MTFCA Forum

I have a 25 roadster. New perches, bushings, king pins, all tie rods are tight. I have the toe in set as directed. I’m running 21 wood wheels. They are not perfect, but as straight as my other cars that drive reasonable. .This car likes to wander. No shaking or vibration as everything is tight. It has 26/27 spindles. I’m not sure why these spindles are there, but that is how i purchased it. Would these lower spindles cause it to drift, or should I look at something else? I have a coupe with a complexly worn out front end that goes down the road straighter. Open to suggestions. Thanks

You need to check the caster on the front axle. The kingpins should lay back at 5 degrees at the top. This is adjusted by bending the front adius rod/yoke.

Allan from down under.

Another thing that could play a part would be the rear shackles, they need to be good as well, also check that the rear spring U bolts are tight too.

How about the front Perches being fitted back to front (left fitted to right side) this will cause the front Axle
to lean the incorrect way? The centring marks on top of the perch should be at the rear from memory. Double check to confirm
that the front wheels are actually toe in.
Alan

Check toe in.
As an aside, That 5 degree axle rake can be increased a bit to give more stability at higher speeds. Will be a little tighter steering around corners.

I’ve double and triple checked the perches. I do have rake at the top. Not sure how many degrees, but I can try to measure it. It doesn’t seem to be as much as my other cars, but they are likely more than 5 degrees. I will check rear springs to make sure they are tight I don’t see where the later lower spindles would be an issue, but was curious of others thoughts. My gears under the steering wheel are not perfect, but then again they are better than my other cars that steer better.

Quick check for axle angle is a carpenter's square on the floor & a #2 pencil - it should fit into the gap at the top of the spindle bushing.

I’m willing to bet that what you are describing as “wandering” is actually the steering not properly self-centering itself when driving down the road because you have the kingpins adjusted too tight.

Second thing that would cause a wandering feeling is if the front spring is even slightly loose in the crossmember or the crossmember is broken inside between the spring and front motor mount / spring clamp.

RajoRacer wrote: ↑

Wed May 19, 2021 9:18 am

Quick check for axle angle is a carpenter's square on the floor & a #2 pencil - it should fit into the gap at the top of the spindle bushing.

Hi Steve, I'm still learning in this hobby. Can you send a picture of what you said because I want to validate if I'm right either with my front axle as well with my 2 cars. I'm a visual person and image for me worth thousand words.

I have a late roadster with the late spindles and it steers great. Adam is correct about tight kingpins. They should be free of play but they must move freely. The same is true of all the steering connections and the steering shaft and the gears up under the steering wheel. Motor mounts need to be in good shape. If they are loose, both the rear axle and front axle can shift slightly and cause the car to self-steer. If everything is properly adjusted, suspect a lack of caster or caster split,where caster is significantly different on side due to a bent axle. Inadequate caster will cause the car to go everywhere but straight. The radius rod ball/socket condition can affect caster and axle stability. A mis-aligned steering column could bind and cause erratic steering. All parts in the steering system need to be free of lost motion, yet move freely without any binding or friction. A lack of lubricant in the system or any part of it can cause wander and other problems. Wood wheels need to have tight spokes. Any slight looseness where the pitman arm attaches to the steering shaft will cause sloppy steering. The bearing assembly at the frame end of the steering shaft must be attached to the car frame securely and should allow free movement of the steering shaft without any play.

The alignment procedure for a Model T front end is in the Ford Model T service manual pages 45, 46, and 47. Paragraphs 146-154. It shows pretty much what you can check for alignment with pictures, written information and etc.
But that takes in consideration that there is not lots of wear and the correct parts are being used.
Every T owner should have the manual for reference.

To add to the above suggestions, I would also add. A bent or sagging frame can cause a problem with the steering, because the location of the ball socket under the crankcase would be offset.
Norm

Being you have 26/27 spindles you need the correct drag link.The correct drag link is 30 13/16 in length.
Besides measuring the drag link you can point the front wheels straight forward and pitman arm should be vertical.

