240/260 Power Steering options - Subaru vs MX5

[KatoKid]

I needed a break from the rust repair work on my shell so decided to tackle the final installation of the WRX rack onto the crossmember.

 

As I need to get the car engineered for rego I wanted top keep everything looking as stock as possible so this shaped the way I went about the installation, if I wasn't getting the car engineered then I would do it differently.

 

The WRX rack is larger in diameter than the original rack and I know I will have sump clearance issues so the WRX rack needs to be mounted as low as possible and this creates its own set of complications with pipe work and clearance around the engine mount. In addition the taller pinion shaft and the angle it sits at positions the universal joint higher and further outboard which brings the shaft going to the base of the steering column very close to the chassis rail.

 

I used the original Subaru rubber mount insulators as they are reasonably hard and can be replaced with aftermarket poly versions if desired. Using 30mm wide strap I made a 90 degree V section and a semi circular section to support the insulators and then cut corresponding sections out of the crossmember.  Care needs to be taken here to get the rack as low as possible, level from side to side and on the correct inclination to give the necessary clearance between the pinion shaft/universal and the engine mount (more on this later). Sounds easy but it's a case of taking small cuts and checking position many times. The top brackets were bent with lots of heat from 5mm plate and drilled and tapped for the original Z mounting bolts. Once I had dummied it all up and was sure the rack was positioned properly I welded the bottom V and semi circular sections into the crossmember.

[KatoKid]

More...

[KatoKid]

More...

[KatoKid]

What I thought would be a pretty quick and easy job ended up taking a fair bit of time as a small adjustment in positioning of the rack on the crossmember has a big effect on the position of the pinion shaft/universal and its clearance of the engine mount. Essentially the inclination of the rack is determined by the engine mount clearance required for the universal joint.

 

I trimmed 10mm off the back edge of the engine mount and made a cut parallel with the pinion shaft so I could bend the side of the mount to provide clearance for the shaft. The Subaru universal joint is a pretty bulky piece which is a stamping and at its widest point I’ve allowed about 7mm of clearance on the underside of the engine mount. You need to keep the pinion shaft as high as possible otherwise it will cause the steering shaft to hit the chassis rail as it runs up to the base of the steering column. I’m guessing the engineers won’t be too crazy about the weakening of the engine mount so I filled in the back side of the mount that was previously just open. There is a big hole for access to the rubber mount nut on the front side.

 

The Pictures do a better job…….

 

[620Z]

Great pics Dave. Looks like a lot of work there. I have printed copies of your pics and hope to get started on mine in the next few weeks. Chop, Chop. I to will make sure everything is filled in and strengthened even if not getting engineered.

I also have a clearance problem with my harmonic balancer where you have with your sump. I don't like the idea of lowering the rack for clearance. As doing this only increases the size of spacers required to eliminate the bump steer. But I will probably have to do the same. As I don't want to cut into or shave anything off the balancer.

Anyway you've really made some progress. I want to have mine chopped and fitted for display at the Xmas BBQ and ready for fitting around March next year when the car might go back in to hibernation for the winter. Then there is no rushing around, as I want to ensure the car is fine to drive to Thredbo in mid Feb.

[KatoKid]

As you try and position the rack in the crossmember and rotate it backwards to get the correct inclination and engine mount clearance it causes the ports for the inlet and outlet of the rotary valve to point down into the crossmember at the rear and the also causes clearance issues with the “ears” where the rotary valve bolts to the aluminium rack housing at the front of the crossmember. Remember the rotary valve (or power head) has been removed and rotated 180 degrees as this position is the lesser of the two evils when it comes to providing clearance for the pipes.

 

Initially I thought I could get the clearance I needed by deforming the crossmember with plenty of heat and a hammer. I did get the clearance I needed at the front but there was no way I would get the clearance I needed for the high pressure line going into the rotary valve at the rear, in fact I actually bent the whole crossmember in the process and had to straighten it out again!  In an effort to keep the crossmember as original as I could I decided to cut as small a notch as possible in the rear of the X member to provide clearance for the high pressure pipe to the rotary valve. I then used a section of 50 x 3mm tube to fill in the notch. To be honest the pounding with heat on the front of the crossmember isn’t that pretty when combined with the notch and inset at the rear so next time, and particularly if I wasn’t getting it engineered, I would just cut a large notch in the crossmember from front to back and fill it in with a larger diameter piece of tube (or just formed 3mm plate) to suit. I will likely run a piece of plate along the front edge of the crossmember where I’ve deformed it for more strength anyway. The rear is OK as is…I think, will depend on the engineers.

