Woodward power steering project

[JMortensen]

I haven't actually started on this yet, but I did talk to Tony Woodward and learned some interesting things, and I thought I'd put them down here for the benefit of everybody. So the plan for my car is to run the rear FA slicks all around. That's a 15x14 wheel with a 15x12 or 15x13 tire, both tires are designed for the 14" wheel, it's not a hellaflush stretch thing. I eyeballed it at 5" of scrub, which is A LOT, and I figured there was no way in hell I was going to do this without ps. I've been casually looking into the Subaru and other ps options for a while, and hearing things like the pump can't keep up, and the rack feels dead and steering feels numb, etc. I finally got interested enough to call Woodward steering, and got Tony Woodward on the phone. This guy is awesome, knows his stuff backwards and forwards, and really went through every one of my questions and answered them all.

 

So here is what I found out:

 

Do not buy an 18†race steering rack and put longer ends on it. Too much lever hanging out unsupported. He was pretty clear that this is a bad idea, was going off on people getting bad advice, etc.

 

Woodward racks come with a 6†stroke, Z comes with a 5†stroke. I just went and measured the Z rack at 1.8125 inches per turn of the wheel. The Woodwards come in a wide variety of ratios, but I was looking at a 3.14 in per turn rack, which would be VERY fast, about 1.75x as fast as stock. Now I'm thinking I might go slower, maybe a 2.5 or so inch per turn. Even that would probably be pretty twitchy for a street car, but should be great for autoxing, and since it doesn't require shorter steer knuckles, doesn't have an adverse effect on Ackerman. Some sort of steering stop will need to be devised. When I called Tony I had measured the rack travel wrong and thought I had 6 3/4" of rack movement because I measured at the wrong place, so I didn't ask about this, but the tech info on their website seems to indicate that what fixes this is using a housing that is 1" longer than the rack itself. Basically then the tie rod runs into the housing, preventing it from using the last bit of available rack gears.

 

Tony suggested a 950-1 servo and a 210 torsion bar and said that would give very light effort. He said if you put this rack on a new Mustang you could steer it with one finger. Effort can be adjusted later with a heavier torsion bar (spring that returns the wheel to center) or a smaller servo.

 

I gave him the center to center control arm pivot distance of 23.44†and he suggested that I use an off the shelf 23.25†wide rack measured from center of monoball to center of monoball. He said if the tie rod is shorter than the control arm, you’ll get toe in on bump which is bad, and with the 23.25†rack it will be close enough to dial out bumpsteer to the point where the difference would not be noticeable. He said they could do a 23.44 rack if I wanted, but he would go with the shorter one just to be sure.

 

He suggested the high load option based on the scrub, and also said that 5†of scrub was nothing compared to what some modified stock cars run. This made me feel like I wasn’t a complete idiot for considering running 5†of scrub. His opinion was that it wasn't going to affect the handling negatively, it would just make it nearly impossible to drive without ps. If you have ps, no problem.

 

He said Woodward is the only company that makes their own valves inside the rack, and that every other manufacturer was using smaller valves, and the restricted orifices cause the "damping" on a factory rack.. No damping on a Woodward rack, but you will have damping on any other rack, race or not.

 

Said the rack needs 2.6 gpm @ flow controlled rpm. Once you get up above a certain rpm, the rack still only puts out x gpm. He estimated most pumps put out about 3 gpm at their flow controlled rate, which was going to be achieved by about 1200 (pump) rpm. Also said that it would be likely that I would have a 5†pulley on the crank and a 6†pulley on the pump, so I would have .8x rpm on the pump vs at the crank. So basically, he didn’t think pump volume was going to be a problem, even with a stock pump. Also said pump bearings are submerged in the ps fluid, so they can handle very high rpms with no trouble whatsoever

 

He suggested moving the rack back, and I told him that I already did that looking for Ackerman. He was impressed. The cost of the rack is $1560. As soon as I finish typing, I'll go back to rubbing some nickels together.

 

There is some really good tech info on Ackerman and a bunch of other stuff on their website, www.woodwardsteering.com

Edited December 17, 2010 by JMortensen

[garvice]

Subscribed. I want to see how this one turns out, lots of good info there. Power steering would be great, but I would hate to lose the feel of what the car is doing, this is looking promising.

[JMortensen]

Garvice, if you're looking for info quick, you had best not follow my thread. Would be better to go do it yourself, then I can follow YOU. Otherwise you'll be waiting a while for a result...

[garvice]

Ha, J, look at my signature.

I pulled the head off my L28 to replace a gasket.

 

Now it is on my hoist with a RB26 sitting in it. This is not going to be done anytime soon.

