio. Hope it's not too quick.
56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension
Other vehicles:
56 Chevy 2-door BelAir sedan
56 Chevy 210 4-door sedan
57 Chevy 210 4-door sedan
1962 327/340HP Corvette
1961 Willys CJ3B Jeep
2001 Porsche Boxster S
2003 Chevy Silverado 2500 HD Duramax
2019 GMC Sierra Denali Duramax
That will be great on a road course, but the standard c4 steering drives me nuts on a straight road.
Well I hope it isn't as bad in a longer wheelbase car, but I have been concerned about it. Especially after spending all the time polishing and painting a rebuilt one. When I bought it years ago I didn't even know there were 2 kinds of racks. To change it is going to be a real pain in my car. I had intended to do a k-member modification to make it easier to change, but I forgot to do it before I got the frame painted.Originally Posted by LEE T
But the interesting thing is the ratios. The CPP rack is 14:1 and the standard C4 rack is 15.7:1. My rack is 13:1. I assume that's the ratio between the angle of the steering wheel and the angle of the tires, including steering arms, for a rack. I always thought for a box the ratio was the angle of the steering wheel to the angle of the output shaft/pitman arm, not including the steering arms. So how do you compare a rack to a box?
Last edited by chevynut; 04-01-2016 at 07:00 AM.
56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension
Other vehicles:
56 Chevy 2-door BelAir sedan
56 Chevy 210 4-door sedan
57 Chevy 210 4-door sedan
1962 327/340HP Corvette
1961 Willys CJ3B Jeep
2001 Porsche Boxster S
2003 Chevy Silverado 2500 HD Duramax
2019 GMC Sierra Denali Duramax
"Steering ratio refers to the ratio between the turn of the steering wheel (in degrees) or handlebars and the turn of the wheels (in degrees).[1] The steering ratio is the ratio of the number of degrees of turn of the steering wheel to the number of degrees the wheel(s) turn as a result. In motorcycles and bicycles, the steering ratio is always 1:1, because the steering wheel is fixed to the front wheel. A steering ratio of x:y means that a turn of the steering wheel x degree(s) causes the wheel(s) to turn y degree(s). In most passenger cars, the ratio is between 12:1 and 20:1. For example, if one complete turn of the steering wheel, 360 degrees, causes the wheels to turn 24 degrees, the ratio is then 360:24 = 15:1."
So my Z51 rack ratio is a little faster than a CPP500 box, and the standard "base" C4 rack is a little slower. The fact that the lock to lock is less turns means it just reaches the lock quicker. The CPP box is a lot faster than the stock box.
Let's compare....
A stock steering box is 25.7:1 ratio and 5.34 turns lock to lock. So it turns 1922.4 degrees lock to lock or 961.2 degrees center to lock. At 25.7:1 ratio the wheels turn 37.4 degrees based if there's no stop.The stops on the a-arms stop the wheels at around 32-35.5 degrees per GM specs.
For the CPP box at 14:1 and 3.5 turns lock to lock, the steering wheel turns 1260 degrees total. Half of that is 630 degrees center to lock. At 14:1 ratio the wheels would turn 45 degrees if they didn't hit the stop first...but they do. So the effective lock to lock is a lot less than advertised since the stops are contacted.
For the base C4 rack the steering wheel turns 835 degrees lock to lock or 417.6 center to lock. with a 15.7:1 ratio the wheels turn 26.6 degrees.
For the Z51 rack the steering wheel turns 705.6 degrees lock to lock or 352.8 degrees center to lock. At 13:1 ratio the wheels turn 27.14 degrees.
So as I always knew, the C4 rack limits the steering angle. I don't know how significant 5-8 degrees is in the real world. This makes me feel better about my rack since it's not that much different than the CPP500
Last edited by chevynut; 04-01-2016 at 07:49 AM.
56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension
Other vehicles:
56 Chevy 2-door BelAir sedan
56 Chevy 210 4-door sedan
57 Chevy 210 4-door sedan
1962 327/340HP Corvette
1961 Willys CJ3B Jeep
2001 Porsche Boxster S
2003 Chevy Silverado 2500 HD Duramax
2019 GMC Sierra Denali Duramax
To compare a rack to a box, you have to either calculate the overall ratio which includes the length of the pitman arm on the box and the length of steering arms on both - or if you want to eliminate the steering arms' effect, do a similar analysis comparing the rack travel to the horizontal travel of the pitman arm.
As an example, usually if you use a rack with the stock suspension/steering, you'll need shorter steering arms to get full travel. Most rack kits either include these or recommend them. This is because most racks have less travel than the horizontal travel of the pitman arm.
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