 

By the way, the high pressure inlet pipe had to be heated and reshaped so it gave a nice tight bend right on the flare nut where it goes into the rotary valve.

[KatoKid]

Finished..

[KatoKid]

Craig.

 

Its not really a lot of work....just takes a heap of time to get right. I'm actually going to Robco tomorrow as the Z steering shaft from the column is too large in diameter to fit into into the Subaru universal joint so I need Rob to turn it down. I will take the assembled rack etc so Rob can have a look at it. I'm pretty sure the steering shaft will just touch the chassis rail once its assembled, will probably move the base of the steering column to get the clearance I need.

 

[620Z]

Great Dave,

Yes I was going to drop down to Rob's today as well. What time were you going down?

[620Z]

I dropped my steering shaft off at Rob's this morning for a slight mod to fit into the Subi steering knuckle. I see he has had another heavily modified steering rack with a slightly different Subi rack mounted in there for some slight mods. (anyone care to own up to that one?) That's three he has on the go in one form or another.

Anyway we hope mine will be cut and mounted in the next 3 weeks so I can put it on display at the Xmas BBQ before we mount it in the new year. We have sourced a new Harmonic balancer for the front of my V8 down from 7" to a 6.35". This should give me an extra 8mm on the down side to play with (16mm in total). Also since the Subi rack is 12mm larger in diam we will still have to lower it as you have done Dave to ensure the two miss each other. The clearance at the moment is about 3mm. So the lowering of the rack combined with the smaller diam balancer should clear when all bolted together.

Only have to work on the pump now.

Cheers

[jamo240]

Hi Craig. The subi rack and Xmem you saw at Rob's is mine. I have a 73 240Z with a turbo L28. The wife got the shyts with the heavy steering, so I am putting pwr steering in it, along with a 550HP RB25DET. So it's out with the old and in with the new. I finished the cross member tonight, and am doing things a little different to you guys. I didn't want the fittings pointing at the xmem, so I am re-welding the rotary valve mounting lugs to position the rack feeds each side of the bellows, the pump lines kinda point at the block, but have plenty of clearance. My Xmem is redrilled to fix the bump steer (move the LCA pivot points out and up), so I only machined 10mm off the rack to retain the original steering lock. I also went with the Subaru Liberty rack, as it has a slower ratio than the WRX. My car has 245/40R17's on it, and is too darty now, so I wanted to slow the gain down a bit, and give it more progressive turn-in, not just faster. I will have to come to a Z event one day and show you...i've been outta the scene for many years now, but decided to give the old girl a new lease on life, so we'll be ready to go this summer.

[620Z]

Well done Jamo. I also want the wife and kids, when old enough to be able to drive the Zed. Hence the steering conversion. Plus I am getting old and lazy so some power steering should transform the car. I like your subtle changes to ours and look forward to seeing the car one day. You should come out to our Annual Xmas BBQ to have a chat and look at some other Zeds. Keep us advised on your progress. Regards Craig.

[peter mc]

My BMW rack was a lot easier to fit  it was a 5hour job all fittings face the right way and i am using datsun tie rods

[garvice]

Peter you can't just leave out at that, details please.

[peter mc]

have a look at my gallery pics, the rack is out of a 318 BMW i think from memory it is a '97' model but i will have to check.

It was a very easy conversion.

I used 1600 tie rods with relatively easy mods to make it fit to the cross member, i got it all done in one weekend with no bump steer problems.

[jamo240]

have a look at my gallery pics, the rack is out of a 318 BMW i think from memory it is a '97' model but i will have to check.

It was a very easy conversion.

I used 1600 tie rods with relatively easy mods to make it fit to the cross member, i got it all done in one weekend with no bump steer problems.

 

Looks like a nice installation, on a beautifully engineered car. I reckon the rotary valve angle is nicer than the subi installation too. I would have looked at the Beemer rack, but didn't know about it! The Subi one isn't far off though now, so I'll press on.

