PLEASE Help - Power steering just not right on my 65 Fastback

Hello everyone my name is Rick from Northern, KY... I am a total newbie when it comes to this message board stuff so please bare with me.... Just about one year ago I bought a 1965 Mustang Fastback 289ci 4 barrel 4 speed. The car had been stored in a barn and had not run for almost 20 years. I now have the car running, and drivable. I had to rebuild the entire front suspension and found it very difficult to get many of the parts for a car that was equipped with power steering. The biggest problem so far has been with the steering. The car wants to wonder left to right while being driven. It seems the steering is always trying to correct itself one direction and then the other. Its almost dangerous. I have been working with a neighbor who is a car enthusiast and a damn good mechanic. We have not been able to solve this problem. Below are his comments as to what we have done to date. I would greatly appreciate help from anyone who has experienced similar problems including what you did to resolve it. The car has a factory Ford power steering pump and as part of the chassis rebuild the steering valve, cylinder, and all other components were replaced....

The V8 front end has been completely rebuilt with new parts, All new except the spindles and the PS pump.

The problem is that I cannot get the power steering to work correctly. below is the work tried...

When I installed the new parts "as is" the steering would pull hard to the right. Adjusting the nut on the out side of the valve only made is worse. I modified slightly the length of the valve to help mechanically center the valve in the valve body. This worked well and the system is balanced. car drives well. But the power assist is almost non existent! It's there but you still need to muscle the wheel in a parking lot. Installed the rubber bumpers from the old valve into the new valve. They were about .015" thinner than the new ones. This provides great balanced power assist. But now the car drifts terribly on the road. Hunting constantly. My thoughts are that; When the valve is loose enough to move and provide power assist, it also promotes "hunting" on the road as the steering is not ridged. Pitman arm is not tight to the drag link. Instead it moves the steering valve first..This causes one to constantly fight the wheel. When the valve is set up tight, the pitman arm is ridged to the drag link and provides good steering on the road. But it no longer moves the steering valve enough and there is little of no assist!

The car was never driven before the new parts were installed. So I cannot compare how the power steering should perform. The wheel alignment has been and checked verified to be good twice. A local "Mustang" shop tried to fix it but they only made it worse!

LMan said:

Did you align the front end to spec after installing all the parts?

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65 fastback said:

I don't think the problem is in your power steering. To me it sounds like you have one of two possible problems:
1. Not enough Caster in the Alignment
or
2. A Bumpsteer problem

What Alignment specs did you have the alignment set to? The stock alignment specifications were good for the bias ply tires of the day. Today’s new radial tires will accentuate the poor manners of the stock suspension's geometry.

The original stock alignment setting for '64 - '66 Mustangs are:
Caster: -0.5*
Camber: -0.5*
Toe-In: 9/32"

The Performance alignment settings are:
Caster: +1.5° to +2.5°
Camber: 0 to -.5°
Toe: 1/8"

The biggest difference being in the Caster setting. A positive Caster setting will help the car to track straighter and return to center more quickly after a corner. The easiest way to describe it would be to think of a bicycle and angle of the front wheel fork. If the fork that connects the handle bars to the front wheel were to be straight up and down (0 degrees Caster) you would constantly need to steer to keep the bike going in a straight line. Now if the front fork were installed at an angle (think chopper - Positive Caster), you could take your hands off of the handle bars and the bike would continue to track in a straight line.

So even if you have not done the "Shelby drop" modification, you will still benefit from an increase in Positive Caster in a street driven car. I would suggest at least 2 full degree positive caster.

The other possible issue could be a bumpsteer issue, but this does not generally show up unless the front suspension is lowered and low profile tires are used. What are your front end components and tire sizes?

Post a little more information and I'm sure we can point you in the right direction.

Tim

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Tim, thank you very much for your detailed and useful reply. The car has been aligned twice. One on 9/17/05 and the second one on 11/19/05. I actually took pictures of EACH different alignment, thinking you would understand it much better to see it rather then me try to type it all out. Here are the two different alignment sheets....

Alignment on 9/17/05 -




Alignment on 11/19/05 -




As you will note the caster was increased on the second alignment to 2.5 left, and 2.1 right. The alignment tech claimed this was all the caster he could get out of the alignment. It made ZERO improvement to the wandering. The car does have radial tires ( P185/75/R14's ). The tires are about 50% worn, and they are not meant to be my final tire selection. The front end has all factory style GT components, including a 1 inch swaybar. The car has NOT been lowered. Again, thanks for your help and great input.

TheEvII said:

did you adjust the steeing box on your car?

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No... I was not aware that it was adjustable. There is minimal play in the steering box. I will talk with my mechanical buddy and I will look at the FORD Factory Repair manual and see if we can try your suggestion. Thanks much for the help.

