260z Power Steering
Posted 12 August 2011 - 06:19 PM
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.
Posted 12 August 2011 - 06:42 PM
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.
Posted 12 August 2011 - 07:05 PM
Is the 280ZX unit not compatable in S30 cars?
Posted 12 August 2011 - 07:15 PM
Posted 12 August 2011 - 07:32 PM
in a word no - front mount rack = 240z/260z S30
May be a silly question, but.
Is the 280ZX unit not compatable in S30 cars?
but the 280zx S130 are rear mounted rack
Peters BMW unit looks to be the best easiest I have seen on the net
Posted 13 August 2011 - 12:56 PM
Out of respect for your work, what you do in a weekend would probably take me a week
mate do the BMW rack so easy i did the conversion in a weekend, have a look at my build page
Though the photo on the first page there does make it look easy. One day!
Posted 15 August 2011 - 08:08 PM
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.
Posted 15 August 2011 - 08:31 PM
Posted 15 August 2011 - 09:14 PM
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.
Posted 17 August 2011 - 06:06 PM
Posted 21 August 2011 - 07:48 PM
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.
Posted 23 August 2011 - 10:45 AM
Posted 23 August 2011 - 08:00 PM
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!
Posted 24 August 2011 - 09:42 AM
Posted 24 August 2011 - 03:45 PM
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.
Posted 25 August 2011 - 08:22 PM
If you are in Melbourne I can show you how I did mine, and give you some ideas.
There is a good Subie wrecker down here if you are having trouble up there. I used a Liberty rack I think...it has identical turns lock to lock once you shorten it to get the travel the same as what the std 240 rack is (approx 11mm off each side of the rack)....Rob at RC engineering (down here in Vic) can do the turning without stripping the rack. Supasteer in Bayswater has the Lexus rackends that you need to get the right overall length, and you can carry over the std subie tie rod ends as they have the right thread to suit the Lexus rack ends, as well as the same taper as the std 240 steering arms. Rob can also do the welding to the valve assembly if you want to go that way. If you choose not to, it is a bit of a challenge to modify the rack without putting big divots in it to clear the fluid pipes...your engineer may baulk at that. Rob has access to a very good welder who did mine, and he has made up mandrels to ensure the valve body does not deform during welding.
Anyway, happy to help you if I can.
Posted 26 August 2011 - 12:29 PM
Picked up a pretty good WRX rack yesterday in Newcastle, would like to have been able to do the mod the way you did it but my rotary valve assembly is either cast iron or cast steel so it may be an issue getting it welded properly, and if it looks the slightest bit sus the engineer will jump on it. RTA rules here in NSW say you are not allowed to weld any cast steering components. I am not questioning the safety of rewelding the ears, if I could do it with the iron/steel housing and it looked as clean as yours does I would do it and clean the weld up so it could not be seen once it got a coat of paint. The Lexus rack ends you mentioned. I assume they are soarer is that correct.
Posted 26 August 2011 - 05:08 PM
Yes, the WRX appears to have the cast iron/steel body, whereas Liberty is aluminium. You can do it without re-orienting the valve body, but the clearance are tighter and you will have to chop up your x-member a bit...but, given the regulatory thing, I guess you're stuck.
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