My '27 was all over the road. I checked everything that I could think of, replaced a number of parts and it made only a small difference in the way the car handled. I finally found that the steering column had worn where it passes through the frame bracket. (The shaft had done it's job and sacrificed itself to save the bushings). I found a decent used steering column and made one good one out of the two. With the column snug in the bushings of the frame bracket, the car handles beautifully. A little play made a huge difference.

Why check toe in 10" above ground ?? Wheel center is about 15".

I agree John - I've always set at centerline.

One thought/question here that I didn't see mentioned. What is the tread pattern on your tires? A few years back a friend of mine had the same issue with his '27 with 21" wheels. I went through the front end assembly/steering system and everything seemed right. The car had Bedford brand ( if my memory serves me correctly) tires with ribbed tread, meaning the tread consisted of ribs running around the circumference of the tire. The car wandered much more on uneven road surfaces than smoother surfaces. It seemed to me that with no tread running across or diagonally the tires tended to follow the irregularities in the pavement. I didn't have a different set of 21" wheels to swap and test my theory, so it's just a thought.

Are your radial rod and steering ball joint caps tight or is there excessive play? If there is play, perhaps a set of spring loaded APCO steering ball joint caps (anti-rattlers) would help. Jim Patrick

I'm not convinced that the service manual is accurate. It states:

"The front axle should have a 5-1/2° pitch toward rear of car. To check the pitch, place the
car on a floor having a level surface. A square is then positioned with one edge on the floor
and the other edge resting against lower spindle body bushing in front axle (See “A” Fig.
119)."
...and also:

"The distance between the square “B” and the upper spindle body bushing “C” should now
be measured. The distance between these points should measure not less than 1/4” or more
than 5/16”."

Either the 5 1/2° is wrong or the 1/4" to 5/16" is wrong. The spindle body without bushings is 4 1/2" surface-to-surface. With new bushings, my spindles are 4 3/4" from surface-to-surface. I calculated the angle using the mid points of the bushing dimensions (4 5/8") and horizontal distance (9/32"). The angle is 3 1/2°.

If I assume that the 5.5° is correct then the difference between upper and lower points is 7/16", not 9/32". That is calculated by multiplying 4-5/8" by the sine of 5.5°.

Mark. Keen observation. The service manual has an error. I also did the math years ago & found this discrepency.
When I got my 14, it had 5/8" rake. I noticed it steered stiffer than my other T's, but, was real stable @ top speeds. So I investigated & did the math. With this info, I set that rake to 1/2" for freeway stability.

Caster angle choice has to balance roadability, steering effort, and road shocks transmitted to the steering system. With generally better roads today, I'd think a little more caster would be a good choice for more people than less caster. A heavy car with 4:1 steering might do better with a little less, but I'd want to at least meet the Ford spec for caster. Personally, I like a car that tracks straight, and when I turn a corner, I want the steering to have a positive return to center. I don't mind some added turning effort at the steering wheel to get a stable car. Extreme caster might cause issues when backing up, and it can increase road shock. Adding weight on the front end of a T will increase caster. A new front spring could be expected to decrease it. All steering system angles are important, but low caster or reverse caster will really make a car unpleasant to drive, even with a tight steering system. With very low or reverse caster, the car will dart all over the road like a puppy.

Mark, it seems like, by the picture you posted, the backward tilt of the spindles would be pre-determined by the length of the radius rod forks, which are not adjustable from front to back and that the only way increase the tilt would be to lengthen the forks or decrease the tilt, by shortening the forks. Other than this, how else can this adjustment be made short of bending them both precisely, one way or the other.

Mark, John and Pat. You guys sound like three brilliant Mechanical engineering professors discussing a problem at MIT . Jim Patrick

On the MIT thing, thanks, I think?
In the case of the high mount wishbone, its flexible. (too flexible, hence, a 2nd lower stiffener is/was a common add on.) On later T's, 4 dip pans, the ball mount is more flexible & prone to change from front axle "taps"
The prescribed adjustment is a 4' bending tool @ the axle outboard ends. A 3' pipe wrench + a cheater bar works also.
Model T front ends are not that tough.
Example: This weekend A buddy lost his brakes at the end of a 25 mile dirt road. (those new disk brakes!!!) His spindle hit anothers running board edge/fender. Created a 1 3/4" toe out & bent the left side of the axle up. I would not have believed the damage looking @ the t he hit. It had scraped paint & a flat spot on the front side of the rear fender.