I have a 4month old son, by the time it is finished he will probably be old enough to ask for the keys.

 

Ha (nice try though)

[Snailed]

Interesting project. I read a lot of the woodward tech and learned quite a bit. I wonder how an electric rack would be for an application like this. It sure feels great in an S2000. Being able to have less assist with road speed is pretty attractive but obviously hydraulic racks are getting the job done already...amperage draw on small racecar charging systems might be an issue too...

[Wout van Aken]

Hi,

in Holland is a company that build in a electric powersteering. The powerunit is mounted unther the dash so you don't see anything from it.

It works great and the steering power is adjustable!

See http://www.ezpowersteering.nl/

 

Greetz, Wout van Aken http://picasaweb.google.com/ZZXCLUBHOLLAND/ZRestauratieWoutVanAken#

[ZT-R]

Hi,

in Holland is a company that build in a electric powersteering. The powerunit is mounted unther the dash so you don't see anything from it.

It works great and the steering power is adjustable!

See http://www.ezpowersteering.nl/

 

Greetz, Wout van Aken http://picasaweb.google.com/ZZXCLUBHOLLAND/ZRestauratieWoutVanAken#

 

how much do those run?

[Snailed]

how much do those run?

 

They are around $2-2500.

 

Didn't mean to derail your thread JM

 

I like the part in the woodward tech about the baffle in the PS resevior. I build them sometimes at work and reading that makes me want to improve my baffle designs. Most of the ones provided by the aftermarket have none or poor (accoring to woodward) baffling. I'm curious what the woodward one looks like. I usually position a piece of aluminum at a slight (15-20 degree) angle and maybe 5/8"-3/4" away from the inlet. Or I have made a V shape the dispered the stream to either side, below the fluid level when running.

[JMortensen]

No problem, the more ideas that get tossed around the better. Problems with electric steering are that it doesn't quicken the ratio and that I've read some posts from people who felt that it felt totally disconnected from the car.

[ZT-R]

They are around $2-2500.

 

:angry: :angry:

[Zbuff]

No problem, the more ideas that get tossed around the better. Problems with electric steering are that it doesn't quicken the ratio and that I've read some posts from people who felt that it felt totally disconnected from the car.

 

I have had electric assisted steering in my car now for about a year. I have found that my car (280Z 2+2)a much more enjoyable car to drive. The way my steering is set up the ps is only engaged when it is needed i.e. very slow speeds (when you need some assistance) once you are rolling the ps disengages and you are back to your normal drive. The system is totally quiet and from a visual you can not see it. Don't know what systems the above people were using but I have had just the opposite reaction. I purchased this system from Brian K at azcarbum@msn.com

 

Zbuff

[JMortensen]

I have had electric assisted steering in my car now for about a year. I have found that my car (280Z 2+2)a much more enjoyable car to drive. The way my steering is set up the ps is only engaged when it is needed i.e. very slow speeds (when you need some assistance) once you are rolling the ps disengages and you are back to your normal drive. The system is totally quiet and from a visual you can not see it. Don't know what systems the above people were using but I have had just the opposite reaction. I purchased this system from Brian K at azcarbum@msn.com

I've dealt with Brian before, he is a good guy. Curious, how does the ps get the car speed? Sensor on the driveshaft? What was the cost? I guess another option would be a 1.5:1 steering quickener and the electric setup, but still have worries about feel and space might also be a concern. Not sure how much power you can get with the electric setup as well. If I'm adding a buttload of scrub and a quickener, will it keep up?

[Snailed]

I have read about people swapping over entire systems from newer cars. I'm assuming the factory ones have a better feel since they have so much more time into the programming and materials r&d. I think the AP1 s2000 is a non CANBUS system so you could wire it up just by feeding the right signals or voltage to each pin on the steering module. I have no idea is if the honda rack is even usable on a Z but it's an interesting idea...plus the modules are going for about $90 on ebay so the price is right. I saw a few of the column munted motors for under $200 on ebay too.

[JMortensen]

I was talking to a guy who has a Woodward rack on a BMW, and I'm pretty convinced I'm going that way. Reason? I don't want to literally tear the stock rack apart. I'm going to be putting a lot of strain on the rack due to the crazy tire size and scrub. He was telling me that the Woodward rack is a lot beefier than any stock rack he's seen and that the loads that it can put up with are pretty tremendous.

[Snailed]

I was talking to a guy who has a Woodward rack on a BMW, and I'm pretty convinced I'm going that way. Reason? I don't want to literally tear the stock rack apart. I'm going to be putting a lot of strain on the rack due to the crazy tire size and scrub. He was telling me that the Woodward rack is a lot beefier than any stock rack he's seen and that the loads that it can put up with are pretty tremendous.

