Go for it better flow is more gooder right

 

This is something I have been trying to find out for go fast racing aplications. How to get more fluid through the box so that the ram assist ram takes on more of the work than the steering gear does. I would like to figure out how to make the box be passive and more for feedback, and the ram be almost full hydro in its role.

If any one has drilled those ports out to a larger size, I havnt yet found them to report on how it did or didnt work. Obviously if you can get more fluid through the steering gear it will take a pump to supply it. I think that part is covered by the aftermarket already.

 

Looking closer at this, can anyone explain why there is a spring loaded restriction on the pressure port in the box?

Looking at this photo:



The return port is the left port. It is a straight shot bored into the vane chamber of the box.

You can see there is a plate at the bottom of the pressure port on the right. When I push on it it opens and then closes when released. I can barely blow through this port. Makes you think that any internal mods will be a waste if fluid is so restricted when it enters the box itself. If I fill this port with water it sits and does not run in until the plate is pushed on.

 

Looking closer at this, can anyone explain why there is a spring loaded restriction on the pressure port in the box?

My guess is that it is a check valve so that hitting a curb doesn't send a pressure spike back to the pump... saves the pump from shock loads.

I think this is a great thing to look into. If a person could speed up hyd assist there would be less of a reason to go to full hydro. :grinpimp:

 

I actually did drill the ports out in the valve. Unfortunately I noticed no change in speed.

I was having your standard ram assist teething issues, a cavitating pump and lots of noise. My steering also felt slow. I tried a couple of different reservoir mounting spots, a new CB style pump from PSC and eventually what fixed the cavitation issue was a PSC resivior. Honestly now I don't really even notice the steering being slow.

In the middle of all that I tried drilling the passages in the valve out to see if I could get the flow up to reduce cavitation and increase speed. I believe I drilled the passages out to 3/32" and that should have doubled the flow. It just didn't seem to really have any effect on it.

I never did drill the passages through the box though, so those might be the current bottle neck and not the valve. On mine, that passage way winds up being on the edge of one of the seals. It wasn't as simple as chasing the passage way with a larger drill, I would have had to physicaly move it over.

I'd be interested to hear others that have tried this and what they thought of it. Keep in mind that valve is hardened and I couldn't get it drill with anything less than a carbide drill.

In addition, you can also turn the torsion bar in there down to get fluid to flow sooner and that should help with speed also.

Hope that helps in some way,
Kevo

 

On mine, that passage way winds up being on the edge of one of the seals. It wasn't as simple as chasing the passage way with a larger drill, I would have had to physicaly move it over.

I just noticed this. The port for right turn is definitely restricted where it receives fluid from the vane. However, enlarging will be tough because of the distance to the edges of the teflon o-rings that seal the passage. You could open it up, but just barely.



That hole is the biggest blockage, so likely not worth pursuing.

Interesting that PSC drills the ports in the rotary vane though, it is clearly shown in the pictures.

 

I was exploring how to make a Toyota box work better with a larger HA cylinder. Here is the thread. http://www.pirate4x4.com/forum/toyo...oyota-truck-4runner/1333986-toyota-steering-box-vs-ford-77-79-steering-box.html

 

Always a glutton for punishment...

I drilled the port feeding the lower chamber for right turn applications within the rotary housing. It is awfully close to where the teflon seal rides. I need to chase with emory paper and then I will run a hone lightly to give a fresh surface.

 

Yours looks to have been in a much better spot than mine. You can see my passageway and the dark spots from the seals in the one pic in that thread.

Are you going to also drill out the rest of the passage way to the front of the box? I believe its all the same size, so widening that one spot still leaves a bottleneck.

Kevo

 

You can see my passageway and the dark spots from the seals in the one pic in that thread.

Kevo

Interesting, mine is in a better spot. I am worried I may get a bit of pressure on the edge of the teflon and encourage the o-ring to "lift."

On my box the bore down the outer casting is looks to be a similar size to what I drilled. The opening into the lower cavity is larger. I think this is the best I can do beyond opening up the rotary valve to the 3/32.

Hole I drilled:



Bore down exterior casting for right hand turn:



Hole going into lower cavity where power piston is:



Another interesting note, look where PSC is taking pressure from for their right turn function for the ram:



Directly from the rotary vane housing. Rather than the casting down the side of the box. The only reason I could see them taking the trouble of doing this is the pressure drop from the rotary housing through the small hole (the one I drilled) into the exterior casting where we all tap the boxes.

