From another donor car? I have a 70 Chevelle and the steering is way too mushy feeling. No feedback what so ever. How about a Z28 box? What years will bolt on?

Thx.

LK

Yes there is. My 68 has a 79 Z28 box and it is 2 and 3/4 turns lock to lock. There also aftermarket/restored boxes that do the same thing. Might try a search in the suspension forum.

I'd do a search in "Brakes and Suspension" area. You should see lots of posts about steering box ideas.
-Bill

80's GM Gbody cars have the fast ratio, and also the 93-98 Jeep Grand Cherokee box is fast ratio as well, and a drop in replacement.

aaron

ACE841 - Is that Z box a bolt in? Is the pitman arm the same? How about the splines for the steering? Hose ends? What year did they go metric?

Thx.

LK

You want a steering gear box that has close to the same pitman shaft travel as your original gear box. This will enable your car to make the same turning circle as original. Your original 1970 gear has a pitman shaft travel of 81 degrees.

Most Z28 gears have pitman shaft travel of 71 degrees or less. This will cause your turning circle to become quite large.

The following websight has a paper on installing a fast ratio steering gear into a Chevelle like yours.

www.corvettefaq.com/A-car.asp (http://www.corvettefaq.com/A-car.asp)

The very first paper addresses your gear swap. Following there are several excel spreadsheets that list various fast ratio gears that can easily interchange into your A-car.

wow, that's a great site. lot's of good info. thanks for posting it. is there a section that explains what the numbers in the spreadsheets mean? sort of hard to figure what he means by "effort" and "degrees".

Tom

sort of hard to figure what he means by "effort" ans "degrees"Do you mean effort and "Travel"?

The effort is the steering wheel input effort required... Notice that the larger T-bars cause a higher effort... That means it takes more driver input force...

The "Travel", listed in Degrees/Minutes ("minutes are 1/60th of a degree) is the output shaft turning range from center to full-lock (multiply the Travel by 2 to get the full range the output shaft will turn... If you check the "stock" Chevelle travel values, you can see they are higher than many of the F-body Quick Ratio boxes...

Because of the differing "Travel" values and the different ratios, a simple "X.X Turns, Lock-to-Lock" value can't really determine if the box is really a "Quick Ratio", 12.7:1... For example, as Jim mentioned in his post, the Z box with only 71-degrees of travel will reach its "Lock-to-Lock" much sooner than a Caprice/Chevelle/Grand Cherokee box... Therefore is the box really a quick ratio, or just has limited travel?

ACE841 - Is that Z box a bolt in? Is the pitman arm the same? How about the splines for the steering? Hose ends?If you want the easiest bolt-in, and a clean, "New" box, then try the AGR boxes...

They have boxes that have had the quick-ratio parts installed into the older box, so the original hoses fit, without the Lee adapters, and they also use the early input shaft on certain models... They use mostly new parts, except the box itself...

They cost about $275 and up, but a greta way to go for someone not wanting to pull a used box, do the parts hunting and cleanup (and rebuilding if needed)...

Just an option...

My 68 has a 79 Z28 box and it is 2 and 3/4 turns lock to lock. AlWhite, and Jeff

Jeff's box is not the 12.7:1 quick ratio...

First, using JimL82's infor for the 1979 Camaro, listed below. Note the 1979 Z is listed as having a 14:1 ratio (not 12.7):


1979
CC F Perf V8 16-13:1 17-22 0.185 Dia 33deg 30min

CB F 16-13:1 14-20 0.175 Dia 33deg 30min

CD F-Z28 14:1 17-22 0.185 Dia 33deg 30minAlso if we do a little calculation...
the 79Z has a Travel of 33deg/30 minutes (33.5 degrees) 33.5 X 2 = 67 degrees total

67 X 12.7 = 850.9 (degrees of travel for the input on the 79Z box)

850.9 / 360 = 2.36 turns L-to-L, IF it was the 12.7 ratio...

67 X 14 (listed 79 Z ratio) = 938

938 / 360 = 2.60 turns, Lock-to-Lock (closer to Jeffs 2.75 turns)...

This illustrates why the Lock-to-Lock count doesn't work for determining the ratio...

The 79 Z is quicker than a stock Chevelle, but not the quickest...

Sorry Jeff, didn't mean to give you a bad time, just trying to help other's avoid the same mistakes I have made ( I had a 79 TransAm box in mine until 2 years ago... I always thought it was the quick ratio until I installed the 12.7:1 AGR box... Wow...

I had sort of figured the effort deal, but it's backwards from the way I thought it worked.

On the Travel deal, the numbers, even doubled were so so far off from what Jim posted above (81*) that I thought I must be not understanding. I guess there's really no getting around changing out the chevelle internal stops in the box. It's just such a PITA working on the boxes when a guy only does one every few years....

Sometimes the fast boxes aren't all that great, I have a 57 BBW/SSS pickup with a Camaro front stub. It has a genuine WS-6 TA box (barely two turns L-to-L) and it's really twitchy on the freeway. Cough and you've just changed lanes, stuff like that.

Tom

Thanks for all of the input guys. Can anyone simplify this and tell me what car woud be a bolt in with a faster ratio and the same (or close) degree of swing.

LK

As mentioned above, 93-98 Jeep GRAND Cherokee, readily available & reasonably priced at the wrecking yard. You WILL need the Lee adapters & different rag joint. Total cost of these from Lee is about $65.00 as I recall.

Originally posted by JIML82:
...This will cause your turning circle to become quite large... THAT is what the posi is for (or the e-brake depending on your speed) ;)

I've read about people using the ZQ8 (right? I know the ZQ is right) box from a mid 90s - 2k's F body cars. Might look into that.

These are descriptions of the various catagories on the excel spreadsheets that list power steering gears that are posted at www.corvettefaq.com/A-car.asp (http://www.corvettefaq.com/A-car.asp)

I will be adding the descriptions to the actual spreadsheets shortly. Please note that the Tech Area of the Chevelle forum has not been updated for several years. So I cannot update the spreadsheets on that sight. The latest papers and information will always be at the above sight.

Jim

Alpha Code – A two letter code affixed to the gear to help the assembly plant install the correct steering gear onto a vehicle chassis. The code can either be ink stamped or a paper sticker. The alpha code can be located on the aluminum end cover, the aluminum side cover, or both locations.

Gear Ratio - The number of degrees that the input shaft turns for the output (pitman) shaft to rotate one degree. Low numbers (i.e. 12.7:1) are fast ratio. Two numbers are variable ratio (i.e. 16-13:1) the first number being the on-center ratio.

Valve Effort - The torque in inch-lbs that has to be applied to the input shaft to create a fixed amount of assist pressure. Low numbers (i.e. 12-17) are very light effort.

T-Bar Size - The diameter of the control valve torsion bar in inches. The larger the bar the higher the effort required to steer the car.

Travel - The number of degrees from the gear being centered to full lock. The number generally has to be doubled to determine full travel. Note, there are a few gears with unequal travel from center to right full lock versus left full lock. (Don’t ask me why some Chevelle steering systems weren't symetrical!)

jim,

you have email at the aol adress in your profile here.

Thanks, Tom