Nothing wrong with overbuilding it. From what I hear they are one of the innovators in that industry. I work with a guy that builds circle track chassis and he likes their racks a lot. I guess the customers prefer sweet and a some other one I can't seem to remember, for cost reasons though.

[JMortensen]

Sweet and Appleton are the two others that I'm familiar with. Supposedly Woodward's stuff is a lot better, but it is definitely a lot more expensive.

[Zbuff]

The cost of the unit was a total of $1600.00 this does not include installation. I only mention this as I am all thumbs and don't have everything needed to do this.

 

The sensor is attache to the transmission. For my way of driving it is great. I have made this car a cruiser but, I do like to goose it sometimes to have some fun. I have not noticed any problems with this kind of driving. Ron Tyler has driven my car so he could give you probably better feed back then myself.

 

Zbuff

[JMortensen]

Ordered my rack today. Ended up with part number HLM266CC-2325/2475 950-1/210. So this is an HL rack with monoballs, high load, 23.25" rack with 24.75" housing 950-1/210. The housing being 1.5" longer than the rack limits the travel by 1.5", so it will have 4.5" of stroke vs the stock 5". I had previous issues with the tires hitting the TC rods, and although the new TC rods are in a slightly different location, I figured it wouldn't hurt to cut the travel back. I used my Ackerman charts and this brings my max angle on the outside wheel from about 33 degrees to about 30 degrees, so I don't think it will have a very dramatic effect on turning radius. Also ordered a KRC pump.

 

Will take pics when the rack is received.

[JMortensen]

Got the rack today. Looks good. Now I just have to figure out how to install it. I thought this thing would have your typical circle track rack type of setup where the rack attached with three screws on each end. Looks like it attaches with one big ass bolt. I haven't measured, but I think it's 7/16", and there is a machined flat spot on the bottom of the rack where whatever mount is used will sit. I see this as good in that you can adjust bumpsteer out with shims fairly easily. It also appears that the pinion doesn't have much vertical angle to it, so that leads me to believe the rack will have to be mounted pretty high for the pinion to clear the crossmember. I could tilt the mounts, but then the hydraulic cylinder would be hanging down lower than the crossmember, which is already going to be pretty low. Don't want that. I guess the other option is to move the rack forward again, and that might unfortunately be the only solution. At least now after having looked at the Ackerman issue in detail I realize that I wouldn't be giving up much to move it forward a little bit.

 

I guess I'll just have to start playing with it and see what works, my biggest fear is that I can't get it in without redesigning the crossmember. Not that this would be a huge project in comparison to some of the others I've done, but it's just one more thing to do, and I need less of those.

 

The reservoir for the ps fluid is a two layered can where the feed to the pump is at the bottom of the center can and the return dumps into the outer shell. There are perforated holes about 3/16" in diameter in the inner can to keep aeration to a minimum, and the can is nice and tall to keep any bubbles that make it through at the top. Came with a nice bracket as well.

 

Some pictures:

[JMortensen]

Tony warned me that the rack would be so much more powerful that I should beef up the frame rails to deal with the additional strain. I had already done some strengthening of the frame rails, but the Z crossmember is not the strongest looking thing and I don't really see a good way to increase its rigidity.

 

Just playing around with the rack and an old crossmember I figured out that the old 6 cylinder engine mount towers had to come off, so those got cut. No biggee as I need to fab mounts for the L33 V8 anyway. Then I realized that the horns that stick off the front that hold the stock rack had to get cut back just to get the rack in position, so I did that. At this point I was able to get the rack positioned essentially in the stock position, but about 1/4" higher. Moving the rack back to the stock position fore/aft negates the work I did to move the rack back, but after graphing it out on the Ackerman thread, the difference will be minimal, so I'm not worried about it.

 

The rack mount is my biggest dilemma right now. I think the most logical way to mount the rack is to weld two pieces of angle iron to the front of the crossmember so that the flat part of the rack sits right on them. This may improve the rigidity a bit over the long unsupported saddles that the stock rack used, but they're not exactly what I would call "overbuilt". I thought of using a long piece of angle iron all the way across the front and I think that would be sturdier, but then there really wouldn't be a good way to put the bolts in, unless I drilled a big hole in the bottom of the crossmember, although that's sounding like it will be the best option at this point.

 

About the only thing I can think to do with regards to the crossmember would be to add a folded sheet metal gusset like a taco gusset between the crossmember and the frame rail, so that the lateral loads imparted into the frame go through two sides of the frame rail, instead of just the bottom. If anyone has any other ideas or previous experience, I'm all ears.