Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 02-11-2019, 02:39 AM   #1
Dazza
Junior Member
 
Join Date: Dec 2018
Location: Christchurch, New Zealand
Posts: 2
Default Newby with a question - Castor angle

Hi Guys
Ive got a '29 Model A with a bit of a handling issue.
Its been like it since i got it 18mths ago.
She tracks and pulls up beautifully.
But digs in going around corners and if i hit a bump she'll change lanes on me, but carries on straight.
Now thats fine on the dirt track, but scares anyone man enough to brave a ride in the co-pilots seat haha.
Ive had it on crossplys, ive had it on radials.
All the joints are tight and good.
One thing i have noticed is that the king pins have a slightly negitive castor angle (leaning forward)
I dont see a way to alter this so assume its correct???
Unless the front is (and can be) in back to front???
Any help much appreciated
Thanks
Daz
Dazza is offline   Reply With Quote
Old 02-11-2019, 02:59 AM   #2
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 4,080
Default Re: Newby with a question - Castor angle

If your king pins are leaning forward at the top, they are indeed waaay out. The first thing to come to my mind is that the A frame with the ball under the bell housing has been bent. You might inspect it closley to see if that is so. Replacing it would be the easiest fix if it is.
Please let us know what you find and OH, yeh - welcome to the barn. May I also suggest you put more information on your profile so others in your area might be able to help.
__________________
I want to live forever.
So far so good.
Synchro909 is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 02-11-2019, 07:19 AM   #3
chap52
Senior Member
 
chap52's Avatar
 
Join Date: Jun 2013
Location: Marana Arizona
Posts: 1,305
Default Re: Newby with a question - Castor angle

Welcome aboard. Lots of great info here and people willing to share their wisdom. Might also want to check out https://www.vintagefordforum.net/forum a lot of the same folks, but also a few others.
Enjoy the adventure, Chap
chap52 is offline   Reply With Quote
Old 02-11-2019, 07:51 AM   #4
Tinbasher
Senior Member
 
Tinbasher's Avatar
 
Join Date: May 2010
Location: Innisfil, Ontario Canada
Posts: 923
Default Re: Newby with a question - Castor angle

You should have around 6 degs. of Postive caster. Check the ball mount at the transmission. Make sure all of the parts are there and that the ball or cups it mounts in aren't worn excessively. Along with checking the radius arm as mentioned. JP
Tinbasher is offline   Reply With Quote
Old 02-11-2019, 08:40 AM   #5
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 2,964
Default Re: Newby with a question - Castor angle

Almost ALL Model A have a bent front axle. I have five front axles including the one on the car - and except for the one on the car (which I straightened) they are all bent.

The typical damage is the passenger side wheel is "pushed back" probably from hitting things on the edge of the road away from sight of the operator. Along with getting pushed back come change to toe-in (which can be compensated) caster, (which is built into the mount but can differ between right and left), and camber (which is built into the axle king-pins - and which can differ between right and left.)

The ABSOLUTE positive solution is to remove and de-mount the axle - and then to bend/twist as required to bring the holes back into alignment - and check that camber.

A pix of the gauge used for this below.

This is shown on a Model T axle - but the principle - and the tool are the same as used on the Model A.

Victor Page in his "Model A Ford" book shows these rods/gauges being used - although if memory serves, his Model A book shows the rods applied to the Model T axle. The pix above may be Page's. Page wrote a similar service book for the "T." Seemingly some pix got "recycled."

I always enjoy re-reading the Page book. Anyone who dresses like me (cut-off sweatshirt and jeans) must be possessed of good sartorial taste.


Its a big job to rebuild an entire axle down to "nuts & bolts." One of the reasons I have four spare axles and one always in the pipeline. We're at the point where the pipeline is getting clogged on axles.

Joe K
__________________
Shudda kept the horse.

Last edited by Joe K; 02-11-2019 at 08:53 AM.
Joe K is offline   Reply With Quote
Old 02-11-2019, 10:54 AM   #6
WHN
Senior Member
 
Join Date: Mar 2017
Location: Old Lyme Connecticut
Posts: 964
Default Re: Newby with a question - Castor angle

Bent or twisted axel.

When we had our 29’s front end rebuilt, wishbone would not go back together with the axel. Worn front end parts had allowed for the slack before rebuild. Once all that slack was gone, wishbone no longer fit.

Axel had to be corrected.
WHN is offline   Reply With Quote
Old 02-11-2019, 11:11 AM   #7
Tacoma Bob
Senior Member
 
Tacoma Bob's Avatar
 
Join Date: May 2010
Location: Tacoma, WA
Posts: 727
Default Re: Newby with a question - Castor angle

Do a search and put in F-100 steering box resolved. It's a long pdf read of my front end issues. After doing everything already mentioned the problem was my spring perch nuts. I would suggest pulling the cotter pins and checking how tight the nuts are.
Tacoma Bob is offline   Reply With Quote
Old 02-11-2019, 11:48 AM   #8
1930artdeco
Senior Member
 
1930artdeco's Avatar
 
Join Date: May 2010
Location: Oakland, CA
Posts: 2,553
Default Re: Newby with a question - Castor angle

Don't forget to check the steering balls. If they are out of round it will shimmy and jump like you said.


