260z Power Steering

[wally57]

Guys,

Have read a number of threads regarding power steering conversions. For one reason or another I am going to use the Mazda MX5 NA rack. Does anybody know where I am likely to pick one up at a reasonable price. The condition does not matter because it is going to be rebuilt after being modified to suit the zed steering dimensions.

Wally 57

[Sirpent]

Wally

I may be way off the mark, but I believe that the MX5 and Mazda 3 not excluding the Ford Capri and ironically the Laser of the early to mid 90's all shared the same rack 

May be worth investigating.

Cheers

John

[luvemfast]

May be a silly question, but.
Is the 280ZX unit not compatable in S30 cars?

[peter mc]

mate  do the BMW rack so easy i did the conversion in a weekend, have a look at my build page

[NZeder]

May be a silly question, but.
Is the 280ZX unit not compatable in S30 cars?

in a word no - front mount rack = 240z/260z S30
but the 280zx S130 are rear mounted rack

Peters BMW unit looks to be the best easiest I have seen on the net

[sco_aus]

mate  do the BMW rack so easy i did the conversion in a weekend, have a look at my build page

Out of respect for your work, what you do in a weekend would probably take me a week
Though the photo on the first page there does make it look easy.  One day!

[wally57]

Peter,

I looked at your build page and it looks like you removed the original rack mounts off the front of the crossmember and modified the engine mount pedestal on the RH side.
With the engine transplant I am doing the engineer only wants absolutely minimum mods to the cross member and I think he would probably see the BMW conversion as a bit too much. He was happy with a bit of re-shaping of the rack mounts required to fit the MX5 rack, but thats about it, thats why I am looking at the MX5 even over the WRX.

wALLYU

[peter mc]

there are no mods to the engine mount but i did remove the original rack mounts and i welded a plate to the bottom of the x member and two mounts for the bolts at the top  and some light shaping work near the RH engine mount in total it took me 6 hours to fit

[jamo240]

Hey Wally

If you're interested in doing the Subaru rack, check out my latest build thread for some pics on how it all goes together (Jamo's RB 250Z builup).

I think you might run into trouble doing the MX5 rack as the centre-centre lengths are too great from memory. One of the power steering threads on here goes into it, but I did some prelim research myself, and while the MX5 rack packages nicely, it's geometry isn't ideal for Z's. I don't know about the Sydney area, but there's a Mazda wrecker down here that has just about any rack you can imagine. I seem to recall an MR2 rack is about the right dimensions too, but dont quote me on that!

Although I haven't seen Peter Mac's BMW installation myself, in my view, the Subaru installation is probably of a similar complexity EXCEPT that the orientation of the rotary valve is more complicated than what the BMW configuration appears to be. In my case, I re-oriented the valve by removing the two mounting lugs and re-welding them back on. While is was not difficult to do, this may upset your engineer. I should point out too, that if you haven't got a bit of fabricating experience and a good selection of tools including welders etc, I would outsource the job...I don't believe its a job you want to take on with no experience.

Finally, you can use the standard Subaru tie rod outers, as they have the same taper as std Z, as well as ball joint offset to preserve steering geometry. I used Lexus IS300 (I think!) rack ends as these allow the right adjustment to get the tie rod centre - centre distance right.

Also, I moved the lower control arm inner pivot point up 25mm and out 12mm each side to put the LCA pivot point on the same axis as the rack end pivot point...this corrects bump steer issues that Z's are blessed with.

Cheers

Jamo

[wally57]

Thanks for the advice Jamo. The BMW and Suby installations look pretty good but I am puting in an LS1 and the Engineer is already a bit iffy about the standard engine mounting pillars with the LS1. If I modify them at all I think he will have a real dummy spit. The fabrications not an issue I've got all the gear and been doing this sort of stuff for years, so I can handle that part of the job ok. I don't want to move the LCA mount points if I can avoid it because I don't want to change the roll couple if it is at all possible. What I am actually looking at doing is re-engineering the rack itself to bring it down to the same dimensions as the original zed rack. It won't be easy but I think it can be done, guess I'll just have to give it a go.

Wally

[jamo240]

Hey Wally

Fair enough re the engineer. I actually closed the rear of the RH engine mount pedestal to strengthen the structure. I am happy it will not fail under max load (ie ultimate strength is adequate) and I am happy I will not run into fatigue problems during more conventional use (let's face it, it can't be subject to max torque loads all the time...all roads run out eventually!). I don't think you'll have any problems with an LS1.

My subie installation does put the steering rack back on the original Z rack axis (in the X, Y & Z planes). This was a key feature of the installation.

I am not sure if the roll couple is balanced front to rear in standard configuration...maybe other people on the site can answer that question in terms of whether modifying the front inner LCA point helps or hinders the coupling front to rear. I have certainly been happy with the changes I made to mine years ago...it corners a lot flatter with much less front bar than it needed before I increased the height above road of the LCA point.

From what I've seen though, Peter Mac's BMW installation fits the RH engine pedestal better, so I think that would be the way for you to go, given the accreditation issues you face.

Cheers

Jamo

[wally57]

Thanks for all that Jamo it sounds like your mod is working for you and I must admit the BMW rack does look very neat. The problem as I said before is because of the length of time my project is taking my Engineer is making sure the car will comply to current NSW regulations as well as the National Code of Practice for Light Vehicles which could be in place by the time I get it finished. As such apparently one of the vehicles cross members must remain standard. As I have changed the gearboc mount to a Commodore cross member he wants the front cross member standard. He will allow mods to the original rack mounts but nothing at all to the cross member itself or the pedestals so that sort of ties me to the MX5.

Wally

[jamo240]

OK Wally...that's interesting to know.

I am not sure how you'll get any rack to work without some modification to the X member. While the MX5 rack does package fairly well at first blush, its geometry does not suit the car...from memory, it's too wide, and to get the rotary valve in the right spot, the rack is not in the middle of the car....on top of that, you'll have to shorten the rack to the point where you'll have insufficient travel to effect a sensible turning circle.

If those are the rules you have to comply with, you may have to ditch the idea of power steering altogether. It seems like a dumb rule to me, but that's nothing new for automotive regulation.

Maybe you could try to go back to a standard gearbox mount (by modifiying the body to accept it), and then you can do what you need to do with the front X-member.

It's something of a conundrum!

Jamo

[Tj]

FWIW I stumbled across an early model MX5 at pick n paythruthenose in Blacktown yesterday.

[wally57]

Jamo, TJ.

Thanks for the input. Jamo you got me thinking that it does seem stupid that because I have replaced the gearbox cross member I cannot even strengthen the engine crossmember to take the extraq torque of the LS1, so I harrassed my Engineer again today. It seems he was basing his decision on NSW RTA rules that say "if at least one structural crossmember is not located in the exact position as it was originally then the vehicle will not be classified as a modified production vehicle but will be classified as an individually constructed vehicle". Anyway I have finally convinced him that the lower beam of the radiator support panel is a structural crossmember as is the boxed in beam in front of the spare wheel well. As a consequence he has agreed to allow the engine crossmember to be modified provided I dont reduce it's strength. So I am going to take everyones advice and give the MX5 mod a miss and I will be going with the WRX conversion. With the LS1 I need the steering shaft to run as close to the engine mount pedestal and chassis rail as is possible to give the required 10mm clearance on the LS1 headers and I think the WRX rack will give me more clearance than the BMW one will. Anyway I want to thank everyone for their help and suggestions, now all I have to do is find the right Suby rack.

Thanks again

Wally