Norval,
I have told the forum previously about the ETO rack I installed as part of the conversion to RHD. I can look up the dimensions for you if you want. I have zero bump steer. The main modification is to shorten the steering arms and lower the tierod end to give full steering travel and the correct angles for the zero Bump Steer.
The rack fits up near the sump and is 250mm back from the centre line of the front axle so the tierods are angled forward. I used a 4mm plate coming back from the crossmember with arms up to the chassis to mount it and it adds ridgidity to the chassis. As part of the conversion I calculated the correct achermann angle and set the steering for this as well. (It would be easy to maintain the existing achermann angles and this gives you a tighter turning circle.) You will have to shorten the column to give a straight access to the rack input instead of using an intermediate shaft like Steeroids.
I am running a BB with extractors and the motor in the original position. Because of the tight dimensions on our driver side I made the extractors around the steering shaft. FYI, most of the steering conversions here move the motor across to the centre or further. With your fabricating skills you should be able to duplicate or improve on my design.

 

You have some great information that I would really appreciate. I am looking for all the help I can get. Send me anything you are willing to share, either here or to nwilhelm@rogers.com
Any input would be certainly appreciated and used.
Thanks

 

Norval,
I sent you an eMail last week indicating that I had some layouts of the Saginaw 600 gear versus the C3 manual gear. I need your eMail address if you are interested.

I also have some detailed information on the Saginaw center-take-off rack and pinion if you want it. Rack and pinion output/input is in terms of C-factor. The movement of the rack in mm for one revolution of the input shaft. The higher the number the faster the gear.

Saginaw made two different C-factor gears 61.75mm/rev and 53.48mm/rev. The racks had two different strokes 154mm and 144mm. They came in all different T-bar sizes and valve effort rates. All of these parameters were mixed and matched throughtout the many, many years of CTO R&P production. I have all of it charted.

Jim Shea

 

I'd like to see pics to see how on earth you got the bump steer geometry right without having an awfully big angle on the tie rods (forward), what kind of rack is it? I have a 16,25" rack and it's about the right size for a normally placed rack & the tie rods sticking out straight to the sides instead of at an angle.

 

OK guys here's what I did.This was for my conversion from Left hand Drive to Right hand Drive but the principles remain the same. Some of my descriptions of measurements are longwinded to give an idea of what I am trying to say. Non technical terms because I am not sure of the correct names.
I chose an Australian Commodore rack (Right Hand Drive,Power steer, rear mount, End Take Off) whose length was 625mm from the centre of tierod to centre of tierod.(this is the pivot point on the end of the rack) This was too long so I ended up shortening it to 615mm. The distance measured between the pivot axis of the stub axles(line through the ball joints, I think this may be called the axis of inclination) at the height of the tierod ends was 1192mm. Rack travel is 130mm. The stock steering arms are too long (From memory they are 180mm) for this amount of travel so to get enough angular travel in the steering I shortened these to 140mm from the pivot axis to the centre of the tierod end. This gave me enough angular travel around the pivot axis to rub the tyres on the chassis rail. (Stops were installed after all the testing.) To get the achermann to what I calculated to be perfect, the inside wheel turns at 30 deg and the outside wheel turns at 24.30 deg. This is proportional throughout the steering travel. To get this to happen I did a suck it and see mathematical approach. I tried several different values of offset of the pivot axis/tierod end to see what happened to the achermann. For my measurements of the suspension I found that 4mm to the centre of the car worked.
By the way, I started working it out using high school trig before I got hold of Autocad and then everything was much easier

this is the static, straight ahead diagram of the steering from above.


and this is the steering with the inside wheel turning 30deg.

The tierods are angled forwards because of several physical limitations such as the length of the steering arms, the engine sump position and the position of the rear mounts of the lower wishbone. The rack had to be placed behind the wishbone mountings and under the sump to clear everything.(fairly obvious)
Once I had the Achermann sorted I measured the bump steer and it was there. By changing the height of the outer tierod end (lower, similar to what the guldstand bumpsteer kit does) the bumpsteer went away. I had to lower the outer tierod end about 30mm from memory but the suspension has no bumpsteer through out the entire travel apart from 3mm(measured at the edge of the tyre) in the last 25mm of full droop. This is with out shocks installed and they limit the full droop of the suspension. You would have to be airborne to see this part of the suspension travel.
But the tierods are not long enough to match the arc the outer tierod travels through attached to the suspension you say, true, but because the tierods are angled forward they travel through a flatter arc simulating the longer tierods. So a short tierod simulates the longer tierods arc by being on an angle forward (in a horizontal plane). Steeroids and other systems reduce bump steer by using the longer tierods and mounting the inner tierod end higher.
The angular travel of the tierod joints on the rack have to be taken into account when designing the steering or you may end up with bind in these joints(bonus points for avoiding this).
I had an engineer shorten and modify the steering arms (heat treated, Xrayed etc) because they are too important a component for me to cut and weld. He also inspected the rack set up and I showed him the zero bumpsteer. I expected him to pick my methodology to pieces but he agreed with my measurements and the results.
The rack position ended up at 256mm behind the axis of inclination. It is mounted by a 4mm plate coming back from the two holes in the rear lip of the crossmember and an arm on each side up to the chassis. I check the tierods every time I get under the car to change oil etc and none of the joints are showing wear in the three years, 10,000 miles I have had it on the road.

This is all bolted in but not a bolt in conversion, and it does show an ETO rack can work in our chassis. My steering arms could be copied and the rack mounts would need to be made for Left Hand Drive. You have a lot more room on the drivers side and could probably use a setup like steeroids to get to the rack from the column or shorten the column for a straighter angle to the rack.
Well I hope I made some sense. If you have further questions I am available between the hours of 8am and 5pm (Australian) eastern standard time for a nominal fee of $50 per non related question

 

Thanks Jim but all the information would not really help. If I went with rack and pinion I would use the one used by Steroids. It works and is center take off to allow me to use my existing tie rod lengths, that is important for bump. Stock tie rods are about 3 inches too short.
With a rack that has end take offs I am forced to use whatever tie rod works and that is not good for bump. With center takeoff I can custom tailer tie rod length.
I also need to push the inner tie rod as high as possible, agian for bump. End take off limits tie rod mounting.
As for comparing steering boxes is seems a general opinion that the Jeep Cherokee box works well and has enough pitman shaft length to work. If I went with any box it would be the Jeep Cherokee.
I just have to decide if I want to cut and weld the frame for the box or make a steroid type rack and pinion.
Thanks

 

That was very good RHD '68L89. I am trying to avoid the end take off rack to allow me adjustment of the tie rod lengths and hieight of inner mount. I feel the center take off is more versatile into where I position things. It is also cheap at $150 CDN.
I particularly like the end comment It's want I got from another party.

 

i still think you need a variable speed rack and pinion unit...i installed steeroids and its really nice...if i could have figured out how to put in a variable speed set up i would have....it was beyond my ability to make it happen but thats what i really wanted