Tale of Two Gearboxes - Same Lock to Lock Turns
 

A common misconception - you can purchase a small lock to lock turn-count gearbox, labeled "fast-ratio", and you'll have responsive steering.  

The table below identifies two gearboxes with the same lock to lock numbers to illustrate the issue. Gearbox number 1 is a true fast ratio gearbox with a small lock to lock number. Gearbox number 2 is a slow ratio gearbox with large internal stops, (the stops are creating the small lock to lock number.)  Not all gearboxes use internal stops, but many do. If they aren't appropriate for your vehicle, they will increase your turning radius.  

 
Turns table.JPG
 

Gearbox no. 2 will have unresponsive steering and require a larger turning radius when parking or making a u-turn. It will lead to disappointment. Make sure you understand the details when purchasing a fast ratio gearbox, lock to lock numbers alone don't tell the full story.  

 
Marty Preuss
Pump Pressures & Flows

Chris, our customer, is an Assistant Professor and Automotive Department Head at a Pennsylvania technical college. We rebuilt the pump and gearbox for his 1973 Buick Century Regal. He posted a video of his checks of the power steering system after the rebuild. You'll see some typical pump pressures and flows in this video. 

Marty Preuss
Can the power steering on my Ford be upgraded to a fast ratio?
 

Some Fords, from 1965 to 1979 (Mustangs from 1971 to 1973) used Saginaw gearboxes, but not all of them. Those with Saginaw power steering gearboxes can be upgraded to the 12.7:1 ratio.

It's easy to tell if you have a Saginaw box in your Ford. Saginaw's have 4 hold-down bolts on the adjustment cover, the Fords have 2 bolts on that cover. If you've got the 4 bolt cover, your gearbox can be upgraded to the 12.7:1 ratio. (click the image to see full size)

 

Saginaw Gearbox - with 4 bolt cover


 
 

Ford Gearbox - with 2 bolt adjustment cover

 

Marty Preuss
Why is there a yellow sticker on my gearbox? (Extreme Detailing)

The yellow sticker - after an extreme detailing rebuild

Between 1968 and 1972, Saginaw gearboxes left the factory with a yellow sticker. We reproduce this original factory condition when we perform extreme detailing on a gearbox for vehicles in that range of years.

How the yellow sticker might appear - prior to rebuilding

 

Marty Preuss
Measuring your Saginaw 800 Gearbox - 3" or 3.25" box?
 
 3" Gearbox measurement

3" Gearbox measurement

Customers often end up with a gearbox - but they are unsure of the vehicle it came from.  Then, they want to know "can it be upgraded to a fast ratio?" One way to answer that question is to know what size gearbox it is.  

Saginaw 800s come in two sizes; 3" and 3.25". When talking about 1960s through 1980s GM automobile boxes, most early B-bodies (full size GM cars) came with the 3.25" box, later models went with the 3". A-body and F-bodies came with the 3" gearbox. The 3" can be upgraded to the 12.7:1 fast ratio, the 3.25" cannot. (The 3" box can be a drop-in replacement for the 3.25". That's how full sizes vehicles are upgraded to 12.7:1.) 

To check your gearbox size, measure the round aluminum endcap (which faces the front of the car) as shown. 

 3.25" gearbox measurement

3.25" gearbox measurement

There are other ways to tell what gearbox you have, but sometimes you still need to know the size. Other ways to identify your gearbox will be covered in a future post.

 


Marty Preuss
Rag Joint Pinch Bolts

A common mistake with rag joints (flexible couplings) is to think that loosening its "pinch" bolt is all that's required to remove the rag joint from the steering gearbox. Loosening the bolt is not enough, the bolt must be removed from the rag joint for it to slip off the input shaft. The same goes for installation - insert the bolt after the rag joint is positioned on the shaft.

1977 and up had a bolt head with 6 points, prior to 1977 they were 12 point bolts, so you'll need a 12 point socket for these. 

 
 
 Rag Joint and Pinch Bolt

Rag Joint and Pinch Bolt

 Pinch bolt installed on rag joint

Pinch bolt installed on rag joint

 

Marty Preuss
Is my steering gearbox on center?

Centered Gearbox

PowerSteering.com's practice is to ship gearboxes on center. And as the heart of your steering system, its center position is important during installation. However its not difficult to tell if a gearbox is on center. The majority of steering gearbox brands, power & manual, have gaps in the pitman shaft splines that tell you if it's at center; the input shaft provides a clue too.

Most pitman shafts are indexed with 4 large spline gaps. When the spline gaps line up with the axis of the steering box, its on center. If they aren't lined up, it's not on center.

Furthermore, when at center the flat on the input shaft will be at top-dead-center. If there is a rag joint attached, the rag joint's pinch bolt will be at top-dead-center. See photos for examples. The input shaft alone doesn't tell you if you're at center, i.e. if its a 4 turn lock-to-lock gearbox it will be at top-dead-center in 4 places. (These conditions do not all apply to reverse rotation or 4 x 4 GM gearboxes.) 

 
 

Uncentered Gearbox

If you have a rag joint (flexible coupling) on your input shaft, the pinch bolt is at top-dead-center when the gearbox is at center, as seen below. 

 

Marty Preuss