Saginaw pump workable with Bendix box?
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
The Thompson pump used in both applications are the same. When I swapped my Bendix box out for a Saginaw/Ford box I left the original pump in place, and it's working just fine.
Did you bleed the air out of the system by repeatedly turning the wheel from lock to lock with the engine running?
Did you bleed the air out of the system by repeatedly turning the wheel from lock to lock with the engine running?
Last edited by TigerDan; Nov 9, 2007 at 08:26 AM.
Posting Guru
Joined: Jul 2003
Posts: 2,222
Likes: 1
From: East Central Florida
AHhh. . . ERrrr. . ?
I don't want to be a wet blanket, but I must respectfully disagree with Tger Dan on his above comment.
I would say you may have already damaged your Saginaw Style Steering Gear Box form over pressuring it. Although the systems can be combined in mismatch, and may function some, they are not working as they were built to. Longevity may suffer as a result.
Bendix pumps are not slipper type pumps like Saginaws are. The higher Engine RPM gets, the greater Output Pressure is with Bendix pumps. Bendix Steering gear boxes are built & sealed to tolerate that high PSI Operation. Saginaw (Ford) Steering gear boxes, or systems are not.
Saginaw Boxes operate better at lower line Pressures from using the Slipper Type Pumps. PSI Fades as RPM climbs, producing all important "Road Feel" that makes Saginaw type P/S the superior system all around for best steering performance capability.
With A Bendix set up at highway speed steering gets Light, Oversensitive, & Touchy, resulting in the "Tip Toe Dancing" effect. The last thing you want to do with a Bendix set up is power off a turn, or out of curve, at road speeds, especially if your engine makes horsepressure. . . . It could be suicidal when there is an error, or when one is not ready for it.
Last point, it is a Power Steering SYSTEM meaning it was engineered & designed with "system matched" parts & components to achieve a specific, upgraded, goal or state of operation. Although the Bendix pump will drive the saginaw box, it is overpressurizing it, and there is no relief valve because Saginaw pumps seldom, if ever, over-pressureize a system. Eventually the mismatch will cause the Saginaw box to leak or fail with use & overtime.
I will add however, the Bendix Pumps make pretty good Hydraulic Pumps if you need Hydraulic capability & lack a PTO, like when you hav a A/T, & want to lift or angle a Snow Plow, or operate a dump body or a roll back carrier and so forth. . . .
FBp
I don't want to be a wet blanket, but I must respectfully disagree with Tger Dan on his above comment.
I would say you may have already damaged your Saginaw Style Steering Gear Box form over pressuring it. Although the systems can be combined in mismatch, and may function some, they are not working as they were built to. Longevity may suffer as a result.
Bendix pumps are not slipper type pumps like Saginaws are. The higher Engine RPM gets, the greater Output Pressure is with Bendix pumps. Bendix Steering gear boxes are built & sealed to tolerate that high PSI Operation. Saginaw (Ford) Steering gear boxes, or systems are not.
Saginaw Boxes operate better at lower line Pressures from using the Slipper Type Pumps. PSI Fades as RPM climbs, producing all important "Road Feel" that makes Saginaw type P/S the superior system all around for best steering performance capability.
With A Bendix set up at highway speed steering gets Light, Oversensitive, & Touchy, resulting in the "Tip Toe Dancing" effect. The last thing you want to do with a Bendix set up is power off a turn, or out of curve, at road speeds, especially if your engine makes horsepressure. . . . It could be suicidal when there is an error, or when one is not ready for it.
Last point, it is a Power Steering SYSTEM meaning it was engineered & designed with "system matched" parts & components to achieve a specific, upgraded, goal or state of operation. Although the Bendix pump will drive the saginaw box, it is overpressurizing it, and there is no relief valve because Saginaw pumps seldom, if ever, over-pressureize a system. Eventually the mismatch will cause the Saginaw box to leak or fail with use & overtime.
I will add however, the Bendix Pumps make pretty good Hydraulic Pumps if you need Hydraulic capability & lack a PTO, like when you hav a A/T, & want to lift or angle a Snow Plow, or operate a dump body or a roll back carrier and so forth. . . .
FBp
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
Thanks for the clarification , Pete. I was fairly sure there was no difference in the pumps, but I checked another source this morning before posting the above and the info I got was that there was indeed no difference...guess I need a better source! I should have just waited till you responded...!
So I should plan on changing out my pump soon, eh...?
So I should plan on changing out my pump soon, eh...?
Posting Guru
Joined: Jul 2003
Posts: 2,222
Likes: 1
From: East Central Florida
Dan,
Not necessarily if you don't push it too hard, or run around at higher RPM all the time but it will handle better if you do, as there will be more feel at road speed. I believe FoMoCo called it "Part Time Power Strg." I agree they are dimensionally the same but they have diferent functions, meaning they bolt up & pump fluid. But at diferent rates at different times. . . .
In fact the Higher PSI output of the Bendix system was what prompted FoMoCo to opt for the Slipper style system and lower Operating PSI's.
That was in late 1968 for the 69 production run. . .
FBp
Not necessarily if you don't push it too hard, or run around at higher RPM all the time but it will handle better if you do, as there will be more feel at road speed. I believe FoMoCo called it "Part Time Power Strg." I agree they are dimensionally the same but they have diferent functions, meaning they bolt up & pump fluid. But at diferent rates at different times. . . .
In fact the Higher PSI output of the Bendix system was what prompted FoMoCo to opt for the Slipper style system and lower Operating PSI's.
That was in late 1968 for the 69 production run. . .
FBp
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Post Fiend
Joined: Dec 2003
Posts: 6,658
Likes: 4
From: "Islander"
Something stinks here.
I have a early 68 CS that has a Thompson pump and had a Bendix box.
My collection of donors is two 70 CS's a 71 CS and two 72 CS's with pumps and boxes, last two from Pick-N-Pulls.
All six trucks had a Thompson pump, all six pumps were taken apart and were the same inside including the pressure by-pass plunger as well the pressure relief spring. Measured and tested on a spring tester. Not one difference in in internal parts as well output operating pressures and the maximum when the pressure relief valve opened.
On boxes one Bendix from the 68 the other 5 boxes all Saginaws.
If there was a problem like you posted this is news to me besides zero box leak problems the last 240K miles. A few other Bumpside friends that converted from Bendix to Saginaw are on their original Thompson pump without your stated leaking problem. When should we all start leaking as a few of us run many times over 5,000 rpm's for long distances on the highway
playing around in the top end zone?
I have a early 68 CS that has a Thompson pump and had a Bendix box.
My collection of donors is two 70 CS's a 71 CS and two 72 CS's with pumps and boxes, last two from Pick-N-Pulls.
All six trucks had a Thompson pump, all six pumps were taken apart and were the same inside including the pressure by-pass plunger as well the pressure relief spring. Measured and tested on a spring tester. Not one difference in in internal parts as well output operating pressures and the maximum when the pressure relief valve opened.
On boxes one Bendix from the 68 the other 5 boxes all Saginaws.
If there was a problem like you posted this is news to me besides zero box leak problems the last 240K miles. A few other Bumpside friends that converted from Bendix to Saginaw are on their original Thompson pump without your stated leaking problem. When should we all start leaking as a few of us run many times over 5,000 rpm's for long distances on the highway
playing around in the top end zone?
Last edited by "Beemer Nut"; Nov 10, 2007 at 08:57 PM.
