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Author
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Topic: caster adjusting help
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grego37
Gearhead Posts: 411
From: los angeles,CA,USA
Registered: May 2004
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posted 04-01-2005 10:37 AM
 
A 68 mustang uses a strut rod for adjusting caster, when you lengthen the strut rod it pushes the lower control arm towards the rear of the car, and when you shorten the strut rod it pulls the lower control arm towards the front of the car.If I wanted to achieve more positive caster, which way would I adjust the strut rod , longer or shorter.
Thanks.
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SteveLaRiviere
Administrator Posts: 48752
From: Saco, Maine
Registered: May 99
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posted 04-01-2005 10:43 AM
Longer.------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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blackford
Journeyman Posts: 76
From: Corona, Ca
Registered: Jan 2004
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posted 04-01-2005 02:11 PM
It needs to be shortened to increase positive caster. The upper ball joint will be further back than the lower ball joint (looking at the side of the wheel) for positive caster. I didn't know 68's did it this way. My 65 had non adjustable strut rods and caster was adjusted using UCA shims. I put TCP strut rods on it which are adjustable but just the same you don't want to pull the LCA too far forward or the LCA bushing can bind. Maybe not an issue with a '68.------------------
Tracy Blackford
'65 "Black" ford FB, 331 with H beam 289 rods, KB322s, fully prepped 351w heads, 282S cam, C-4 auto, 3.50 9" posi. Many Suspension and handling mods. 4.5 year restomod project completed in May '04. 313 RWHP @ 6300.
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grego37
Gearhead Posts: 411
From: los angeles,CA,USA
Registered: May 2004
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posted 04-01-2005 03:00 PM
OK,
Im still confused.All the articles I find say:
while looking at the tire from the side view,
picture the lower and upper ball joints connected with an invisible line,with an invisible vertical line from 12o'clock to 6 o'clock (spindle center) and when you shorten the lower arm , the upper pivot moves back behind the vertical line (positive caster?) and vise versa when you lengthen the strut rod . "To achive positive caster, the upper pivot point moves back towards the rear of the car"
Does this mean I would shorten the overall length of the strut rod to desired length bringing the top pivot point back. And when I call an alignment shop, they say to lengthen the strut rod, but this would pull the upper pivot piont towards the front bumper.
Anymore feedback is greatly appreciated.
thanks
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grego37
Gearhead Posts: 411
From: los angeles,CA,USA
Registered: May 2004
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posted 04-01-2005 04:07 PM
UPDATE:
I called a reputable align shop that is mainly fords "Marlos Alignment" Chatsworth CA.
He confirmed to shorten the strut rod to pull the lower arm towards the front of the car , this will bring the upper ball joint (upper pivot point) towards the rear of the car achieving positive caster.Word of caution, he said to leave at least 1/2" of thread remaining on the inner adjustment nut.
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DidgeyTrucker
Gearhead Posts: 1813
From: Greenbrier, TN USA
Registered: Oct 99
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posted 04-02-2005 01:38 AM
We've all experienced positive caster.
When an imaginary line drawn the pivot points intersects the ground in front of the tire contact point you have positive caster. This leads to high speed stability. Look at a bicycle. Ever wonder why the tube at the front is angled a little bit. Draw a line through the front fork pivot tube (called a head tube) and it will hit the ground in front of the tire. A shopping cart has front wheels with a TON of positive caster. Look at a Top Fuel dragster and watch the front wheels almost lay over when they are turned sharply. That's due to positive caster.
More positive caster also makes it harder to turn the wheels. Positive caster will make your car go straight when you let go of the steering wheel. Positive caster makes it hard to drive a car fast backwards - the wheels now have negative caster and will turn too easily.Tracy
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SteveLaRiviere
Administrator Posts: 48752
From: Saco, Maine
Registered: May 99
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posted 04-02-2005 06:16 PM
I must be losing my memory along with my mind.Caster:
Caster is the tilting of the uppermost point of the steering axis either forward or backward (when viewed from the side of the vehicle). A backward tilt is positive (+) and a forward tilt is negative (-). ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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