Thought a new page was in order for the suspension setup.

Starting to get enough bits together to have a bit of a play around.

The beginning - 1 second hand almost complete UC Torana front end. Only the bare subframe and whatever power steer rack will be used for this project - all the control arms and other bits and pieces here are being used just for testing and measuring and will be left over at the end.

Picked up a TF Cortina power steering rack from e-bay as the first contender for the conversion. The pic on the right shows the Cortina rack dummy fitted to get an idea how it will all work. Bit of interferance with the drivers side engine mount.

Also picked up a '99 WRX STI rack from the wreckers. It is much lighter and more compact than the Cortina one (which is mostly made of cast iron and weighs a ton) The top one is the TF cortina, the middle the WRX, and the bottom, the Torana manual rack.

The original Torana Rack has an inner balljoint spacing of 625mm which is a good starting point for a suitable substitute.
The Cortina one measures approx 620 between inner balljoints and the WRX is 650mm between inner balljoints (including all models from 93 to 05 WRX or not, and forester.)

It appears I was wrong on my initial calcs of the steering ratios these racks will achieve, I have revised this below. I say approximate ratio as this will still depend which steering arms I end up using as the LX,UC and A9X arms are all slighly different effective lengths.
On the Torana, the '99 WRX rack will give a final steering ratio of approximately 15.5:1 which is great. The Cortina one although power steer, is the same ratio as the LX Torana manual rack (18:1). The Forester will result in a steering ratio of approx 21.3:1 so not too bad if you like light steering.
Not sure of the ratio for the standard impreza racks as there were none to measure/check at the wreckers but I would gues somewhere closer to 18:1 so there is a good range between the 3 types of rack if they measure up okay for bumpsteer. Subaru lists them as a different part - the wreckers reckon they are visually the same as the WRX ones so I would guess it is the ratio that is different - most likely something in between the 2. The post '03 WRX's changed steering rack which is slightly bigger around the rotary valve area and you cannot remove the rotary valve should you want to turn it around the other way. They would probably still be okay and come in an even quicker ratio but the wreckers want about $1K second hand for the quick ones as all the WRX guys want them.

The WRX must have a wider track than the Torana as the Tie rods are too long as well - by approx 70mm each side.
I bought a pair of 85 to 89 L series subaru Rack ends new. They fit the WRX rack nicely, use the same M14x1.5 thread for the tie rod and shorten both sides by approx 35mm each side. The WRX has a very long outer tie rod end so a modified/ differnt one of them should do the trick.

Some pics showing how the WRX rack dummies up against the standard Torana crossmemeber. The rack needs to go across towards the drivers side approx 6mm to line up the centre lines of the cross member and the centreline of the rack - it is the engine mount and one of the hydraulic lines which are interfereing the most.

I cut out a section of the engine mount to see how that would effect the fit of the 2 racks.

I have repeated my measurements as someone had double checked their Cortina one and got different mesurements to me.
I have revised the following as my mesurments now show the cortina one is not too bad a candidate after all, my cortina rack one is a bit stiff at one end of the travel and I didn't measure the entire range of rack travel or rack centre line correctly. I now measure the Cortina rack travel as 132mm which is the same as the Toranas rack.

The cortina rack still hits the engine mount and order to line up the centre line of rack and centre line of crossmemeber, the cortina one still needs to move toward the drivers side and rearward but the subframe will need some reshaping to allow this to happen.

The wrx one fits nicely into the recess for the Torana rack - unfortunately it also still needs to move across another 5 to 6mm to centre it but still not too bad.

Okay fist stage for fitting an LT5 to an LX Torana is to do those engine mounts. First up, those pesky holden engine mounts have to go altogether.

Took me about 3 hours of stuffing around on the ground before I decided to build a stand - one I can move the suspension through it's travel whilst on the stand too. I have now moved up in the world from the status of ground sloth.

I have bought a toe-in gauge and a castor/camber gauge and another neat angle gauge and a spirit level too.

I wanted to get fully floating style polygraphite bushes for the upper and lower control arms to see if that stops the squeaking. I have the following upper(3.3117G) and lower(3.3132G) Energy suspension kit which are from 64 and 68 model Chevelle's respectively. They line up spot on in every dimension for the Torana - hows that. The pic on the right shows how the bushes pop apart and also shows the grease grooves in them.

I linished up the cross bars for the upper control arms to take the casting crud off, then HPC'd them and the nuts and washers - not sure if I'll use these but they look good just in case now.

Decided to HPC the upper control arms and also the shells for the UCA bushes as you can see them a fair bit.

Assembling the upper control arms. First have to press one of the bushing shells in, then put the cross bar in place, then press the other shell in.

The HPC is very easy to damage doing this - the second one I did a much better job using lots of masking tape to keep the cross bars under control.

The poly bushings then slide nicely in by hand.

I have some cheap ball joints to use for my testing as I don;t think i will use these arms for my final setup - they do look good though.

The final pair all done.

Next the lower control arms, I have shot blasted them and installed the bushes and balljoints, Again using the energy suspension floating type - they are heaps easier to press in just the bare shells.

Completed lower arms in zinc rich primer. Press tools I made on the right - just used some cut of bits of pipe.

I made adjustable feet for my stand so I can level it and drilled some holes to bolt the subframe down solid.

Also got some big washers to adapt my Camber/castor gauge to the spindles - works like a dream.

Standard UC geometry on left and with spindle extender on right. I can't measure with the extender yet as the top balljoint bottoms out before full suspension bump is reached so I need to make a wedge spacer for the top balljoint - same sort of thing TSS used to sell.