Mike
__________________
1930 TownSedan (Briggs)
Still learning after all these years....
1930artdeco is offline   Reply With Quote
Old 02-11-2019, 11:27 PM   #9
KR500
Senior Member
 
KR500's Avatar
 
Join Date: Mar 2012
Location: Addison,ll.
Posts: 348
Default Re: Newby with a question - Castor angle

After advisement from Steve Plucker, and explaining to him that I believed that the caster of the Model A is established by the front cross member, he suggested that I send for the blueprint from the Ford Benson Research Center. After receiving the print for part 5020A it does show that the front spring pocket in the cross member is tipped back 5 degrees. Whats odd is that companies such as Bear, Bee Line, Weaver, John Bean, John Duby, and others market bending correction equipment which is tied to the axle itself. Why they dont address correction of front cross member deviation of the 5 degrees is a mystery. Since the Ford axle is symmetrical in its construction, it can be installed one of two ways, and bending in the field to correct for caster angle correction could place an uninstalled axle into the hands of a restorer eventually, if not checked for straightness it could be installed with negative caster. The front radius rods aid in keeping the front axle stabilized, but it can still be bent in a front end collision. Positive caster keeps the front axle tracking in straight ahead travel and also aid in returning to straight ahead after a turn. Comment and opinions welcome.
KR500 is offline   Reply With Quote
Old 02-12-2019, 12:40 AM   #10
Mike V. Florida
Senior Member
 
Mike V. Florida's Avatar
 
Join Date: May 2010
Location: South Florida
Posts: 13,860
Send a message via AIM to Mike V. Florida
Default Re: Newby with a question - Castor angle

Quote:
Originally Posted by chap52 View Post
Welcome aboard. Lots of great info here and people willing to share their wisdom. Might also want to check out https://www.vintagefordforum.net/forum a lot of the same folks, but also a few others.
Enjoy the adventure, Chap

You have to change the .net to .com in order to visit the site. This site automatically changes it to .net.
__________________
What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II
Mike V. Florida is offline   Reply With Quote
Old 02-12-2019, 09:09 AM   #11
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 2,964
Default Re: Newby with a question - Castor angle

Quote:
Since the Ford axle is symmetrical in its construction, it can be installed one of two ways, and bending in the field to correct for caster angle correction could place an uninstalled axle into the hands of a restorer eventually, if not checked for straightness it could be installed with negative caster.
Caster is set by the position of the wish-bone on the transmission - the frame mount is "tilted" to match. Hence the reluctance of many to use the cast iron "aftermarket" wish-bone ball attachments which does affect caster.

Camber is set by the position of the king-pins relative to the rest of the axle. A good "thumping" impact can curl the end of the axle upwards around the spring perch/spring/shock absorber attachment.

A good side impact of the axle curls it backwards around the perch and can affect both caster and camber - although change to toe-in can be adjusted out.

Bending in the field is more a matter of luck. One could get lucky and correct camber or caster - or one could make one worse at the advantage of the other.

Not to say it can't be done. Porta-powers, frame straightening shops, and uber I-beams can accomplish a lot in the hands of a restorer. But putting a 3" full length of pipe over the end of the axle while on the car and pulling hard is more likely to bring you to a worse position quickly.

Joe K
__________________
Shudda kept the horse.
Joe K is offline   Reply With Quote
Old 02-12-2019, 10:56 AM   #12
Tacoma Bob
Senior Member
 
Tacoma Bob's Avatar
 
Join Date: May 2010
Location: Tacoma, WA
Posts: 727
Default Re: Newby with a question - Castor angle

The July/August 2018 Restorer has a pretty good article by Bob Grady and Alex Janke on axle straightening. Worth a look.
Tacoma Bob is offline   Reply With Quote
Old 02-12-2019, 01:35 PM   #13
BillLee/Chandler, TX
Senior Member
 
BillLee/Chandler, TX's Avatar
 
Join Date: May 2010
Location: The sticks of east Texas
Posts: 444
Default Re: Newby with a question - Castor angle

Quote:
Originally Posted by Joe K View Post
Caster is set by the position of the wish-bone on the transmission - the frame mount is "tilted" to match. Hence the reluctance of many to use the cast iron "aftermarket" wish-bone ball attachments which does affect caster.
Joe, could you elaborate on this? My car came to me with the cast iron mount w/rubber ball insert. The rubber had deteriorated due to the typical oil soak of the Model A, so I replaced it with a stock set up. Looks to me that the two are totally interchangeable with no effect on the position of the wishbone..