 

I sort of looked into this some time back. I wanted to increase the size of the fittings feeding the ram thinking that might help. After reading the articles below I'm guessing that is only part of it and torsion bar and barrel valve modifictions would need to be done as well.

My original thought was moving the port for right hand turning out of that tiny vein thinking it was a restriction. I looked at where PSC put their port, had a buddy give me some rough measurements and tore into a box I had at home.

The black arrow is pointing to the hole that is the vein you normally hit on the lower of the two tap points. Well at least looking at the steering box and how it mounts on a Jeep frame. The hole you are talking about porting.

The red arrows are the seal lines and are where I need to drill between in order to tap where I'm pretty sure PSC ends up. The best I can measure is about 5/16" inside the seal marks, maybe 3/8". I'm guessing PSC drills the through hole smaller than that then brazes or welds a fitting in. I havent looked at one of their boxes up close, just online pics.

The yellow arrow is where the top port (left hand turn) is when you normally tap the box. It lands in the rough section of housing where no seals or parts ride.

The blue arrow is the supply/pressure hole from the steering pump.

Red circle is a slightly better pic of where the left hand turn port ends up. You could make this fitting pretty much any size, I had planned to move to 3/8" fittings instead of 1/4".

These are the top and bottom ports I am referring too, from Billavista's article on tapping the gear box. Top port is left turn, bottom is right.

Fluid flow diagram.

I'm just a dummy but my peabrain was thinking that if you could put a fitting where PSC does, which is probably going to take welding, it would end up being bigger than the vein you normally tap and the hole you are trying to port. Unless you can increase the size of that whole vein I'm not sure what good porting will do. By putting a hole in between the seals you get the fluid from that seal area before its traveled into the vein restriction. Even then I'm guessing you'd need some barrel valve and torsion bar work to see the full benefits.

Articles I was referring to in the first paragraph that explained it a little bit more. Reading the patents might help as well.

Power Steering 103 - Dirt Sports Magazine
Power Steering 102 - Dirt Sports Magazine
Power Steering 101 - Dirt Sports Magazine

 

I ran a homebrew drilled & tapped box on my XJ, and eventually went to the PSC box. Relocating that hole definitely makes a difference because not only do you have less pressure drop, but if you look at the homebrew spot, even just screwing a fitting in there will cover the port slightly by the time you have enough threads engaged. Maybe if you were to weld/braze a fitting there instead of tapping & threading it, it'd be a little better?

PSC does weld/braze their fitting in at the new location, it's not threaded.

What I found over the course of racing my XJ with hydro assist on it, is that you pretty much have to open up the entire system to notice any significant changes. I ran the PSC TC pump and drilled out the stock orifice from 1/8" to 3/16" if I remember right; at one point I tried 1/4" which flowed like a mother****er but cavitated the pump way too easily. 3/16" seemed to be a good compromise and I ran that pump for ~5 years, and it's still on my shelf as a spare.

Then I used as many straight or mandrel-bent fittings on the hoses as possible (no block 90's), cut & re-welded the ram body so the fittings pointed straight up, all that kind of stuff. I don't have many pics but here's how the ram ended up:

and at the box side:

It was definitely one of the best hydro-assist systems I've driven (and raced), still had some room for improvement but by that point the whole truck needed improvement, hence the new build. :laughing:

Which, I'm also pursuing steering box options for. The steering shaft routing is going to be interesting and will likely need a 'carrier bearing' of sorts to sneak it around the alternator, which means I might be interested in using a separate steering servo like this one from Sweet Manufacturing:

They sell them in a ton of different ratings; site is kinda lacking on info but what I'd possibly do is run that as the power stage for the ram and either run the standard box unpowered or try to find a manual box (only problem there would be the ratio; most unpowered boxes are gonna be more turns to make up for the leverage).

