chancecasey

I just did some searching and found a lot of info for 944's but very little for 964s. I just removed my power steering pump and I'm wondering what the best thing to do to my power rack is. (I can't afford to spring for a $$$ RSA rack).

One thing I've heard is to just connect the "in" and "out" lines together. Is there anything else I should do - especially for the purposes of making it easier to steer or not fail for some reason?

springer3

Don't know, but I would flush out the old fluid by turning the wheel from stop-to-stop while a drain hose was fitted. I would not completely re-fill the rack, but rather put just enough fresh oil in there to keep the hydraulic cylinders lubricated. You don't want to risk the pistons running dry and getting sticky, but at the same time you don't want to pump Dexron II through an orifice, particularly when parking.

If the by-pass option makes the PS rack feel like the manual RS rack, somebody needs to go into the business of selling the hose with fittings. Does anyone know if the gear ratio is faster on the power rack?

elbeee964

+1 Concur!

Would really like hearing from Rennlist's more mechanically brilliant types regarding this: potential pitfalls, longevity, experience w/ this... etc. (Jason? Garrett?)

911addict

I'm sure I saw a recent post on exactly this. I think Geoffrey the racecar guru commented also. Try a search...

chancecasey

Yeah I've been searching to no avail so far. I think most of the 964 owners on this board aren't so cheap.

Not even sure why I did this - I was planning on running PS but came across a free block-off plate, I'm going to trailer the car, I'm fighting like mad to get somewhere near 2100 pounds, so there it is.

Maybe the next step is to rig up a steering wheel exercise machine in my garage so I'll be ready to man handle those 11 inch slicks in front.

FYI the pump itself (empty, along with the housing tin, cog, belt, no hoses) weighs 10 pounds. High and rear-ish. And rotating As long as I'm not fatigued it will be a good thing.

Colin 90 C2

just keep the car moving and it shouldn't be too much effort.
If it works for you, keep us posted.

Azikara

Well, I'm going through the same debate and I'm not as bold as you are. I have a 90 C2 race car that I want to run as an RS America in G class. To do that I need to make the car like a RS America (except for parts noted as "free" in the PCA rule book e.g., wing, decals, door panels etc.). The only thing I can think of is the manual steering rack. Now I am an engineer so the engineer in me says that when designing a power assisted rack some of the load is taken by the hydraulic action of the fluid which pushes to aid the movement of the rack in a certain direction. This takes load off of the internal components. With the manual rack this is not the case - it has to be designed to cope without hydraulic support. I would be willing to bet that there is a substantial mechanical difference between the two in terms of ability for the parts to take the un-assisted load. One is clearly designed for it and the other...well, the other is probably designed to be able to get you to a place where you can restore hydraulic power and not much more. Of course I could be 100% wrong but I'm not willing to take the chance of it failing at 110 mph through the kink at Road America until I can find suitable evidence that it is in fact designed to take the appropriate abuse.

Tristan

chancecasey

Purely speculation here, but considering the low production numbers of these cars, they usually try to re-use as many "common" parts as possible - so having "beefier than needed" components in the PS system would probably be more cost-effective than designing, tooling up, and manufacturing 2 versions of those components. Of course, wherever it's practical. Obviously there are major differences in the systems which do require very different components.

I really wanted to avoid even dropping it out of the car - just re-hose and be done. And I might do that. I MIGHT however drop it and start disassembling it to see if I can figure out if something "better" can be done besides filling with fluid and re-hosing. Would be nice to know if that's a waste of time before I begin, though.

Tom W

Chance: Good luck on the 2100 lbs. I've given up on that target as way more money than I want to pay and am currently focused on getting it to just below 2200 lbs. It's going to be close, but I'll know more next week once we have the cage complete (cage weight was the big uncertainty). I've kept my PS.

Wasn't there just a discussion on the use of the power rack with hose ends connected to make it a "manual" rack on Pelican?

springer3

You give way too much credit to the hydraulic assist. It changes the load at the steering wheel by at most 50 lb. The rack must be able to sustain shock loads in the 1000s of pounds. The rack proper is the same size on both the manual and PS units. The only concern I have over the PS-to-manual conversion is the gear ratio or turns lock-to-lock. I have one of each and will attempt to determine if there is a gearing difference. If the gearing is the same, the only difference will be the drag of the pistons, and the work required to pump the oil around. I suspect both are small relative to total steering effort.

Azikara

I have one out from a C4. What do you want to know?

Tristan

chancecasey

Tristan - just what the title implies. Now what? Is there something I should remove, rearrange, modify, or service on the inside to make the conversion *better*?

I may just go for it as a nice little benchtop project - check it out, see how it works, see if anything is worn, etc. Plus, I'll need to get it out to do a *good* job of re-hosing it anyway. If I photo everything it might make a good DIY or at least serve as evidence to others not to bother doing anything other than connecting the "in" to "out" and be done. I recall a couple of 944 guys in my search mentioning draining the fluid completely and just greasing some stuff inside.

Tom - I think my cage will come in around 125 pounds (1.5 x .090) including associated sheet metal. I'll be very surprised if you don't break 2200.

jgrosjean

I was lucky to get a manual rack several years ago and like the feel. It's fine on the road but requires a lot of effort at low speeds. I can measure the ratio if someone knows an easy way to do it. Since the stops are adjustble, measuring the turns from stop to stop may not be accurate.

chancecasey

I have successfully dismantled the rack and in the middle of modifying it - unfortunately I have been sick yesterday and today so progress has been temporarily halted. I am really excited about how I think it will turn out, however, and will post photos and document the play-by-play for anyone else wanting to do this.

Larry Herman

IIRC the manual rack has a slower ratio than the PS rack. Keeping the rack full of fluid and connecting the ports together is the way most of the 944 guys do it, with no problems.