Regards,

Bill Lee
__________________
Bill Lee
http://www.CedarCreekAs.org
BillLee/Chandler, TX is offline   Reply With Quote
Old 02-12-2019, 05:49 PM   #14
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 2,964
Default Re: Newby with a question - Castor angle

Quote:
Originally Posted by BillLee/Chandler, TX View Post
Joe, could you elaborate on this? My car came to me with the cast iron mount w/rubber ball insert. The rubber had deteriorated due to the typical oil soak of the Model A, so I replaced it with a stock set up. Looks to me that the two are totally interchangeable with no effect on the position of the wishbone..

Regards,
Bill Lee
In the original setup the flywheel housing casting is actually made to "clear" the arms of the wishbone yoke and the ball centerline is only slightly lower than the diamond flange with hole which the thin metal "cup" mounts to.

The aftermarket fitting moves the ball down about 3/4 inch necessary to insert the cast iron "doo-hickey" (technical term) and the ball center-line is probably about 3/4 inch down too considering the thickness of the rubber ball cover. You can do the arithmetic and figure the change in caster on a (say) 30 inch wishbone.

Does it make that much difference? Probably not. I didn't indicate that it did. I have used both systems on Model A of my ownership and see little if any difference in the drive/handling. My current Model A is cast iron which I think I prefer as it is somehow "easier" on the wishbone ball. I have changed out the original black rubber ball for a neoprene once due to the "oil soak" you mention.

A converse thought. Ford offered a front leaf spring in "12 Leaf" for cars subjected to "unusually rough service" (their words.) One would expect that a 12 leaf spring would be somehow "taller" than the standard 10 leaf stack and require an "adjustment" at the other end of the wishbone to compensate - and yet Ford made no recommendation for "lowering" the wishbone ball.

It probably didn't make much difference for a car used in "rough service."

Joe K
__________________
Shudda kept the horse.
Joe K is offline   Reply With Quote
Old 02-12-2019, 09:41 PM   #15
Ruth
Senior Member
 
Join Date: May 2016
Location: Glide, Oregon
Posts: 211
Default Re: Newby with a question - Castor angle

I can't see moving the wishbone ball down will help that much in adjusting caster. In my (very rough) calculations the ball would have to be moved ~1" for every 1 change in caster realized at the spindles.

The OP states he has negative caster? If that is the case he would need to drop the wishbone ball almost 5". Sounds to me like he has some (un)bending to do.
Ruth is offline   Reply With Quote
Old 02-12-2019, 10:54 PM   #16
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 4,080
Default Re: Newby with a question - Castor angle

Quote:
Originally Posted by Ruth View Post
I can't see moving the wishbone ball down will help that much in adjusting caster. In my (very rough) calculations the ball would have to be moved ~1" for every 1 change in caster realized at the spindles.

The OP states he has negative caster? If that is the case he would need to drop the wishbone ball almost 5". Sounds to me like he has some (un)bending to do.
I fully agree. That was the reasonng behind my post at #2. While a bent axle will affect the front end geometry, ti have BOTH king pins leaning the wrong way suggests that it is more like a bent A frame.
__________________
I want to live forever.
So far so good.
Synchro909 is offline   Reply With Quote
Old 02-13-2019, 12:00 AM   #17
Kurt in NJ
Senior Member
 
Kurt in NJ's Avatar
 
Join Date: May 2010
Location: on the Littlefield
Posts: 4,567
Default Re: Newby with a question - Castor angle

The other end also changes caster, worn sagging spring can lower front end several inches , change caster too
Kurt in NJ is offline   Reply With Quote
Old 02-13-2019, 08:03 PM   #18
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 4,080
Default Re: Newby with a question - Castor angle

Quote:
Originally Posted by Kurt in NJ View Post
The other end also changes caster, worn sagging spring can lower front end several inches , change caster too
A sagging front spring will increase caster but not by much.
__________________
I want to live forever.
So far so good.
Synchro909 is offline   Reply With Quote
Old 02-14-2019, 04:16 PM   #19
1931 flamingo
Senior Member
 
1931 flamingo's Avatar
 
Join Date: May 2010
Location: new britain,ct 06052
Posts: 7,876
Default Re: Newby with a question - Castor angle

Find an "old time" spring/front end shop (possibly one that deals in big trucks), give them the dimensions you need, they will be able to "form" your axle to get the "correct" caster.
Before doing this make sure the wishbone ball is round and correctly attached and king pins are NOT worn. JMO
Paul in CT


Where are youlocated??
WELCOME to the FordBarn
1931 flamingo is offline   Reply With Quote
Old 02-14-2019, 08:38 PM   #20
31Abone
Senior Member
 
31Abone's Avatar
 
Join Date: Apr 2013
Location: Big pine Ca 93513
Posts: 638
Default Re: Newby with a question - Castor angle

If you change or modify rear motor mounts you automatically change caster..went thru all thay on a 31 tudor..rear of engine is set as well as caster at factory by stock motor mounts ..change that and you are screeeeewed..sc
31Abone is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 03:38 AM.