JeepFreak21
NAXJA Forum User
- Location
- Cameron Park, CA
OK, the more I research this, the more confused I get! I decided that I don't want to choose a gear and/or pump without having a better understanding of the variables. So, let's get more in-depth than "I'm running a ZJ box w/ 35's and it turns great".
As I understand it, there are two main Saginaw boxes for us to consider. The 800 model (like the stock one) and the 808 model (like are found in Durangos and J20s). The model number refers to the "case", but also determines the piston/bore size. Either case can have a variety of different line thread sizes, ratios, speeds (lock to lock), and mounting bolt patterns. These options seem to vary by vehicle year/make/model and are not easily identified by any casting numbers on the box.
So... let's determine the stock XJ specs (correct me if I'm wrong!)...
Saginaw 800
3 Mounting Bolts
(Variable??) Ratio of 14.1:1 or higher?
3 3/8 - 3 1/2 turns lock-to-lock
2.75" Piston Bore?
Line Thread Size: M18x1.5 (return); M16x1.5 (pressure)
Type of Hose Ports:Tube O-Ring
Input Shaft Diameter: 3/4"
Output Shaft Diameter: 1.25"
Now... let's talk about the room for improvement...
A larger piston bore will result in more power, but will also require more fluid. From what I've read, the 808 box has a 3.175" bore, which seems to work just fine with the stock XJ power steering pump, but if a hydro assist ram is added and the stock XJ power steering pump is used, the system will be slow to react. Since a larger bore would no longer be needed with a hydro assist ram, it is usually recommended that the 800 box be used for hydro assist.
Now, I haven't been able to confirm whether the XJ box is a variable or fixed ratio. From what I understand, a variable ratio makes the wheel easier to turn when the steering gets closer to full lock, correct? And this could be identified by the worm gear and it's consistency from end to end? Can anybody confirm whether the XJ box is or isn't a variable ratio? Which would be preferred (for street use, rock crawling, pre-running, etc)?
So... the ratio represents the ease and speed of which the jeep would turn when the driver turns the steering wheel? A 12:1 ratio would be faster than a 16:1 ratio, but the 16:1 ratio would have more torque? And torque is going to effect road feel as well? Again, what would be more desirable (for street use, rock crawling, pre-running, etc)?
Is the ratio (above) also a direct correlation to the number of turns lock-to-lock? Some people seem to have the desire to decrease the number of turns lock-to-lock, but searching on another forum, there was a lot of concern about doing this on a vehicle with a higher-than-normal center of gravity (and especially with a short wheelbase). Can we hear some arguments on that?
OK, that's probably a good start. I'll get into replacement options and PS pumps later (likely in addition to a bunch more questions).
Billy
As I understand it, there are two main Saginaw boxes for us to consider. The 800 model (like the stock one) and the 808 model (like are found in Durangos and J20s). The model number refers to the "case", but also determines the piston/bore size. Either case can have a variety of different line thread sizes, ratios, speeds (lock to lock), and mounting bolt patterns. These options seem to vary by vehicle year/make/model and are not easily identified by any casting numbers on the box.
So... let's determine the stock XJ specs (correct me if I'm wrong!)...
Saginaw 800
3 Mounting Bolts
(Variable??) Ratio of 14.1:1 or higher?
3 3/8 - 3 1/2 turns lock-to-lock
2.75" Piston Bore?
Line Thread Size: M18x1.5 (return); M16x1.5 (pressure)
Type of Hose Ports:Tube O-Ring
Input Shaft Diameter: 3/4"
Output Shaft Diameter: 1.25"
Now... let's talk about the room for improvement...
A larger piston bore will result in more power, but will also require more fluid. From what I've read, the 808 box has a 3.175" bore, which seems to work just fine with the stock XJ power steering pump, but if a hydro assist ram is added and the stock XJ power steering pump is used, the system will be slow to react. Since a larger bore would no longer be needed with a hydro assist ram, it is usually recommended that the 800 box be used for hydro assist.
Now, I haven't been able to confirm whether the XJ box is a variable or fixed ratio. From what I understand, a variable ratio makes the wheel easier to turn when the steering gets closer to full lock, correct? And this could be identified by the worm gear and it's consistency from end to end? Can anybody confirm whether the XJ box is or isn't a variable ratio? Which would be preferred (for street use, rock crawling, pre-running, etc)?
So... the ratio represents the ease and speed of which the jeep would turn when the driver turns the steering wheel? A 12:1 ratio would be faster than a 16:1 ratio, but the 16:1 ratio would have more torque? And torque is going to effect road feel as well? Again, what would be more desirable (for street use, rock crawling, pre-running, etc)?
Is the ratio (above) also a direct correlation to the number of turns lock-to-lock? Some people seem to have the desire to decrease the number of turns lock-to-lock, but searching on another forum, there was a lot of concern about doing this on a vehicle with a higher-than-normal center of gravity (and especially with a short wheelbase). Can we hear some arguments on that?
OK, that's probably a good start. I'll get into replacement options and PS pumps later (likely in addition to a bunch more questions).
Billy