Changing to rack & pinion....but non standard application. Questions for the gurus!

Ok, so I'm in the process of restoring and modifying 1964 Fiat Abarth (600 based). Yeah, yeah....I can hear all the laughing! But, this will be a pretty great little Abarth, with coilovers front and rear, with wildwood brakes all around, full cage, and ready to race.

The steering box is shot, and to fit a wildwood master cylinder, it will interfere with the steering idler arm, so I'm thinking I should just go with rack and pinion for smother operation with fewer wear points. So, to do this, I have some questions.

• How do I chose the length of the unit?
• It's a Fiat, so I'm assuming the rod ends are metric...does this change which rack I buy?
• Steering column is splined, so I'm assuming I'll need to extend that, and have a knuckle depending on location/angle. Any other considerations there?
• Should the rack be mounted essentially at the same position relative to the suspension, etc, or is there some guidline for mounting location?
• Anything else that I should consider with this project?

Thanks for any guidance!

Ideally, the length of the unit at the pivot point of the tie rods would be the same as the distance between the inner mounts of the lower control arms to eliminate a bump steer issue. The rack should also be mounted so the steering arms at ride height are level with the tie rods, again for bump steer issues.

It may seem dumb but which unit you use also depends on whether the car is front steer or rear steer! A front steer car with a rear steer rack would turn left when the steering wheel is turned right, and vice versa..... It seems basic, but a local guy here actually mounted the rack in the wrong position----would be unique, but certainly present some "challenges" to driving the car!!!!

As for the splines on the column, you'll need to know the spline count and the OD of the shaft, there are a lot of different adapters made to go from the column to a Double D shaped shaft. If there's not an adapter made to fit the splines on your column you might have to do some machine work on the column end and weld (TIG preferred) an adapter to it.

Eliminating bump steer problems is probably the biggest issue on converting to a rack. I use a Bump steer gauge which is a flat plate that mounts to the wheel flange, then dial indicators, one mounted on a fixed stand at either end of the plate to make sure the wheels on the car don't turn in or out as they move through the range of suspension travel. Adjustments to the mounting height of the rack, and/or spacers between the steering arms and the tie rods can correct any issues.

I'm not all that good at putting down in words what I do in the shop....I hope my "guidance" hasn't just added to your difficulties!!!!!!

Dave covered some good points. I changed the standard steering in my GMC Safari van to rack and pinion. Here's a few more pointers. The rack should have enough travel to put the steering knuckles against their stops. The rack and tierods should be as close to a straight line as possible with the attaching points on the knuckles. Don't worry if they are a few degrees off. Just get them as close as possible. Use a rack from a vehicle that's close to the weight of your finished vehicle. Metric is no problem. Almost all rack and pinion units in modern vehicles are metric. When I changed mine I used all over the counter stock pieces with the exception of the pressure hose which had to be modified to fit a GM power steering pump and a Ford rack and pinion. If you are not using power then that's not a problem. The column link will probably need to be fabricated from scratch. I had to add an extra u-joint which meant there had to be a support to hold the column ridgid. I used a 3/4 heim joint. In my case it wasn't nearly as challenging as most would think. It's been in the van for several years with no problems. Good luck.

Tried to get to my bump steer gauge, but it's buried in the shed with no heat and the temp is 0---so here's a pic of one I used as a reference when I built mine;