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Old 09-04-2013, 05:54 PM
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Too Quick MII Steering on 54 Chevy

I am about out of ideas. I have a 54 Chevy with a bolt in MII type front suspension. It is set at 3 degrees caster, slight neg. camber and 1/8" toe in. It has Monroe shocks on it and a Chassis Engineering front sway bar. It also has a 3 turn lock to lock rack and a 15" steering wheel.

The rear suspension has the standard 1 3/4" leaf springs with two short leaves removed to de arch the springs some and give me a lower ride height. Also has 1 1/2" lowering blocks and a CE rear sway bar. I have been through 3 different sets of shocks and am now using a set of Monroe's for a 2000 Crown Vic with Touring suspension.

The car tracks reasonably well and corners very well. The problem is that the steering is too touchy. It only takes a small amount of input for it to turn a curve in the road....less than any other vehicle I've ever driven on the road. Some of it feels like the rear is steering. I.e. when you turn the wheel, you feel the rear start to turn before you feel any slip angle build in the front tires.

I have put plastic bushings in the rear springs and I have shimmed the relief valve in the Tuff Stuff power steering pump. It had 4 shims, it now has 6 and I can't tell any difference.

When I first got the car, it had no sway bars and soft rear shocks. Also. The front end was too low and I got a lot of bump steer. Also, a cross wind would move you over abruptly and quite a distance. Scary. Now, it drives pretty well except that the steering is simply too quick. I hate to put a manual rack in it and I'm not sure that would change anything.

Ideas? Are the narrow rear leaf springs deflecting? I sure would love to get this last item off my punch list.

Thanks!
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Old 09-04-2013, 06:42 PM
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You probably have an Ackerman "problem",a MII was a lot shorter than your Chevy,although I've installed MII under about everything in my shop,sometimes on a longer WB car it will act that way. You should be able to draw a theoretical line from the front spindle tie rod end,through the center of the bottom ball joint,and end up in the center of the rear end,you will probably end up a few feet in front of your rear on the Chev. On straight axle cars,sometimes you can heat and bend the spindle at the tie rod to correct this.On a rack and pinion front I'm not sure that would be possible.
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Old 09-04-2013, 07:10 PM
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castor

My guess would be you need more castor, If you do a search here on hotrodders Mustang II alignment you will get a lot of info
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Old 09-04-2013, 07:20 PM
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My alignment tech said he put all the caster he could get into it. I would have to make some mods to get more.

Ackerman, huh. I sure hadn't considered that but it makes sense. I will definitely give it a look.
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Old 09-05-2013, 04:14 PM
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It will be this weekend before I can properly check out the Ackerman theory. Lets just say it is off....and I don't want to bend the steering arms yet. Wouldn't zero toe or toe out help it be a little less sensitive rather than toe in?
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Old 09-05-2013, 04:56 PM
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Copied and pasted from the Tuff Stuff website.......

Is the PSI the same in all pumps?
No, at Tuff Stuff we currently carry pumps that are valved at 1200-PSI and at 850-PSI. Most applications will accept the 1200-PSI pump, with exception of the Mustang II rack, which uses an 850-PSI valve (Tuff Stuff #6174)

Rockable, is this the valve you're using? Do you have a pressure reading on the system?
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Old 09-05-2013, 05:06 PM
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To me it sounds like a too much pressure problem. I have a 51 Chev with a Mustang 2 P.S. rack and when i first took it for a ride it steered so quick it was scarey. I found an article in a rodding mag explaining how to de pressurise a Chevvy pump to give you back some road feel and control. I think i added 8 shims to get down to where it is now. I can feel the road again when driving.
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Old 09-05-2013, 05:10 PM
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Quote:
Originally Posted by 51 styline View Post
To me it sounds like a too much pressure problem. I have a 51 Chev with a Mustang 2 P.S. rack and when i first took it for a ride it steered so quick it was scarey. I found an article in a rodding mag explaining how to de pressurise a Chevvy pump to give you back some road feel and control. I think i added 8 shims to get down to where it is now. I can feel the road again when driving.
It makes me nuts to think that any hot rodder who has the wherewithall to do an engine swap and/or suspension swap, doesn't have the wherewithall to make up some mounts to bolt a Ford pump onto the motor, one with the proper pressure in the first place. WTF?
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Old 09-05-2013, 05:27 PM
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Well, first off I did not build this car. I bought it to drive while I finished my 41 Plymouth. A year and a half later, I'm still sorting out things that were not done to my standards. I found out it is easier to build one right than fix someone else's half done job.

I don't know the model number of the TS pump and don't know where to look for it. What I do know is that it had 4 shims on the relief valve. Mi added 2 more to further reduce the pressure and it didn't change anything. Nhonestly, I don't think that is the problem but I could be wrong.

Anyone know where the number is stamped? Mi could put two more shims in it if you think that will make a difference. I have them.
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Old 09-05-2013, 06:02 PM
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I had a 47 Chevy with similar problems. I modified the bolt slots on the hats so I could get 6 degrees caster, and set the toe to 1/16". That cured the problem.

If you can find a Dodge Omni PS pump it's a GM Saginaw pump factory set at 850 psi. All you need is the valve out of it.
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Old 09-05-2013, 06:37 PM
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more info

I have read that some of the T bird racks interchange and will take the Higher Pressure.
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Old 09-05-2013, 06:41 PM
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bolt in ?

I would have thought that a bolt in kit would have had enough adjustment designed into it, You might have to pull the upper A arms and slot it a bit more, Mabe the lower strut bracket was not welded in the right spot.
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Old 09-06-2013, 06:47 AM
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Quote:
Originally Posted by timothale View Post
I have read that some of the T bird racks interchange and will take the Higher Pressure.
I put the later model MII rack in my '38 and the pressure reducing valve from Speedway in the Saginaw pump. It's still a bit touchy. I don't have the spec sheet handy for the alignment specs.

1/8" toe with modern radials seems a tad more than necessary. That alone can add to a "darting" feeling in the steering.

Nice looking car and you have the "look of a rake but the added weight on the front may require increased air pressure in the tires. I find most modern tires now spec 44-50 lbs of pressure for max weight capacity. This means the old standard of 32-35 lbs in the steer tires may not be enough, causing excessive sidewall defection and poor handling. I have found that running more pressure helps eliminate some "mushy" or wandering feel from the steering too.
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Old 09-06-2013, 07:02 PM
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Quote:
Originally Posted by Too Many Projects View Post
I put the later model MII rack in my '38 and the pressure reducing valve from Speedway in the Saginaw pump. It's still a bit touchy. I don't have the spec sheet handy for the alignment specs.

1/8" toe with modern radials seems a tad more than necessary. That alone can add to a "darting" feeling in the steering.

Nice looking car and you have the "look of a rake but the added weight on the front may require increased air pressure in the tires. I find most modern tires now spec 44-50 lbs of pressure for max weight capacity. This means the old standard of 32-35 lbs in the steer tires may not be enough, causing excessive sidewall defection and poor handling. I have found that running more pressure helps eliminate some "mushy" or wandering feel from the steering too.
Thanks. The car doesn't have that much rake now. This picture was taken by the seller. I will definitely play with toe and pressure some.
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Old 09-06-2013, 10:17 PM
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more castor ?

You might be able to add some large washers-spacers to the lower strut mount to push the bottom ball joint foreward to get more castor. probably easier than pulling to upper a arms and increasing the slot size
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