[jamo240]

Hey guys

 

Well, Rob is through with my rack now, and I ended up going with the rewelded lugs on the rotary valve body (to relocate it to clear the cross member). I made up the fluid lines now, and it all looks factory, like I wanted it to. I am feeding it with the standard Skyline pump (on the RB25DET engine)...plumbing to and from the pump runs around the rear face of the cross member and up to the pump/reservoir. All in all it's come out well. Unfortunately won't be ready for the xmas party, so I will have to show you all at the next event...I reckon it'll be fully finished by March.

 

Rear trans mount has come out well for the RB25 install as well...I drilled the spot welds and moved the lateral mount back about 80mm and then rewelded it into the body, and re-applied the body deadener etc...all looks factory, and very stiff mount. I cut down the Skyline Xmember to fit the Z body (much narrower), but it's all good now.

 

Cheers, Jamo

[jamo240]

have a look at my gallery pics, the rack is out of a 318 BMW i think from memory it is a '97' model but i will have to check.

It was a very easy conversion.

I used 1600 tie rods with relatively easy mods to make it fit to the cross member, i got it all done in one weekend with no bump steer problems.

 

Hi Peter

 

I was wondering if you could give me some info on the 1600 tie rod ends. I am running into a few snags to get my tie rod/rack end length sorted. The common setup uses the 84 Celica rack ends with the subaru tie rod ends, but in my case (with extra neg camber), that combination is too short to get sufficient thread engagement. I saw your 1600 tie rod ends, and thought that might do it....I need the standard 240Z steering arm taper, and then an overall length from the centre of the ball joint to the end of the tie rod of approx 155-160mm, with an M14 x 1.5 female thread...are the 1600 ones on your car in that ballpark?

 

I found some TRW ones that are spot on, except the taper is slightly larger in diameter, and won't go in the steering arm properly...if I can't find an appropriate tie rod end per above dimensions, I reckon I will have to ream the steering arms to get the TRW ones to fit.

 

Cheers, Jamo.

[KatoKid]

Jamo.

 

Use Toyota Soarer rack ends they may be slightly too long but you can cut them down if required.

[jamo240]

Hey Kato

 

Thanks for that...I picked up on your post to that effect after I wrote to Peter! That said, when I hunted for them, I couldn't find a part number or supplier...you didn't get that kind of information when you were researching did you? I am hoping to get them via Repco or similar, but happy to go genuine if I have to.

 

Cheers  Jamo

[peter mc]

hey jamo240

 

Will have a look at my tie rods and get back to you.

I did mine in 1 weekend a year ago and didn't pay that much attention to the threads coz they just bolted on! lol

I will take a look tomorrow and let you know.

I think i might have been pretty lucky with the BMW rack as it looks like it was a much easier conversion, when i went looking in the wreckers it was the first car i found and with my tape measure it looked like it would do the job so i just put it in! lol

 

[jamo240]

Hey Peter

 

I think you may have been a little lucky, but the engineering in your car indicates you have a good eye for details that matter!

 

I am happy with how the subi install is going...it looks factory and will come turn out well...the biggest compromise has een the cutaway of the engine mount pedestal on the xmember to clear the rotary valve input, but it's only cosmetic...it will all work fine.

 

Thanks for the info on the tie-rod ends. Kato Kid is also recommends using the Toyota Soarer ends, so hopefully one or the other will work.

 

Cheers mate

 

Jamo

[haul]

Peter, If you get the time could walk us through what you needed to do to fit the bmw rack, and confirm it was a 318 97 model.

Cheers Tony

[peter mc]

hay haul

 

Hi i think i will talk to lurch about a 'how to' youtube vid on the BMW rack, its not that hard if you are handy and have a welder it can be done in a weekend.

The valves all point in the right way, the engine mounts dont have to be cut mine has been braced under neith with a plate that doubles as the locating holes for the bottom of the rack.

I will check all the details on which rack but it did come out of a '97' 318.

[KatoKid]

Hi Jamo.

 

Supasteer Australia. These guys had them the shelf, about $70 per side I think.

 

3/ 10 Sydney Road, Bayswater VIC 3153

 

Ph: (03) 9738-0345

 

David