If any of you all would like to see pictures of the 65 Fastback that we're talking about in this thread, please click on the link below to where I've posted up pictures of the car.

http://forums.stangnet.com/showthread.php?t=637055

65 fastback said:

fastback1965,

It seems that your alignment tech was thinking in the same direction as I am. Also, 2.5 degrees positive Caster is probably all you are going to be able to get out of a stock suspension set up. The one thing that jumped out at me while looking at your two separate alignment specifications, is the change in the final setting on 9/17 to the initial setting on 11/19 - these settings should be close to identical.

9/17 - Lft Frt Camber final - (+0.7) / Rt Frt Camber final (+0.7)
11/19 - Lft Frt Camber initial - (+0.7) / Rt Frt Camber initial (+0.9)

9/17 - Lft Frt Caster final - (+0.4) / Rt Frt Caster final ( 0.0)
11/19 - Lft Frt Caster initial - (+1.1) / Rt Frt Caster initial (+0.8)

9/17 - Lft Frt Toe final - (+0.26) / Rt Frt Toe final (+0.26)
11/19 - Lft Frt Toe initial - (+0.07) / Rt Frt Toe initial (+0.20)

Your final and initial Caster settings show a pretty large margine. Was any front end work done between the alignments? Also, there is a pretty significant change in the Toe setting on the left front. If there was no work done between alignments, you might have some worn or loose components.

Also, can you describe how the car "wonders" more?
Does the car seem to dart to one side or the other if you cross the crown in the road?
How does the steering react under hard braking (apply the brakes agressively enough to get the front end to dive)? Does the car track straight or want to pull to one side or the other - or want to twitch back and forth to each side?

Instead of trying to explain Bump Steer, here is a link to a site that may be of use - http://www.thedirtforum.com/bumpsteer.htm . Check your Tie-Rods to make sure one of them is not bent (especially the left side) - that could lead to bumpsteer issues.

Does your steering wheel have a "dead spot" at top dead center? How much play do you have in the steering wheel before the wheels actually start to react?

Also, with your 75 series tires make sure they are properly inflated, as the side walls may be rolling a little, if the tires are under inflated.

Tim

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Tim - Im going to copy and past an e-mail that my mechcanic sent me to your reply above. I hope this answers all of your questions.

" First to add that the car did not drift when the valve was installed with the new rubber bumper cushions. No drifting, but little to no power assist. And very unbalanced power assist.
No that the power assist is adequate (still not perfectly balanced however) the car wanders at a speed of 40 mph and above.

seems that your alignment tech was thinking in the same direction as I am. Also, 2.5 degrees positive Caster is probably all you are going to be able to get out of a stock suspension set up. The one thing that jumped out at me while looking at your two separate alignment specifications, is the change in the final setting on 9/17 to the initial setting on 11/19 - these settings should be close to identical.

9/17 - Lft Frt Camber final - (+0.7) / Rt Frt Camber final (+0.7)
11/19 - Lft Frt Camber initial - (+0.7) / Rt Frt Camber initial (+0.9)

9/17 - Lft Frt Caster final - (+0.4) / Rt Frt Caster final ( 0.0)
11/19 - Lft Frt Caster initial - (+1.1) / Rt Frt Caster initial (+0.8)

9/17 - Lft Frt Toe final - (+0.26) / Rt Frt Toe final (+0.26)
11/19 - Lft Frt Toe initial - (+0.07) / Rt Frt Toe initial (+0.20)

I gave it some thought and nothing was done to promote any change in the alignment during this period. Any differences must be a result of either.
New bushings in the upper and lower control arms taking their "Set" positions.
Ride height changing slightly as new coil springs were installed. And the car was aligned just a few days afterwards.
Adding or reducing the air pressure in the rear air shocks. Which may have been done. And If the alignment shop did not correct for frame/body angle.
Error in the alignment process.
Uncertainty of the alignment equipment. Nothing is "zero" and repeatable in any equipment period.


Your final and initial Caster settings show a pretty large margine. Was any front end work done between the alignments? Also, there is a pretty significant change in the Toe setting on the left front. If there was no work done between alignments, you might have some worn or loose components.

Also, can you describe how the car "wonders" more? car drifts left. turn wheel right slightly, car turns to the right, turn wheel to the left, car goes left, turn wheel right, car goes right. etc...
Does the car seem to dart to one side or the other if you cross the crown in the road? No
How does the steering react under hard braking (apply the brakes agressively enough to get the front end to dive)? Does the car track straight or want to pull to one side or the other - or want to twitch back and forth to each side?

Instead of trying to explain Bump Steer, here is a link to a site that may be of use - http://www.thedirtforum.com/bumpsteer.htm . Check your Tie-Rods to make sure one of them is not bent (especially the left side) - that could lead to bumpsteer issues. All the tie rods are new and no contact has taken place with any other components. Further the problem occurs on a flat level road so I do not feel bump steer would be a factor in this case.

Does your steering wheel have a "dead spot" at top dead center? How much play do you have in the steering wheel before the wheels actually start to react? About 10 degrees movement when the wheel is centered. Less as the wheel is turned to either extreme.

Also, with your 75 series tires make sure they are properly inflated, as the side walls may be rolling a little, if the tires are under inflated. "