You can see my threaded bukka rod shock replacements too so I can make reasondably accurate measurements.

I got my new delivery from Caloundra sheet metal today - the Stainless hardware for the top control arm bushes (nuts and curved washers) and 2 set of stainless alignment shim packs.
The shim packs were only $11 each and I could only buy the steel type in $150 workshop packs so these S/S ones were a far better deal in the end.

Time to start taking a few measurements and find some more parts :)

To get an idea of what improvements I make, I took a baseline of the UC geometry first. I have just added the A9X camber curve (which is about as much as you can achieve by redrilling the subframe to reposition the UCA mountin bolts as low as they can go)

After a fair bit of head scratching, I have now done a series of measurements of the horizontal movement of the stub axle as that would significantly effect the bumpsteer curves. These curves are different depending on the camber curve as seen by the following plots.

If you subtract these curves from my Toe-in curves above the end result is the bumpsteer curves below - these curves are much more what I was expecting to see.

I have plotted the curves for the A9X arms and the LH/LX arms on the UC front end and the UC steering arm is the best one for the job.

Very interrestingly with the spindle extender fitted, the UC one still gives decent bumpsteer but the LH/LX arm becomes the best option.

The 2" Tall Spindle extender makes a very nice improvement to the camber curve if you compare the 2 charts. The LX RTS camber curve is inbetween the 2 as shown by my new plot above.

These charts show the effect of lowering the front of the car by 1" on the camber curve. There is really not anything bad happenning geometry wise here with the lowering, the concerning thing to me would be how close you are getting to the bumpstops - only 40mm of bump travel to play with.

I still have a little more work to do on my Castor measurement rig before I can post caster curves.

I have now plotted the bumpsteer curves using the 3 differnt steering arms fitted to the HQ to HZ (and a9x) stub axle as shown above. The A9X setup is close to ideal - this is measured using 3 degrees postive castor - Interrestingly this setup would be pretty much ideal bumpsteer if I took the castor up to approx 4 degrees, the UC arm would be the pic of the arms if I backed the castor down to approx 1.5 degrees positive (which goes against one of my missions here)

These pics compare the Torana Stub axle to the HX (same as HQ to HZ)the Stub on the left is Torana. Note the different ride height. KPI is 9 degrees on the Torana and 7 degrees on the HX. You also get a 30mm drop in ride height using these stub axles.
I will have to redraw the Rollcentres for the Torana stubs as I worked them out based on a 25mm height difference between stubs but they are still pretty close anyway.

The bumpsteer curves shown above indicate that the tie rods are pretty close to the correct length as the bumpsteer is not too bad. This is good as I am really starting to get a sensible baseline to go by and some comb�'s of parts are starting to look interresting for what my goals are here.
It is looking like the Power steer setups will work if my gut feel is right.

There is numerous other combinations of castor settings and camber curves I could plot to do absolutely every combo just for completeness but at this rate I will never get the PS fitment done so I am pressing on from this stage.

The obvious combo's I havn't tried is the standard LH/LX setup running standard Camber and castor alignment setting and the UC Torana setup with the UCA's mounted as low as you can get them - I may do these later if there is enough demand but not needed for my purposes.

I found some nice short Tie rod ends from a Mitsubishi Magna which have the correct thread and look to be the correct length for my purpose - still needs the torana steering arms reamed out to suit but that is easy enough.

My spare subframe is now on the test bed and ready for PS fitment, it has the Torana engine mounts still on it so it is better suited to checking how power steer will fit up for a regular Torana setup...(anyone want to loan me a 253 block, sump and engine mounts?)

To make accurate measurements on my spare subframe,I wanted it straightened as it was 2mm narrower than my other one so I set it up in a mates press.

It pressed it out to the correct measurement fairly easily but a bit of advice if you are doing this.
This subframe was dented from underneath - if you have the same issue, I would recommend pulling out any big dents before pressing straight - I did not do this and the dent "popped in" about 2 times as deep.

I have plotted out the adjustable camber and castor ranges on the UC front end, and then repeated the process with LH/LX upper control arms to see the difference.

As part of my baseline measurements from the UC, I have taken measurements of my balljoint and control arm lengths etc and drawn up diagrams to locate the roll centre in the front end and what effect all my options of camber curve will have.
I have just measured the difference in hieght between the Torana and HX stubs and the difference is 30mm (not 25mm as I used in these roll centre scketches)so the ones for the Torana stubs are slightly out. I will have to redraw these shortly.

First one is the standard UC Torana setup as accurate as I could workout from measuring my car. It is a bit hard to see at that scale but the roll centre is 49.97mm above the ground.

This second diagram has the upper control arms drilled 1"lower as per the a9X's - the roll centre has move up by 4mm to 54mm above the ground. I have had this discussion about how this change effects roll centre with a few people so this is sure to generate a bit of discussion.

Next sketch shows the effect of putting the spindle extender on the Std UC setup. Again, the roll centre goes up, to 147mm above the ground. If I use the spindle extender and a CRS 2" drop stub, I end up with the front roll centre 171mm above the ground (this sketch not shown)- this is the sort of figure I was hoping for.

The next pic shows what happens to the roll centre if you lower the front of the car 2" on a std UC setup. The roll centre has now gone to about 5mm above the ground.

I have now pulled the test setup all apart and wirebrushed the bare subframe to almost bare metal.

then nicely primed to stop it rusting.

I have now taken sufficient baseline measurements to do the power steering conversion so I am going to move on.