Vintage Mustang Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
118 Posts
Discussion Starter #1
Guys and gals: Can you please help me one more time on my epic saga of improving the power steering on my 1970 Mach 1 ?

Here is the background ( very long story made somewhat shorter ): Back in 1988, two mechanic friends helped me to install a PS parts kit on my car. Roger Rode in Ohio sold me the kit and said that I should also change the manual gearbox to a power gearbox, but that it was not mandatory. I did not change the gearbox because it seemed like we would almost have to remove the 351C engine to get it out.

The rest of the install went A-OK, except that we had to fabricate a large bracket to hold the threaded end of the power piston in place. The smaller Ford bracket had torn loose from the left front chassis member on our first test run. The PS system worked very nicely, did not leak, but the turning circle radius of the car went up noticeably. I just chalked this up to the fact that I did not switch out the gearbox. ( Wrong )

Fast forward to 2003, the Summer which I had planned to do many, many resto projects on my beloved Mustang. Amazingly, I noticed for the first time that the Pitman arm was contacting the big bracket that we made, and I thought that this was the culprit in keeping ther car from turning fully. So I took the bracket off ( giant headache by itself ) and took it down to Georgia to my brother who ground it down.

But upon re-assembly, imagine my surprise when the Pitman arm now does NOT contact the bracket at all, but the steering still does not turn any further whatsoever !! Hhmmm ! Now I am thinking that the steering gearbox was not properly centered when we did the original install.

So last night I pulled off the Pitman arm, dropped the center link, and centered the steering gearbox. The manual gearbox will turn five complete turns from lock to lock. When I took it off, it had three turns to the left and two turns to the right, which seemed to corroborate my thinking, especially since the car can turn left much sharper than it can turn right.

Now, here is the final surprise ! After I centered the gearbox last night and tried to re-install the Pitman arm, I had to turn the wheel darn near one complete turn before the splines on the Pitman arm could be aligned with the splines on the gearbox shaft !!! In other words, the gearbox shaft does not seem to turn very much at all in relation to the steering wheel ! From other posts, I believe that the gearbox has a 16:1 ratio ( sixteen turns of the steering wheel would turn the Pitman arm shaft one turn ). Therefore, since the steering wheel can turn five turns, the Pitman arm shaft should be able to turn 5/16 of a turn ( about 1/3 of a complete turn ).
I am using up a huge amount of the 1/3 of a turn just to get the darm Pitman arm to re-align back on the splines !!!!

Am I reading this situation right ?? Who can give me some helpful hints and advice ??

Could the gearbox be so old and shot that there is tremendous play between the steering wheel going around and the Pitman arm shaft not going around as much as it should ??

Any help is MUCH appreciated ? ( Pray for me, too ! )


-Jeff
 

·
Registered
Joined
·
3,363 Posts
Wow! That is a saga! Jeff, have you looked at adjusting the steering box, and taking some of the play out of it? That might get rid of some of the slop.

Did you PS kit come with a new center link? I think they are different from MS to PS.

The location of the ram mounting point could also be contributing to the overall stroke not being adequate to get a tight turn.

I have standard PS and am not happy with my turn radius either. After I got my car back and on the road after many years, I forgot how large it was, and hit a curb and ended up crushing my headers!!

Good luck.
 

·
Registered
Joined
·
118 Posts
Discussion Starter #3
Feex, thanks for the reply.

Yes, the center link was replaced with a PS center link back in 1988. And I did adjust the current manual gearbox earlier this summer to eliminate the play in the steering wheel, which behaves nearly perfectly under all driving circumstances. The problem is that the car has a wide turning circle when turning to the left and a very wide turning circle when turning to the right. I have also experimented with various washers on the power piston rod bracket so as to move the actual fixed mounting end point for the piston ram.

Back to the specific question of the day: Shouldn't I be able to re-align the splines on the Pitman arm with the gearbox shaft just by turning the steering wheel very slightly to one side or another of dead center ?? Shoul I have to turn the steering wheel almost one full turn to get the Pitman arm to align back up ???


-Jeff
 

·
Registered
Joined
·
935 Posts
There is another adjustment you might check.
The Control Valve/Ball Stud assembly screws onto the end of the centerlink. There is a certain point where it is correctly mounted, making the Control Valve/Centerlink assembly the correct length. If you do not have it threaded on far enough, the steering box may not be able to move the linkage as far one way as it does the other before you run out of travel in the box.
Measuring from the centerline of the Ball Stud (or the grease fitting ditectly underneath it) to the centerline of the hole on the centerlink where the LH inner tie rod goes - needs to be 5". Any more or less effectively changes the "length" of the centerlink and affects how far the steering box can move the linkage.
 

·
Premium Member
Joined
·
19,215 Posts
I may be cracked up, but here's my guess:

You can adjust your tie rods to accomodate the new pitman arm/steering box alignment that's now off-center from your present positioning. Does this make sense?
 

·
Registered
Joined
·
118 Posts
Discussion Starter #6
Got yet another amazing revelation last night working on the PS problem. Guess what ?? The Ford engineers are smarter than the average bear ! The splines on the steering gearbox output shaft can only match to the splines on the Pitman arm in ONE way. I looked closely at the gearbox output shaft last night ( on my back, chin pressed up into some piece of metal underneath the car, thinking what a great 911 episode this could be if ..... ) when I noticed that the splines are not uniform. At each 90 degree point going around the output shaft, the spline is twice or three times as wide as all the other splines. Correspondingly, the Pitman arm has a gap at each 90 degree point that accepts the wider spline on the output shaft !! In other words, you cannot mis-align the Pitman arm unless you put it on 90 degrees out of whack !!!

Guess what else ??? In the glare of the trouble light, I happened to glance over at the left tie rod end. Hhmmmm !! It dawned on me that there were no threads visible on the tie rod coupler that mates to the centerlink. That's interesting, I thought to myself !

Then I wiggled out from under the car and went over to the right wheel. Wow !! It looks like the tie rod coupler has almost all of its threads visible !! In other words, the tie rod adjustment is almost maxed out in a left hand turn bias.

Now, in my optimism, I am hoping that if I take the car to have it re-aligned WITH THE STEERING GEARBOX CENTERED, it will return the car to a normal turning radius in BOTH left hand turns and right hand turns.

I have been working on this PS problem since May. Can somebody please have their wife or GF send me a box of chocoloate chip cookies as a reward for Mustang persistence ???


-Jeff
 

·
Registered
Joined
·
3,363 Posts
How about some delicious locally made chocolate covered potato chips or pretzels??? Send me your addy. You too Mid!

This has been a very informative thread. New things to check on mine! ::
 
1 - 8 of 8 Posts
Top