 

The steering shaft routing is going to be interesting and will likely need a 'carrier bearing' of sorts to sneak it around the alternator, which means I might be interested in using a separate steering servo like this one from Sweet Manufacturing

I was doing some more reading along this line of thought...check this out:

http://woodwardsteering.com/images/power steering system components.pdf

Take a look at page 2 where they talk about the ports & spool valve and how they achieved more flow in that area. In their words:

A 900 servo is capable of filling a large diameter
cylinder at velocities well beyond the quickest race car steering and in most
applications will allow 5W-40 engine oil to be used as the hydraulic medium.

edit: up to 10 GPM according to this promo pic:

I'm really thinking that's gonna be the way to go vs. trying to squeeze every ounce of flow through a Saginaw box. It's been a while since I've had one apart but I wonder if the spool valve itself could be usefully ported in a similar way. I think at that point the torsion rod might become too sensitive and Saginaw boxes don't have torsion rod assortments available like the aftermarket valves do (at least not that I know of).

 

This is stuck in my head now.

What if you were to block off the pressure & return ports on the steering box, and 'backfeed' the box through the hydro-assist ports, using an external servo like I posted above?

I *think* you should be able to crack the return plug to bleed it, and then leave the spool valve in place to isolate both sides of the power piston so the only fluid path is in/out of the hydro assist ports...

edit: or heck, leave the return open and run it back to the reservoir as well? Trying to puzzle it out...

 

Just curious why you think this is necessary? I'm thinking just running either a manual box or converting a power steering box to manual and powering the ram solely off the servo valve. Basically replicating a power rack setup, unless I'm misunderstanding how they work?

 

Well, one, because I already have the PSC high-performance assist box. :laughing:

The recirculating ball needs some kind of oil, so even if you did remove all power from it, you'd still have to lube/vent the box somehow. Not the end of the world.

Manual box in the right ratio would work too, or a longer pitman arm to make up for it (and just not use the full travel of the piston).

But I'm just thinkin that two T's in the pressure feeds and a second return port on the reservoir isn't all that much more work, and would let one use as many existing components as possible. I.E., if you already had an assist set up, you'd be able to keep the box & ram where they were, add the servo, and just plumb it a little differently.

 

Interestingly enough, if I were to try and 'backfeed' the box that way, I think it'd be better off being tapped at the 'homebrew' spot than at the PSC-modded location above the valve so that I'm not still stuck with that little port we've been talking about.

Another method replaces the end cap and uses that for the 'right' turn pressure port, I think that'd work even better still. EMS Offroad made a part that does this:

With an external valve you'd be putting the fluid right where it's needed and bypassing the internal restrictive ports completely. The 'left' port is already in a pretty good spot.

Leaving the return hooked up to the reservoir in tandem with the servo return would just give the low-pressure fluid two exit paths from the box, and I think that might be just enough to give any air trapped a way to get out.

Hmm...

 

I was thinking about this the other night and came to the same conclusion that running an external servo valve like you've shown would be the way to go.

If you wanted to run a power box though, I don't think you'd be able to run the return off of it. The return requires the valve in the box to operate. The external servo valve should cancel that internal valve out for the most part. I'm talking about forces on the steering shaft here not hydraulic forces. Steering shaft load determines how much that torsion bar flexs and how much hydraulic fluid is admitted to the lines.

In the end, to get the external servo valve to function properly, you may need to remove the internal valve in the box all together. You'd just have to make up a plug with seals to block all the valve ports at the box, then tie the worm shaft in the box to the steering shaft.

Kevo

 

I was thinkin about the torsion rod situation too.

It'd take some tuning but since you're running them in series, it's the same as stacking coil springs on a coilover...they will both deflect but your effective 'spring rate' will be approximately halved, or put another way, your steering displacement doubled before both valves opened fully. I don't know how much displacement it takes to open the valve fully, but the valve in the box wouldn't be doing anything at that point (it'd be a "passive" valve, kinda), so it'd be kind of a dead spot. I think you'd probably end up having to run a lighter torsion rod in the servo to compensate.

But I don't think that necessitates plugging off the return completely, I think it'd just not open as much. That torsion rod will still operate. Leave it hooked up and I think it'd be enough to let any accumulated air get out even if it doesn't pass much fluid. The rest would just go out the other hydro port, same as the low pressure side of a ram.

Otherwise I'd be worried about air building up in the top chamber of the steering box with nowhere to go.

I dunno, just spitballin'.

 

Good read on torsion rod tech, with some displacement data.

9a. How power steering works (the torsion bar):

For the Woodward valve, fully opened is ~5 degrees I guess. So if you were to have a torsion rod in the servo that matched the torsion in the Saginaw box, it'd take 10 degrees on the wheel to fully open both valves. With a softer rod in the servo you could drop that down.