Thread: Improving manual steering

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I have manual MII steering on my 37 Ford, and I was wondering if anyone had any tips on how to improve ease of steering before I spend several hundred and many hours putting a power rack on it?

I've been running it with 25 psi in the front tires (205 width) because some other rodders recommended that to improve the ride since the car was so light. I'm sure that is part of the problem. It drives great at speed, but it takes two arms and some effort to maneuver in the driveway and in parking lots. I thought about a bigger steering wheel for leverage, but wasn't sure if that would be worth the money.

bigger wheel will work more air in the tires will work but I'd just put in a power rack

You can determine your ideal tire pressure by taking a portable air bottle and a piece of "driveway chalk" (big sticks made for kids to color) to a big, empty parking lot. With your tires aired up to maybe 28psi or so, chalk a line across your tire tread side to side, then drive about 100' on pavement, stop and look at the mark. You should see the center worn off, leaving chalk on the outside (tire is crowned out). Let out 1 or 2 psig, re-chalk and do it again, repeating until it is wearing evenly across the whole width. If you get to the point where it's leaving chalk in the center you let out too much - add 1psig back and try again. This will put your tire contact patch even, maximizing both traction and tire wear. Any higher pressure will wear the center, and any lower will wear the outside edges.
A larger steering wheel will definitely help your steering effort if you have room for it while maintaining your driving position. You said "power rack", so a longer pitman arm is not an option...

Measure the wheel diameter....stock is 17" but an aftermarket column addition probably resulted in a 15" wheel.....and a Mustang II front end is probably harder to turn on a heavier car anyway. Going to an original wheel will result in a
8.5/7.5 = 13% improvement in leverage..... wider tires probably dont help the bicepts either.

Check your caster , too much will steer hard .

Thanks for the tips. I'll play with the tires pressures, check the caster, and look into a bigger steering wheel and go from there...since those are the cheapest and least labor intensive options.

Andy,
You would not want to drive on the road, but I would probably try clamping a 3/4" plywood "wheel" to my smaller steering wheel, maybe using some padded u-bolts on the rim or spokes, to experiment with different diameters of wheel to see how much improvement you can expect. Lots cheaper than buying a new wheel, and you can start big, try it and then trim it down an inch to see what difference it makes. Just a thought...

That '37 is not really that light in the front end as the engine is fairly well forward. Now, what you don't say is what ratio the unit you have on your car is currently. I believe most aftermarket versions always seem to be the fast 15:1 where all you probably need is the OEM style 20:1 ratio. An added bonus with the 20:1 is that any bump steer doesn't have you fighting to stay in a straight line.

I increased the air pressure to 34psi, but I can really tell much difference.

How can you determine the ratio on a rack? If I can improve that, that would be a big help.

As far as the caster, I originally set everything to MII specs. I can't recall what those numbers are at the moment, but I'll find out what kind of caster it was.

I also checked, and my steering whell is already a 14", and there aren't many out there over 15" for an application like this. Seems like I'd have to get a 16" to make it worth it.

I hope you have good solid tooth fillings w/34psig

You might be lucky and have the ratio stamped on the rack, possibly the end caps, but here is a good way to calculate the ratio, but it does require some equipment.

Drive the car on some alignment turntables and set them to zero, both sides. Turn the steering wheel exactly one full turn either way. If the read out is, say 36 degrees (for ease of describing), you then using 360 degrees, then divide with the 36 degrees you then come up with 10:1 (yeah, I know!!). 18 degrees divided into 360 would then be 20:1.

A note though, alignment specs will show different for each side, but you can average (guesstimate) and be close enough.

My guess is that you have the 15:1 making stiff slow speed turning (or maybe it just needs a good grease job

I've been snooping around and have seen where some retailers show the "lock to lock" turns of their manual racks. I've seen everything from 3.5 to 4.15. I'm hoping I have the 3.5 (15:1). Looks the 20:1 is 4.0. I'm not sure about the other ratios. I guess those are custom designs because they seem to cost more.

That's probably an OK assumption - that is until you get to the length of the steering arms which become part of the equation to compute the actual ratio and then becomes steering effort. By using the turn plates you can figure your exact (or at least pretty close) ratio.

Short steering arms = tougher steering, long - you know the rest.

I would look for 4 turns or more lock to lock for non assisted steering (just found out mine is 14:1 - curiosity while answering your post)

I'm not sure what you mean by steering arms.

Just by looking at over a dozen different units, I figure the easiest way to compare them is to dive the lock to lock by the travel length. That will give me a turns per inch of travel. This way I can compare apples to apples, detmine what mine is and try to find the unit with the larget turns per inch value.

Andy,
On older spindles the steering arm bolted on, providing the connecting point for the tie rods. Most IFS it is the steering knuckle, forged as part of the spindle assembly. The geometry of the steering arm/knuckle affects the turn ratio, speeding it up or slowing it down in proportion to the distance from the spindle centerline. Lock to lock vs travel length gives you one part, but travel length to degrees of turn is another piece of the puzzle as Dave points out. Your way will let you compare racks which may solve your problem.

Well, it appears I already have a 20:1. The wheel turns about 3.9 times before it completely stops. There's about a tenth of a turn on each end where you have to put a more effort in to get that last little bit. I'm not sure if that counts or not. Either way, I have at least a 3.75, with 5" of travel, so it wouldn't be worth it to buy another rack. It just doesn't make sense that it should be hard to steer. I'm just going to have to jack it up, check the caster and camber, and make sure everything is greased and operating freely.

I understand now about the steering arms. I just have the aftermarket single-piece forged spindles. I can't find anything where they define the steering arm length, and I don't see where different lengths are available. They all appear to be the same, geometry-wise.