Don't forget that when your hands are on the steering wheel there is a moment arm of 6 or 7 inches that reduces the force you feel. So your comparison isn't really valid.

As was stated in the above post, there is a 6 or 7 inch lever arm that you're dealing with when using the steering wheel. This will reduce the force that you feel. Imagine you're driving down the road at 80, 90, or maybe even 100 (come on, it's a sports car, 100mph isn't unheard of), and you hit a bump/pothole/expansion joint. You've got 50+ pounds of mass in each wheel, plus (what i'm assuming is a good assumption) sticky ass r-compound tires. The tires won't let go, so the force is absorbed by the sidewall, the mounts, and the gear itself.

Now on to the torsion bar. It is made to actuate the valve. The valve routes pressure to the correct side of the piston, turning your wheels. The t-bar in a power rack isn't designed to turn the car without any hydraulic pressure. When you have no pressure, the t-bar does ALL of the steering of your car (it's the only mechanical link between your steering wheel and your pinion). There are no stops to prevent the torsion bar from winding up excessively when there isn't any hydraulic pressure, and why should there be? If there were stops, you wouldn't be able to use all of the steering capability of the rack, and that wouldn't be very safe, now would it?

Finally, the pinion. Case hardening is only ~.005-.001" deep. The internal material microstructure hasn't been changed by the heat treatment process, which means it is just mild steel under that very, very thin top layer. All it will take is one good hard impact without any hydraulic pressure to absorb the energy to split through the brittle top layer. After that, the mild steel will fail very quickly. When you're running a manual rack, you must have a through hardened pinion to keep things safe, because there is no hydraulic pressure pushing the rack side to side, absorbing the steering force. The pinion is taking all of the steering force, and if you don't have a through hardened pinion, it will fail very quickly.

I will concede that a full conversion is safer than looping the lines, because the torsion bar is taken out of the equation by welding the input shaft to the pinion. The vast majority of the time, there is absolutely no warning for when the torsion bar will break.

The way that we test the t-bars is by fixing one end of the bar, and using a motor with a cam mounted to it's output shaft, adjust so the t-bar will load up to a certain angle. To test for failure, we check the torque required to reach that angle. Anything over 20% loss in torque is considered a failure. Most of the time, when the bar is heat treated, it will keep torque up until the very end, and then it will break. No warning. Nothing. Sometimes, the torque will fall off, but that is very rare.

Before I started at the company, they were doing max input torque testing on the input shaft. Just for S&G, they took a few guys from the steering group over to the test building, mounted a torque cell on a gear with a steering wheel on the other side of the torque cell, and went at it to see if any human could break it with just a steering wheel. They set the rack at one of it's stops, and twisted. All but one of them averaged between 100 and 115 newtons. One of the guys was like 6'6, 250 and a body builder. He put 155 newtons into the gear and managed to snap the input shaft. That is a non-welded, heat treated input shaft.

How they took the t-bar out of the equation is beyond me, but he snapped the input shaft, not the t-bar.

interesting

Anyone have the pictures from the first post?

Heres the pics again, sorry for the delays

more

Hi folks-

I've got a problem....I've gotten everything off according to the writeup, including the end cap on the long end after removing the wire retainer. However, when I try to remove the rack, there's a positive stop preventing me from pulling out of the carrier. Anyone know what this could be?

Thanks,
Chris

Figured it out, thanks much to Bacon.
c

Anytime,

Once you get it torn down to the point you pushing the rack out, you will have to hit it from the opposite end pretty hard to get the seal out. It may seem like you hitting it pretty hard but it needs a few good shots. Don’t worry you wont hurt it
:-)

One more thing :^). I know I saw this on a search, but I'm still looking 20 minutes later. Anyone got a pic of the weld that needs to be made to the quill?

Thanks,
Chris

i have a picture somewhere i can dig up. its pretty obvious where to make the weld once u have it all apart though

:-)

https://www.rx7club.com/attachment.p...0&d=1214424612

other side
https://www.rx7club.com/attachment.p...1&d=1214424984

bacon wins a crispy slice

Killer, that's what I was looking for. Have a great eve fellas.
c

Sorry to resurrect this, but I thought people would be interested. To remove the huge hex cover, the head of a 1/2x13 bolt (snagged a grade 8 one from lowe's) fit perfectly. You just put the head of the bolt in the hex, put two nuts on the bolt, and then crank on the nut closer to the bolt head. It took some serious muscle, but it gave before the bolt did. This way you don't have to weld a fakey SST.

^ THANK...YOU...SIR !!!

ill be giving that a go this weekend....

So I am curious as to the points that were mentioned by whitey.. It seems that research study was well executed and the data should have a good deal of validity. BUT I am curious of those who have been using the Maval rack, AND those that have done this conversion themselves....Has anyone experienced failure?? I would really like to hear from a few that track thier cars on a regular basis as this is going to provide the most stress to those components than just normal city driving.

Even if whitey is perfectly correct from an engineering standpoint, it doesn't seem to match with real world data. He suggests that failure is only a matter of time, but I've never heard of the failure of a single manually converted rack. He also said that a looped line setup is even worse and people do that all the time with no ill effects.

For me, if Damian runs this conversion on his track car and hasn't had any problems with his huge tires I'm sold.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/power-steering-removal-catching-up-writeups-part-3-a-448757/

So is there an actual Manual rack that is made without an "conversion"?

I know Mustangs and other various cars have companies that produce manual racks.

Yes but its pricey. Search on a thread from gmonsen. Atomic Rex in the UK makes it.

Yeah AR makes the $1000 billet one.

ouchhh 1000$