The service manual paragraph 148 says:

"If the distance is greater or less than these limits, it can be adjusted by slightly
tilting the front axle with straightening bar until the correct adjustment is obtained. The bar
is placed on the lower side of the axle over the ends of the spring perches."

Does that mean you are actually bending the end of the wishbone? I have never seen one of these tools.

Yes, you end up bending the end of the wishbone. Here is a modern reproduction of the tool. I bought it on Ebay, I think. Might have been the forum classifieds, I don't remember. It is 4 feet tall and laser cut out of 3/4 inch steel.

Before you bend anything, verify that your spring perches are oriented correctly. If they are installed backwards, the axle will tilt forward rather than lean back, making the car unstable.

I would do any bending as a last resort only. It would be important to get both sides the same. You might try putting a shim in the upper side of the radius rod ball socket on the oil pan, something like a disc-shaped piece of tough leather 1/8" thick or thereabouts and greased on both sides. That will add some caster. (Don't get the radius rod ball in a tight bind. It has to be able to move) I would expect that many original pans have considerable wear in the upper radius rod ball socket, and that, plus any wear on the radius rod ball itself, would tend to reduce caster.

Adding a shim or leather may temporarily reduce wear slop, but, it will have no measurable effect on rake. 1/8" over a 3' length is near nothing.
I have come up with a fix for a worn pan radius rod ball. The idea is to use a second radius rod cap as the base. Space it up from the original mount. 2 7/16 nf nuts work. Longer studs(.75-1" longer). Drill for safety wire add springs & nuts as original. This mod lowers the radius rod ball 5/8-3/4" If i did my math right, thats less than 1.4 degrees.

That's a better idea, and it would probably be enough to get you in the ball park. A spherical bushing machined out of Delrin, then split and hollowed out asymetrically to fit the ball would work well. It would need some kind of key or lug to prevent it from turning. Some Jeep people with late model Wranglers have had wander issues related to low caster, and getting to 6 or 7 degrees seems to work well in those cases.

Thanks for all the input. I will be back to the shop this weekend. I am going to check the tilt of the axle. Are the reproduction perches fairly correct? Doesn’t sound like anyone sees a concern with having the wrong lower 26/27 spindles on a 25 car. Thanks Mike

John, I had to do something similar to fix my wishbone's socket.
I bought a wishbone cap and milled it to fit into the existing giant cavity and JB Welded it in place. It will have to do until I get a better engine pan. This method lowered the ball by less than 1/4". I made longer studs and I plan to reinstall my front axle this weekend.

There is another thing to consider. There are more than one length and angle of under-axle wishbones. There was a thread about that a year or so ago. I think it was in a thread where a member was repairing a wrecked front end.

Didnt know about different length wishbones. Must be 26-7 with the lower spring arch would be shorter.
I have seen where a worn mount is welded up & remachined with a ball end mill. The cost of that cutter turns me off. I do build up the wishbone ball with welding & grinding back to stock diameter.
No reason I can see your fix is not a permanent one. I wouldnt be in a hurry to find a "less worn" pan.

A couple of other things to consider: I have Bedford tires on one of my T's and it handles very well. The other thing is that the castor will even vary with the load on the car. More weight will lower the radius rod ball joint and increase the positive castor. A very high rear spring combined with a sagging front spring can also change the location of the ball joint, so it is important to measure the castor. The stiff rear spring would be used on a sedan, where a softer rear spring would be used on a Roadster. Also the arch of the front spring on a 26 is lower than on the earlier cars.
Norm

I don't think the 26-27 spindles on a 25 axle will cause wandering. They will lower the front of the car somewhat, but they won't change the relationship between the axle and the radius rods. The 26 27 axles were lower in the center to prevent bottoming, but I think that was due to adopting a lighter front spring. I may be overlooking somethiing. These Ts are all the same, except they aren't.