Extreme caster but works great

[roadmonster]

I've been driving my T for 5 years with its original "eyeball" caster and finally got around to measuring it. I was surprised to find it was 12 degrees! The funny thing is, the car tracks and steers beautifully and will track hands-off forever. With suicide front end and pusher fan, wheelbase is only 93", so it's extremely short. It is a little heavy at parking speed, but not much. It does NOT shimmy at any speed or on any surface. My question is, with its delightful handling, would it get even lighter or better with 7 degrees or should I just leave it alone?

 

[2old2fast]

I lean toward's the " If it ain't broke, don't fix it " camp, JMHO
dave

 

[409T]

Here is a quote from an earlier post by Ron Pope

"The more caster the more the steering wants to return to center. A lot of drag race cars run 10-15* of caster with no problems at all. However the more caster that is run the harder it is to turn the steering wheel. Caster causes the front end to have to raise the chassis to make a turn. Increasing caster makes the chassis have to raise more when the steering wheel is turned"

I would agree with 2old2fast.

 

[roadmonster]

Thanks for the input. It seems like such extreme caster would induce shimmy instead of suppress it. The car has all the ingredients for poor steering (spring-over front end, traditional steering, very short hairpins and drag link, etc.) BUT somehow it is a real sweetheart with steering many Ts could only dream of. I guess the extra stability compensates for the short wheelbase.

 

[guilld]

If I understand correctly caster would be the same as rake on a motorcycle frame. The more rake a bike has the more difficult to steer and or ride at low speed, but the straighter it tracks at highway speed. I built a 3 wheeler once with 15" over front end and enough rake to sit level. It rode like it was on tracks.

 

[fordsbyjay]

I had about 4* and increased mine to about 8* when experimenting. Low speed turning is harder for sure. If your setup is working I would leave it alone.

 

[Youngster]

There is nothing wrong with extreme caster (anything over 7 degrees). By the book your best compomise is 5 degrees. The thing is you have to look at each individual car and the intended usage. A light car with a short wheelbase or a heavy car with a low percentage of the weight on the front axle will respond well to over 7 degrees especially at highway speeds but not so well at low speeds.

I prefer to have the car to handle well driving at low speeds so I set mine at 5 degrees. To each their own.

Ron

 

[roadmonster]

I suspect that if it works well with extreme caster, it will work with conservative caster as well. I think I will try 7 or 8 degrees to see if it gets lighter, sportier steering. I can always go back. The short wheelbase means heavy front axle load and this may be why it likes lots of caster.

 

[hollywood]

If you don't mind my asking, what do you have your camber and toe set at?

 

[roadmonster]

If you don't mind my asking, what do you have your camber and toe set at?

Sorry, just noticed your reply. Toe-in is 1/8", camber is unknown but appears typical for I-beam drop axle.

 

[oldttman]

front end geometry 101 the steering response depends also on king pin angle to castor angle. as you increase castor you will load left and right sides differently during turning

 

[oldttman]

the lighter the front scale weight the more castor you will need to get the same feel since the king pin angle is fixed. I have seen custom uspensions with 10 to 15 of king pin angle so they did not need extreme castor angle It depends on the ratio of front to rear weight.

 

[fordsbyjay]

the lighter the front scale weight the more castor you will need to get the same feel since the king pin angle is fixed. I have seen custom uspensions with 10 to 15 of king pin angle so they did not need extreme castor angle It depends on the ratio of front to rear weight.

With cars like our is the wt distribution pretty even being that the motor is so far behind the front wheels? I have never weighed my car front to back just total wt. (1830 lbs)